bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract C40: Large-scale isolation of prostate cancer cells by combining leukapheresis and elutriation with chemoaffinity capture
Authors: Wu Lisa Y. , Abernathy Dana E. , Liu TianCheng , Van Wie Bernard J. , Davis William C. , Berkman Clifford E.
Published: May 2013

Circulating tumor cells (CTCs) in the peripheral blood are shed from either the primary tumor or its metastases. These disseminated CTCs are directly responsible for the most cancer deaths and the major cause of prostate cancer-related mortality. Therefore, the earlier detection of CTCs and the ability to remove CTCs from circulation could result in more positive patient outcomes. However, capturing low abundant CTCs from peripheral blood remains a challenge. The cell-surface enzyme prostate-specific membrane antigen (PSMA) is an important biomarker in prostate cancer research. Its upregulation on prostate tumor cells has attracted significant attention as a target for imaging and therapeutic agents. We recently developed a technology to enrich CTCs from a large blood volume by combining apheresis and elutriation technologies with a CTC selection technology based on immobilized high-affinity irreversible PSMA inhibitor. The commercial centrifugal apheresis and elutriation processes can concentrate PCTCs from large blood volumes in a standard elutriator. In this presentation, we will describe a selective and sensitive methodology to enrich, capture, and quantify metastatic prostate cancer cells.

Citation Format: Lisa Y. Wu, Dana E. Abernathy, TianCheng Liu, Bernard J. Van Wie, William C. Davis, Clifford E. Berkman. Large-scale isolation of prostate cancer cells by combining leukapheresis and elutriation with chemoaffinity capture [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C40.
Abstract C42: Predicting prostate cancer aggressiveness and progression using a new quantitative nanoparticle assay
Authors: Huo Qun , Litherland Sally , Decker David
Published: May 2013

Background: Over-diagnosis and treatment of prostate cancer has been a major problem in prostate cancer care and management. Currently the most relevant prognostic factor to predict a patient's risk of death due to prostate cancer is the Gleason score of the biopsied tissue samples. However, pathological analysis is subjective, and the Gleason score is only a qualitative estimate of the cancer malignancy. Molecular biomarkers and diagnostic tests that can accurately predict prostate tumor aggressiveness are rather limited.

Method: We report here for the first time a nanoparticle test that not only can distinguish prostate cancer from normal and benign conditions, but also is capable of predicting the aggressiveness of prostate cancer quantitatively. To conduct the test, a prostate tissue lysate sample is spiked into a pure human IgG protein solution and the spiked sample is incubated with a citrate-protected gold nanoparticle solution. IgG is known to adsorb to citrate-protected gold nanoparticles to form a “protein corona” on the nanoparticle surface. From this study, we discovered that certain tumor-specific molecules can interact with IgG and change the adsorption behavior of IgG to the gold nanoparticles. This change is reflected in the nanoparticle size of the assay solution and detected by a dynamic light scattering technique. Assay data were analyzed by one-way ANOVA for multiple variant analysis, and using the Student t-test or nonparametric Mann–Whitney U-tests for pairwise analyses.

Results: IgG solutions spiked with prostate tumor tissue exhibit significantly smaller nanoparticle size than the solutions spiked with normal and benign tissues. An inverse, quantitative correlation of the average nanoparticle size of the assay solution with tumor status and histological diagnostic grading was observed from the nanoparticle test. The higher grade the tumor is, the smaller the nanoparticle size is. The test particularly revealed large differences among the intermediate Grade 2 tumors, and suggested the necessity to treat them differently.

Conclusion: The new nanoparticle test provides a quantitative measure of the prostate cancer aggressiveness. The test is easy to conduct, requires less than 5 μL of tissue lysate samples, and results are obtained in less than 10 minutes. It can be easily adapted for clinical application using the current needle-biopsy sampling system. This test will provide a more accurate tool to distinguish aggressive cancer from indolent tumor than the current diagnostic practices, if successfully validated by large cohort clinical studies.

