Patent Publication Number: US-2018051340-A1

Title: Methods and uses for diagnosis and treatment of prostate cancer

Description:
FIELD OF THE INVENTION 
     The present invention relates to a novel biomarker for prostate cancer. In particular, the present invention relates to methods and uses of a novel long non-coding RNA (lncRNA), termed PCAT18, for the early detection, diagnosis, prognosis, classification, treatment monitoring, or treatment of prostate cancer (PCa). 
     BACKGROUND OF THE INVENTION 
     The vast majority of prostate cancer (PCa)-related deaths are attributed to the progression from localized, indolent disease to metastatic castration-resistant PCa (mCRPC) (1). Despite enormous research efforts, risk stratification of PCa patients at diagnosis is still based on T stage, Gleason grade and plasma PSA levels, a method that overlooks many potentially aggressive cases (2) and can have false positives. For example, testing plasma PSA levels has a high false positive rate with only approximately 25% of men with elevated PSA levels actually having PCa. More importantly, rising PSA levels are not an accurate early indicator of disease progression. According to a recent meta-analysis, PSA screening does find additional cases of prostate cancer, but most studies do not show a corresponding effect on PCa-specific mortality. Of the patients with PCa, only a limited number will have disease progression or will die from their disease while a substantial proportion of men with clinically insignificant disease are being over treated. In other words, their disease will never cause morbidity or mortality. The use of the PSA test, therefore, is controversial. For example, the US Preventative Services Task Force does not recommend PSA screening and PSA screening is not routinely provided in Canada. 
     Human transcriptome analysis has recently revealed that most RNA molecules produced in human cells are not translated, and thus protein-coding genes account for only a small percentage of all RNAs (3). These non-coding transcripts include the well-so known ribosomal-, transfer- and micro-RNAs (rRNA, tRNA, miRNA respectively). MiRNA profiling in tumor specimens and patient-derived biological fluids is emerging as a powerful tool to differentiate localized and metastatic PCa (4). A less investigated class of non-coding RNAs is represented by long non-coding RNAs (lncRNAs), i.e. transcripts longer than 200 bp with no protein-coding function (5). Recent evidence indicates that lncRNAs may be an overlooked source of cancer biomarkers and therapeutic targets. The term lncRNA has been used as a catch-all definition, including poly-adenylated and non-poly-adenylated sequences, as well as intergenic and intronic transcripts. Estimates suggest the number of human lncRNAs rivals the count of protein-coding genes, ranging from 10,000 to 20,000 (6). Despite these large numbers, only a handful of lncRNAs have been characterized. Notably, most characterized lncRNAs display deregulated expression in cancer cells, where they play oncogenic or tumor suppressive functions (6). A striking feature of some lncRNAs is their tissue-specificity which prompted some authors to propose them as novel biomarkers (6). Two previously characterized lncRNAs (PCGEM1 and PCA3) are specifically expressed in PCa compared to an array of normal and neoplastic tissues (7, 8). PCA3 is present in urine samples from PCa patients and is able to detect the disease with 77.5% sensitivity and 57.1% specificity (9). PCA3 levels, however, are not able to discriminate between indolent and clinically aggressive PCa (9). The clinical utility of PCGEM1 has also not been determined. Accordingly, it is unclear whether PCA3 or PCGEM1 is a viable therapeutic target. 
     A new diagnostic, prognostic and therapeutic biomarker is, therefore, needed for early recognition, detection, diagnosis and effective management of PCa. In particular, such a biomarker should be able to distinguish between localized, indolent PCa and clinically aggressive PCa and detectable in a subject&#39;s blood, urine, saliva, plasma or tissue. It would be especially useful to have a biomarker that can identify those subjects whose prostate cancers are at an elevated risk for progression or transformation to life-threatening androgen-resistant or metastatic disease. 
     SUMMARY OF THE INVENTION 
     The present invention relates generally to methods and uses of diagnosing, determining risk of developing, prognosing, monitoring treatment of, detecting, classifying and treating prostate cancer in a subject suspected of having or having prostate cancer by assessing the expression level of PCAT18. PCAT18 RNA is a long noncoding RNA identified herein as being differentially expressed in cancer calls, particularly in prostate cancer cells, as compared to normal prostate cells and as being specific for prostate cancer as compared to other neoplasms. 
     In an aspect, the present invention relates to method for diagnosing prostate cancer in a subject suspected of having prostate cancer comprising: (a) assessing the expression level of PCAT18 in a biological sample obtained from the subject; (b) comparing so the expression level of PCAT18 in the biological sample to a reference expression level; and (c) identifying the subject as having prostate cancer when the expression level of PCAT18 in the biological sample is greater than the reference expression level, or identifying the subject as not having prostate cancer when the expression level of PCAT18 in the biological sample is not greater than the reference expression level. 
     In another aspect, the present invention relates to a method for determining the risk of a subject for developing prostate cancer comprising: (a) assessing the expression level of PCAT18 in a biological sample obtained from the subject; (b) comparing the expression level of PCAT18 in the biological sample to a reference expression level; and (c) identifying the subject as having an increased risk of developing prostate cancer when the expression level of PCAT18 in the biological sample is greater than the reference expression level, or identifying the subject as not having an increased risk of developing prostate cancer when the expression level of PCAT18 in the biological sample is not greater than the reference expression level. 
     In another aspect, the present invention relates to a method for monitoring a treatment for prostate cancer in a subject diagnosed with prostate cancer comprising: (a) obtaining a baseline level by assessing the expression level of PCAT18 in a biological sample obtained from the subject prior to administration of the treatment; (b) administering the treatment to the subject for a treatment period; (c) after the treatment period, assessing the expression level of PCAT18 in a second biological sample obtained from the subject (d) comparing the expression level of PCAT18 in the second biological sample to the baseline level; and (e) identifying a poor response to the treatment when the expression level of PCAT18 in the second biological sample is greater than the baseline level, or identifying a good response to the treatment when the expression level of PCAT18 in the second biological sample is not greater than the baseline level. 
     The present invention further relates to a method for determining a prognosis of a subject diagnosed with having prostate cancer comprising: (a) assessing the expression level of PCAT18 in a biological sample obtained from the subject; (b) comparing the expression level of PCAT18 in the biological sample to a threshold expression level; and (c) determining a prognosis for the subject diagnosed with having prostate cancer based on the expression level of PCAT18 in the biological sample relative to the threshold expression level. 
     In yet another aspect, the present invention relates to a method for determining a risk of metastatic spread of prostate cancer in a subject diagnosed with prostate cancer comprising: (a) assessing the expression level of PCAT18 in a biological sample obtained from the subject (b) comparing the expression level of PCAT18 in the biological sample to a threshold expression level; and (c) identifying the subject as having an increased risk of metastatic spread when the expression level of PCAT18 in the biological sample is greater than the threshold expression level, or identifying the subject as not having an increased risk of metastatic spread when the expression level of PCAT18 in the biological sample is not greater than the threshold expression level. 
     In the methods described herein, the biological sample may be plasma, blood, serum, urine, saliva or tissue obtained from the subject. The tissue may comprise a cancerous prostate tissue sample, a benign prostatic hyperplasia tissue, or a normal prostate tissue. 
     Furthermore, the assessing of the expression level of PCAT18 in the biological samples obtained from subjects may be performed by evaluating the amount of PCAT18 RNA in the biological samples. 
     In another aspect the present invention relates to a method of treating a subject diagnosed with prostate cancer by administering a therapeutically effective amount of an inhibiting agent of PCAT18, wherein the inhibiting agent of PCAT18 is an antisense oligonucleotide, an siRNA, or a combination thereof. 
     The siRNA used in the method of treating described above may comprise an antisense nucleotide sequence corresponding to SEQ ID NO:22 or SEQ ID NO:23. 
     The antisense oligonucleotide used in the method of treating described above comprises a nucleotide sequence corresponding to SEQ ID NO:24 or SEQ ID NO:25. 
     In yet another aspect the present invention relates to a pharmaceutical composition comprising a therapeutic agent effective to reduce an amount of PCAT18 in cancerous prostate cells exposed to the therapeutic agent, and a pharmaceutically acceptable carrier, wherein the therapeutic agent is an antisense oligonucleotide, an siRNA, or a combination thereof. 
     The siRNA used in the pharmaceutical composition described above may comprise an antisense nucleotide sequence corresponding to SEQ ID NO:22 or SEQ ID NO:23. 
     The antisense oligonucleotide used in the pharmaceutical composition described above may comprise a nucleotide sequence corresponding to SEQ ID NO:24 or SEQ ID NO:25. 
     In another aspect, the present invention relates to a use of PCAT18 RNA for diagnosing prostate cancer in a subject suspected of having prostate cancer, wherein PCAT18 RNA comprises a nucleotide sequence corresponding to SEQ ID NO:1. 
     In another aspect, the present invention relates to a use of PCAT18 RNA for determining the risk of a subject in developing prostate cancer, wherein PCAT18 RNA comprises a nucleotide sequence corresponding to SEQ ID NO:1. 
     In yet another aspect the present invention relates to a use of PCAT18 RNA for monitoring a treatment for prostate cancer in a subject diagnosed with prostate cancer, wherein PCAT18 RNA comprises a nucleotide sequence corresponding to SEQ ID NO:1. 
     The present invention further relates to a use of an inhibiting agent of PCAT18 RNA for treating a subject diagnosed with prostate cancer, wherein PCAT18 RNA comprises a nucleotide sequence corresponding to SEQ ID NO: 1. 
     Accordingly, in broad terms, a novel use of a lncRNA (LOC728606), herein termed JUPITER or PCAT18, as a biomarker for diagnosis and prognosis of prostate cancer is provided. 
     In broad terms, a novel use of a lncRNA (LOC728606), herein termed JUPITER or PCAT18, as a target for development of therapies for treatment of prostate cancer (including but not limited to localized, invasive, androgen (castration) resistant and metastatic prostate cancer) is provided. 
     In an aspect of the present invention, a novel use of a lncRNA (LOC728606), herein termed JUPITER or PCAT18, as a biomarker for the early detection of prostate cancer provided. 
     In another aspect of the present invention, a novel use of a lncRNA (LOC728606), herein termed JUPITER or PCAT18, as a biomarker for the diagnosis of prostate cancer is provided. 
     In another embodiment of the present invention, a novel use of a lncRNA (LOC728606), herein termed JUPITER or PCAT18, as a biomarker for the prognosis of prostate cancer, whereby increased levels of JUPITER measured in samples obtained from a patient with prostate cancer is predictive of poorer disease outcome or increased risk of disease relapse is provided. 
     In an aspect of the present invention, a novel use of a lncRNA (LOC728606), herein termed JUPITER or PCAT18, is provided as a biomarker for assessment of the metastatic potential of a prostate tumour whereby measurement of increased levels (relative to sampling at earlier timepoints) of JUPITER in samples from a subject with prostate cancer is indicative of increased risk or potential for metastatic spread (metastasis). 
     In an aspect of the present invention, a novel use of a lncRNA (LOC728606), herein termed JUPITER or PCAT18, is provided as a biomarker for detection of prostate cancer at increased risk of progression to or that has already progressed to the stage of androgen (castration) resistant disease. 
     In another aspect of the present invention, a novel use of a lncRNA (LOC728606), herein termed JUPITER or PCAT18, is provided as a biomarker that may be used in combination with other prostate cancer biomarkers (including but not limited to PSA, PCGEM1, PCA3 etc.) in tests or methods for the detection, prognosis or treatment monitoring of prostate cancer. 
     In another embodiment of the present invention, a novel use of a lncRNA (LOC728606), herein termed JUPITER or PCAT18, as a biomarker useful in tests/assays for monitoring the outcome of patients with prostate cancer (treatment response) that are treated with curative intent is provided. 
     In another embodiment of the present invention, lncRNA (LOC728606), herein termed JUPITER or PCAT18, may be measured for use in the novel methods of the present invention, in patient samples including but not limited to prostate tumour tissue, benign prostatic hyperplasia tissue, normal prostate tissue, blood (including whole blood, serum or plasma), urine, saliva or other tissues. 
     In another aspect of the present invention, a novel use of a lncRNA as a prostate cancer biomarker (i.e. including but not limited to use of said biomarker for detection, diagnostic, prognostic or treatment-monitoring) or target for treatment of prostate cancer is provided, whereby the nucleotide sequence of the lncRNA is of about 90% or greater similarity to the sequence of JUPITER (LOC728606) (SEQ ID NO:1). 
     In another aspect of the present invention, a novel use of a lncRNA as a prostate cancer biomarker (i.e. Including but not limited to use of said biomarker for detection, diagnostic, prognostic or treatment-monitoring) or target for treatment of prostate cancer is provided, whereby the nucleotide sequence of the lncRNA is of about 95% or greater similarity to the sequence of JUPITER (LOC728606) (SEQ ID NO:1). 
     In another aspect of the present invention, a novel use of a lncRNA as a prostate cancer biomarker (i.e. including but not limited to use of said biomarker for detection, diagnostic, prognostic or treatment-monitoring) or target for treatment of prostate cancer is provided, whereby the nucleotide sequence of the lncRNA is of 99% or greater similarity to the sequence of JUPITER (LOC728606) (SEQ ID NO:1). 
     In yet another embodiment of the present invention, a novel use of any lncRNA as a prostate cancer biomarker (i.e. including but not limited to use of said biomarker for detection, diagnostic, prognostic or treatment-monitoring) or target for treatment of prostate cancer is provided, whereby the lncRNA comprises a contiguous nucleotide sequence of at least 200 base-pairs in length and whereby said lncRNA comprises a 200 base-pair (or longer) nucleotide sequence that is a fragment of the nucleotide sequence of JUPITER (LOC728606) (SEQ ID NO:1). 
     Further aspects of the invention will become apparent from consideration of the ensuing description of exemplary embodiments of the present invention. A person skilled in the art will realise that other embodiments of the invention are possible and that the details of the invention can be modified in a number of respects, all without departing from the inventive concept. Thus, the following drawings, descriptions and examples are to be regarded as illustrative in nature and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings. 
         FIG. 1  (A) Hematoxylin-eosin staining of the prostate cancer xenograft (PCa Xenograft: left panels) and mouse lung tissue (Mouse Lung: right panels) of transplantable prostate cancer tumor lines LTL-313H and LTL-313B is shown. LTL-313H cells are more locally invasive to the adjacent kidney than LTL-313B cells, and show signs of distant metastatic spreading (never found in LTL-313B-engrafted mice). (B) Quantitative PCT (qPCR) confirmation of RNA sequencing data (columns represent average value, bars represent standard deviation, 2 replicate experiments). Values indicate relative expression level in LTL-313H vs. LTL-313B cells (i.e., the fold change of 313H/313B). The 4 most up-regulated transcripts were chosen (LOC728606, PCGEM1, H19, LINC461_1), along with 3 randomly selected transcripts (LOC285419, NCRNA116, LINC461_3). (C) Schematic representation of the PCAT18 locus (NLM “Gene” website). The gene is located in a region between 24,286 and 24,266 K (Chromosome 18 primary assembly). Lines represent introns, rectangles represent exons. Dotted lines represent a relative distance that is larger than the one shown in the schematic representation. Arrows represent transcription direction. The genes flanking the PCAT18 locus (AQP4, aquaporin-4; KCTD1, Potassium Channel Tetramerization Domain-Containing Protein 1) are shown. (D) ORF (open reading frame) finder output for PCAT18 sequence. Open Reading Frames are shown as shaded squares throughout the sequence. Each lane represents a possible reading frame. The software identified no ORF longer than 267 bp for a transcript longer than 2 Kb. Considering 6 possible reading frames, protein-coding regions could account for no more than 16% of the whole transcript. 
         FIG. 2  (A) PCAT18 expression in normal prostate (n=6) and prostate cancer PCa (n=7) samples (horizontal bar represents median value, vertical bars represent minimum and maximum value per group). Data are from the Cbio Cancer database. ***p&lt;0.001 (2-tailed unpaired T test). Fold change: 2.3. (B) PCAT18 expression in normal prostate (n=29) and PCa (n=131) samples (horizontal bar represents median value, vertical bars represent minimum and maximum value per group). Data are from the Oncomine™ database (Compendia Bioscience, Ann Arbor, Mich.). ***p&lt;0.001 (Oncomine Analysis). Fold change: 7.2. (C) Expression of PCAT18 in 12 benign tissues (GEO database, http://www.ncbi.nlm.nih.gov/geo/, study ID: HG-U95D, n=2 per tissue, horizontal bar represents mean value, vertical bars represent minimum and maximum value per group). *p&lt;0.05 compared to prostate (ANOVA and Holm-Sidack&#39;s post-test). Fold Change: 2.78-8.75 (prostate cancer compared to other tissues). (D) Oncomine™ analyis of PCAT18 expression in 16 tumor tissues (median-centered values, bars represent minimum and maximum value per group). Data are centered to the median level of expression in the whole cohort. Sample size for each tumor type is in brackets: 1. Bladder Cancer (32); 2. Brain and CNS Cancer (4); 3. Breast Cancer (328): 4. Cervical Cancer (35), 5. Colorectal Cancer (330); 6. Esophageal Cancer (7); 7. Gastric Cancer (7); 8. Head and Neck Cancer (41); 9. Kidney Cancer (254); 10. Liver Cancer (11); 11. Lung Cancer (107); 12. Lymphoma (19); 13. Ovarian Cancer (166); 14. Pancreatic Cancer (19); 15. Prostate Cancer (59); 16. Sarcoma (49). ***p&lt;0.001 (Oncomine™ Analysis). 
         FIG. 3  (A) PCAT18 expression (qPCR) in benign prostatic hyperplasia (BPH, n=5), low-Gleason PCa (n=5) and high-Gleason PCa (n=6) samples (Median-centered values, bars represent minimum and maximum value per group). ***p&lt;0.001 (ANOVA and Tukey&#39;s post-test). (B) PCAT18 expression (qPCR) in plasma samples from normal individuals (normal) and from patients affected by localized PCa (Primary PCa) or metastatic castration-resistant PCa (MCRPC) (median-centered values, bars represent minimum and maximum value per group). **p&lt;0.01 (ANOVA and Tukey&#39;s post-test). (C) PCAT18 expression in various prostate cancer cell lines (22RV1; LNCaP: human prostate cancer cell line, C4-2; PC3; and H660) relative to that in a benign prostatic hyperplasia cell line (BPH1). (D) siRNA-mediated PCAT18 silencing using two PCAT18-specific siRNAs (siRNA 1 and siRNA2) compared to a control. (E) Cell growth inhibition in the human prostate cancer cell line (C4-2) after specific silencing of PCAT18 expression using two PCAT18-specific siRNAs (siRNA 1 and siRNA2). Compared to a negative control (NC). 
         FIG. 4  (A) Transcripts positively associated with PCAT18 (Significance Analysis of Microarrays, SAM, analysis, Q&lt;0.5%) were analyzed in Oncomine™ for “literature defined concepts” (threshold, p&lt;1 E-4, odds ratio&gt;2). Top 3 concepts associated with PCAT18-associated expression signature are shown (Down-Regulated genes in PCa after androgen ablation; Up-regulated genes in PCa in response to synthetic androgen R1881; and Up-regulated genes in prostate cancer cells in response to androgen). (B) Expression of 3 genes in xenografts from mice supplemented with Testosterone (Test) (2.5 mg/mouse, n=2) or after castration (1 week, 1 W.; 2 weeks, 2 W.; and 3 weeks 3 W. n=3). LOC728606 (PCAT18) down-regulation is comparable to PSA. Data are from LTL-331 xenografts human prostate cancer xenografts (www.livingtumorlab.com) and normalized to the average HPRT1 expression level in testosterone-supplemented animals. HPRT1 expression is stable pre- and post-castration (unpublished microarray data). 
         FIG. 5  shows the nucleotide sequence of the PCAT18 transcript (SEQ ID NO:1) (Entrez Gene ID: 728606; RefSeq ID: NR_024259.1). 
         FIG. 6  (A) PCAT18 expression levels in untreated LNCaP cells (Control) and cells supplemented with dihydrotestosterone (DHT, 10 nM, 6-24-48 h). LNCaP cells were grown in phenol red-free medium (RPMI-1640) supplemented with 10% charcoal-stripped FBS. Columns represent mean value (2 independent experiments performed in triplicate), bars standard deviation. (B), (C) The living tumor lab (www.livingtumorlab.com) comprises a collection of patient-derived PCa tumor tissue xenografts, originated with a method described in ref. An androgen-dependent PCa line (LTL313B) has been exposed to castrate-levels of testosterone for a prolonged time, in order to generate a castration-resistant subline. The figures show LTL313B tumor volume (B) and serum PSA levels (C) before and after castration. Neoplastic cells were implanted in male NOD/SCID intact mice, supplemented with testosterone until castration. Serum PSA was measured and mice were sacrificed for tumor volume measurement at indicated time points, as described before (Lin D, et al. High fidelity patient-derived xenografts for accelerating prostate cancer discovery and drug development.  Cancer research.  2013). At 12-16 weeks post-castration, a castration-resistant, AR-positive cell line was generated (LTL-313BR). (D) PCAT18 expression was measured by qPCR in testosterone-supplemented. LTL313B, castrated xenografts (3 weeks) and in a CRPC sub-line (LTL313BR, no testosterone supplementation). 
         FIG. 7  (A) C4-2 invasion was quantified 24 h after the start of the invasion assay. Cells were transfected with 2 nM Negative Control (NC) or PCAT18-targeting siRNA1 and siRNA2. Columns represent mean value (4 experiments) bar SD. ***p&lt;0.001 (ANOVA and Dunnet&#39;s post-test). (B) C4-2 cell migration was quantified at 6 h, 24 h or 48 h post-transfection. **P&lt;0.01, ***P&lt;0.001 (siRNA vs. NC), 2 way ANOVA and Tukey&#39;s post-test (C), (D), (E), MTT assay was performed on LNCaP (C) C4-2 (0) and BPH (E) cells treated with negative control (NC) or PCAT18-targeting siRNAs (both at 2 nM concentration) on days 1-3-5 post-transfection, as previously described (Watahiki A, et al. MicroRNAs associated with metastatic prostate cancer.  PloS one.  2011; 6(9):e24950). Dots represent mean value, lines standard deviation (2 experiments performed in triplicate, data normalized to cell number in NC-day1) ***p&lt;0.001 (2 way ANOVA and Tukey&#39;s post-test). (F) LNCaP cells were transfected with negative control (NC) or PCAT18-targeting siRNAs for 5 days. Bars represent mean values, lines standard deviations (2 independent experiments performed in triplicate). ***p&lt;0.001 with respect to NC (ANOVA and Dunnet&#39;s post-test). 
         FIG. 8  (A) TaqMan qPCR confirmation of PCAT18 expression in PCa xenograft models. (B) TaqMan qPCR confirmation of PCAT18 expression in clinical samples. (C) Basal expression levels of PCAT18 in a panel of prostate cancer cell lines. Columns represent mean values, bars standard deviations (2 independent experiments). (D) Sub-cellular localization of PCAT18. GAPDH and MALAT1. Cellular (C) and Nuclear (N) RNA fractions where extracted and quantified by TaqMan assay, as described in methods section as of the Examples. Columns represent mean value, bars standard deviation (2 independent experiments). (E) TaqMan qPCR confirmation of siRNA-mediated PCAT18 silencing (C4-2 cells). Columns represent mean value, bars standard deviation (2 independent experiments). 
         FIG. 9  shows the nucleotide sequences of the antisense oligonucleotides. (A) shows the nucleotide sequence of antisense oligonucleotide (NC) with no known specific target in human or mouse genome (SEQ ID NO:26). (B) shows the nucleotide sequence of antisense oligonucleotide ASO2 (SEQ ID NO:24). (C) shows the nucleotide sequence of antisense oligonucleotide ASO7 (SEQ ID NO:25). 
         FIG. 10  shows the results of PCAT18 knockdown in C4-2 cells using antisense oligonucleotides ASO2 and ASO7 corresponding to SEQ ID NO:24 and SEQ ID NO:25, respectively, and using antisense oligonudeotide (NC) with no known specific target in human or mouse genome (corresponding to SEQ ID NO: 26). The columns and the bars represent mean value and standard deviation, respectively. ****p&lt;0.0001 (ANOVA and Dunnetts&#39;s post-test). 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the present invention. However, the present invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive sense. 
     The present invention relates to a long noncoding RNA (lncRNA) and methods and uses of the lncRNA for diagnosing, prognosing, monitoring and treating PCa. 
     lncRNAs may be transcribed from any genomic region, including, but not limited to, intergenic lncRNA or intervening non-coding RNA (lincRNA), which refers to lncRNA transcripts that are located between two protein-coding genes and transcribed from the + and/or −DNA strand(s); and intragenic lncRNA, which refers to lncRNA transcripts that are located within a protein-coding gene. Intragenic lncRNAs may be located within a coding region (i.e., an exon) of the gene and/or within a non-coding region (i.e., an intron) of the protein-coding gene, and transcribed from the + and/or −DNA strand(s). 
     Therefore, the present invention relates generally to identifying and characterizing long noncoding RNAs (“lncRNAs”) that are differentially expressed in cancer cells, particularly in prostate cancer cells, as compared to normal prostate cells. In particular, one such lncRNA, PCAT18 (Prostate Cancer-Associated Transcript-18; also referred to herein as JUPITER), located in the intergenic genomic region of chromosome 18q11.2, has been shown to be unregulated in cancerous cells found in the prostate. 
     As described herein, a multi-step profiling strategy was used to identify PCAT18 whose expression is: (1) significantly higher in PCa compared to 26 other benign and neoplastic tissues; (2) detectable in plasma samples; (3) able to discriminate between localized disease and mCRPC, as described further below. 
     Definitions 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. 
     As used herein, the term “about” refers to an approximately +/−10% variation from a given value. It is to be understood that such a variation is always included in any given value provided herein, whether or not it is specifically referred to. 
     The term “plurality” as used herein means more than one, for example, two or more, three or more, four or more, and the like. 
     The use of the word “a” or “an” when used herein in conjunction with the term “comprising” may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one” and “one or more than one.” 
     As used herein, the terms “comprising,” “having,” “including” and “containing,” and grammatical variations thereof, are inclusive or open-ended and do not exclude additional, un-recited elements and/or method steps. The term “consisting essentially of” when used herein in connection with a composition, use or method, denotes that additional elements and/or method steps may be present, but that these additions do not materially affect the manner in which the recited composition, method or use functions. The term “consisting of” when used herein in connection with a composition, use or method, excludes the presence of additional elements and/or method steps. A composition, use or method described herein as comprising certain elements and/or steps may also, in certain embodiments consist essentially of those elements end/or steps, and in other embodiments consist of those elements and/or steps, whether or not these embodiments are specifically referred to. 
     As used herein, the term “localized prostate cancer” or “primary prostate cancer” refers to prostate cancer that is only in the prostate gland and has not metastasized or spread to another part of the body. An expression level of PCAT18 in a biological sample that is between about a 1.1 fold-change and about a 4 fold-change over the reference expression level, or any amount therebetween is indicative of primary prostate cancer. 
     The term “metastatic prostate cancer,” as used herein, refers to prostate cancer that has metastasized or spread outside the prostate gland to the lymph nodes, bones or other areas of the body. An expression level of PCAT18 in a biological sample that is greater than about a 4 fold-change over the reference expression level, for example greater than about 4 fold to about 1000 fold, or any amount therebetween is indicative of metastatic prostate cancer, or metastatic castration-resistant prostate cancer. 
     The term “metastatic castration-resistant prostate cancer” or “mCPRC,” as used herein, refers to prostate cancer that is resistant to medical (e.g., hormonal) or surgical treatments that lower testosterone, and has metastasized or spread to other parts of the body. 
     The progression of PCa may be classified using several methods including measuring PSA levels, Gleason Score, tumour stage typing, or a combination thereof (see for example, www.cancer.gov/cancertopics/treatment/prostate/understanding-prostate-cancer-treatment/page3). For example, low risk PCa may be defined as having a Gleason Score of 6 or lower (tumour stage T1 or T2a), a medium-risk PCa may be defined as having a Gleason Score of 7 (tumour stage T2b), and a high risk PCa may be defined as having a Gleason Score of 8 or higher (tumour stage T2c; Mazhar &amp; Waxman. (2008) Nature Clinical Practice Urology 5: 486-493; D&#39;Amico, et al. (1998) JAMA 280 (11):969-974). A low Gleason PCa, as used herein is characterized as having a Gleason Score of less than 6. A more aggressive PCa; as used herein is characterized as having a Gleason Score of 7 or greater than 7 (i.e. medium risk and high risk prostate cancer). 
     As used herein, an “expression level” of a transcript in a subject, for example, of the PCAT18 transcript, refers to an amount of transcript, such as PCAT18 RNA, in the subject&#39;s undiagnosed biological sample. The expression level may be compared to a reference expression level to determine a status of the sample. A subject&#39;s expression level can be either in absolute amount (e.g., number of copies/ml, nanogram/mil or microgram/ml) or a relative amount (e.g., relative intensity of signals; a percent or “fold” or “fold-change” increase). 
     A “reference level” or “reference expression level” (may also be considered a control), as used herein refers to an amount of the PCAT18 RNA or a range of amounts of the PCAT18 RNA measured in a normal individual or in a population of individuals without prostate cancer. For example, a reference expression level of the PCAT18 may be determined based on the expression level of PCAT18 in samples obtained from normal individuals. A reference expression level can be either in absolute amount (e.g., number of copies/ml, nanogram/ml or microgram/ml) or a relative amount (e.g., relative intensity of signals: a percent or “fold” or “fold-change” increase). 
     As used herein, a “threshold level” or “threshold expression level” refers to an expression level of PCAT18 in a biological sample that is between about a 1.1 fold-change and about a 4 fold-change over the reference expression level, or any amount therebetween. A threshold expression level is indicative of localized prostate cancer or primary prostate cancer. 
     As used herein, a “baseline level” refers to an expression level of PCAT18 in a first biological sample obtained from a subject that is determined prior to any treatment or during any treatment, and is used as comparison to a second expression level of PCAT18 that is assessed from a second biological sample that is obtained from the subject at a time after the first biological sample is obtained. This baseline level may be used, for example, without limitation, in monitoring the progression of PCa in a subject, monitoring a treatment regimen or treatment modality in a subject having PCa, determining whether a treatment regimen or treatment modality should be considered in a subject, determining whether a treatment regimen or treatment modality should be discontinued in a subject, or determining whether a treatment regimen or treatment modality should be modified in a subject. 
     As used herein, “normal individual” refers to an individual that has been tested for prostate cancer using a combination of diagnostic methods, including T stage, Gleason grade, plasma PSA levels and PCAT18 expression levels and determined to not have prostate cancer by a physician. 
     The term “gene,” as used herein, refers to a segment of nucleic acid that encodes an RNA, which RNA can be a coding or noncoding RNA. 
     The term “selectively hybridize.” as used herein, refers to the ability of a particular nucleic acid sequence to bind detectably and specifically to a second nucleic acid sequence. Selective hybridization generally takes place under hybridization and wash conditions that minimize appreciable amounts of detectable binding to non-specific nucleic acids. High stringency conditions can be used to achieve selective hybridization conditions as known in the art and discussed herein. Typically, hybridization and washing conditions are performed at high stringency according to conventional hybridization procedures with washing conditions utilising a solution comprising 1-3×SSC, 0.1-1% SOS at 50-70° C., with a change s of wash solution after about 5-30 minutes. 
     The term “identity” or “% identical” as used herein refers to the measure of the identity of sequence between two nucleic acids molecules. Identity can be determined by comparing a position in each sequence which may be aligned for purposes of comparison. Two nucleic acid sequences are considered substantially identical if they share at least about 80% sequence identity or at least about 81% sequence identity, or at least about 82% sequence identity, or at least about 83% sequence identity, or at least about 84% sequence identity, or at least about 85% sequence identity, or at least about 86% sequence identity, or at least about 87% sequence identity, or at least about 88% sequence identity, or at least about 89% sequence identity, or at least about 90% sequence identity. Alternatively, two nucleic acid sequences are considered substantially identical if they share at least about 91% sequence identity, or at least about 92% sequence identity, or at least about 93% sequence identity, or at least about 94% sequence identity, or at least about 95% sequence identity, or at least about 96% sequence identity, or at least about 97% sequence identity, or at least about 98% sequence identity, or at least about 99% sequence identity. 
     Sequence identity may be determined by the BLAST algorithm which was originally described in Altschul et al. (1990)  J. Mol. Biol.  215:403-410. The BLAST algorithm may be used with the published default settings. When a position in the compared sequence is occupied by the same base, the molecules are considered to have shared identity at that position. The degree of identity between sequences is a function of the number of matching positions shared by the sequences and the degree of overlap between the sequences. Furthermore, when considering the degree of identity with SEQ ID NO:1 or a contiguous portion of SEQ ID NO:1, it is intended that the equivalent number of nucleotides be compared to SEQ ID NO:1 or the contiguous portion of SEQ ID NO:1, respectively Additional sequences outside of those being compared are not intended to be considered when determining the degree of identity with. The sequence identity of a given sequence may be calculated over the length of the reference sequence (i.e., SEQ ID NO:1 or the contiguous portion of SEQ ID NO:1). 
     The terms “corresponding to” or “corresponds to” indicate that a polynucleotide sequence is identical to all or a portion of a reference polynucleotide sequence. In contradistinction, the term “complementary to” is used herein to indicate that the polynucleotide sequence is identical to all or a portion of the complementary strand of a reference polynucleotide sequence. For illustration, the nucleotide sequence “TATAC” corresponds to a reference sequence “TATAC” and is complementary to a reference sequence “GTATA.” 
     The term “target gene,” as used herein, refers to the gene the expression of which is to be modulated with a siRNA molecule or ASO molecule or other inhibiting agent of the present invention. In the context of the present invention, the target gene is the lncRNA locus LOC728606 or the PCAT8 gene. 
     The term “target RNA.” as used herein refers to the RNA transcribed from a target gene. 
     The term “antisense strand” refers to a nucleotide sequence that is complementary to the nucleotide sequence corresponding to SEQ ID NO:1 or that is complementary to a contiguous nucleotide sequence of a portion of the nucleotide sequence corresponding to SEQ ID NO:1. The term “sense strand” refers to a nucleotide sequence that corresponds to SEQ ID NO:1 (or a contiguous nucleotide sequence of a portion of the nucleotide sequence corresponding to SEQ ID NO:1) and thus is complementary to the antisense strand. 
     The terms “therapy,” and “treatment.” as used interchangeably herein, refer to an intervention performed with the intention of improving a recipients status. The improvement can be subjective or objective and is related to the amelioration of the symptoms associated with, preventing the development of, or altering the pathology of a disease, disorder or condition being treated. Thus, the terms therapy and treatment are used in the broadest sense, and include the prevention (prophylaxis), moderation, reduction, and curing of a disease, disorder or condition at various stages. Prevention of deterioration of a recipient&#39;s status is also encompassed by the term. Those in need of therapy/treatment include those already having the disease, disorder or condition as well as those prone to, or at risk of developing, the disease, disorder or condition and those in whom the disease, disorder or condition is to be prevented. In the context of the present invention, the disease, disorder or condition is prostate cancer, including benign prostate cancer, localized prostate cancer, indolent prostate cancer, mCRPC and other stage of prostate cancer. 
     The term “subject” or “patient,” as used herein, refers to a mammal in need of treatment. 
     The term “effective amount” as used herein refers to an amount of a compound that produces a desired effect. For example, a population of cells may be contacted with an effective amount of a compound to study its effect in vitro (e.g., cell culture) or to produce a desired therapeutic effect ex vivo or in vitro. An effective amount of a compound may be used to produce a therapeutic effect in a subject, such as preventing or treating a target condition, alleviating symptoms associated with the condition, or producing a desired physiological effect. In such a case, the effective amount of a compound is a “therapeutically effective amount.” “therapeutically effective concentration” or “therapeutically effective dose.” The precise effective amount or therapeutically effective amount is an amount of the composition that will yield the most effective results in terms of efficacy of treatment in a given subject or population of cells. This amount will vary depending upon a variety of factors, including but not limited to the characteristics of the compound (including activity, pharmacokinetics, pharmacodynamics, and bioavailability), the physiological condition of the subject (including age, sex, disease type and stage, general physical condition, responsiveness to a given dosage, and type of medication) or cells, the nature of the pharmaceutically acceptable carrier or carriers in the formulation, and the route of administration. Further an effective or therapeutically effective amount may vary depending on whether the compound is administered alone or in combination with another compound, drug, therapy or other therapeutic method or modality. One skilled in the clinical and s pharmacological arts will be able to determine an effective amount or therapeutically effective amount through routine experimentation, namely by monitoring a cell&#39;s or subject&#39;s response to administration of a compound and adjusting the dosage accordingly. For additional guidance, see Remington: The Science and Practice of Pharmacy, 21st Edition, Univ. of Sciences in Philadelphia (USIP), Lippincott Williams &amp; Wilkins, Philadelphia, Pa., 2005, which is hereby incorporated by reference as if fully set forth herein. 
     The term “in combination” or “in combination with.” as used herein, means in the course of treating the same disease in the same patient using two or more agents (including other siRNA or other ASO), drugs, treatment regimens, treatment modalities or a combination thereof, in any order. Administration of a PCAT18 siRNA or an ASO “in combination with” one or more other anti-cancer therapeutics or chemotherapeutics is intended to include simultaneous (concurrent) administration and consecutive administration, as well as administration in a temporally spaced order of up to several days apart. Consecutive administration is intended to encompass administration of the other therapeutic(s) and the siRNA molecule(s) and/or the ASO molecule(s) to the subject in various orders. Such combination treatment may also include more than a single administration of any one or more of the agents, drugs, treatment regimens or treatment modalities. Further, the administration of the two or more agents, drugs, treatment regimens, treatment modalities or a combination thereof may be by the same or different routes of administration. 
     A “biological sample” refers to any material, biological fluid, tissue, or cell obtained or otherwise derived from a subject including, but not limited to, blood (including whole blood, leukocytes, peripheral blood mononuclear cells, plasma, and serum), sputum, mucus, nasal aspirate, urine, semen, saliva, meningeal fluid, lymph fluid, milk, bronchial aspirate, a cellular extract, and cerebrospinal fluid. This also includes experimentally separated fractions of all of the preceding. For example, a blood sample can be fractionated into serum or into fractions containing particular types of blood cells, such as red blood cells or white blood cells (leukocytes). If desired, a sample may be a combination of samples from an individual, such as a combination of a tissue and fluid sample. A biological sample may also include materials containing homogenized solid material, such as from a stool sample, a tissue sample, or a tissue biopsy; or materials derived from a tissue culture or a cell culture. Tissue may be normal tissue or cancerous tissue, such as a cancerous prostate tissue, a benign prostatic hyperplasia tissue, or normal prostate tissue. 
     Identification and Expression Analysis of PCAT18 
     PCAT18 (SEQ ID NO:1; see  FIG. 5 ) is a long intergenic noncoding RNA at locus LOC728606, exhibiting high expression in a metastatic xenograft model (see Example 1). PCAT18 showed a similar magnitude of fold-change as the oncogenic lncRNAs H19 and PCGEM1 (see  FIG. 1(B) ). 
     Locus LOC728606, which encodes the intergenic lncRNA PCAT18, is flanked by AQP4 (Aquaporin-4) and KCTD1 (Potassium channel tetramerisation domain containing-1) loci and is part of the 18q11.2 genomic locus. PCAT18 is a 2598 bp RNA containing 2 exons ( FIG. 1(C) ) and consists of the nucleotide sequence referenced as SEQ ID NO:1 ( FIG. 5 ). 
     Expression analysis of PCAT18 using publically available databases (i.e., Oncomine™, Geo and cBio database) showed up-regulation of PCAT18 in PCa as compared to normal tissues (see  FIGS. 2(A)  and (B). Using quantitative PCR (QPCR), it was further determined that PCAT18 is highly over-expressed (8.8-11.1 fold, p&lt;0.001) in both low-Gleason (i.e., a lower grade PCa; Gleason Score of 6 or lower) and high-Gleason PCa (i.e., more aggressive PCa; Gleason Score of 7, or higher than 7) samples as compared to benign prostatic hyperplasia (see  FIGS. 3(A)  and (B)). A person skilled in the art would recognize that this up-regulation is, thus, not merely the function of prostate cell hyperproliferation. 
     Expression of PCAT18 is significantly higher in normal prostate tissue than in normal tissues (see  FIG. 2(D) ) and that it is over-expressed specifically in PCa as compared to 15 other neoplastic tissues ( FIG. 2(C) ), including, bladder cancer, brain and central nervous system cancer, breast cancer, cervical cancer, colorectal cancer, esophageal cancer, gastric cancer, head and neck cancer, kidney cancer, liver cancer, lung cancer, lymphoma, ovarian cancer, pancreatic cancer, and sarcoma. PCAT18 is, therefore, prostate cancer-specific and prostate tissue-specific, which suggests its usefulness as a biomarker for disease detection, diagnosis and monitoring of PCa and for treatment of PCa, as indicated for other noncoding RNAs. 
     Patients affected by mCRPC had significantly higher levels of PCAT18 in their plasma samples as compared to patients affected by localized PCa (see  FIG. 3(B) ). In addition, those patients affected by localized PCa had significantly higher levels of PCAT18 in their plasma samples when compared to plasma samples from normal individuals. Accordingly, those plasma samples derived from patients having a poor prognosis showed a tendency toward having higher levels of PCAT18 as compared to plasma samples derived from patients having a good or better prognosis than the patients having a poor prognosis. This finding also indicates that PCAT18 is detectable in plasma samples and could provide a non-invasive method for diagnosis, prognosis and monitoring of PCa and treatment of PCa. 
     In addition to the PCAT18B transcript described above (i.e.,  FIG. 5 , SEQ ID so NO:1), one skilled in the art would understand that many additional transcript variants of PCAT18 may also exist and could be applicable for the uses and methods described herein. For example, one or more transcript variants may include, without limitation, a variant that is at least about 90% identical, at least about 91% identical, at least about 92% identical, at least about 93% identical, at least about 94% identical, at least about 95% identical, at least about 96% identical, at least about 97% identical, at least about 98% identical, at least about 99% identical to SEQ ID NO:1. Methods of determining sequence identity are known in the art and can be determined, for example, by using the BLASTN program of the University of Wisconsin Computer Group (GCG) software or provided on the NCBI website. The PCAT18 transcript variants that may be used in accordance with the methods described herein are not limited to those described above. The transcript variants may include any addibonal variants of PCAT18 described herein and other lncRNAs that are transcribed from genomic locus LOC728606, as one skilled in the art would understand that many additional transcript variants related to PCAT18 may exist that have differential expression found in prostate cancer cells as compared to normal cells. 
     In certain embodiments, the transcript variant is capable of selectively hybridizing under stringent conditions to a portion of the genomic region at locus LOC728606. Suitable stringent conditions include, for example, hybridization according to conventional hybridization procedures and washing conditions of 1-3×SSC, 0.1-1% SDS, 50-700 C with a change of wash solution after about 5-30 minutes. As known to those of ordinary skill in the art, variations in stringency of hybridization conditions may be achieved by altering the time, temperature, and/or concentration of the solutions used for the hybridization and wash steps. Suitable conditions can also depend in part on the particular nucleotide sequences used. 
     It is understood that modifications of the PCAT18 lncRNA may also be used as a biomarker for detecting, prognosing and monitoring cancer according to the methods and uses described herein. Modifications of PCAT18 transcripts that may be detected and that may be indicative of PCa when used according to the methods and uses described herein may include, but are not limited to, single nucleotide polymorphisms (SNPs), DNA methylation or unmethylation. RNA methylation or unmethylation, and gene mutations or deletions. Such modifications may result in an alteration in the expression, formation, or conformation of the PCAT18 transcript in a cancerous or biological sample, as compared to a control, and may result in inhibition or impairment of a therapeutic agent targeting such PCAT18 transcript. Alternatively, downstream targets of the PCAT18 transcript may be used as biomarkers for detecting, prognosing and monitoring cancer according to the methods described herein. 