Citation Format: Qun Huo, Sally Litherland, David Decker. Predicting prostate cancer aggressiveness and progression using a new quantitative nanoparticle assay [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C42.
Abstract C44: The identification and characterization of androgen-independent cells prior to hormonal manipulation in prostate cancer
Authors: Terada Naoki , Shiraishi Takumi , Zeng Yu , Aw-Yong Koh-Meng , Mooney Steven M. , Luo Jun , Kulkarni Prakash , Getzenberg Robert H.
Published: May 2013

Introduction and Objectives: The Mechanisms contributing to androgen-independent progression in prostate cancer (PCa) are not fully elucidated. PCa lesions are heterogeneous and thus, it is important to understand whether among the heterogeneous collectives of cell types, androgen-independent cells exist prior to hormonal manipulation. The identification of these cells may predict patient prognosis as well as provide a better understanding of treatment resistance.

Methods: LNCaP cells (10,000 cells in 10cm dish) were grown for 40 days in normal medium. Fifty colonies were selected and 22 subclones were established. To compare their androgen-dependence, six of these clones were grown in normal and androgen-depleted medium and their cell proliferation rates were examined. Between an androgen-dependent clone (LNCaP-ADc) and an androgen-independent clone (LNCaP-AIc) gene copy number and gene expression were compared using Human SNP array 6.0 and Human Genome U133 Plus 2.0, respectively. One of the genes differentially expressed between these clones was knocked down by siRNA in LNCaP cells and the influence on cell proliferation was evaluated. The expression levels of this gene in PCa tisssue samples were examined by real-time PCR.

Results: Cell proliferation was significantly suppressed by androgen depletion in LNCaP-ADc, but not in LNCaP-AIc. Gene copy numbers were different at 1q (ADcAIc), indicating that these clones contain genetic differences. The most differentially expressed gene was SPRY1 (ADc>AIc, ratio=5.699). Knocking down of SPRY1enhanced proliferation and PSA expression of LNCaP cells. SPRY1 expression in PCa tissues were negatively associated with PSA recurrence after surgical treatment (p=0.0076).

Conclusions: A random population of LNCaP cells comprises a genetically heterogeneous group of cells that have different levels of androgen dependence. Included among them are those that appear to be able to be resistant to androgen depletion. Among the changes associated with this independence, SPRY1 appears to be differentially expressed in such clones and may represent a novel biomarker for differentiating aggressive cells in PCa.

Citation Format: Naoki Terada, Takumi Shiraishi, Yu Zeng, Koh-Meng Aw-Yong, Steven M. Mooney, Jun Luo, Prakash Kulkarni, Robert H. Getzenberg. The identification and characterization of androgen-independent cells prior to hormonal manipulation in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C44.
Abstract C47: Quantitative mass spectrometry reveals that enzymes of the ketogenic pathway are upregulated during high-grade prostate cancer
Authors: Saraon Punit , Jarvi Keith , Diamandis Eleftherios P.
Published: May 2013

Prostate cancer is the most common malignancy and the second leading cause of cancer related deaths in men. One common treatment is androgen-deprivation therapy, which reduces symptoms in most patients. However, over time, patients develop tumors that are androgen-independent and ultimately fatal. The mechanisms that cause this transition remain largely unknown, and as a result, there are no effective treatments against androgen-independent prostate cancer. As a model platform, we used the LNCaP cell line, and its androgen independent derivative, LNCaP-SF. By using stable isotope labeling with amino acids in cell culture (SILAC) coupled to mass spectrometry, we assessed the differential global protein expression between the two cell lines. Our proteomic analysis resulted in the quantification of 3355 proteins, in total. Bioinformatic prioritization resulted in 42 up-regulated and 46 down-regulated proteins in LNCaP-SF cells, compared to LNCaP cells. Our top candidate was HMGCS2, an enzyme involved in ketogenesis, was found to be 9-fold elevated in LNCaP-SF cells, based on peptide ratios. After analyzing the remaining enzymes of this pathway (ACAT1, BDH1, HMGCL, OXCT1), we observed increased expression of these proteins in the LNCaP-SF cells. This was further verified using western blotting, indicating the importance of this pathway during the progression of prostate cancer to androgen-independence. To determine whether these enzymes are up-regulated in clinical samples, we performed qPCR analysis on human prostate cancer tissues, from which we observed significantly increased transcript levels of HMGCS2 (p<0.05), OXCT1 (P<0.05), ACAT1 (p<0.001), and BDH1 (p<0.001). In addition, the protein expression of all five ketogenic pathway enzymes was elevated in high grade prostate cancer (Gleason Grade >8) based on immunohistochemistry analysis. ACAT1 displayed the most prominent protein expression patterns, as it exhibited very minimal staining in normal samples, moderate levels in low grade cancer, and high expression during high grade disease. Further assessment of ACAT1 expression demonstrated significantly greater ACAT1 expression in bone metastatic lesions (P<0.001). Altogether, our results indicate that enzymes belonging to the ketogenic pathway become up-regulated during high grade prostate cancer, and could serve as potential biomarkers for diagnosis of high grade disease.

Citation Format: Punit Saraon, Keith Jarvi, Eleftherios P. Diamandis. Quantitative mass spectrometry reveals that enzymes of the ketogenic pathway are upregulated during high-grade prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C47.
Abstract C48: Regulation of expression of CXCL12 and its receptors CXCR4 and CXCR7 by PTEN in prostate cancer
Authors: Conley-LaComb M. Katie , Chen Yong Q. , Kim Hyeong-Reh C. , Cher Michael L. , Chinni Sreenivasa R.
Published: May 2013

Introduction: Expression of the chemokine CXCL12, also known as SDF-1, and its receptors, CXCR4 and CXCR7, are associated with prostate cancer (PC) metastasis. Loss of the tumor suppressor PTEN (phosphatase and tensin homolog) occurs in 30-80% of primary PCs, and up to 50% of PC bone metastases. In mouse models, prostate-specific deletion of PTEN leads to Akt activation and increased expression of CXCR4 and CXCL12. Moreover, the level of PTEN expression is inversely associated with prostate tumorigenesis. Additionally, HIF-1α, a hypoxia-induced transcription factor previously shown to induce expression of CXCR4, is regulated by Akt. Thus, we hypothesize that the PTEN loss-mediated activation of HIF-1α regulates the function of CXCR4 and CXCR7 receptor pathways in PC progression.

Methods: Prostate-specific deletion of floxed exon 5 of PTEN was achieved by Cre recombinase expressed under the control of an androgen-responsive probasin promoter. Stable cell lines developed from PTEN+/+, PTEN+/−, and PTEN−/− murine prostate epithelial cells that were isolated from the prostates of corresponding mice at 8 weeks of age, and the PTEN status in these cell lines was confirmed by genotyping and immunoblot analyses. Subsequently, these cells were treated with inhibitors of the PI3K/Akt pathway, and gene expression was determined by real time PCR.

Results: We found that loss of PTEN resulted in increased expression of CXCR4, CXCR7, and CXCL12, suggesting that loss of PTEN may play a key role in the regulation of these chemokines in prostate cancer. Additionally, expression of HIF-1α was also upregulated upon PTEN loss. Upon treatment of PTEN−/− cells with inhibitors of the PI3K/Akt pathway, the induction of CXCL12 and CXCR7 was reversed, further demonstrating the role of the PTEN regulated pathway in the expression of these genes.

Conclusions: These results suggest a molecular basis for activation of CXCL12 signaling through its receptors in prostate cancer driven by the loss of PTEN through the induction of HIF-1.