     As used herein “PCAT18 transcript” or “PCAT18” or “JUPITER” may be PCAT18 RNA comprising the nucleotide sequence referenced as SEQ ID NO:1, a variant transcript of PCAT18, as described above, comprising from about 90% to about 100%, or any amount therebetween, identity or sequence similarity with SEQ ID NO:1, or a modification of either PCAT18 or a related transcript, or may be any other lncRNA that is transcribed from genomic locus LOC728606, which has increased expression in prostate cancer cells as compared to normal cells. 
     Methods of Diagnosis or Prognosis Using PCAT18 
     PCAT18, and/or one or more of the individual PCAT transcript variants, may be isolated from a biological sample (e.g., blood, serum, plasma, urine, saliva or prostate tissue) and the expression level of PCAT18 assessed in the biological sample to determine a diagnosis or prognosis of PCa and any stage of PCa. As described above, the expression of PCAT18 is tissue-specific (i.e., prostate tissue) and cancer-specific (PCa), with overexpression of PCAT18 in biological samples obtained from patients having PCa. 
     As described herein, the expression levels of PCAT18 in a biological sample (such as plasma, urine, tissue, saliva) show a progressive increase from non-cancerous (i.e., a sample from a normal individual) to primary PCa to metastatic PCa. The more aggressive form of prostate cancer (mCRPC) exhibit the highest levels of PCAT18, as compared to primary, localized PCa and normal individuals. Accordingly, the expression level of PCAT18 in a biological sample is associated with clinical aggression of PCa and, consequently, patient survival from PCa. Therefore, according to certain embodiments, the PCAT18B transcript is associated with the presence or absence of primary PCa, metastatic PCa, including mCRPC, local or distant metastases, and the progression or aggressiveness of the PCa. As the expression levels of PCAT18 is also associated with patient survival, PCAT18 and other variants of PCAT18 and transcripts of the LOC728606 genomic locus may be used as biomarkers for diagnosing, prognosing, assessing risk and monitoring PCa. Further, such diagnoses, prognoses and assessments of risk of PCa based on expression levels of PCAT18 transcripts and related variants may be used to monitor a PCa patient&#39;s treatment and/or make clinical decisions regarding optimization of a PCa patient&#39;s treatment regimen. 
     Therefore, the present invention relates to methods for diagnosis of a subject suspected of having prostate cancer, which involves assessing or determining PCAT18 expression levels in a biological sample obtained from the subject and comparing the expression level to a reference expression level. The reference expression level may be obtained from the expression level of PCAT18 in samples obtained from normal individuals determined as not having PCa. Such methods further include a step of diagnosing a subject as having PCa or identifying the subject as having PCa when the expression level of PCAT18 in the biological sample of the subject is greater than the reference expression level. The subject may also be diagnosed as not having PCa or identified as not having PCa when the expression level of PCAT18 in the biological sample of the subject is not greater than a reference expression level. Depending on the level of expression of PCAT18 in the biological sample as compared to the reference expression level, the subject may be diagnosed with localized prostate cancer or a metastatic prostate cancer, including, without limitation, metastatic castration-resistant prostate cancer (mCRPC). For example, if the expression level of PCAT18 in a subject&#39;s sample is between about a 1.1 fold-change and about a 4 fold-change, or any amount therebetween, over the reference expression level, then the subject may be diagnosed with a localized prostate cancer, and if the expression level of PCAT18 in a subject&#39;s sample is greater than about a 4 fold-change, for example greater than 4 to about 1000 fold or any amount therebetween, over the reference expression level, then the subject may be diagnosed with a clinically more aggressive prostate cancer, for example, without limitation, mCRPC. In certain embodiments, the diagnostic methods described herein may detect, determine, or recognize the presence or absence of PCa; prediction or diagnosis of metastasis or lack of metastasis, type or sub-type, or other classification or characteristic of PCa; whether a specimen is a benign lesion, such as benign prostatic hyperplasia (BPH), or a malignant tumor, or a combination thereof. 
     By “greater than the reference expression level,” it is meant that the expression level of PCAT18 in the subject&#39;s sample is at least about a 1.5 increase or fold-change over the reference expression level, for example, the expression level of PCAT18 may be at least about a 2 fold-change (as shown, for example, in  FIG. 3(B) ), at least about a 2.3 fold-change (as shown, for example, in  FIG. 2(A) ), at least about a 2.78 fold-change (as shown, for example, in  FIG. 2(C) ), at least about a 3 fold-change, at least about a 3.5 fold-change, at least about a 4 fold-change, at least about a 4.5 fold-change, at least about a 5 fold-change, at least about a 5.5 fold-change (as shown in, for example,  FIG. 3(B) ), at least about a 6 fold-change, at least about a 6.5 fold-change, at least about a 7 fold-change, at least about a 7.2 fold-change (as shown, for example, in  FIG. 2(B) ), at least about a 7.5 fold-change, at least about an 8 fold-change, at least about an 8.5 fold-change, at least about an 8.75 fold-change (as shown, for example, in  FIG. 2(C) ), at least about a 9 fold-change, at least about a 9.5 fold-change, at least about a 10 fold-change, at least about a 11 fold-change, at least about a 12 fold-change, at least about a 13 fold-change, at least about a 14 fold-change (as shown, for example, in  FIG. 3(A) ), at least about a 15 fold-change (as shown, for example, in  FIG. 3(A) ), at least about a 16 fold-change, at least about a 17 fold-change, at least about an 18 fold-change, at least about a 19 fold-change, at least about a 20 fold-change, at least about a 30 fold-change, at least about a 40 fold-change, at least about a 50 fold-change, at least about a 60 fold-change, at least about a 70 fold-change, at least about an 80 fold-change, at least about a 90 fold-change, at least about a 100 fold-change, at least about a 200 fold-change, at least about a 300 fold-change, at least about a 400 fold-change, at least about a 500 fold-change, at least about a 600 fold-change, at least about a 700 fold-change, at least about an 800 fold-change, at least about a 900 fold-change, at least about a 1000 fold-change, or any other fold-change therebetween, over the reference expression level. Furthermore, the change in expression may be from about 1.5 to about 150, fold increase or fold-change, or any amount therebetween, over the reference expression level (as shown in  FIG. 3C : LNCap), or from about 1.5 to about 1000 fold increase or fold-change, or any amount therebetween, over the reference expression level (as shown in  FIG. 3C : C4-2). For example, the increase in expression of PCAT18 over the reference expression level may be about 1.5, 2, 4, 6, 8, 10, 20, 25, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000 fold increase or fold-change, or any amount therebetween, over the reference expression level. 
     By “not greater than the reference expression level,” it is meant that the expression level of PCAT18 in the subject&#39;s sample is less than about a 1.4 increase or fold-change over the reference expression level, for example, the expression level of PCAT18 is less than about a 1.3 fold-change, less than about a 1.2 fold-change, less than about a 1.1 fold-change, less than about a 1 fold-change, less than about a 0.8 fold-change, less than about a 0.5 fold-change, less than about a 0.2 fold-change, less than about a 0.1 fold-change over the reference expression level. The phrase “not greater than the reference expression level” may also include situations in which the expression level of PCAT18 in the subject&#39;s sample is the same as or less than the reference expression level. 
     The present invention further relates to methods for determining the risk of a subject for developing prostate cancer. Such methods comprise a step of assessing or determining the expression level of PCAT18 in a biological sample obtained from the subject and comparing the expression level to a reference expression level. The reference expression level may be obtained from the expression level of PCAT18 in samples obtained from normal individuals determined as not having PCa. Such methods further include a step of identifying the subject as having an increased risk of developing PCa when the expression level of PCAT18 in the biological sample of the subject is greater than the reference expression level. The subject may also be identified as not having an increased risk of developing PCa when the expression level of PCAT18 in the biological sample of the subject is not greater than a reference expression level. By “increased risk of developing PCa,” it is meant a greater than about a 10% chance of developing PCa as compared to a normal individual, for example, a greater than about a 15%, about a 20%, about a 25%, about a 30%, about a 35%, about a 40%, about a 45% or about a 50% chance of developing PCa as compared to a normal individual. 
     PCAT18 expression levels in a biological sample from a subject may also be used in the prognosis of a PCa patient (i.e., a subject having PCa), which involves assessing or determining PCAT18 expression levels in a biological sample obtained from the subject and comparing the expression level to a threshold level. Such methods described herein may, therefore, include a step of determining a prognosis for a subject having PCa when an expression level of PCAT18 is greater than, less than or within the threshold level. The prognosis may refer to a prediction of a future course of PCa in a subject who has the disease or condition (e.g., predicting disease outcome, such as, but not limited to, predicting patient survival), and may also encompass the evaluation of the response or outcome of the disease in the individual after administering a treatment or therapy to the individual, and may refer to a prediction of an increased or reduced risk of PCa relapse. The prognosis may be a poor prognosis or a good prognosis, as measured by a decreased length of survival or a prolonged (or increased) length of survival, respectively. The prognosis may be a poor prognosis if the expression level of PCAT18 in the subject&#39;s biological sample is greater than the threshold level; that is, if the expression level of PCAT18 in the subject&#39;s biological sample is greater than about a 4 fold-change over the reference expression level. The prognosis may be good if the expression level of PCAT18 in the subject&#39;s biological sample is within the threshold level; that is, if the expression level of PCAT18 is between about a 1.1 fold-change and about a 4 fold-change over the reference expression level. The prognosis may be even better if the expression level of PCAT18 in the subject&#39;s biological sample is less than the threshold level. 
     In other embodiments, the methods described herein may also be used to differentiate between an early stage cancer (i.e., primary tumor); or a metastasized PCa when the expression level is significantly different than threshold level. Accordingly, a method for determining a risk of metastatic spread of (i.e. risk of metatsis in other organs or parts of the body that can be determined using standard tests) PCa in a subject diagnosed with PCa is provided herein. Such a method involves assessing or determining the expression level of PCAT18 in a biological sample obtained from the subject diagnosed with PCa and comparing the expression level to a threshold level. The subject is identified as having an increased risk of metastatic spread when the expression level of PCAT18 in the subject&#39;s biological sample is significantly greater than the threshold level. By “significantly greater than the threshold level,” it is meant that the expression level of the PCAT18 in the subject&#39;s biological level is at least about a 6 fold-change over a reference expression level, and may be about a 7 fold-change, about an 8-fold-change, about a 9 fold-change, about a 10 fold-change, about an 11 fold-change, about a 12 fold-change, about a 13 fold-change, about a 14 fold-change, about a 15 fold-change, about a 16 fold-change, about a 17 fold-change, about an 18 fold-change, about a 19 fold-change, about a 20 fold-change, about a 30 fold-change, about a 40 fold-change, about a 50 fold-change, about a 60 fold-change, about a 70 fold-change, about an 80 fold-change, about a 90 fold-change, about a 100 fold-change, about a 200 fold-change, about a 300 fold-change, about a 400 fold-change, about a 500 fold-change, about a 600 fold-change, about a 700 fold-change, about an 800 fold-change, about a 900 fold-change, about a 1000 fold-change over a reference expression level, or any amount therebetween of the expression level of PCAT18 to a reference level. By “increased risk of metastatic spread,” it is m(eant a greater than about a 10% chance of metastatic spread as compared to a normal individual, for example, a greater than about a 15%, about a 20%, about a 25%, about a 30%, about a 35%, about a 40%, about a 45% or about a 50% chance of metastatic spread as compared to a normal individual. The increased risk of metastatic spread includes, for example, without limitation, an increased risk of a locoregional metastasis, a distant metastasis or an increased risk of progression to a more clinically aggressive PCa, including, mCRPC. 
     The present invention further relates to methods for monitoring a treatment administered to a patient diagnosed with PCa and involves analyzing the expression level of PCAT18 at two different timepoints, such as prior to administration of treatment and after administration of treatment. Accordingly, the method comprises obtaining a baseline level of expression of PCAT18 in a biological sample obtained from the subject. This baseline level is obtained prior to administration of a treatment, or prior to a second timepoint at which an expression level of PCAT18 will be determined. The method then comprises the step of administering the treatment for a treatment period and then determining or assessing the expression level at a second timepoint from a second biological sample obtained from the subject. A comparison of the expression level at the second timepoint to the baseline level will identify whether the patient has responded poorly to the treatment or whether the patient has had a good response to the treatment. The second timepoint may also be after a certain period of time has elapsed from obtaining the first biological sample from the subject, without a treatment step in between. This may be the case if the method comprises a step of determining whether a treatment course, treatment regimen or treatment modality should be started, for example, if the patient&#39;s PCa was in remission and determining whether there has been a relapse in the patient, or if the patient&#39;s disease has progressed to mCRPC and determining whether surgery or hormonal therapy should be administered. 
     Accordingly, the methods described herein may also include monitoring or assessing the progression of PCa in a subject monitoring or assessing a response to treatment in a subject having PCa; monitoring or assessing a metastatic spread of PCa in a subject monitoring or assessing a remission state or a recurrence of PCa in a subject or a combination thereof. Such monitoring or assessing may include an individuals response to a therapy, such as, for example, predicting whether an individual is likely to respond favorably to a therapeutic agent, is unlikely to respond to a therapeutic agent, or will likely experience toxic or other undesirable side effects as a result of being administered a therapeutic agent; selecting a therapeutic agent for administration to an individual, or monitoring or determining an individual&#39;s response to a therapy that has been administered to the individual. 
     An expression level of PCAT18 in a subject or a reference expression level used in the methods for diagnosis, prognosis, monitoring, treating, or assessing risk of developing PCa or progression to metastatic risk, as described herein, may be measured, quantified and/or detected by any suitable RNA detection, quantification or sequencing methods known in the art, including, but not limited to, quantitative PCR (QPCR) or quantitative/gel-based electrophoresis PCR reverse transcriptase-polymerase chain reaction (RT-PCR) methods, microarray, serial analysis of gene expression (SAGE), next-generation RNA sequencing (e.g., deep sequencing, whole transcriptome sequencing, exome sequencing), gene expression analysis by massively parallel signature sequencing (MPSS), immune-derived colorimetnc assays, in situ hybridization (ISH) formulations (colorimetric/radiometric) that allow histopathology analysis, mass spectrometry (MS) methods, RNA pull-down and chromatin isolation by RNA purification (ChiRP), and proteomics-based identification (e.g., protein array, immunoprecipitation) of lncRNA. In an embodiment, the method of measuring the expression level of PCAT18 may also include non-PCR-based molecular amplification methods for detection. A combination of the above methods for assessing the expression level or reference expression level is also contemplated. 
     A diagnosis or prognosis of PCa based on the methods described herein may be used to optimize or select a treatment regimen for a subject diagnosed with PCa. For example, a method for diagnosing or prognosing PCa may be performed as described above. In an embodiment, a subject that is diagnosed with primary PCa based on an expression level of PCAT18 or a related variant may be treated according to FDA approved protocols and standards known in the art for a particular therapeutic agent for primary PCa. Alternatively, a diagnosis of primary PCa may be treated using surgery, such as, but not limited to, radical prostatectomy, and/or primary PCa may be treated using a “wait and see approach” before or after surgery, since such a diagnosis indicates that metastasis of the primary PCa has not occurred. In other embodiments, primary PCa may be treated using a therapeutic or pharmaceutical agent that targets PCAT18 and/or one or more related variants, and inhibits or silences the expression of PCAT18, as described below. After any of the above treatments, monitoring of the PCa and progression of the PCa to a more clinically aggressive PCa, such as mCRPC, is performed by periodically assessing the expression levels of PCAT18 and/or any related variants in a patient&#39;s biological sample, such as blood, plasma, urine or prostate tissue. 
     Similarly, a diagnosis of a subject that is diagnosed with metastatic PCa based on an expression level of PCAT18 or a related variant may be treated more aggressively according to FDA approved protocols and standards known in the art for metastatic PCa. A diagnosis of a more aggressive PCa may be treated using surgery, such as, but not limited to, radical prostatectomy, if such a surgery is deemed acceptable. In other embodiments, a more aggressive PCa may be treated using a therapeutic or pharmaceutical agent that targets PCAT18 and/or one or more related variants, and inhibits or silences the expression of PCAT18, as described below. After any of the above treatments, monitoring of the PCa is performed by periodically assessing the expression levels of PCAT18 and/or any related variants in a patient&#39;s biological sample, such as blood, plasma, urine or prostate tissue. 
     Methods of Treating Prostate Cancer 
     Because PCAT18 has been found to be overexpressed in PCa, PCAT18 and related variants may also be used as a therapeutic target in PCa. Therefore, the present invention also relates to targeting PCAT18, including but not limited to additional transcript variants of PCAT18, modifications of PCAT18 and related variants, and other lncRNAs that may be transcribed from genomic locus LOC728606, using an inhibiting agent or therapeutic targeting strategy, such as antisense oligonucleotides, RNA interference (RNAi), esiRNA, shRNA, miRNA, decoys, RNA aptamers, small molecule inhibitors, RNA/DNA-binding proteins/peptides or other compounds with different formulations to inhibit one or more physiological actions effected by PCAT18 and to thereby treat PCa. Such therapeutic targeting strategies may be used to develop a therapeutic agent or pharmaceutical compositions that target PCAT18 and/or one or more related variants for treating PCa. Treatment of PCa may include administering to a subject having PCa a therapeutically effective amount of a therapeutic agent, such as an inhibiting agent of PCAT18 or a pharmaceutical composition, as described herein. 
     Accordingly, in a general aspect, the present invention provides for methods of treating a subject diagnosed with PCa by administering a therapeutically effective amount of an inhibiting agent of PCAT18. The inhibiting agent of PCAT18 may be an antisense oligonucleotide, RNA interference (RNAi), siRNA, esiRNA, shRNA, miRNA, decoys, RNA aptamers, small molecule inhibitors, RNA/DNA-binding proteins/peptides, or a combination thereof. 
     siRNA Molecules 
     In certain embodiments, the present invention provides for methods of treating PCa in a subject diagnosed with PCa using small interfering RNA (siRNA) molecules against PCAT18. siRNA molecules targeted to PCAT18 have been found to decrease proliferation of cancer cells when used as a single agent. For example, siRNA1, which comprises a nucleotide sequence corresponding to SEQ ID NO:22, and siRNA2, which comprises a nucleotide sequence corresponding to SEQ ID NO:23, both independently silence PCAT18. Moreover, siRNA1 and siRNA2 silencing of PCAT18 elicited significant and stable growth inhibition in a human prostate cancer cell line (C4-2) (see  FIGS. 3(D) and 3(E) ). 
     Generally, siRNAs used in the present invention are targeted to a PCAT18 gene, or the genomic region at locus LOC728606, and are capable of silencing or inhibiting the expression of PCAT18 RNA. siRNAs targeted to a PCAT18 gene or locus LOC728606 comprise a specific antisense sequence that is complementary to a portion of the noncoding RNA transcribed from the target gene (i.e., the target RNA) and can be double-stranded (i.e. composed of an antisense strand, comprising the specific antisense sequence, and a complementary sense strand) or single-stranded (i.e. composed of an antisense strand, comprising the specific antisense sequence, only) as described in more detail below. Short-hairpin siRNA (shRNA) against PCAT18 are also included in the present invention. 
     As is known in the art, the specificity of siRNA molecules is determined by the binding of the antisense strand of the molecule to its target RNA. Effective siRNA molecules are generally from 14 to 100 base pairs in length, or any length therebewteen to prevent them from triggering non-specific RNA interference pathways in the cell via the interferon response, although longer siRNA can also be effective. For example, the siRNA molecules contemplated by the present invention may be 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 35, 40, 50, 60, 70, 80, 90, 100 base pairs in length or any number of base pairs therebetween in length. 
     Design and construction of siRNA molecules is known in the art (see, for example, Elbashir, et al.,  Nature,  411:494-498 (2001); Bitko and Barik, BMC Microbiol., 1:34 (2001)]. 
     For the siRNA molecules used in the present invention, the target RNA is a noncoding RNA transcribed from the PCAT18 gene or the genomic region at locus LOC728606, including, without limitation, the nucleotide sequence corresponding to SEQ ID NO:1 (shown in  FIG. 5 ). Therefore, in an embodiment, the target RNA for the PCAT18 siRNA is PCAT18 RNA corresponding to the nucleotide sequence as set forth in SEQ ID NO:1. The siRNA may comprise a sequence that is complementary to a target sequence within SEQ ID NO:1. 
     Suitable target sequences within the target RNA are selected using one or more of several criteria known in the art (see for example, Elbashir. S. M., et al. (2001)  Nature  411, 494-498; Elbashir, S. M., et al. (2002)  Methods  26, 199-213; Elbashir, S. M., et al. (2001)  Genes Dev.  15, 188-200; Elbashir, S. M., et al. (2001)  EMBO J.  20, 6877-6888; and Zamore, P. D., et al. (2000)  Cell  101, 25-33). Target RNA sequences within the target RNA are typically between about 14 and about 50 nucleotides in length, or any length therebewteen, but may be longer in length, for example, the target RNA sequence may be about 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250 base pairs in length, or any number of base pairs therebetween in length. The target RNA sequence can be selected from various regions within the PCAT18 RNA. For example, siRNA1 comprises an antisense sequence SEQ ID NO:22 which is complementary to a target sequence within SEQ ID NO:1, and siRNA2 comprises an antisense sequence SEQ ID NO:23, which is complementary to a target sequence within SEQ ID NO:1. 