Citation Format: M. Katie Conley-LaComb, Yong Q. Chen, Hyeong-Reh C. Kim, Michael L. Cher, Sreenivasa R. Chinni. Regulation of expression of CXCL12 and its receptors CXCR4 and CXCR7 by PTEN in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C48.
Abstract C50: Regulation of the chemokine receptors CXCR7 and CXCR4 in 3-D culture models of prostate cancer
Authors: Kiss Debra L. , Windus Louisa CE , Avery Vicky M.
Published: May 2013

CXCR7 was recently identified as the second member of the chemokine receptor family to bind stromal derived factor-1α (SDF-1α), a chemokine which is known to influence the establishment of cancer metastasis. Whilst expression of CXCR7 is highly restricted in non-malignant cells, it is widely expressed in many different tumor cell lines. In prostate cancer, a disease known to be highly regulated by the other SDF-1α -binding receptor CXCR4, CXCR7 has been found to regulate cell growth and invasion. In vivo prostate tumor biopsies show a pattern where CXCR7 expression increases with invasive grade, as previously reported for CXCR4. However, there is limited knowledge on the role of CXCR7 and its function in prostate cancer.

In this study, we aim to more thoroughly characterize CXCR7 function across prostate cancer cell lines, in particular its regulation of cell growth and behavior. We will also assess its expression and function in response to its ligands and inhibitors, alongside CXCR4, in order to assess how these receptors are regulated in relation to each other. For this we employ western blotting expression studies, immunocytochemical visualization, and metabolic-based proliferation assays.

Further, we will study the regulation of both CXCR7 and CXCR4 in 3D culture models of prostate cancer cell lines. Our preliminary data from 2D culture suggests that less invasive prostate cancer cell lines express higher levels of CXCR7 than more invasive cell lines, contrary to reports in vivo where CXCR7 expression was seen to increase with invasive grade. We have chosen to assess these aspects in 3D cultures of prostate cancer cell lines to determine whether culturing in 3D permits a phenotype more reflective of what has been reported for CXCR7 expression in prostate cancer in vivo.

Further elucidation of CXCR7 function with respect to CXCR4 will shed light on how these receptors contribute to regulation of the metastatic process in prostate cancer – a process known to be heavily regulated by CXCR4. As CXCR4 has been established as a therapeutic target in prostate cancer, a more detailed knowledge of the CXCR7 receptor with which it shares a partial redundancy may indicate whether combinatorial therapies may be more effective in combating prostate cancer progression.

Citation Format: Debra L. Kiss, Louisa CE Windus, Vicky M. Avery. Regulation of the chemokine receptors CXCR7 and CXCR4 in 3-D culture models of prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C50.
Abstract C52: Semi-high-throughput whole-animal bioimaging assay identifies novel players in prostate cancer progression
Authors: Singh Ghotra Veerander Paul , H.E Shuning , Bont Hans De , Spaink H.P. , de Water Bob Van , Snaar Jagalska B. Ewa , Danen Erik H.J.
Published: May 2013

Although genetic mouse models for cancer and human tumor cell xenotransplantation models in rodents remain essential, such systems are costly, slow, and not amenable to high-throughput assays for cancer drug target discovery. There is a clear need to develop fast, semi-automated in vivo systems for medium to high-throughput screening applications in preclinical target discovery and lead compound identification. In this study, we developed an automated, semi-high throughput, noninvasive and quantitative platform for imaging one critical aspect of cancer progression, namely tumor cell dissemination, in a zebrafish xenotransplantation model. This is the first semi-automated whole organism based bio-imaging assay of tumor progression in a vertebrate. We have used this platform to screen for prostate cancer relevant drug and gene targets, and have identified novel regulators of prostate cancer dissemination. Using 3D in vitro invasion assays, we show a critical role for these molecules in prostate cancer migration strategies. Further validation of these targets is underway in mouse models and human cancer specimens.

Citation Format: Veerander Paul Singh Ghotra, Shuning H.E., Hans De Bont, H.P. Spaink, Bob Van de Water, B. Ewa Snaar Jagalska, Erik H.J. Danen. Semi-high-throughput whole-animal bioimaging assay identifies novel players in prostate cancer progression [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C52.
Abstract C57: The expression of 2′-5′ oligoadenylate synthetase in prostate cancer and its effect on prostate cancer cell cycle
Authors: Mandal Sanjay Kumar , Chaudhary Jaideep
Published: May 2013

2-5 oligoadenylate synthetase (OAS) is an IFN inducible enzyme that is part of innate immune response. During viral infections 2′-5′ OAS is activated by viral dsRNA or cellular RNA with significant double strand structure to synthesize 2-5 oligoadenylates (2-5A) from ATP; which in turn activates RNaseL, the latent ribonuclease. RNAseL degrades infectious RNA which imparts antiviral protection to the cell. OAS-RNaseL system also degrades cellular RNA and inhibits protein synthesis. The role of RNAseL as a tumor suppressor has been studied in prostate cancer cell lines and has been linked to hereditary prostate cancer (HPC). However HPC accounts for less than 9% of the overall prostate cancer incidence but the role of RNAseL in sporadic prostate cancer has not been established. Since OAS1 is the rate limiting enzyme in RNaseL activation, we therefore hypothesized that OAS could potentially act as tumor suppressor in the context of sporadic prostate cancer.

Methods: Immunohistochemistry was performed on human prostate cancer and normal prostate tissue to determine the expression of OAS1. RT-PCR and western blot was performed to detect the expression of OAS1 in LNCaP, DU145 and PC3 cell lines. Two alternative approaches were then used to investigate the effect of OAS1 on cell survival and its potential mechanism of action: OAS1 was over-expressed in LNCaP whereas it was silenced in DU145 cells. Cell cycle and apoptosis was quantitated by FACS analysis and the expression of key regulatory genes was determined by qRT-PCR and western blot analysis.

Results: Immunohistochemistry demonstrated that OAS1 expression is high in the normal prostate but decreased progressively with stage in prostate cancer. OAS1 was not expressed in LNCaP cells but its expression was high in DU145 and PC3 prostate cancer lines. Overexpression of OAS1 in LNCaP cells induced apoptosis and G1 arrest that was associated with increased p53, BAX and p21 expression. Alternatively, silencing of OAS in DU145 cells led to an increase in S phase and G2 cell population with a concomitant decrease in apoptosis.

Conclusion: Our prostate cancer cell line and prostate cancer tissue data strongly suggest that OAS1 is a candidate tumor suppressor that could be used as a potential biomarker for prostate cancer. Moreover, our previous study had shown a link between OAS1 polymorphism and prostate cancer incidence. Collectively data suggest the role of immune/inflammatory pathway in prostate cancer progression.

Citation Format: Sanjay Kumar Mandal, Jaideep Chaudhary. The expression of 2′-5′ oligoadenylate synthetase in prostate cancer and its effect on prostate cancer cell cycle [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C57.
Abstract C68: Phenotypic and functional heterogeneity of prostate cancer stem cells
Authors: Liu Xin , Chen Xin , Laffin Brian , Yin Binglan , Calhoun-Davis Tammy , Wang-Johanning Feng , Tang Dean G.
Published: May 2013

Recent evidence in many tumor systems suggests that there may exist several or even many tumorigenic subpopulations in each tumor. Utilizing 4 xenograft human prostate cancer (PCa) models, including two AR+/PSA+ (LAPC9 and LAPC4) and two AR-/PSA- (Du145 and PC3) xenografts, and by performing exhaustive limiting-dilution tumor regeneration assays in NOD/SCID mice using purified PCa cells based on functional properties (i.e., side population and Aldefluor assays) or preferential expression of surface markers (ABCG2, CD44, or integrin α2β1), we provide evidence for both the phenotypic and functional heterogeneity of PCa stem cells (i.e., PCa cell subpopulations with enhanced tumor-regeneration activity). Our results show that no single marker or assay seems to be able to capture all tumorigenic subsets in all 4 xenografts. We further show that different tumor-initiating subpopulations appear to co-exist in a common tumorigenic pool. We also demonstrate that some tumorigenic PCa cells overexpress stem cell-associated gene expression profiles. Finally, we provide evidence that primary prostate tumors possess subsets of tumor cells that bear similar phenotypic features to those in xenografts. Our results raise the possibility that different PCa patient tumors may harbor CSCs with distinct phenotypic and functional properties.