     Following selection of an appropriate target RNA sequence, as described above, siRNA molecules that comprise a nucleotide sequence complementary to all or a portion of the target RNA sequence, i.e. an antisense sequence, can be designed and prepared. As indicated above, the siRNA molecule can be double stranded (i.e. a dsRNA molecule comprising an antisense strand and a complementary sense strand) or single-stranded (i.e. a ssRNA molecule comprising just an antisense strand). The siRNA molecules can comprise a duplex, asymmetric duplex, hairpin or asymmetric hairpin secondary structure, having self-complementary sense and antisense strands. 
     Double-stranded siRNA may comprise RNA strands that are the same length or different lengths. In one embodiment, the siRNA is a double-stranded siRNA. In another embodiment, the siRNA is a double-stranded siRNA wherein both RNA strands are the same length. 
     Double-stranded siRNA molecules can also be assembled from a single oligonucleotide in a stem-loop structure, wherein self-complementary sense and antisense regions of the siRNA molecule are linked by means of a nucleic acid based or non-nucleic acid-based linker(s), as well as circular single-stranded RNA having two or more loop structures and a stem comprising self-complementary sense and antisense strands, wherein the circular RNA can be processed either in vivo or in vitro to generate an active siRNA molecule capable of mediating RNA interference. 
     Small hairpin RNA (shRNA) molecules thus are also contemplated by the present invention. These molecules comprise a specific antisense sequence in addition to the reverse complement (sense) sequence, typically separated by a spacer or loop sequence. Cleavage of the spacer or loop provides a single-stranded RNA molecule and its reverse complement, such that they may anneal to form a dsRNA molecule (optionally with additional processing steps that may result in addition or removal of one, two, three or more nucleotides from the 3′ end and/or the 5′ end of either or both strands). The spacer can be of a sufficient length to permit the antisense and sense sequences to anneal and form a double-stranded structure (or stem) prior to cleavage of the spacer (and, optionally, subsequent processing steps that may result in addition or removal of one, two, three, four, or more nucleotides from the 3′ end and/or the 5′ end of either or both strands). The spacer sequence is typically an unrelated nucleotide sequence that is situated between two complementary nucleotide sequence regions which, when annealed into a double-stranded nucleic acid, comprise a shRNA (see, for example, Brummelkamp et al., 2002  Science  296:550; Paddison et al., 2002  Genes Develop.  16:948; Paul et al.,  Nat Biotechnol  20:505-508 (2002); Grabarek et al.,  BioTechniques  34:734-44 (2003)). The spacer sequence generally comprises between about 3 and about 100 nucleotides. 
     Single-stranded siRNA molecules are generally single-stranded RNA molecules with little or no secondary structure. 
     The overall length of the siRNA molecules can vary from about 14 to about 100 nucleotides depending on the type of siRNA molecule being designed, and can be more than 100 nucleotides, such as, for example, about 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90 100 nucleotides in length, or any number of nucleotides in length therebetween. For example, the siRNAs may be siRNA1 and siRNA2, as described above, corresponding to SEQ ID NO: 22 and SEQ ID NO: 23, respectively, which are each 36 oligonucleotides in length. 
     In an alternative embodiment, the siRNA molecule is a shRNA molecule or circular siRNA molecule between about 35 and about 100 nucleotides in length. In a further embodiment, the siRNA molecule is a shRNA molecule between about 40 to about 60 nucleotides in length. 
     As indicated above, the siRNA molecule comprises an antisense strand that includes a specific antisense sequence complementary to all or a portion of a target RNA sequence, such as, the PCAT18 noncoding RNA. One skilled in the art will appreciate that the entire length of the antisense strand comprised by the siRNA molecule does not need to be complementary to the target sequence. Thus, the antisense strand of the siRNA molecules may comprise a specific antisense sequence together with nucleotide sequences at the 5′ and/or 3′ termini that are not complementary to the target sequence. Such non-complementary nucleotides may provide additional functionality to the siRNA molecule. For example, they may provide a restriction enzyme recognition sequence or a “tag” that facilitates detection, isolation or purification. Alternatively, the additional nucleotides may provide a self-complementary sequence that allows the siRNA to adopt a hairpin configuration. Such configurations are useful when the siRNA molecule is a shRNA molecule, as described above. 
     The specific antisense sequence comprised by the siRNA molecule can be identical or substantially identical to the complement of the target RNA sequence. In the context of the present invention, the specific antisense sequence comprised by the siRNA molecule can be identical or substantially identical to the complement of the PCAT18 RNA sequence, that is, the complement of a contiguous portion of the RNA sequence corresponding to SEQ ID NO:1. In one embodiment of the present invention, the specific antisense sequence comprised by the siRNA molecule is at least about 75% identical to the complement of a contiguous portion of the RNA sequence corresponding to SEQ ID NO:1. In another embodiment, the specific antisense sequence comprised by the siRNA molecule is at least about 90% identical to the complement of a contiguous portion of the RNA sequence corresponding to SEQ ID NO:1. In a further embodiment, the specific antisense sequence comprised by the siRNA molecule is at least about 95% identical to the complement of a contiguous portion of the RNA sequence corresponding to SEQ ID NO:1. In another embodiment, the specific antisense sequence comprised by the siRNA molecule is at least about 98% identical to the complement of a contiguous portion of the RNA sequence corresponding to SEQ ID NO:1. Methods of determining sequence identity are known in the art and can be determined, for example, by using the BLASTN program of the University of Wisconsin Computer Group (GCG) software or provided on the NCBI website. 
     In one embodiment of the invention, the siRNA molecules comprise a specific antisense sequence that is capable of selectively hybridizing under stringent conditions to a portion of a naturally occurring target RNA, such as PCAT18 RNA. Suitable stringent conditions include, for example, hybridization according to conventional hybridization procedures and washing conditions of 1-3×SSC, 0.1-1% SDS, 50-700 C with a change of wash solution after about 5-30 minutes. As known to those of ordinary skill in the art, variations in stringency of hybridization conditions may be achieved by altering the time, temperature, and/or concentration of the solutions used for the hybridization and wash steps. Suitable conditions can also depend in part on the particular nucleotide sequences used, for example the portion of RNA sequence corresponding to SEQ ID NO:1. 
     The siRNA molecules can be prepared using several methods known in the art, such as chemical synthesis, in vitro transcription, the use of siRNA expression vectors, and any other conventional techniques known in the art. For example, general methods of RNA synthesis and use of appropriate protecting groups is well known in the art (see, for example, Scaringe, S. A., et al.,  J. Am. Chem. Soc,  1998, 120, 11820-11821; Matteucci, M. D. and Caruthers, M. H.,  J. Am. Chem. Soc,  1981, 103, 3185-3191; Beaucage, S. L. and Caruthers, M. H.,  Tetrahedron Left.,  1981, 22, 1859-1862: Dahl, B. J., et al.,  Acta Chem. Scand.,  1990, 44, 639-641; Reddy, M. P., et al.,  Tetrahedron Left,  1994, 25, 4311-4314; Wincott, F. et al.,  Nucleic Acids Res.,  1995, 23, 2677-2684; Griffin, B. E., et al.,  Tetrahedron,  1967, 23, 2301-2313; Griffin, B. E., et al.,  Tetrahedron,  1967, 23, 2315-2331). As is also well known in the art, modified siRNA molecules, such as phosphorothioated and alkylated derivatives, can also be readily prepared by similar methods 
     Various methods of testing the efficacy of the siRNA molecules are known in the art and may be employed to test the efficacy of the PCAT18 siRNA molecules, including siRNA1 and siRNA2. 
     Antisense Oligonucleotdies 
     The present invention also provides for methods of treating PCa in a subject diagnosed with PCa using antisense oligonucleotides (ASOs). ASOs targeted to PCAT18 have been found to decrease proliferation of cancer cells when used as a single agent. For example, ASO2, which comprises a nucleotide sequence corresponding to SEQ ID No:24, and ASO7, which comprises a nucleotide sequence corresponding to SEQ ID NO:25 both independently silence PCAT18. Moreover, ASO2 and ASO7 inhibition of PCAT18 elicited significant knockdown of PCAT18 expression in a human prostate cancer cell line (C4-2) as compared to an antisense nucleotide (NC) with no known specific target in human or mouse genome (see  FIG. 10 ). 
     Generally, ASOs used in the present invention are targeted to PCAT18 RNA, or any other additional RNA transcribed from the genomic region at locus LOC728606. The ASOs of the present invention are effective in reducing the amount of expression of PCAT18 RNA in vivo. ASOs targeted to the PCAT18 RNA or other transcripts derived from locus LOC728606 comprise a specific antisense sequence that is complementary to a portion of the noncoding RNA transcribed from the target gene (i.e., the target RNA) and can be either DNA, RNA or a chemical analogue. ASOs are generally single-stranded (i.e. composed of an antisense strand, comprising the specific antisense sequence, only) and bind to the complementary portion of the target RNA. 
     Suitable ASOs have a length of from about 12 to about 35 oligonucleotides and any amount therebewteen, and have sequence specificity (i.e., are complementary) to the PCAT18 noncoding RNA sequence. However, the ASOs of the present invention may compose more than about 35 oligonucleotides, for example, about 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250 oligonucleotides in length, or any number of oligonucleotides therebetween. Exemplary ASOs comprise a nucleotide sequence complementary to a contiguous portion of the nucleotide sequence (i.e. a target sequence) corresponding to SEQ ID NO:1. The contiguous portion of the nucleotide sequence may be between about 12 to about 250 oligonucleotides in length, or any number of oligonucleotides in length therebetween. For example, the ASOs may be ASO2 and ASO7, as described above, corresponding to SEQ ID NO: 24 and SEQ ID NO: 25, respectively, which are each 20 oligonucleotides in length. 
     The specific antisense sequence comprised by an ASO of the present invention can be identical or substantially identical to the complement of the target RNA sequence. In the context of the present invention, the specific antisense sequence comprised by the ASO molecule can be identical or substantially identical to the complement of the PCAT18 RNA sequence, that is, the complement of a contiguous portion of the RNA sequence corresponding to SEQ ID NO:1. In one embodiment of the present invention, the specific antisense sequence comprised by the ASO molecule is at least about 75% identical to the complement of a contiguous portion of the RNA sequence corresponding to SEQ ID NO:1. In another embodiment, the specific antisense sequence comprised by the ASO molecule is at least about 90% identical to the complement of a contiguous portion of the RNA sequence corresponding to SEQ ID NO:1. In a further embodiment, the specific antisense sequence comprised by the ASO molecule is at least about 95% identical to the complement of a contiguous portion of the RNA sequence corresponding to SEQ 10 NO:1. In another embodiment, the specific antisense sequence comprised by the ASO molecule s at least about 98% identical to the complement of a contiguous portion of the RNA sequence corresponding to SEQ ID NO:1. Methods of determining sequence identity are known in the art and can be determined, for example, by using the BLASTN program of the University of Wisconsin Computer Group (GCG) software or provided on the NCBI website. 
     In one embodiment of the invention, the ASO molecules comprise a specific antisense sequence that is capable of selectively hybridizing under stringent conditions to a portion of a naturally occurring target RNA, such as PCAT18 RNA or any other RNA transcribed from the genomic region at locus LOC728606 Suitable stringent conditions include, for example, hybridization according to conventional hybridization procedures and washing conditions of 1-3×SSC, 0.1-1% SDS, 50-7000 with a change of wash solution after about 5-30 minutes. As known to those of ordinary skill in the art, variations in stringency of hybridization conditions may be achieved by altering the time, temperature, and/or concentration of the solutions used for the hybridization and wash steps. Suitable conditions can also depend in part on the particular nucleotide sequences used, for example the portion of the antisense sequence corresponding to SEQ ID NO: 1 
     The oligonucleotides employed as ASOs in the present invention may be modified to increase the stability of the ASOs in vivo. For example, the ASOs may be employed as phosphorothioate derivatives (replacement of a non-bridging phosphoryl oxygen atoms with a sulfur atom) which have increased resistance to nuclease digestion (as done with ASO2 and ASO7). MOE modification (ISIS backbone) is also effective. 
     The ASOs used in the present invention may be prepared according to any of the methods that are well known to those of ordinary skill in the art. For example, the ASOs may be prepared by solid phase synthesis. See, Goodchild, J.,  Bioconjugate Chemistry,  1:165-167 (1990), for a review of the chemical synthesis of oligonucleotides. Alternatively, the ASOs can be obtained from a number of companies which specialize in the custom synthesis of oligonucleotides. 
     Administration of the Therapeutic Agents 
     Administration of the therapeutic agents described herein can be carried out using the various mechanisms known in the art, including naked administration and administration in pharmaceutically acceptable lipid carriers. For example, lipid carriers for ASO delivery are disclosed in U.S. Pat. Nos. 5,855,911 and 5,417,978 which are incorporated herein by reference. The carrier may also be any one of a number of sterols including cholesterol, cholate and deoxycholic acid. In general, the therapeutic agents describe herein, including the ASOs and siRNA molecules, may be administered by intravenous, intraperitoneal, subcutaneous or oral routes, or direct local tumor injection. 
     Suitable formulations for parenteral administration include aqueous solutions of the therapeutic agents in water-soluble form, for example, water-soluble salts. In addition, suspensions of the active compounds as appropriate oily injection suspensions may be administered. Suitable lipophilic solvents or vehicles include fatty oils, for example, sesame oil, or synthetic fatty acid esters, for example, ethyl oleate or triglycerides. Aqueous injection suspensions may contain substances which increase the viscosity of the suspension include, for example, sodium carboxymethyl cellulose, sorbitol, and/or dextran. Optionally, the suspension may also contain stabilizers. 
     In other embodiments, a therapeutic agent may be co-administered with an agent which enhances the uptake of the therapeutic agent by the cells. For example, a therapeutic agent may be combined with a lipophilic cationic compound which may be in the form of liposomes. The use of liposomes to introduce nucleotides into cells is taught, for example, in U.S. Pat. Nos. 4,897,355 and 4,394,448, the disclosures of which are incorporated by reference in their entirety. See also U.S. Pat. Nos. 4,235,871, 4,231,877, 4,224,179, 4,753,788, 4,673,567, 4,247,411, 4,814,270 for general methods of preparing liposomes comprising biological materials. 
     In addition, the therapeutic agents described herein may be conjugated to a peptide that is ingested by cells. Examples of useful peptides include peptide hormones, antigens or antibodies, and peptide toxins. By choosing a peptide that is selectively taken up by the cancerous prostate cells, specific delivery of the therapeutic agent may be effected. 
     The amount of a therapeutic agent administered in the present methods describe herein is one effective to reduce the amount of PCAT18 expression. It will be appreciated that this amount will vary both with the effectiveness of the ASO, siRNA or other therapeutic inhibiting agent employed, and with the nature of any carrier used. The determination of appropriate amounts for any given therapeutic agent is within the skill in the art, through standard series of tests designed to assess appropriate therapeutic levels. 
     The therapeutic agents described herein may also be administered as part of a pharmaceutical composition or preparation containing suitable pharmaceutically acceptable carriers comprising excipients and auxiliaries which facilitate processing of the therapeutic agents into preparations which can be used pharmaceutically. 
     Accordingly, the present invention contemplates pharmaceutical compositions comprising a therapeutic agent effective to reduce the amount of PCAT18 in cancerous prostate cells exposed to the therapeutic agent, and a pharmaceutically acceptable carrier. The therapeutic agent may be an inhibiting agent of PCAT18, such as, for example, antisense oligonucleotides, RNA interference (RNAi), esiRNA, shRNA, miRNA, decoys, RNA aptamers, small molecule inhibitors, RNA/DNA-binding proteins/peptides or other compounds which inhibit the expression of PCAT18. In certain embodiments, the pharmaceutical composition may comprise one or more than one therapeutic agent, and a pharmaceutically acceptable carrier. 
     The pharmaceutical compositions used in the present invention include all compositions wherein the one or more than one therapeutic agent is contained in an amount which is effective to achieve inhibition of expression of PCAT18. While individual needs vary, determination of optimal ranges of effective amounts of each component is within the skill of the art. 
     The present invention further contemplates a method of treating PCa in a so subject comprising the administration of a therapeutically effective amount of a PCAT18 siRNA in combination with any other treatment, agent, drug, regimen or therapy, including without limitation, administration of ASOs, hormonal therapy, surgery, radiation therapy, chemotherapy, biologic therapy, bisphosphonate therapy, cryosurgery, high-intensity focused ultrasound, and proton beam radiation therapy. Alternatively, a method of treating PCa in a subject diagnosed with PCa may comprise administering a therapeutically effective amount of an ASO in combination with any other treatment or therapy, including without limitation, administration of PCAT18 siRNA molecules, hormonal therapy, surgery, radiation therapy, chemotherapy, biologic therapy, bisphosphonate therapy, cryosurgery, high-intensity focused ultrasound, and proton beam radiation therapy. 
     The following examples are intended to illustrate various embodiments of the invention. As such, the specific embodiments discussed are not to be construed as limitations on the scope of the invention. It will be apparent to one skilled in the art that various equivalents, changes, and modifications may be made without departing from the scope of invention, and it is understood that such equivalent embodiments are to be included herein. Further, all references cited in the disclosure are hereby incorporated by reference in their entirety, as if fully set forth herein. 
     EXAMPLES 
     Patients and Methods 
     Patient-Derived Prostate Cancer Xenografts 
     PCa biopsy specimens were collected at the BC Cancer Agency with the patient&#39;s written informed consent. The protocol for this procedure was approved by the University of British Columbia (UBC) Research Ethics Board (REB). NOD/SCID mice used for this study were bred and maintained at the British Columbia Cancer Research Centre Animal Facility (Vancouver, Canada). All experimental protocols were approved by the University of British Columbia Animal Care Committee. Transplantable PCa tissue xenograft lines were established and maintained using subrenal capsule grafting as previously described (10). 
     LTL313B and LTL313H tumor tissue cell lines were derived from 2 primary neoplasm biopsies obtained simultaneously from the same patient (total biopsies performed=8). At the time of biopsy, the donor was affected by treatment-naive prostate adenocarcinoma (Gleason Score=8) with signs of pelvic infiltration and bone metastasis. Immediately after pathological diagnosis, the patient received hormonal therapy, and 9 months after commencing treatment PSA reached a nadir 0.28 ng/ml from a pre-treatment value of 19 ng/ml. 
     RNA Sequencing 
     Total RNA was extracted from non-metastatic LTL-313B and metastatic LTL-313H xenografts using RNAeasy kit (Qiagen), harvested on the same day, using Trizol (Invitrogen). RNA was sent to Otogenetics (Norcross, Ga.) for RNA sequencing. Sequenced reads were aligned to the hg19 human genome assembly and contrasted to the transcriptome generated from all the spliced sequences annotated in the RefSeq database using the DNAnexus suite (www.dnanexus.com). Transcript level was quantified by calculating the RPKM (reads per kilobase of transcript per million mapped reads) value (11). RPKM values were normalized to the root mean square (RMS) for each sample. Mapped transcripts were annotated using the gene cards database (www.genecards.org). Genes were categorized as “protein coding” and “non-coding” based on their functional annotation. Among non-coding sequences rRNAs, tRNAs, miRNAs snoRNAs and other known classes of RNAs were excluded from further analysis. LncRNAs were defined as all non-coding sequences longer than 200 bp and not belonging to other RNA categories. Based on those filtering criteria, 1653 lncRNAs expressed in PCa xenografts were identified. 
     Database Analysis 
     LOC728606 expression was also queried in Oncomine (www.oncomine.com) GEO (www.ncbi.nlm.nih.gov/geo/) and Cbio portal (www.cbioportal.org) gene expression databases. Analysis was restricted to PCa and prostate-derived samples. 
     Selected non-coding RNAs were analyzed through the cBio cancer genomic portal (12), which includes clinico-pathological and gene expression information from 29 normal prostate and 131 primary PCa samples (13). Gene expression data were downloaded from the portal as log 2 whole transcript normalized RNA expression values (Affymetrix Human Exon 1.0 ST arrays). To further characterize LOC728606 (JUPITER), expression patterns of JUPITER were analyzed in Oncomine (www.oncomine.com) and Gene Expression Omnibus (GEO) (http://www.ncbi.nim.nih.gov/geo/) databases, which include large collections of microarray data from human samples. Albeit these classical microarray platforms are restricted to mRNA detection, some of them might fortuitously hold probes matching a few lncRNAs. For Oncomine, a p value threshold of 0.01 (fold change&gt;2) was selected. For GEO data (HG-U95D), normalized values were plotted and analyzed using Graph Pad Prism 6 software (La Jolla, Calif.). 
     Significance Analysis of Microarrays (SAM) was performed in R using the 20 PCa samples expressing the highest and lowest levels of PCAT18 from the Cbio database (21)prostate cancer samples (22). Transcripts positively associated with PCAT18 (with Q&lt;0.5%) were analyzed using Oncomine to investigate correlations with clinical variables (threshold: p&lt;E −4 , odds ratio &gt;2). 
     Clinical Samples 
     Characteristics of al enrolled patients are summarized in Table 1 below. 
     Prostate Tissue Samples: 
     Samples from patients with benign prostatic hyperplasia (BPH) or PCa were collected at the Stephanshorn Clinic in St. Gallen Switzerland, after study protocol approval by the local ethical committee. Resected specimens were immediately transferred on ice to the Institute for Pathology of the Kantons Hospital, St. Gallen for examination. Small tissue samples from macroscopically visible tumor and non-tumor prostate tissue were dissected, snap frozen in liquid nitrogen and cryo-preserved at −80° C. These samples were cut in a cryo-microtome and a slide of each probe was stained with hematoxylin-eosin for histological verification. RNA was isolated from frozen materials using the TRI-reagent (Ambion) method according to the manufacturer&#39;s guidelines. Extracted RNA was quality-checked using the Agilent Bioanalyzer 2100 (Agilent). The cDNA was synthesized from 1 μg of total RNA using Superscript II RNase H-reverse transcriptase (Invitrogen). 
     Plasma Samples: 
     Upon study protocol approval by UBC REB, and after obtaining written informed consent from study participants, blood samples and clinico-pathological data were collected at the British Columbia Cancer Agency (BCCA), Vancouver Centre. Three cohorts were evaluated: 25 individuals with no clinical sign of neoplasm; 25 PCa patients with treatment-naïve localized disease (Localized PCa); 25 patients with a clinically confirmed metastatic PCa and a progressive disease despite castration therapy (mCRPC). Samples were processed as previously described (4) for plasma separation, RNA extraction and retrotransciption. 
     
       
         
           
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Clinical-pathological characteristics of enrolled patients. 
               
               
                   
               
             
            
               
                 PROSTATE TISSUE SAMPLES (N = 16) 
               
            
           
           
               
               
            
               
                   
                 Benign Prostatic 
               
            
           
           
               
               
               
            
               
                   
                 Prostate cancer 
                 Hyperplasia 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                 Median Age (Range) 
                 63 
                 (58-75) 
                 62 
                 (52-67) 
               
               
                 Median PSA at 
                 8 
                 (4.5-23.1) ng/ml 
                 4.1 
                 (2.9-5.3) ng/ml 
               
               
                 diagnosis (Range) 
               
            
           
           
               
               
               
            
               
                 Gleason Score 
                   
                   
               
               
                 ≦8 
                 5 
                 N.A. 
               
               
                 ≧8 
                 6 
                 N.A. 
               
               
                 TNM Stage 
               
               
                 T2a/N0/M0 
                 2 
                 N.A. 
               
               
                 T2c/N0/M0 
                 5 
                 N.A. 
               
               
                 T3/N0/M0 
                 4 
                 N.A. 
               
               
                   
               
            
           
           
               
            
               
                 PLASMA SAMPLES (N = 50) 
               
            
           
           
               
               
               
               
            
               
                   
                 Localized 
                   
                   
               
            
           
           
               
               
               
            
               
                   
                 Prostate Cancer 
                 mCRPC 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                 Median Age (Range) 
                 67 
                 (51-82) 
                 73 
                 (45-86) 
               
               
                 Median PSA at 
                 9.2 
                 (0.6-22) ng/ml 
                 120 
                 (6.3-4948.5) ng/ml 
               
               
                 diagnosis (Range) 
               
            
           
           
               
               
               
            
               
                 Risk Group 
                   
                   
               
               
                 Intermediate 
                 22 
                 N.A. 
               
               
                 Low 
                 3 
                 N.A. 
               
               
                 High 
               
               
                 Metastatic Sites 
               
               
                 Bone 
                 N.A. 
                 17 
               
               
                 Lymph nodes and 
                 N.A. 
                 5 
               
               
                 Others 
               
               
                 Others 
                 N.A. 
                 3 
               
               
                   
               
            
           
         
       
     
     “Risk groups” in Table 1 are defined based on pre-prostatectomy serum PSA value, T stage and Gleason Grade, as recommended by the Genito-Urinary Radiation Oncologists of Canada (2). PCa diagnosis was confirmed by pathological examination of tumor biopsies for each enrolled patient. Localized PCa cases were defined as those with no pathological evidence of lymph node dissemination and no clinical evidence of metastatic diffusion. PSA measurement and RNA extraction were performed on samples collected before prostatectomy and on treatment-naive patients. Metastatic cases were defined as those having clinical or pathological evidence of cancer dissemination to any of the following: lymph nodes, bones or soft tissues (lung, brain, spine, testis). 
     Quantitative PCR 
     Primers targeting selected lncRNAs were designed using BLAST software. Primer sequences (as listed in Table 2 below) were contrasted to the  Homo Sapiens  and  Mus Musculus  trancriptome to ensure their specificity for the intended target gene. Custom DNA oligos were provided by Invitrogen. RNA, extracted from xenografts as described above, was retrotranscribed using QuantiTect Reverse Transcription kit (Qiagen) following manufacturer&#39;s instructions. RNA extraction and retrotranscription for clinical samples are described above. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Primer Sequences for Amplifying Select IncRNAs  
               
            
           
           
               
               
               
               
               
            
               
                   
                 SEQ ID 
                   
                 SEQ ID 
                   
               
               
                 Gene 
                 NO. 
                 Forward Primer 
                 NO. 
                 Reverse Primer 
               
               
                   
               
               
                 HPRT1 
                  2 
                 GGTCAGGCAGTATAATCCAAAG 
                  3 
                 CGATGTCAATAGGACTCCAGATG 
               
               
                   
               
               
                 GAPDH 
                  4 
                 CACCAGGGCTGCTTTTAACTC 
                  5 
                 GACAAGCTTCCCGTTCTCAG 
               
               
                   
               
               
                 PCAT18 
                  6 
                 AGGAGACAGGCCCCAGATTT 
                  7 
                 TGAAGTGCTGGGACAACGTA 
               
               
                   
               
               
                 PCGEM1 
                  8 
                 TTGCCCTATGCCGTAACCTG 
                  9 
                 ACGTTGAGTCCCAGTGCATC 
               
               
                   
               
               
                 H19 
                 10 
                 CCAGTGAGGAGTGTGGAGTAG 
                 11 
                 CAGCTGCCACGTCCTGTAAC 
               
               
                   
               
               
                 Linc461_1 
                 12 
                 AGGAAACAGCTCTGGCATCC 
                 13 
                 CAGATTCCCCACCCCCTTTC 
               
               
                   
               
               
                 Linc461_3 
                 14 
                 GTTCCTGCCCAGCTGGATTT 
                 15 
                 TCAGAGTAGTCCACGCCAGA 
               
               
                   
               
               
                 LOC285419 
                 16 
                 TGACTCAACTTCTGGTGCAGAT 
                 17 
                 GGATGTGGCATATCTCTTGGTTTA 
               
               
                   
               
               
                 NCRNA116 
                 18 
                 GAGACTGCTCAGAGGAAGAGAA 
                 19 
                 CAGACAGCCCAGTGTCTTGG 
               
               
                   
               
               
                 KLK3 
                 20 
                 AGTGCGAGAAGCATTCCCAAC 
                 21 
                 CCAGCAAGATCACGCTTTTGTT 
               
               
                   
               
            
           
         
       
     
     Quantitative PCR was performed as previously described (14) using cDNA, primers and KAPA SYBR fast Universal Master Mix through ABIPrism 7900HT (Applied Biosystems) and following manufacturers&#39; instructions. The 2 −ΔΔCT  method was used for calculating the fold changes relative to the endogenous controls (HPRT and GAPDH, whose expression was stable in primary and metastatic xenografts, according to RNA Seq. data). Primers specific for the 2 main variants of linc461 (transcript variant 1 LINC461_1 and transcript variant 3 LINC461_3) were designed to confirm separately their up-regulation. For plasma sample studies, mir30e was used for normalization since its expression has been shown to be stable in plasma samples of normal and PCa patients (4). 
     To confirm PCAT18 expression patterns with another methodology, Applied Biosystem Non-coding RNA assay Hs03669364_m1 was employed, which is specific for LOC728606 (PCAT18) and spans the exon1-exon2 boundary. QPCR was performed according to manufacturer&#39;s instructions on the ABIPrism 7900HT (Applied Biosystems). The 2 −ΔΔT  method was used for calculating the fold changes relative to endogenous control (GAPDH). 
     TaqMan qPCR was also performed to quantify the sub-cellular localization of PCAT18. GAPDH and MALAT1 (Hs00273907_s1). Total, cytoplasmic and nuclear RNA was extracted and purified using the Ambion PARIS kit (Life Technologies), following manufacturer&#39;s instruction. 
     In Vitro Experiments 
     Unless otherwise specified, Prostate cancer- and benign prostatic hyperplasia-derived cell lines were maintained in 10% fetal bovine serum (GIBCO, Life Technologies) and RPMI 1640 growth medium (GIBCO, Life Technologies). 
     Gene Silencing: cells were treated with 2 nM PCAT18 (LOC728606)-targeting siRNAs (siRNA1 and siRNA2) or negative control (NC) reagent (Dicer substrate siRNAs, Integrated DNA Technology, Duplex names: NR_024259_1 (siRNA1); NR_024259_2 (siRNA2); DS_NC1), following manufacturer&#39;s instructions. NC (negative transfection control) is a DsiRNA duplex that does not target any known human or mouse transcript. Lipofectamine RNAiMaX (Invitrogen) was employed as the transfection reagent RNA extraction, retrotranscription and qPCR were performed as described in  FIG. 1(B)  legend. 
     MTT assay was performed on LNCaP, C4-2 and BPH cells treated with NC or PCAT18-targeting siRNAs (both at 2 nM concentration) on days 1-3-5 post-transfection, as previously described (Watahiki A, et al. MicroRNAs associated with metastatic prostate cancer. PloS one. 2011; 6(9):e24950). 
     Caspase 3 and 7 activity was quantified through Caspese-Glo 3/7 assay (Promega), as previously described (Crea F, et al. BMI1 silencing enhances docetaxel activity and impairs antioxidant response in prostate cancer.  International journal of cancer Joumal international du cancer.  2011; 128(8):1946-1954) on cells transfected with the above described protocol. 
     The wound healing assay was performed in triplicate on C4-2 cells as previously described (Decker K F, et al. Persistent androgen receptor-mediated transcription in castration-resistant prostate cancer under androgen-deprived conditions.  Nucleic acids research.  2012; 40(21):10765-10779). Transfection protocols were identical to those described above. 12 hours post-transfection, a ‘wound’ was produced using a P20 pipette tip. Pictures were taken at marked spots 0-6-24-48 h post-wounding, using a Zeiss Axiovert 40 CFL inverted microscope connected to Axiovision 4.7 software. Invasion assay was performed in triplicate on C4-2 cells using BD BioCoat™ BD Matrigel™ Invasion Chambers (24-well plates) and following manufacturers instructions. Transfection was performed on day 0, as described above. After 12 hours, cells were plated in the invasion chambers. 16 hours post-plating, we followed a previously described method for analysis and quantification of invading cells (Crea F, et al. Pharmacologic disruption of Polycomb Repressive Complex 2 inhibits tumorigenicity and tumor progression in prostate cancer.  Molecular cancer.  2011; 10:40). 
     Antisense Oligonucleotide Knockdown. C4-2 cells were treated with 160 nM of PCAT18-targeting antisense oligonucleotides (ASO2 and ASO7), or antisense oligonucleotide (NC) with no known specific target in human or mouse genome. ASO sequences ASO2 and ASO7 are detailed in  FIGS. 9(B) and 9(C) , respectively. The antisense oligonucleotide (NC) is detailed in  FIG. 9(A) . The antisense oligonucleotides were purchased from Integrated DNA Technologies. The ‘*’ in the sequences represent phosphorothioate backbone. The oligonucleotides were re-suspended in 1×TE buffer as per manufacturers instructions. ASO transfections were performed following manufacturers instructions using Oligofectamine (Life Technologies) as the transfecting reagent. Gene quantification (via quantitative PCR) was performed as described above. 
     Statistical Analysis 
     Unless otherwise specified, all statistical analyses were performed using Graph Pad Prism 6 software (La Jolla, Calif.). 
     Example 1: Identification of PCAT18 
     The identification of novel biomarkers and therapeutic targets for mCRPC has been hampered by the lack of suitable models that accurately reflect the clinical reality. This hurdle has been overcome by the generation of xenograft models developed from primary patient samples. In the present application, 2 PCa xenograft lines were exploited: LTL-313B and LTL-313H. Both models were derived from PCa biopsies of the same patient, yet they display a strikingly different phenotype. LTL-313B cells (non-metastatic) showed little local invasion and no distant metastasis while LTL-313H xenografts (metastatic) showed invasion into the mouse host kidney and distant metastases were detectable in the hosts&#39; lungs 3 months after engraftment ( FIG. 1A ). 
     RNA Sequencing was performed on paired metastatic/non-metastatic PCa orthotopic xenografts derived from clinical specimens. The most differentially expressed lncRNA was further analyzed in clinical samples and publically available databases. 
     New lncRNAs associated with PCa metastasis were identified using RNA Sequencing analysis on the patient-derived PCa xenografts was performed using the strategy outlined in Table 3. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 RNA Sequence Analysis on Matched Primary and Metastatic PCa 
               
               
                 Xenografts. 
               
            
           
           
               
               
               
            
               
                   
                 Non-metastatic 
                 Metastatic 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Mapped Reads 
                 17,259,797 
                 15,244,256 
               
               
                   
                 Unique Reads 
                 15,711,473 
                 13,704,330 
               
               
                   
                 Protein coding genes 
                 18872 
                 18872 
               
               
                   
                 Up-regulated IncRNAs (total) 
                 77 (1668) 
                 153 (1668) 
               
               
                   
                   
               
            
           
         
       
     
     In Table 3 above, genes were categorized as “protein coding” and “non-coding” based on their functional annotation. Among non-coding sequences rRNAs, tRNAs, miRNAs and other known classes of RNAs were excluded from further analysis. LncRNAs were defined as all non-coding sequences longer than 200 bp and not belonging to other RNA categories. Based on those filtering criteria, 1668 lncRNAs expressed in PCa xenografts were identified. 
     Sequencing analysis on the patient-derived PCa xenografts showed that 153 lncRNAs were up-regulated and 77 were down-regulated in metastatic vs non-metastatic xenografts (see Tables 4 and 5 below). The vast majority of these transcripts have not been previously characterized. Of note, the list of up-regulated transcripts included two known oncogenic lncRNAs, H19 and PCGEM1 (8, 15), while the down-regulated transcripts included the only known onco-suppressive lncRNA in PCa (PTENP1) (16). PCA3 was detectable in both models, but its differential expression was below the significance threshold (LTL313H vs. LTL313B RPKM ratio=1.38). One or more than one of the lncRNAs listed in Table 4 may be used in combination with PCAT18 in order to diagnose or treat prostate cancer using the methods as described herein. 
                     TABLE 4                  IncRNAs Up-regulated in Metastatic (313H) vs. Localized (313B)       PCa xenografts.                                 Gene Name   Gene Coordinates   Category   RPKM 313H   RPKM 313B                                         LOC728606   chr18: 24267585-24283602   RNA gene   2.992   0.9714       PCGEM1   chr2: 193614571-193641621   RNA gene   2.71   0.3074       LOC100329109   chr2: 206980297-206981296   pseudogene   1.242   0.3546       Linc461   chr5: 87960264-87969146   RNA gene   0.8182   0.1868       C21orf82   chr21: 35552978-35562220   RNA gene   0.7301   0.1746       FLJ40852   chr7: 141404138-141438030   RNA gene   0.7177   0.2155       C6orf41   chr6: 26924772-26991752   RNA gene   0.6849   0.2271       NCRNA00235   chr16: 576847-577407   RNA gene   0.6809   0.237       PMS2L4   chr7: 66757424-66767406   pseudogene   0.665   0.2341       NCRNA00092   chr9: 98782016-98784037   RNA gene   0.6636   0.2569       FLJ12825   chr12: 54452038-54516018   RNA gene   0.6541   0.2586       LOC286094   chr8: 136246374-136311959   RNA gene   0.5404   0.1792       PRO0628   chr20: 39666473-39667632   uncategorized   0.5351   0.1911       LOC441046   chr4: 144480625-144482612   pseudogene   0.5284   0.2453       RPL13AP3   chr14: 56232963-56234434   pseudogene   0.519   0.1806       LOC100009676   chr3: 101395274-101398055   RNA gene   0.5134   0.1111       LOC644145   chr4: 56686237-56703430   pseudogene   0.4923   0.1142       C2orf58   chr2: 38358247-38408991   RNA gene   0.4909   0.2278       GTF2IRD2P1   chr7: 72656902-72685658   pseudogene   0.4833   0.01473       ISCA1P1   chr5: 62071202-62073170   pseudogene   0.4832   0.189       LOC285419   chr4: 124695419-124786732   RNA gene   0.4758   0.1405       NCRNA00116   chr2: 110969106-110980517   RNA gene   0.4719   0.1095       ADAM6   chr14: 106435819-106438358   pseudogene   0.4666   0.1925       TRIM78P   chr11: 5664412-5687608   pseudogene   0.4537   0.07019       TYRO3P   chr15: 76551630-76552493   pseudogene   0.4421   0.0513       LOC100131193   chr9: 139698379-139703300   RNA gene   0.4403   0.1486       RPS10P7   chr1: 201489032-201489718   pseudogene   0.4169   0.06443       LOC339568   chr20: 37842424-37853391   RNA gene   0.41   0.1464       HAS2AS   chr8: 122651586-122656933   RNA gene   0.4079   0.05409       C16orf67   chr16: 31711934-31718743   RNA gene   0.4037   0.09994       LOC440839   chr2: 113917421-114205429   pseudogene   0.4014   0.187       LOC154761   chr7: 143509061-143533810   RNA gene   0.3968   0.1929       HULC   chr6: 8652442-8654077   RNA gene   0.3963   0.09196       SNHG12   chr1: 28905052-28908366   RNA gene   0.3887   0.1804       C2orf52   chr2: 232373137-232379050   RNA gene   0.3725   0.1694       H19   chr11: 2016406-2019065   RNA gene   0.3724   0.03841       UOX   chr1: 84830648-84863576   pseudogene   0.3711   0.1722       DIRC3   chr2: 218148748-218621316   RNA gene   0.3669   0.1476       PCNAP1   chr4: 100081753-100082804   pseudogene   0.3631   0.1264       C1orf220   chr1: 178511931-178518024   RNA gene   0.3515   0.086       HTR7P1   chr12: 13153376-13157762   pseudogene   0.3478   0.1716       CTSLL2   chr10: 48155943-48158691   pseudogene   0.3457   0.1203       C6orf176   chr6: 166337536-166401527   RNA gene   0.3402   0.07894       LOC1518   chr9: 90459660-90462338   pseudogene   0.3363   0.1561       PIPSL   chr10: 95717897-95721672   pseudogene   0.3274   0.1408       FLJ41941   chr22: 18512151-18520734   RNA gene   0.3211   0.1489       C21orf71   chr21: 26955088-26955536   RNA gene   0.319   0.09872       C8ORFK29   chr8: 145576887-145578505   RNA gene   0.3159   0.04887       LOC339535   chr1: 238643686-238649317   RNA gene   0.3123   0.02899       C21orf41   chr21: 30968360-31003067   RNA gene   0.3115   0.08262       MCM3APAS   chr21: 47649158-47671604   RNA gene   0.3095   0.1149       LOC257358   chr5: 169758435-169762104   RNA gene   0.3033   0.06033       C1orf180   chr1: 85093913-85100703   RNA gene   0.298   0.09222       LOC646813   chr11: 50368318-50379802   pseudogene   0.298   0.1037       CIDECP   chr3: 10059237-10067820   pseudogene   0.2973   0.1104       ZSCAN12P1   chr6: 28058929-28063492   pseudogene   0.296   0.1314       LOC389634   chr12: 8509562-8543348   RNA gene   0.2898   0.1345       C17orf91   chr17: 1614799-1619566   RNA gene   0.2845   0.1337       LOC282997   chr10: 112628648-112630662   RNA gene   0.2844   0.06599       LOC146880   chr17: 62774258-62777622   RNA gene   0.2837   0.07714       RBMY2FP   chrY: 24455006-24462350   pseudogene   0.2809   0.04346       LOC152024   chr3: 24141465-24144738   RNA gene   0.277   0.07911       C3orf51   chr3: 55691245-55693497   RNA gene   0.2755   0.01967       C14orf132   chr14: 96505662-96560133   RNA gene   0.2742   0.1238       LOC100129396   chr17: 16692057-16693815   RNA gene   0.2713   0.1008       NCRNA00093   chr10: 101686966-101718755   RNA gene   0.2701   0.1337       LOC401010   chr2: 132199734-132202467   pseudogene   0.262   0.0486       LOC285692   chr5: 9641428-9903936   RNA gene   0.2589   0.02404       LOC100128842   chr1: 1193438-1196954   RNA gene   0.2574   0.1008       RPSAP52   chr12: 66151803-66220754   pseudogene   0.2511   0.03885       DUSP5P   chr1: 228780657-228788159   pseudogene   0.2511   0.07172       FASAS   chr10: 90751183-90752732   RNA gene   0.2465   0.1144       PIN1L   chr1: 70385005-70386000   pseudogene   0.2397   0.08901       SUMO1P3   chr1: 160287055-160288258   pseudogene   0.2379   0.07363       TTC3L   chrX: 74960373-74962914   pseudogene   0.2254   0.06971       NCRNA00110   chr21: 31120494-31136323   RNA gene   0.2188   0.04063       C14orf34   chr14: 56247854-56263392   RNA gene   0.2142   0.06629       NCRNA00052   chr15: 88120160-88122917   RNA gene   0.2139   0.04964       SOX2OT   chr3: 181328151-181459003   RNA gene   0.2107   0.07112       FLJ14107   chr8: 22497884-22499722   RNA gene   0.2077   0.07231       FLJ13224   chr12: 31477250-31478879   RNA gene   0.2051   0.02719       NCRNA00174   chr7: 65841032-65865395   RNA gene   0.2051   0.08016       C6orf217   chr6: 135818939-136011975   RNA gene   0.2044   0.08133       LOC100130522   chr18: 77905807-77929616   RNA gene   0.1957   0.05318       LOC400752   chr1: 45769582-45771290   RNA gene   0.1956   0.05187       FAM92A3   chr4: 183958818-183961271   pseudogene   0.1946   0.05419       C3orf65   chr3: 185431040-185435955   RNA gene   0.1945   0.04514       TMPRSS8P   chr16: 2889575-2892752   pseudogene   0.1935   0.04489       BTN2A3   chr6: 26421619-26430816   pseudogene   0.1923   0.08926       LOC100129534   chr1: 2281853-2284100   pseudogene   0.1912   0.07887       LOC255512   chr11: 1330938-1331936   RNA gene   0.1912   0.08874       EP400NL   chr12: 132568828-132610885   pseudogene   0.1862   0.0576       AKR7L   chr1: 19592476-19600568   pseudogene   0.1804   0.06281       BPESC1   chr3: 138823027-138844003   RNA gene   0.1768   0.07573       SIGLEC16   chr19: 50472912-50479075   pseudogene   0.1763   0.05513       NCRNA00176   chr20: 62665697-62671314   RNA gene   0.1734   0.05082       LOC100130015   chr16: 90106171-90114033   pseudogene   0.1729   0.06581       TTTY11   chrY: 8651359-8685423   RNA gene   0.1728   0.05347       MGC23270   chr14: 105287538-105290055   RNA gene   0.1707   0.07041       C9orf106   chr9: 132083295-132084882   RNA gene   0.1699   0.05258       C11orf64   chr11: 60383224-60454619   RNA gene   0.1687   0.05221       GSTM2P1   chr6: 111367623-111368757   pseudogene   0.1683   0.03905       NCRNA00203   chr14: 93533797-93538476   RNA gene   0.1632   0.07577       NCRNA00226   chr14: 106744269-106744965   RNA gene   0.1608   0.07462       FAM153C   chr5: 177435689-177474656   pseudogene   0.1585   0.0735       LOC723809   chr7: 104535075-104567092   RNA gene   0.1564   0.07258       LOC653113   chr12: 8383646-8395542   pseudogene   0.1548   0.06203       MGC16275   chr17: 72206141-72209460   RNA gene   0.1541   0.05364       PRNT   chr20: 4711929-4721314   RNA gene   0.153   0.06347       SH3GL1P1   chr17: 30367355-30369851   pseudogene   0.1529   0.01773       C4orf12   chr4: 85887971-85928168   RNA gene   0.1522   0.0565       LOC285456   chr4: 109459346-109541613   RNA gene   0.1519   0.04699       BTF3L1   chr13: 77502585-77503223   pseudogene   0.1495   0.06916       INTS4L1   chr7: 64601603-64694599   pseudogene   0.1494   0.06938       FLJ40504   chr17: 26603012-26634408   pseudogene   0.1469   0.02273       CTSL3   chr9: 90387830-90401799   pseudogene   0.1454   0.06747       TUBB4Q   chr4: 190903679-190906024   pseudogene   0.1453   0.03393       CYP2D7P1   chr22: 42536216-42540575   pseudogene   0.1422   0.05279       C17orf44   chr17: 8123949-8127361   RNA gene   0.1369   0.06353       MORF4   chr4: 174537088-174537794   pseudogene   0.1351   0.06269       PYY2   chr17: 26553589-26555083   pseudogene   0.1341   0.0415       FLJ39534   chr3: 47205860-47285605   RNA gene   0.1316   0.05237       LOC650368   chr11: 3402191-3430378   pseudogene   0.1293   0.03001       LOC100133957   chrX: 47518252-47519776   RNA gene   0.1252   0.05813       HLA-DPB2   chr6: 33080293-33096890   pseudogene   0.1186   0.05506       C21orf15   chr21: 15215455-15220685   RNA gene   0.1119   0.03464       PPP1R2P9   chrX: 42636619-42637486   pseudogene   0.11   0.05107       FLJ40292   chr9: 140657474-140659222   RNA gene   0.1092   0.02534       CSDAP1   chr16: 31579088-31580845   pseudogene   0.1086   0.05043       LOC643387   chr2: 239140327-239142983   pseudogene   0.1078   0.01668       LOC642846   chr12: 9436253-9466684   RNA gene   0.1075   0.02531       TDH   chr8: 11197146-11225961   pseudogene   0.1056   0.03266       NCRNA00087   chrX: 134229015-134232733   RNA gene   0.102   0.04731       PI4KAP1   chr22: 20383731-20398695   pseudogene   0.1012   0.03756       UBE2MP1   chr16: 34403802-34404762   pseudogene   0.09938   0.04612       SSX8   chrX: 52651985-52662998   pseudogene   0.09907   0.03065       NF1P1   chr15: 21122021-21134625   pseudogene   0.09875   0.04582       C21orf90   chr21: 45937098-45938859   RNA gene   0.09845   0.0457       LOC553137   chr6: 107218007-107222877   uncategorized   0.09721   0.0361       LOC154822   chr7: 158801045-158818928   RNA gene   0.09521   0.04395       C8orf51   chr8: 144448794-144450805   RNA gene   0.09493   0.02203       LOC285501   chr4: 178649911-178911903   RNA gene   0.09245   0.04291       TBC1D3P2   chr17: 60342069-60353016   pseudogene   0.09224   0.04303       DKFZp434L192   chr7: 56563916-56564977   RNA gene   0.08992   0.04174       LOC100189589   chr2: 74612845-74621008   RNA gene   0.08909   0.04135       FLJ36000   chr17: 21904062-21913070   RNA gene   0.08801   0.03501       FAM35B2   chr10: 47379720-47421236   pseudogene   0.08689   0.04029       LOC283761   chr15: 90048162-90067265   RNA gene   0.0808   0.03771       LOC149837   chr20: 5479218-5485242   RNA gene   0.07978   0.02469       LOC100134259   chr2: 47055003-47086145   RNA gene   0.07893   0.03663       LOC100288778   chr12: 87984-91262   pseudogene   0.07816   0.03624       C14orf48   chr14: 94463642-94478040   RNA gene   0.0749   0.02369       KIAA0125   chr14: 106383838-106398500   RNA gene   0.07452   0.01845                    
Displayed genes showed an RMS-normalized RPKM ratio higher than 2 and were ranked based on expression level in 313H cells.
 