Note: This abstract was not presented at the conference because the presenter was unable to attend.

Citation Format: Xin Liu, Xin Chen, Brian Laffin, Binglan Yin, Tammy Calhoun-Davis, Feng Wang-Johanning, Dean G. Tang. Phenotypic and functional heterogeneity of prostate cancer stem cells [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C68.
Abstract C7: Targeting the androgen receptor with novel combination therapeutic strategies in metastatic/castrate-resistant prostate cancer
Authors: Ellis Leigh , Ramakrishnan Swathi , Ku Shengyu , Pili Roberto
Published: May 2013

While recent advances have resulted in the FDA approval of novel therapies for metastatic/castrate resistant prostate cancer, responses are not often durable and novel therapeutic interventions are still required. Recent work within our laboratory has resulted in the development of a novel orthotopic syngeneic transplant mouse model of prostate cancer. Further, treatment with a HDAC and mTORC1 inhibitor in combination resulted in greater anti-tumor and increased overall survival in tumor bearing animals. HDAC/mTORC1 combination therapy also resulted in decreased androgen receptor (AR) transcriptional activity without loss of AR protein expression. Current investigations are underway to delineate molecular mechanisms underlying sustained AR expression. Through this understanding, novel therapeutic interventions which will augment combined HDAC/mTORC1 inhibitor therapy are under investigation.

Citation Format: Leigh Ellis, Swathi Ramakrishnan, Shengyu Ku, Roberto Pili. Targeting the androgen receptor with novel combination therapeutic strategies in metastatic/castrate-resistant prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr C7.
Abstract IA10: Overcoming castration-resistant prostate cancer
Authors: Sawyers Charles L.
Published: May 2013

Resistance to antiandrogen therapy is associated with increased expression of androgen receptor (AR) mRNA, AR gene amplification or AR mutation. Increased AR levels are necessary and sufficient to promote hormone-refractory growth in models and, paradoxically, alter the cellular response to classic AR antagonists such that they function as weak agonists. Therefore, second generation antiandrogens must overcome these resistance mechanisms. We searched for novel AR antagonists that might retain function in the context of increased AR expression through a cell-based screen. Using the high affinity AR agonist RU59063 as a starting point, we synthesized and screened over 200 compounds to construct a structure/activity profile that defines features of the scaffold essential for receptor binding and for maximal antagonism. We focused our further efforts on a novel compound MDV3100, which retains potent antiandrogen activity in cells expressing increased levels of AR, blocks AR function in mice and impairs the growth of LNCaP and LAPC-4 xenografts engineered to express high levels of AR, whereas bicalutamide had minimal activity. MDV3100 inhibits AR with 10-fold greater affinity than bicalutamide and functions through a novel mechanism of action that impairs nuclear translocation and DNA binding. MDV3100 produced sustained PSA responses (greater than 50% reduction) in about ∼55 percent of men with castrate-resistant prostate cancer in a 140 patient phase I-II clinical trial. In a phase III registration study of 1119 men with castration resistance, chemotherapy refractory prostate cancer, MDV3100 prolonged survival compared to best supportive care (18.4 months versus 13.6 months; hazard ratio 0.631).

The heterogeneity of clinical response to anti-androgen therapy suggests additional molecular determinants of drug resistance. By conducting an integrated genomic analysis of 214 prostate cancers, we have defined a common set of molecular lesions and pathways that may define distinct subsets of prostate cancer as well as responder/non-responder populations to antiandrogen therapy. In preclinical models we found that tumors with PTEN loss are relatively insensitive to androgen ablation therapy due to reciprocal negative feedback between the AR and PI3K signaling pathways. PTEN-mediated resistance can be overcome with combined AR + PI3K pathway inhibition. Studies of these and other molecular abnormalities reveal unique features of prostate cancer progression with implications for downstream drug development.