                     TABLE 5                  IncRNAs Down-regulated in a metastatic (313H) vs. Localized       (313B) PCa xenograft.                                             RPKM           Gene Name   Gene Coordinates   Category   313H   RPKM 313B                                         BCL8   chr15: 20874797-20961480   pseudogene   1.48   4.125       RPL23AP32   chr2: 54756359-54756978   pseudogene   1.494   3.507       GNRHR2   chr1: 145509820-145516076   pseudogene   0.9937   3.053       LOC643837   chr1: 763064-789740   RNA gene   0.4947   1.406       RPL29P2   chr17: 7657638-7658284   pseudogene   0.2952   0.8221       C8orf56   chr8: 104145192-104153570   RNA gene   0.2894   0.8059       LOC146481   chr16: 34711785-34714967   pseudogene   0.2624   0.6819       LOC286467   chrX: 130836679-130964671   RNA gene   0.1293   0.6511       PAR1   chr15: 25380789-25383200   RNA gene   0.2574   0.6432       OR4N3P   chr15: 22413462-22414393   pseudogene   0.1025   0.6182       BDNFOS   chr11: 27528399-27699348   RNA gene   0.2591   0.6119       HPVC1   chr7: 54268917-54270114   RNA gene   0.1993   0.592       DLEU2L   chr1: 64014651-64016307   pseudogene   0.2305   0.5885       LOC100130987   chr11: 67085310-67159158   RNA gene   0.1685   0.5736       SAA3P   chr11: 18134020-18137679   pseudogene   0.149   0.5532       SBDSP1   chr7: 72299952-72307976   pseudogene   0.1685   0.4984       LOC153684   chr5: 43042236-43045370   RNA gene   0.2113   0.4903       LOC440944   chr3: 9430537-9439174   RNA gene   0.154   0.4766       RPL13AP6   chr10: 112696361-112697013   pseudogene   0.1462   0.4752       LOC284900   chr22: 28315364-28398665   RNA gene   0.1402   0.4212       LOC150568   chr2: 105050805-105129214   RNA gene   0.1587   0.4126       LOC202781   chr7: 154795143-154797412   RNA gene   0.08414   0.41       RPL32P3   chr3: 129101678-129118282   pseudogene   0.1151   0.4058       LOC121838   chr13: 44596471-44604598   RNA gene   0.1304   0.3632       LOC595101   chr16: 30278914-30346695   pseudogene   0.111   0.3606       RAB9P1   chr5: 104435175-104435798   pseudogene   0.153   0.3552       LOC100132215   chr2: 63271100-63275656   RNA gene   0.05064   0.3525       LOC202181   chr5: 177045501-177099278   RNA gene   0.06685   0.3413       LOC100233209   chr12: 47602203-47610226   RNA gene   0.1336   0.3366       LOC100101938   chr13: 19836941-19919113   pseudogene   0.1282   0.3332       LOC283914   chr16: 34597902-34624953   RNA gene   0.1045   0.3233       LOC80054   chr19: 33793763-33795962   RNA gene   0.06511   0.3224       SMAD5OS   chr5: 135465205-135470579   RNA gene   0.1321   0.3189       LOC648691   chr22: 22901756-22909006   RNA gene   0.06153   0.3141       FLJ43390   chr14: 62584075-62595131   RNA gene   0.1107   0.3082       C18orf18   chr18: 5236724-5238028   RNA gene   0.07318   0.3057       LOC285733   chr6: 131148324-131156430   RNA gene   0.1074   0.2992       HEJ1   chr1: 102337567-102360299   pseudogene   0.1072   0.2985       LOC285735   chr6: 133409219-133427710   RNA gene   0.1187   0.2938       FLJ37307   chr13: 52387483-52419286   RNA gene   0.04795   0.2893       CCT6P1   chr7: 65216092-65228661   pseudogene   0.1082   0.276       LOC127841   chr1: 204337558-204338847   RNA gene   0.111   0.2749       FLJ35390   chr7: 44079067-44082081   RNA gene   0.089   0.2685       HSP90B3P   chr1: 92100568-92109334   pseudogene   0.07017   0.2605       C1orf213   chr1: 23695464-23698278   RNA gene   0.1018   0.2499       LOC284788   chr20: 22380971-22401281   RNA gene   0.08953   0.2493       PTENP1   chr9: 33673507-33677418   pseudogene   0.08543   0.2492       TMEM191A   chr22: 21055402-21058891   RNA gene   0.07316   0.249       MCART3P   chr6: 66497772-66499375   pseudogene   0.05954   0.2487       LOC286359   chr9: 100153121-100158973   RNA gene   0.09479   0.242       LOC100379224   chr19: 44609494-44617336   RNA gene   0.08527   0.2375       LOC728723   chr5: 76382623-76444175   RNA gene   0.0837   0.2331       LOC541473   chr7: 72440192-72443660   pseudogene   0.09825   0.2279       SYT14L   chr4: 68926330-68929015   pseudogene   0.07273   0.2194       GK3P   chr4: 166198944-166201175   pseudogene   0.0855   0.2183       ST7OT3   chr7: 116822735-116849991   RNA gene   0.09326   0.2164       EGOT   chr3: 4790880-4793274   RNA gene   0.06541   0.2125       ARMCX4   chrX: 100673266-100788446   RNA gene   0.03532   0.1967       AFG3L1   chr16: 90038988-90063028   pseudogene   0.07533   0.1959       SMCR5   chr17: 17680000-17682843   RNA gene   0.06716   0.1868       LOC100126784   chr11: 19732481-19736146   RNA gene   0.0521   0.1865       PMS2L11   chr7: 76610139-76653074   pseudogene   0.05429   0.1763       AMZ2P1   chr17: 62962668-62971703   RNA gene   0.02775   0.1674       MGC2889   chr3: 192959568-192961760   RNA gene   0.06532   0.1617       LOC339524   chr1: 87595448-87602350   RNA gene   0.06287   0.1582       C3orf66   chr3: 108897012-108904107   RNA gene   0.05678   0.1581       HCG27   chr6: 31165537-31171744   RNA gene   0.05556   0.1547       RRN3P2   chr16: 29086163-29128036   pseudogene   0.03989   0.1481       C6orf122   chr6: 170188886-170198921   RNA gene   0.0395   0.1466       CFLP1   chr10: 89578070-89605365   pseudogene   0.04513   0.1466       LOC647946   chr18: 36786888-37331959   RNA gene   0.04448   0.1445       LOC100271722   chr22: 46435789-46440748   RNA gene   0.05939   0.1378       HOTAIR   chr12: 54356098-54362515   RNA gene   0.04097   0.1141       LOC619207   chr10: 135267432-135281949   pseudogene   0.03898   0.09046       ASFMR1   chrX: 146990949-147003676   RNA gene   0.03246   0.08789       ALOXI2P2   chr17: 6756895-6803667   pseudogene   0.03451   0.0801       LOC100303728   chrX: 118599997-118603083   RNA gene   0.03094   0.07179                    
Displayed genes showed an RMS-normalized RPKM ratio lower than 2 and were marked based on expression level in 3138 cells.
 
     To validate the RNA Sequencing data, primers were designed for 7 of the differentially modulated lncRNAs (listed in Table 2 above) and greater than 2-fold up-regulation for each of them in the metastatic vs. non-metastatic xenografts was confirmed ( FIG. 1B ). 
     Among the differentially expressed lncRNAs, the transcript with highest expression in the metastatic xenograft was LOC728606, a previously uncharacterized gene. This transcript showed a similar magnitude of fold-change with 2 previously known oncogenic lncRNAs ( FIG. 1B ). LOC728606, flanked by AQP4 (Aquaporin-4) and KCTD1 (Potassium channel tetramerisation domain containing-1) loci, is transcribed to generate a 2598 bp RNA containing 2 exons ( FIG. 1C ), and is classified as a “long intergenic non-coding RNA” based on Ensembl algorithm (www.ensembl.org). ORF Finder (www.ncbi.nlm.nih.gov/gorf/gorf.html) revealed that the transcript is composed of non-translatable regions for at least 84% of its length ( FIG. 1D ). Test-code software (17) confirmed that the RNA does not encode a protein (p&lt;0.01), and PepBank (Shtatland T, et al. PepBank—a database of peptides based on sequence text mining and public peptide data sources.  BMC bioinformatics.  2007; 8:280) failed to identify any human peptide matching any ORF of this locus. Transcript length and sequence was confirmed by comparative analysis of multiple clones (as shown in Table 6). 
                     TABLE 6                  Summary of All Sequenced Clones from LOC728606 (PCAT18).                                                                 Base                   From   From       differences                   bp to   bp to   Accession   relative to       cDNA       Match   bp in   bp in   match over   genome       accession   Tissue   mRNA   mRNA   accs.   (% length)   (% identity)               AK056805   Prostate   AS   1 to   2 to   2598/2598   9 diff                   2597   2598   (100%)   (99.7% id)        DA865211   Prostate   AS   1 to   2 to   825/825   12 diff                    824   826   (100%)   (98.6% id)        BX119491   poorly differentiated   AS   245 to   458 to   444/444   0 diff           adenocarcinoma, stomach       688   15   (100%)   (100% id)       AI685598   Prostate   AS   245 to   452 to   443/468   0 diff                   687   10    (94%)   (100% id)       FN152668   breast carcinoma   AS   358 to   1 to   90/90   0 diff                   447   90   (100%)   (100% id)       AI926047   poorly differentiated   AS   409 to   290 to   283/290   0 diff           adenocarcinoma with       690   8    (97%)   (100% id)           signet ring cell           features, stomach       AA635604   Prostate   AS   428 to   264 to   264/264   0 diff                   691   1   (100%)   (100% id)       DB329187   Prostate   AS   2162 to   439 to   439/444   0 diff                   2597   1    (98%)   (100% id)                    
All known clones matching the LOC728606 sequence (NR_024259.1) were searched through the AceView database. Eight sequences were found, five of which were from prostate tissue and three from neoplastic tissues. The 5′ end of the gene is confirmed by independent readings. The AK056805 clone was generated using a 5′ oligo-capping method and polydT primers (Watahiki A. et al.,  PloS one.  2011; 6(9):e24950). The reference sequence was derived from AK056805.1 and DA865211. Match mRNA is antisense strand (AS) for all reads. We analyzed the polyA signal of the NP_024259.1 and AK056805.1 clones. A PolyA signal, AATAAA, was identified −25 to −18 bases from the 3′ end.
 
     Example 2: Expression Analysis of JUPITER (Also Known as PCAT18) 
     The expression of LOC728606 was investigated in publically available databases, for example, the Oncomine™ ( FIG. 2A ) and cBio ( FIG. 28 ) databases. LOC728606 expression profiles were mined on Oncomine and Gene Expression Omnibus (GEO) databases, which include large collections of microarray data from human samples. LOC728606 is significantly up-regulated in PCa vs, normal tissue in both the Oncomine™ ( FIG. 2A ) and cBio ( FIG. 28 ) databases. The data from the Oncomine™ analysis is summarized below in Table 7. 
                     TABLE 7                  Summary of all Oncomine ™ Outputs for LOC728606 in PCa, with p       value &gt;0.01 and/or fold change &lt;2.                                 Study   Comparison   P value   Fold Change   Samples                                         Arredouani   PCa vs. normal   0.043   2.0   21           prostate       Arredouani   ERG rearrangement   0.075   2.0   13           vs. no rearrangment       Bittner   PCa-smoker vs. non-   0.503   −1.0   46           smoker       Bittner   Acinar PCa-Grade 2   0.750   −1.80   10           vs. grade 3       Bittner   PCa-Grade 2/3 vs.   0.761   N.A.   46           grade 3       Bittner   PCa-Stage 2/3 vs.   0.750   N.A.   43           stage 4       Bittner   Acinar PCa-smoker   0.903   −2.2   11           vs. non-smoker                    
All PCa studies with patient data included in the Oncomine™ database were selected.
 
     In addition, this LOC728606 gene is significantly over-expressed in normal prostate compared to 11 other benign tissues ( FIG. 2C ) and in PCa compared to 15 other neoplastic tissues ( FIG. 2D ). Based on its chromosomal location and prostate cancer-specificity, this new gene was originally called JUPITER (Just Uncoding, Prostate-specific, Intergenic Transcript located on Eighteen chromosome Region q11.2). The HUGO Gene Nomenclature Committee has officially named this noncoding RNA PCAT18. 
     For further validation, the expression levels of JUPITER were analyzed in human prostate tissue and plasma samples using quantitative PCR (QPCR). JUPITER was highly up-regulated (8.8-11.1 fold, p&lt;0.001) in both low-Gleason and high-Gleason PCa samples, compared to benign prostatic hyperplasia (BPH) ( FIG. 3A ). Therefore, JUPITER up-regulation is not a mere function of prostate cells&#39; hyper-proliferation. 
     Based on its cancer and tissue-specificity, it was determined whether LOC728606 could be detected in plasma samples, and if it could be exploited as a biomarker for disease detection and monitoring. Plasma samples from normal individuals and those with localized PCa or mCRPC (n-25 per group, patients&#39; characteristics summarized in Table 1) were analyzed. The results indicate a positive correlation between plasma LOC728606 levels and disease stage and show a stepwise increase in JUPITER expression ( FIG. 3(B) , p&lt;0.01 for linear trend test), with significantly higher levels in mCRPC compared to all other categories. JUPITER expression (measured by QPCR) was also significantly elevated in 5 well-known human prostate cancer cell lines compared to a BPH cell line (BPH-1); see  FIG. 3C . 
     To further strengthen the above analysis, a new set of primers and a different qPCR methodology was used to confirm the LOC728606 expression profile in both preclinical and clinical samples ( FIGS. 8(A) and 8(B) ). In light of these data, this gene was officially named PCAT18 (Prostate Cancer-Associated Transcript-18) by the HUGO Gene Nomenclature Committee. 
     Example 3: Identification of Transcripts Associated with JUPITER 
     Based on its expression profile, it was hypothesized that JUPITER might contribute to PCa clinical characteristics and interact with known oncogenic pathways. To this end, significance analysis of microarray data (SAM) was used to identify PCAT18-associated to transcripts. A dataset collecting RNA sequencing data and clinical Information on 131 PCa samples and 29 normal prostate tissues was exploited for this purposes. Analysis of this large dataset further confirmed that PCAT18 is significantly (p&lt;0.001) up-regulated in PCa vs normal prostate (data not shown). SAM revealed 402 genes positively and significantly associated with PCAT18/JUPITER expression in PCa samples, as shown in Table 8 below. One or more than one of the genes listed in Table 8 may be used in combination with PCAT18 in order to diagnose or treat prostate cancer using the methods as described herein. 
     