Citation Format: Charles L. Sawyers. Overcoming castration-resistant prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr IA10.
Abstract IA12: Conducting hypothesis testing trials for the treatment of advanced prostate cancer
Authors: de Bono Johann S.
Published: May 2013

There are multiple challenges to the successful development of novel therapeutics for advanced prostate cancer. These include: 1) The identification of novel targets for drug discovery for treating this disease; 2) Intraand inter-patient molecular heterogeneity; 3) The pattern of disease metastases resulting in largely bone disease that is not readily measurable radiologically by standard imaging methods; 4) Difficulty accessing metastatic disease that can be interrogated to elucidate mechanisms of resistance; 5) The widespread use of PSA changes to drive therapeutic decisions; 6) The lack of a proven intermediate endpoint of overall survival to accelerate drug development. Nevertheless, major progress has been made with five novel agents being shown to improve overall survival in this patient population including abiraterone acetate, alpharadin, cabazitaxel, MDV3100 and Sipuleucel T.

Citation Format: Johann S. de Bono. Conducting hypothesis testing trials for the treatment of advanced prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr IA12.
Abstract IA17: Stem cells and prostate cancer
Authors: Witte Owen N.
Published: May 2013

Prostate cancer initiation and progression is associated with a myriad of genetic and epigenetic changes that drives the transformation process in specific cells of origin. Our group has developed a dissociated cell tissue regeneration system in which rodent or human epithelial tissue can be combined with supportive mesenchyme from the urogenital sinus to produce a tissue structure with glandular development. Introduction of specific oncogenic influences can drive normal tissue structure to a malignant histology with invasion and epithelial to mesenchymal transition. An efficient cell of origin from the basal layer of the gland has been defined for mouse and human tissue for this process and can produce malignant glands with luminal characteristics as well as other cellular phenotypes. Recent work has defined a set of changes in the adjacent stroma that can strongly influence the epithelium in its conversion to a cancerous state.

Citation Format: Owen N. Witte. Stem cells and prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr IA17.
Abstract IA18: Altered AR gene architecture and splicing in castration-resistant prostate cancer
Authors: Dehm Scott M.
Published: May 2013

Reactivation of the androgen receptor (AR) during androgen depletion therapy (ADT) underlies castration-resistant prostate cancer (CRPCa). Altered splicing of the AR gene and synthesis of constitutively-active COOH-terminally truncated AR variants lacking the AR ligand binding domain has emerged as an important mechanism of ADT-resistance in CRPCa. To understand mechanisms that may promote synthesis of these species, we have been studying the PCa progression models in which altered AR splicing patterns were originally discovered. Remarkably, these models all harbor distinct intragenic rearrangements in the AR gene, which are linked to their individual splicing signatures. For example, the CRPCa 22Rv1 cell line harbors a 35kb intragenic tandem duplication of AR exon 3 and flanking sequences, which results in expression of an exon 3-duplicated full-length AR and multiple truncated AR variant species. The CRPCa LuCaP 86.2 xenograft harbors an 8,579 bp deletion of AR exons 5, 6, and 7, which promotes synthesis of the truncated AR v567es variant. Targeted paired-end re-sequencing of the AR gene in CWR-R1 cells led to the discovery of a 48 kb deletion in AR intron 1, which is linked to a splice switch favoring synthesis of the AR-V7/AR3 variant. Copy number imbalances occur across the length of the AR gene in clinical CRPCa, often concurrent with amplification, indicating complex patterns of intragenic AR gain and loss in human disease. These findings portend ongoing discovery of diverse truncated AR variants in CRPCa and define a new class of AR gene alterations that may drive ADT-resistance at this stage of the disease.