       
         
           
               
             
               
                 TABLE 8 
               
               
                   
               
               
                 PCAT18-associated expression signature. 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 ACACA 
                 acetyl-CoA carboxylase alpha 
               
               
                 ACADL 
                 acyl-CoA dehydrogenase, long chain 
               
               
                 ACN9 
                 ACN9 homolog ( S. cerevisiae ) 
               
               
                 ACP6 
                 acid phosphatase 6, lysophosphatidic 
               
               
                 ACSM1 
                 acyl-CoA synthetase medium-chain family member 1 
               
               
                 ACSM3 
                 acyl-CoA synthetase medium-chain family member 3 
               
               
                 ACSS1 
                 acyl-CoA synthetase short-chain family member 1 
               
               
                 ACY1 
                 aminoacylase 1 
               
               
                 ADARB2 
                 adenosine deaminase, RNA-specific, B2 (RED2 homolog rat) 
               
               
                 ADRB1 
                 adrenergic, beta-1-, receptor 
               
               
                 ADRB2 
                 adrenergic, beta-2-, receptor, surface 
               
               
                 AGA 
                 aspartylglucosaminidase 
               
               
                 AGAP1 
                 ArfGAP with GTPase domain, ankyrin repeat and PH domain 1 
               
               
                 AGFG2 
                 ArfGAP with FG repeats 2 
               
               
                 AK2P2 
                 adenylate kinase 2 pseudogene 2 
               
               
                 ALDH1A3 
                 aldehyde dehydrogenase 1 family, member A3 
               
               
                 ALG14 
                 asparagine-linked glycosylation 14 homolog ( S. cerevisiae ) 
               
               
                 ALKBH2 
                 alkB, alkylation repair homolog 2 ( E. coli ) 
               
               
                 ALMS1P 
                 Alstrom syndrome 1 pseudogene 
               
               
                 ANAPC5 
                 anaphase promoting complex subunit 5 
               
               
                 ANK3 
                 ankyrin 3, node of Ranvier (ankyrin G) 
               
               
                 ANKRD37 
                 ankyrin repeat domain 37 
               
               
                 ANKRD5 
                 ankyrin repeat domain 5 
               
               
                 AP2S1 
                 adaptor-related protein complex 2, sigma 1 subunit 
               
               
                 APOF 
                 apolipoprotein F 
               
               
                 ARF4P3 
                 ADP-ribosylation factor 4 pseudogene 3 
               
               
                 ARHGAP28 
                 Rho GTPase activating protein 28 
               
               
                 ATPSG2 
                 ATP synthase, H+ transporting, mitochondrial F0 complex, subunit C2 (subunit 9) 
               
               
                 ATP8A1 
                 ATPase, aminophospholipid transporter (APLT), class I, type 8A, member 1 
               
               
                 ATPIF1 
                 ATPase inhibitory factor 1 
               
               
                 BAIAP3 
                 BAI1-associated protein 3 
               
               
                 BCAM 
                 basal cell adhesion molecule (Lutheran blood group) 
               
               
                 BEND4 
                 BEN domain containing 4 
               
               
                 BIK 
                 BCL2-interacting killer (apoptosis-inducing) 
               
               
                 BOLA3 
                 bolA homolog 3 ( E. coli ) 
               
               
                 BPHL 
                 biphenyl hydrolase-like (serine hydrolase) 
               
               
                 BTBD11 
                 BTB (POZ) domain containing 11 
               
               
                 C10orf75 
                 chromosome 10 open reading frame 75 
               
               
                 C11orf10 
                 chromosome 11 open reading frame 10 
               
               
                 C11orf75 
                 chromosome 11 open reading frame 75 
               
               
                 C12orf60 
                 chromosome 12 open reading frame 60 
               
               
                 C14orf149 
                 chromosome 14 open reading frame 149 
               
               
                 C15orf23 
                 chromosome 15 open reading frame 23 
               
               
                 C15orf33 
                 chromosome 15 open reading frame 33 
               
               
                 C15orf61 
                 chromosome 15 open reading frame 61 
               
               
                 C16orf13 
                 chromosome 16 open reading frame 13 
               
               
                 C16orf70 
                 chromosome 16 open reading frame 70 
               
               
                 C17orf61 
                 chromosome 17 open reading frame 61 
               
               
                 C17orf79 
                 chromosome 17 open reading frame 79 
               
               
                 C18orf22 
                 chromosome 18 open reading frame 22 
               
               
                 C19orf46 
                 chromosome 19 open reading frame 46 
               
               
                 C19orf48 
                 chromosome 19 open reading frame 48 
               
               
                 C1orf66 
                 chromosome 1 open reading frame 66 
               
               
                 C2 
                 complement component 2 
               
               
                 C20orf196 
                 chromosome 20 open reading frame 196 
               
               
                 C20orf3 
                 chromosome 20 open reading frame 3 
               
               
                 C20orf96 
                 chromosome 20 open reading frame 96 
               
               
                 C22orf32 
                 chromosome 22 open reading frame 32 
               
               
                 C2orf72 
                 chromosome 2 open reading frame 72 
               
               
                 C2orf76 
                 chromosome 2 open reading frame 76 
               
               
                 C2orf79 
                 chromosome 2 open reading frame 79 
               
               
                 C3orf25 
                 chromosome 3 open reading frame 25 
               
               
                 C4orf14 
                 chromosome 4 open reading frame 14 
               
               
                 C4orf47 
                 chromosome 4 open reading frame 47 
               
               
                 C5orf49 
                 chromosome 5 open reading frame 49 
               
               
                 C6orf108 
                 chromosome 6 open reading frame 108 
               
               
                 C6orf124 
                 chromosome 6 open reading frame 124 
               
               
                 C6orf57 
                 chromosome 6 open reading frame 57 
               
               
                 C7orf53 
                 chromosome 7 open reading frame 53 
               
               
                 C8orf34 
                 chromosome 8 open reading frame 34 
               
               
                 C8orf45 
                 chromosome 8 open reading frame 45 
               
               
                 C9orf152 
                 chromosome 9 open reading frame 152 
               
               
                 C9orf43 
                 chromosome 9 open reading frame 43 
               
               
                 CAMK1 
                 calcium/calmodulin-dependent protein kinase I 
               
               
                 CAMK2B 
                 calcium/calmodulin-dependent protein kinase II beta 
               
               
                 CAMKK2 
                 calcium/calmodulin-dependent protein kinase kinase 2, beta 
               
               
                 CAPN9 
                 calpain 9 
               
               
                 CATSPER2 
                 cation channel, sperm associated 2 
               
               
                 CATSPER2P1 
                 cation channel, sperm associated 2 pseudogene 1 
               
               
                 CBS 
                 cystathionine-beta-synthase 
               
               
                 CCDC110 
                 coiled-coil domain containing 110 
               
               
                 CCDC149 
                 coiled-coil domain containing 149 
               
               
                 CCDC51 
                 coiled-coil domain containing 51 
               
               
                 CCT3 
                 chaperonin containing TCP1, subunit 3 (gamma) 
               
               
                 CDK3 
                 cyclin-dependent kinase 3 
               
               
                 CDK5 
                 cyclin-dependent kinase 5 
               
               
                 CECR5 
                 cat eye syndrome chromosome region, candidate 5 
               
               
                 CECR7 
                 cat eye syndrome chromosome region, candidate 7 (non-protein coding) 
               
               
                 CGREF1 
                 cell growth regulator with EF-hand domain 1 
               
               
                 CHDH 
                 choline dehydrogenase 
               
               
                 CHKA 
                 choline kinase alpha 
               
               
                 CHMP4C 
                 chromatin modifying protein 4C 
               
               
                 CHRNA2 
                 cholinergic receptor, nicotinic, alpha 2 (neuronal) 
               
               
                 CISD3 
                 CDGSH iron sulfur domain 3 
               
               
                 CLDN8 
                 claudin 8 
               
               
                 CLEC18A 
                 C-type lectin domain family 18, member A 
               
               
                 CLEC18B 
                 C-type lectin domain family 18, member B 
               
               
                 CLEC18C 
                 C-type lectin domain family 18, member C 
               
               
                 CMTM4 
                 CKLF-like MARVEL transmembrane domain containing 4 
               
               
                 CNTN3 
                 contactin 3 (plasmacytoma associated) 
               
               
                 CORO1B 
                 coronin, actin binding protein, 1B 
               
               
                 CPNE7 
                 copine VII 
               
               
                 CREB3L4 
                 cAMP responsive element binding protein 3-like 4 
               
               
                 CRYL1 
                 crystallin, lambda 1 
               
               
                 CYB5A 
                 cytochrome b5 type A (microsomal) 
               
               
                 DAK 
                 dihydroxyacetone kinase 2 homolog ( S. cerevisiae ) 
               
               
                 DBI 
                 diazepam binding inhibitor (GABA receptor modulator, acyl-CoA binding protein) 
               
               
                 DCXR 
                 dicarbonyl/L-xylulose reductase 
               
               
                 DECR2 
                 2,4-dienoyl CoA reductase 2, peroxisomal 
               
               
                 DKFZP686I15217 
                 hypothetical LOC401232 
               
               
                 DNAH5 
                 dynein, axonemal, heavy chain 5 
               
               
                 DNAH7 
                 dynein, axonemal, heavy chain 7 
               
               
                 DOPEY2 
                 dopey family member 2 
               
               
                 DPY19L2P4 
                 dpy-19-like 2 pseudogene 4 ( C. elegans ) 
               
               
                 DSC2 
                 desmocollin 2 
               
               
                 DUS1L 
                 dihydrouridine synthase 1-like ( S. cerevisiae ) 
               
               
                 EDEM3 
                 ER degradation enhancer, mannosidase alpha-like 3 
               
               
                 EGF 
                 epidermal growth factor 
               
               
                 EIF4EBP1 
                 eukaryotic translation initiation factor 4E binding protein 1 
               
               
                 ELL3 
                 elongation factor RNA polymerase II-like 3 
               
               
                 ELMO3 
                 engulfment and cell motility 3 
               
               
                 ELOVL5 
                 ELOVL family member 5, elongation of long chain fatty acids (FEN1/Elo2, 
               
               
                   
                 SUR4/Elo3-like, yeast) 
               
               
                 ENOX1 
                 ecto-NOX disulfide-thiol exchanger 1 
               
               
                 EPB41L4B 
                 erythrocyte membrane protein band 4.1 like 4B 
               
               
                 ERBB3 
                 v-erb-b2 erythroblastic leukemia viral oncogene homolog 3 (avian) 
               
               
                 ERGIC1 
                 endoplasmic reticulum-golgi intermediate compartment (ERGIC) 1 
               
               
                 ESRP2 
                 epithelial splicing regulatory protein 2 
               
               
                 EXOSC5 
                 exosome component 5 
               
               
                 FAH 
                 fumarylacetoacetate hydrolase (fumarylacetoacetase) 
               
               
                 FAM128A 
                 family with sequence similarity 128, member A 
               
               
                 FAM13C 
                 family with sequence similarity 13, member C 
               
               
                 FAM19A4 
                 family with sequence similarity 19 (chemokine (C-C motif)-like), member A4 
               
               
                 FAM81A 
                 family with sequence similarity 81, member A 
               
               
                 FASN 
                 fatty acid synthase 
               
               
                 FBXL8 
                 F-box and leucine-rich repeat protein 8 
               
               
                 FHIT 
                 fragile histidine triad gene 
               
               
                 FLJ27352 
                 hypothetical LOC145788 
               
               
                 FLJ46552 
                 FLJ46552 protein 
               
               
                 FRMPD3 
                 FERM and PDZ domain containing 3 
               
               
                 FZD8 
                 frizzled homolog 8 ( Drosophila ) 
               
               
                 GALNT3 
                 UDP-N-acetyl-alpha-D-galactosamine:polypeptide N- 
               
               
                   
                 acetylgalactosaminyltransferase 3 (GalNAc-T3) 
               
               
                 GGCT 
                 gamma-glutamylcyclotransferase 
               
               
                 GJB1 
                 gap junction protein, beta 1, 32 kDa 
               
               
                 GLYATL1 
                 glycine-N-acyltransferase-like 1 
               
               
                 GMPPB 
                 GDP-mannose pyrophosphorylase B 
               
               
                 GRB14 
                 growth factor receptor-bound protein 14 
               
               
                 GRPR 
                 gastrin-releasing peptide receptor 
               
               
                 GTF3C1 
                 general transcription factor IIIC, polypeptide 1, alpha 220 kDa 
               
               
                 H2AFJ 
                 H2A histone family, member J 
               
               
                 HEBP2 
                 heme binding protein 2 
               
               
                 HIST3H2A 
                 histone cluster 3, H2a 
               
               
                 HKR1 
                 HKR1, GLI-Kruppel zinc finger family member 
               
               
                 HMG20B 
                 high-mobility group 20B 
               
               
                 HOXA9 
                 homeobox A9 
               
               
                 HPN 
                 hepsin 
               
               
                 HSF4 
                 heat shock transcription factor 4 
               
               
                 ICT1 
                 immature colon carcinoma transcript 1 
               
               
                 IGSF5 
                 immunoglobulin superfamily, member 5 
               
               
                 IGSF8 
                 immunoglobulin superfamily, member 8 
               
               
                 IL20RA 
                 interleukin 20 receptor, alpha 
               
               
                 ILDR1 
                 immunoglobulin-like domain containing receptor 1 
               
               
                 IMPDH2 
                 IMP (inosine 5′-monophosphate) dehydrogenase 2 
               
               
                 IQCH 
                 IQ motif containing H 
               
               
                 IVD 
                 isovaleryl-CoA dehydrogenase 
               
               
                 KATNB1 
                 katanin p80 (WD repeat containing) subunit B 1 
               
               
                 KCNH6 
                 potassium voltage-gated channel, subfamily H (eag-related), member 6 
               
               
                 KCTD1 
                 potassium channel tetramerisation domain containing 1 
               
               
                 KIAA0182 
                 KIAA0182 
               
               
                 KIAA1543 
                 KIAA1543 
               
               
                 KIAA1549 
                 KIAA1549 
               
               
                 KIAA1804 
                 mixed lineage kinase 4 
               
               
                 KLK15 
                 kallikrein-related peptidase 15 
               
               
                 KRT18 
                 keratin 18 
               
               
                 KRT18P13 
                 keratin 18 pseudogene 13 
               
               
                 KRT18P17 
                 keratin 18 pseudogene 17 
               
               
                 KRT18P19 
                 keratin 18 pseudogene 19 
               
               
                 KRT18P24 
                 keratin 18 pseudogene 24 
               
               
                 KRT18P26 
                 keratin 18 pseudogene 26 
               
               
                 KRT18P28 
                 keratin 18 pseudogene 28 
               
               
                 KRT18P30 
                 keratin 18 pseudogene 30 
               
               
                 KRT18P33 
                 keratin 18 pseudogene 33 
               
               
                 KRT18P34 
                 keratin 18 pseudogene 34 
               
               
                 KRT18P40 
                 keratin 18 pseudogene 40 
               
               
                 KRT18P42 
                 keratin 18 pseudogene 42 
               
               
                 KRT18P46 
                 keratin 18 pseudogene 46 
               
               
                 LASS4 
                 LAG1 homolog, ceramide synthase 4 
               
               
                 LEKR1 
                 leucine, glutamate and lysine rich 1 
               
               
                 LFNG 
                 LFNG O-fucosylpeptide 3-beta-N-acetylglucosaminyltransferase 
               
               
                 LOC100127980 
                 hypothetical protein LOC100127980 
               
               
                 LOC100128332 
                 hypothetical protein LOC100128332 
               
               
                 LOC100128737 
                 hypothetical LOC100128737 
               
               
                 LOC100128841 
                 similar to hCG39453 
               
               
                 LOC100129387 
                 hypothetical LOC100129387 
               
               
                 LOC100129514 
                 hypothetical LOC100129514 
               
               
                 LOC100131047 
                 hypothetical protein LOC100131047 
               
               
                 LOC100131199 
                 hypothetical LOC100131199 
               
               
                 LOC100132111 
                 hypothetical LOC100132111 
               
               
                 LOC100133580 
                 hypothetical protein LOC100133580 
               
               
                 LOC100134348 
                 similar to TBC1 domain family member 3 (Rab GTPase-activating protein PRC17) 
               
               
                   
                 (Prostate cancer gene 17 protein) (TRE17 alpha protein) 
               
               
                 LOC389768 
                 potassium channel tetramerisation domain containing 1 pseudogene 
               
               
                 LOC391811 
                 similar to polymerase (DNA directed), delta 2, regulatory subunit 
               
               
                 LOC399815 
                 chromosome 10 open reading frame 88 pseudogene 
               
               
                 LOC440335 
                 hypothetical LOC440335 
               
               
                 LOC442249 
                 similar to keratin 18 
               
               
                 LOC642384 
                 hypothetical LOC642384 
               
               
                 LOC642590 
                 similar to spermine synthase 
               
               
                 LOC643327 
                 hypothetical LOC643327 
               
               
                 LOC643637 
                 similar to hCG1729961 
               
               
                 LOC646347 
                 similar to spermine synthase 
               
               
                 LOC653380 
                 TBC1 domain family member 3C-like protein ENSP00000341742 
               
               
                 LOC728431 
                 hypothetical LOC728431 
               
               
                 LOC729774 
                 hypothetical LOC729774 
               
               
                 LOC729779 
                 similar to phosphoserine aminotransferase 
               
               
                 LOC81691 
                 exonuclease NEF-sp 
               
               
                 LRGUK 
                 leucine-rich repeats and guanylate kinase domain containing 
               
               
                 LRIG1 
                 leucine-rich repeats and immunoglobulin-like domains 1 
               
               
                 LRRC26 
                 leucine rich repeat containing 26 
               
               
                 LRRC63 
                 leucine rich repeat containing 63 
               
               
                 LRRIQ1 
                 leucine-rich repeats and IQ motif containing 1 
               
               
                 LYPLA2P1 
                 lysophospholipase II pseudogene 1 
               
               
                 MAP1D 
                 methionine aminopeptidase 1D 
               
               
                 MBOAT2 
                 membrane bound O-acyltransferase domain containing 2 
               
               
                 MCCC2 
                 methylcrotonoyl-CoA carboxylase 2 (beta) 
               
               
                 MDH2 
                 malate dehydrogenase 2, NAD (mitochondrial) 
               
               
                 MED12L 
                 mediator complex subunit 12-like 
               
               
                 METTL9 
                 methyltransferase like 9 
               
               
                 MMP26 
                 matrix metallopeptidase 26 
               
               
                 MOSC1 
                 MOCO sulphurase C-terminal domain containing 1 
               
               
                 MPND 
                 MPN domain containing 
               
               
                 MRPL12 
                 mitochondrial ribosomal protein L12 
               
               
                 MRPL24 
                 mitochondrial ribosomal protein L24 
               
               
                 MRPS24 
                 mitochondrial ribosomal protein S24 
               
               
                 MRPS33 
                 mitochondrial ribosomal protein S33 
               
               
                 MYBPC1 
                 myosin binding protein C, slow type 
               
               
                 MYRIP 
                 myosin VIIA and Rab interacting protein 
               
               
                 NAAA 
                 N-acylethanolamine acid amidase 
               
               
                 NDUFA8 
                 NADH dehydrogenase (ubiquinone) 1 alpha subcomplex, 8, 19 kDa 
               
               
                 NDUFB10 
                 NADH dehydrogenase (ubiquinone) 1 beta subcomplex, 10, 22 kDa 
               
               
                 NEIL1 
                 nei endonuclease VIII-like 1 ( E. coli ) 
               
               
                 NME4 
                 non-metastatic cells 4, protein expressed in 
               
               
                 NMRAL1 
                 NmrA-like family domain containing 1 
               
               
                 NPY 
                 neuropeptide Y 
               
               
                 NSUN7 
                 NOP2/Sun domain family, member 7 
               
               
                 NUDT9 
                 nudix (nucleoside diphosphate linked moiety X)-type motif 9 
               
               
                 NUPR1 
                 nuclear protein, transcriptional regulator, 1 
               
               
                 NWD1 
                 NACHT and WD repeat domain containing 1 
               
               
                 OAZ3 
                 ornithine decarboxylase antizyme 3 
               
               
                 OCEL1 
                 occludin/ELL domain containing 1 
               
               
                 OR51A7 
                 olfactory receptor, family 51, subfamily A, member 7 
               
               
                 OR51F1 
                 olfactory receptor, family 51, subfamily F, member 1 
               
               
                 OR51F2 
                 olfactory receptor, family 51, subfamily F, member 2 
               
               
                 OR51G2 
                 olfactory receptor, family 51, subfamily G, member 2 
               
               
                 OR51L1 
                 olfactory receptor, family 51, subfamily L, member 1 
               
               
                 OR51T1 
                 olfactory receptor, family 51, subfamily T, member 1 
               
               
                 OVGP1 
                 oviductal glycoprotein 1, 120 kDa 
               
               
                 OXSM 
                 3-oxoacyl-ACP synthase, mitochondrial 
               
               
                 PAOX 
                 polyamine oxidase (exo-N4-amino) 
               
               
                 PCA3 
                 prostate cancer antigen 3 (non-protein coding) 
               
               
                 PCBD1 
                 pterin-4 alpha-carbinolamine dehydratase/dimerization cofactor of hepatocyte nuclear 
               
               
                   
                 factor 1 alpha 
               
               
                 PCGEM1 
                 prostate-specific transcript 1 (non-protein coding) 
               
               
                 PCGF1 
                 polycomb group ring finger 1 
               
               
                 PCGF3 
                 polycomb group ring finger 3 
               
               
                 PCTP 
                 phosphatidylcholine transfer protein 
               
               
                 PDCD2L 
                 programmed cell death 2-like 
               
               
                 PDE3B 
                 phosphodiesterase 3B, cGMP-inhibited 
               
               
                 PDE9A 
                 phosphodiesterase 9A 
               
               
                 PECI 
                 peroxisomal D3,D2-enoyl-CoA isomerase 
               
               
                 PET112L 
                 PET112-like (yeast) 
               
               
                 PEX10 
                 peroxisomal biogenesis factor 10 
               
               
                 PEX7 
                 peroxisomal biogenesis factor 7 
               
               
                 PIGM 
                 phosphatidylinositol glycan anchor biosynthesis, class M 
               
               
                 PKN1 
                 protein kinase N1 
               
               
                 PLCB4 
                 phospholipase C, beta 4 
               
               
                 PMM1 
                 phosphomannomutase 1 
               
               
                 PODXL2 
                 podocalyxin-like 2 
               
               
                 POLD2 
                 polymerase (DNA directed), delta 2, regulatory subunit 50 kDa 
               
               
                 POLN 
                 polymerase (DNA directed) nu 
               
               
                 POP7 
                 processing of precursor 7, ribonuclease P/MRP subunit ( S. cerevisiae ) 
               
               
                 PPAPDC1B 
                 phosphatidic acid phosphatase type 2 domain containing 1B 
               
               
                 PPM1E 
                 protein phosphatase, Mg2+/Mn2+ dependent, 1E 
               
               
                 PPM1H 
                 protein phosphatase, Mg2+/Mn2+ dependent, 1H 
               
               
                 PPP1R9A 
                 protein phosphatase 1, regulatory (inhibitor) subunit 9A 
               
               
                 PPYR1 
                 pancreatic polypeptide receptor 1 
               
               
                 PRDM10 
                 PR domain containing 10 
               
               
                 PRDX4 
                 peroxiredoxin 4 
               
               
                 PRSS8 
                 protease, serine, 8 
               
               
                 PRTG 
                 protogenin homolog ( Gallus gallus ) 
               
               
                 PSTK 
                 phosphoseryl-tRNA kinase 
               
               
                 PTPN20A 
                 protein tyrosine phosphatase, non-receptor type 20A 
               
               
                 PTPN20B 
                 protein tyrosine phosphatase, non-receptor type 20B 
               
               
                 PTPRN2 
                 protein tyrosine phosphatase, receptor type, N polypeptide 2 
               
               
                 PYCR1 
                 pyrroline-5-carboxylate reductase 1 
               
               
                 RAB17 
                 RAB17, member RAS oncogene family 
               
               
                 RAB3B 
                 RAB3B, member RAS oncogene family 
               
               
                 RAB3D 
                 RAB3D, member RAS oncogene family 
               
               
                 RAB3IP 
                 RAB3A interacting protein (rabin3) 
               
               
                 RABIF 
                 RAB interacting factor 
               
               
                 RAC3 
                 ras-related C3 botulinum toxin substrate 3 (rho family, small GTP binding protein 
               
               
                   
                 Rac3) 
               
               
                 REPS2 
                 RALBP1 associated Eps domain containing 2 
               
               
                 RG9MTD2 
                 RNA (guanine-9-) methyltransferase domain containing 2 
               
               
                 RIMKLA 
                 ribosomal modification protein rimK-like family member A 
               
               
                 RNLS 
                 renalase, FAD-dependent amine oxidase 
               
               
                 RORC 
                 RAR-related orphan receptor C 
               
               
                 RPL14P3 
                 ribosomal protein L14 pseudogene 3 
               
               
                 RPL22L1 
                 ribosomal protein L22-like 1 
               
               
                 RPL29P15 
                 ribosomal protein L29 pseudogene 15 
               
               
                 RPL29P30 
                 ribosomal protein L29 pseudogene 30 
               
               
                 RPL36 
                 ribosomal protein L36 
               
               
                 RPL7AP68 
                 ribosomal protein L7a pseudogene 68 
               
               
                 RPLP2P3 
                 ribosomal protein, large, P2 pseudogene 3 
               
               
                 RPS12P23 
                 ribosomal protein S12 pseudogene 23 
               
               
                 RPS19BP1 
                 ribosomal protein S19 binding protein 1 
               
               
                 RPS24 
                 ribosomal protein S24 
               
               
                 SATB2 
                 SATB homeobox 2 
               
               
                 SCAND3 
                 SCAN domain containing 3 
               
               
                 SCD 
                 stearoyl-CoA desaturase (delta-9-desaturase) 
               
               
                 SHANK2 
                 SH3 and multiple ankyrin repeat domains 2 
               
               
                 SLC19A1 
                 solute carrier family 19 (folate transporter), member 1 
               
               
                 SLC25A33 
                 solute carrier family 25, member 33 
               
               
                 SLC25A42 
                 solute carrier family 25, member 42 
               
               
                 SLC26A6 
                 solute carrier family 26, member 6 
               
               
                 SLC35F2 
                 solute carrier family 35, member F2 
               
               
                 SLC43A1 
                 solute carrier family 43, member 1 
               
               
                 SLC9A2 
                 solute carrier family 9 (sodium/hydrogen exchanger), member 2 
               
               
                 SMOX 
                 spermine oxidase 
               
               
                 SMPDL3B 
                 sphingomyelin phosphodiesterase, acid-like 3B 
               
               
                 SMS 
                 spermine synthase 
               
               
                 SNHG11 
                 small nucleolar RNA host gene 11 (non-protein coding) 
               
               
                 SNORA18 
                 small nucleolar RNA, H/ACA box 18 
               
               
                 SNORA2A 
                 small nucleolar RNA, H/ACA box 2A 
               
               
                 SNORD104 
                 small nucleolar RNA, C/D box 104 
               
               
                 SNORD116-11 
                 small nucleolar RNA, C/D box 116-11 
               
               
                 SNORD35A 
                 small nucleolar RNA, C/D box 35A 
               
               
                 SNORD57 
                 small nucleolar RNA, C/D box 57 
               
               
                 SNORD74 
                 small nucleolar RNA, C/D box 74 
               
               
                 SNRPD2 
                 small nuclear ribonucleoprotein D2 polypeptide 16.5 kDa 
               
               
                 SPAG6 
                 sperm associated antigen 6 
               
               
                 SPATA17 
                 spermatogenesis associated 17 
               
               
                 SPDEF 
                 SAM pointed domain containing ets transcription factor 
               
               
                 SPIN3 
                 spindlin family, member 3 
               
               
                 SPOCK1 
                 sparc/osteonectin, cwcv and kazal-like domains proteoglycan (testican) 1 
               
               
                 SREBF1 
                 sterol regulatory element binding transcription factor 1 
               
               
                 STX19 
                 syntaxin 19 
               
               
                 STYXL1 
                 serine/threonine/tyrosine interacting-like 1 
               
               
                 TAAR6 
                 trace amine associated receptor 6 
               
               
                 TARS2 
                 threonyl-tRNA synthetase 2, mitochondrial (putative) 
               
               
                 TAS2R10 
                 taste receptor, type 2, member 10 
               
               
                 TBC1D3 
                 TBC1 domain family, member 3 
               
               
                 TBC1D3B 
                 TBC1 domain family, member 3B 
               
               
                 TBC1D3C 
                 TBC1 domain family, member 3C 
               
               
                 TBC1D3E 
                 TBC1 domain family, member 3E 
               
               
                 TBC1D3F 
                 TBC1 domain family, member 3F 
               
               
                 TBC1D3G 
                 TBC1 domain family, member 3G 
               
               
                 TBC1D3H 
                 TBC1 domain family, member 3H 
               
               
                 TBC1D4 
                 TBC1 domain family, member 4 
               
               
                 TDRKH 
                 tudor and KH domain containing 
               
               
                 TERC 
                 telomerase RNA component 
               
               
                 TGM3 
                 transglutaminase 3 (E polypeptide, protein-glutamine-gamma-glutamyltransferase) 
               
               
                 TMED3 
                 transmembrane emp24 protein transport domain containing 3 
               
               
                 TMEFF2 
                 transmembrane protein with EGF-like and two follistatin-like domains 2 
               
               
                 TMEM144 
                 transmembrane protein 144 
               
               
                 TMEM223 
                 transmembrane protein 223 
               
               
                 TMEM27 
                 transmembrane protein 27 
               
               
                 TMEM5 
                 transmembrane protein 5 
               
               
                 TMPRSS11F 
                 transmembrane protease, serine 11F 
               
               
                 TMSB15A 
                 thymosin beta 15a 
               
               
                 TMTC4 
                 transmembrane and tetratricopeptide repeat containing 4 
               
               
                 TOM1L1 
                 target of myb1 (chicken)-like 1 
               
               
                 TP53TG1 
                 TP53 target 1 (non-protein coding) 
               
               
                 TREX1 
                 three prime repair exonuclease 1 
               
               
                 TRIM3 
                 tripartite motif-containing 3 
               
               
                 TSPAN1 
                 tetraspanin 1 
               
               
                 TSSC1 
                 tumor suppressing subtransferable candidate 1 
               
               
                 TTC18 
                 tetratricopeptide repeat domain 18 
               
               
                 TTC6 
                 tetratricopeptide repeat domain 6 
               
               
                 TTLL12 
                 tubulin tyrosine ligase-like family, member 12 
               
               
                 TUBA3D 
                 tubulin, alpha 3d 
               
               
                 TUBA3E 
                 tubulin, alpha 3e 
               
               
                 TUT1 
                 terminal uridylyl transferase 1, U6 mRNA-specific 
               
               
                 UAP1 
                 UDP-N-acteylglucosamine pyrophosphorylase 1 
               
               
                 UBE2E2 
                 ubiquitin-conjugating enzyme E2E 2 (UBC4/5 homolog, yeast) 
               
               
                 UBXN8 
                 UBX domain protein 8 
               
               
                 USP54 
                 ubiquitin specific peptidase 54 
               
               
                 VLDLR 
                 very low density lipoprotein receptor 
               
               
                 WIBG 
                 within bgcn homolog ( Drosophila ) 
               
               
                 WWC1 
                 WW and C2 domain containing 1 
               
               
                 XKR6 
                 XK, Kell blood group complex subunit-related family, member 6 
               
               
                 XYLB 
                 xylulokinase homolog (H. influenzae) 
               
               
                 YIPF1 
                 Yip1 domain family, member 1 
               
               
                 ZADH2 
                 zinc binding alcohol dehydrogenase domain containing 2 
               
               
                 ZBTB37 
                 zinc finger and BTB domain containing 37 
               
               
                 ZBTB7B 
                 zinc finger and BTB domain containing 7B 
               
               
                 ZDHHC11 
                 zinc finger, DHHC-type containing 11 
               
               
                 ZDHHC23 
                 zinc finger, DHHC-type containing 23 
               
               
                 ZMYND12 
                 zinc finger, MYND-type containing 12 
               
               
                 ZNF30 
                 zinc finger protein 30 
               
               
                 ZNF485 
                 zinc finger protein 485 
               
               
                 ZNF511 
                 zinc finger protein 511 
               
               
                 ZNF643 
                 zinc finger protein 643 
               
               
                 ZNF692 
                 zinc finger protein 692 
               
               
                 ZNF697 
                 zinc finger protein 697 
               
               
                 ZNF862 
                 zinc finger protein 862 
               
               
                   
               
            
           
         
       
     
     The above PCAT18-/JUPITER-associated expression signature (JES) was then uploaded into Oncomine to identify clinically significant associations and to perform pathway analysis. JES was consistently up-regulated in PCa vs. normal tissue and PCa vs. other neoplasms in several cancer studies, comprising more than 4000 human samples (see Table 9 below). Importantly, JES was significantly up-regulated in metastatic vs. primary PCa. Pathway analysis revealed that JES Is strongly associated with androgen receptor activation and differentiation of epithelial cells ( FIG. 4A ). To experimentally determine whether JUPITER expression is down-regulated following castration, we assessed its expression following to castration in a PCa xenograft model. As shown in  FIG. 4B , there is a larger than 10-fold decrease in JUPITER expression by 3 weeks post-castration. This decrease is comparable to the one observed for PSA (16.6 vs. 14.7 fold change). 

 
     The second column (‘Studies’) in Table 9 above shows the number of independent studies showing up- or down-regulation of JES for a specific concept. Oncomine™ (Compendia Bioscience, Ann Arbor, Mich.) was used for the analysis. 
     To gain insights into PCAT18 function, in vitro studies on the metastatic PCa-derived LNCaP cell line (Horoszewicz J S, et al. LNCaP model of human prostatic carcinoma.  Cancer research.  1983; 43(4):1809-1818) was performed. In this model, dihydrotestosterone (DHT) treatment (24-48 h) induced a more than 50-fold up-regulation of PCAT18 expression ( FIG. 6(A) ). In keeping with this relatively late up-regulation, no androgen-receptor (AR) binding site in the PCAT18 putative promoter (Table 10 below, and data from ChIP-on-chip (Decker K F, et al. Persistent androgen receptor-mediated transcription in castration-resistant prostate cancer under androgen-deprived conditions.  Nucleic acids research  2012; 40(21):10765-10779)) was found. This evidence suggests that androgen indirectly activates PCAT18 expression. To experimentally determine whether PCAT18 is downregulated following androgen ablation, PCAT18 expression was assessed following castration in two PCa xenograft models. The LTL331 model generates a typical androgen-dependent PCa (Lin D, et al., High fidelity patient-derived xenografts for accelerating prostate cancer discovery and drug development.  Cancer research.  2013). In this model, androgen deprivation induced a dramatic PCAT18 down-regulation ( FIG. 4(B) ). The expression profile of PCAT18 was then investigated in a recently developed CRPC subline (LTL313BR). When the LTL313B xenograft is exposed to castrate levels of androgens for several weeks, it reproducibly generates an AR+ CRPC sub-line ( FIGS. 6(B) and 6(C) ) (Lin D, et al.,  Cancer research,  2013). In this model, castration induced PCAT18 down-regulation, but the emergence of the CRPC subline was associated with PCAT18 up-regulation ( FIG. 6(D) ). 
                     TABLE 10                  PCAT18 Promoter analysis                             Transcription Factor   Matrix                       AP-2alphaA   [T00035]           C/EBPalpha   [T00105]           C/EBPbeta   [T00581]           c-Ets-1   [T00112]           c-Ets-2   [T00113]           c-Fos   [T00123]           c-Jun   [T00133]           c-Myb   [T00137]           CTF   [T00174]           Elk-1   [T00250]           ER-alpha   [T00261]           FOXP3   [T04280]           GATA-1   [T00306]           GATA-2   [T00308]           GR   [T05076]           GR-alpha   [T00337]           GR-beta   [T01920]           HNF-1A   [T00368]           Ik-1   [T02702]           IRF-1   [T00423]           NF-AT1   [T01948]           NF-AT2   [T01945]           NF-Y   [T00150]           Pax-5   [T00070]           RelA   [T00594]           RXR-alpha   [T01345]           Sp1   [T00759]           STAT4   [T01577]           STAT5A   [T04683]           T3R-beta1   [T00851]           TBP   [T00794]           TFII-I   [T00824]           USF2   [T00878]           VDR   [T00885]           XBP-1   [T00902]           YY1   [T00915]                        
Promoter analysis—from Chromosome 18 primary assembly (NC_000018.9); 1 Kb of 5′ flanking sequence was downloaded, immediately adjacent to the PCAT18 transcription start site. The sequence was uploaded in PROMO software (http://alggen.lsi.upc.es/cgi-bin/promo_v3/promo/promoinit.cgi?dirDB=TF_8.3), to identify human transcription factor binding sites (maximum dissimilarity: 5%). 36 transcription factors were identified, some with a known oncogenic role (c-Fos, c-Jun, STAT). The unique matrix that identifies each transcription factor is shown beside the official name. Notably, no AR (androgen-receptor) binding site was detected. These findings were confirmed by analyzing a ChIP-on-chip dataset comprising AR binding sites in LNCaP cells exposed to castrate levels of androgens or 10 nM DHT23. The authors identified a set of androgen-dependent and independent AR binding sites throughout the genome. Exploring these datasets, the closest AR binding site was 29.9 Kb from the PCAT18 transcription starting site.
 
     Example 4: Functional Characterization of PCAT18 
     The functional relevance of PCAT18 in PCa cells was then determined. To this aim, PCAT18&#39;s expression levels in a panel of prostate cell lines was measured. In keeping with the previous data. PCAT18 expression was higher in AR-positive than in AR-negative PCa cells ( FIG. 8(C) ) Among AR-positive cells, PCAT18 levels incrementally increased from non-neoplastic (BPH1), to androgensensitive (22Rv1, LNCaP) and androgen-insensitive (C4-2) PCa cells. LNCaP and its castrate-resistant sub-line C4-2 (Wu H C, et al. Derivation of androgen-independent human LNCaP prostatic cancer cell sublines: role of bone stromal cells.  International journal of cancer Journal international du cancer.  1994; 57(3):406-412) were, therefore, selected for lncRNA characterization and functional studies. RNA fractionation and quantification experiments revealed that PCAT18 is mainly located in the cytoplasm of PCa cells ( FIG. 8(D) ). Indeed, the PCAT18 expression profile more similar to the protein-coding RNA GAPDH than to the nuclear-retained lncRNA MALAT1 (Miyagawa R, et al. Identification of cis- and trans-acting factors involved in the localization of MALAT-1 noncoding RNA to nuclear speckles.  Rna.  2012; 18(4):738-751). 
     Example 5: Effect of Silencing PCAT18 Using siRNAs 
     Two small-interfering RNAs (siRNAs) (siRNA1 and siRNA2, the sequences of which are set out in Table 11) were used in a human prostate cancer cell line (C4-2) to silence JUPTER/PCAT18 expression. These two siRNAs induced greater than 80% gene knockdown at a 2 nM concentration ( FIG. 8(E) ) (Kim D H, et al. Synthetic dsRNA Dicer substrates enhance RNAi potency and efficacy.  Nature biotechnology.  2005; 23(2):222-226). PCAT18 silencing (24-48 h) significantly inhibited PCa cell invasion and migration ( FIGS. 7(A) and 7(B) ; see also  FIG. 3(D) ). At later time points (5 days), PCAT18 silencing induced a significant growth inhibition in both LNCaP and C4-2 cells ( FIGS. 7(C) and 7(D) ) (for C4-2 cells, see also  FIG. 3(E) ), with no effect on non-neoplastic BPH1 cells ( FIG. 7(E) ). Prolonged PCAT18 silencing (5 days) also triggered caspase 3/7 activation ( FIG. 7(F) ). 
     
       
         
           
               
             
               
                 TABLE 11 
               
             
            
               
                   
               
               
                 Nucleotide Sequences of siRNA1 and siRNA2. 
               
            
           
           
               
               
               
            
               
                   
                 SEQ 
                   
               
               
                   
                 ID 
                   
               
               
                 siRNA 
                 NO. 
                 Sequence 
               
               
                   
               
               
                 siRNA1 
                 22 
                 AGCAGGAACAUUCCAAUAGAAGAAAUAUUGGAAUGU 
               
               
                   
               
               
                 siRNA2 
                 23 
                 GCAACAUGACCUACAGUUAAUGAGUAACUGUAGGUC 
               
               
                   
               
            
           
         
       
     
     Discussion of Examples 
     The above Examples revealed 153 up-regulated and 77 down-regulated lncRNAs in the metastatic versus non-metastatic xenografts. The most up-regulated transcript was an uncharacterized lncRNA, PCAT18 (also referred to as JUPITER), is characterized herein. Database analysis revealed that PCAT18 is specifically expressed in normal prostate compared to 11 normal tissues (p&lt;0.05) and specifically up-regulated in PCa compared to 15 other neoplasms (p&lt;0.001). Cancer-specific up-regulation of PCAT18 was confirmed on an independent dataset of PCa and benign prostatic hyperplasia samples (p&lt;0.001). In addition, PCAT18 was detectable in plasma samples and increased incrementally from normal individuals to those with localized and metastatic PCa (p&lt;0.01). Co-expression analysis allowed us to identify a PCAT18-associated expression signature (PES or JES for J PCAT18-associated expression), which is highly PCa-specific and is activated in metastatic vs. primary PCa samples (p&lt;1E-4, odds ratio&gt;2). Pathway analysis revealed that PES is significantly associated with androgen receptor activation. PCAT18 expression was experimentally confirmed to be dramatically decreased upon PCa xenograft castration. 
     Due to the slow-growing nature of this disease, PCa samples are often composed of multi-clonal subpopulations, each with a different mutational spectrum and metastatic potential (18). Molecular analysis of PCa samples is affected by this heterogeneity, which often masks the aggressive signature of truly metastatic cells. As a consequence, the development of gene expression profile-based diagnostic and prognostic algorithms is particularly challenging in PCa. 
     As described herein, the transcriptome of tumor tissue cell lines derived from two PCa biopsies of the same patient were analyzed. When engrafted in the sub-enal capsule of immunocompromised mice, one tumor tissue line invariably gave rise to localized and poorly-invasive tumors; the other line was reproducibly able to generate highly invasive tumors, producing distant metastases through predictable routes. Since the two tumor tissue lines are derived from the same patient and share most of the genetic alterations with the donor tissue, they represent an ideal model to study gene expression changes related to PCa progression to a metastatic state. A similar model had been successfully exploited for the identification of PCa-associated miRNAs and protein coding genes (10, 14). 
     Data from 4 independent datasets and more than 600 human samples confirmed that this gene is prostate-specific and highly up-regulated in PCa. Even though the PCAT18 transcript has been reported before (Ota T, et al. Complete sequencing and characterization of 21.243 full-length human cDNAs.  Nature genetics.  2004; 36(1):40-45), its function and expression profile and utility has not been previously determined. Two previous studies performed whole-genome lncRNA expression profiling in PCa. However, due to the highly heterogeneous nature of lncRNAs, and to the fact that most lncRNAs have not been characterized, the available analysis tools do not cover all the lncRNAs expressed by a cell. Chinnaiyan and co-workers previously published a list of 121 unannotated lncRNAs expressed in PCa (19). Since they deliberately filtered out transcripts present in the RefSeq database they likely excluded PCAT18 from their analysis. More recently. Ren and co-workers published a list of lncRNAs expressed in PCa based on the fRNAdb database (20). All the sequences matching PCAT18 were actively searched for in this database, and it was found that this locus is covered by just 4 short sequences that span &lt;10% of the entire transcript (www.genecode.com). Moreover, PCAT18-matching sequences were not found in Ren&#39;s list of PCa-associated lncRNAs Since Ren et al. only analyzed sequences longer than 200 bp, it was assumed they filtered out the short PCAT18-matching sequences present in fRNAdb database. 
     The data herein indicates that PCAT18 is more over-expressed in PCa than PCGEM1 and that a set of patients over-expressing this gene does not express PCA3 (cBio portal, data not shown). Since PCAT18 is so frequently over-expressed in PCa cells and PCa-specific, its measurement in plasma samples (alone or in combination with other non-coding RNAs) can allow earlier and more accurate detection of PCa progression to a metastatic and drug-resistant stage. lncRNA is detectable in plasma samples from PCa patients and can discriminate between localized and mCRPC. 
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