Citation Format: Scott M. Dehm. Altered AR gene architecture and splicing in castration-resistant prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr IA18.
Abstract IA19: Cooperation between androgen receptor and Polycomb in prostate cancer
Authors: Zhao Jonathan C. , Runkle Christine , Yu Jianjun , Wu Longtao , Jin Hongjian , Kuzel Timothy , Lee Chung , Yu Jindan
Published: May 2013

Androgen receptor (AR) is a hormone-activated transcription factor that plays important roles in prostate development, function, as well as malignant transformation. The downstream pathways of AR, however, are incompletely understood. AR has been primarily known as a transcriptional activator inducing prostate-specific gene expression. Although androgen stimulation has been shown to also suppress genes, little attention has been paid to the mechanisms and functions of AR-mediated gene repression. Through integrative analysis of genome-wide AR occupancy and androgen-regulated gene expression, here we report AR as a globally acting transcriptional repressor. This repression is dictated, at least in part, by the Polycomb group protein EZH2 and repressive chromatin remodeling. In embryonic stem cells (ESC), AR-repressed genes harbor bivalent H3K4me3 and H3K27me3 modifications that are characteristic of developmental regulators, the silencing of which maintains the undifferentiated ESC state. Similarly, these genes are down-regulated in poorlydifferentiated, castration-resistant prostate tumors rendering a stem cell-like cellular state. To characterize the function of AR-repressed genes, we nominated NOV as a top AR-repressed gene. We show that NOV is robustly suppressed by androgen through the AR. Using NOV as a model gene we present evidence that AR directly inhibits gene expression through physically binding to the enhancer, establishing promoter-enhancer DNA looping, and inducing repressive chromatin remodeling. We further demonstrate that NOV is down-regulated in aggressive prostate cancer. Concordantly, NOV expression inhibits prostate cancer cell growth, migration, and invasion in vitro and xenograft tumor growth in mice. Collectively, our data reveal an unexpected role of AR in inhibiting non-prostatic differentiation and, upon aberrant signaling, promoting cancerous de-differentiation. Our findings support AR-mediated inhibition of tumor suppressors as a novel mechanism to prostate cancer progression.

Citation Format: Jonathan C. Zhao, Christine Runkle, Jianjun Yu, Longtao Wu, Hongjian Jin, Timothy Kuzel, Chung Lee, Jindan Yu. Cooperation between androgen receptor and Polycomb in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr IA19.
Abstract IA2: Genomic comparisons of coincident prostate cancer foci
Authors: Mardis Elaine R. , Humphrey Peter , McGrath Sean , Demeter Ryan , Magrini Vincent , Dees Nathan , Kanthi Krishna , Maher Christopher , Ding Li , Kibel Adam
Published: May 2013

We have an interest in distinguishing patients with aggressive from those with indolent prostate cancer. The present best indicator of disease aggressiveness is Gleason grade, assigned by histopathological examination of carcinoma in prostate tissue. Clinically speaking, Gleason pattern 4 tumors are more aggressive while Gleason pattern 3 tumors are more indolent. As such, we sought to characterize both patterns at the genomic level by sequencing and analyzing foci of Gleason 3 and 4 patterns from the same patient. By combining laser capture microdissection of coincident Gleason 3 and 4 foci in the same patients, with next-generation sequencing of the derived DNA by our ultr-alow input sequencing library construction techniques, we were able to generate whole genome sequencing data for these samples. Advanced analysis of the aligned whole genome data has permitted an examination of the genomic relatedness of Gleason 3 and 4 foci for two patients. I will present our results to-date from these analyses, shedding light on the fundamental genomic progression evident as Gleason scores increase. More recently, we have complimented these studies with additional whole genome sequencing and analysis of aggressive prostate cancers. Our preliminary findings for these samples also will be reported.

Citation Format: Elaine R. Mardis, Peter Humphrey, Sean McGrath, Ryan Demeter, Vincent Magrini, Nathan Dees, Krishna Kanthi, Christopher Maher, Li Ding, Adam Kibel. Genomic comparisons of coincident prostate cancer foci [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr IA2.
Abstract IA23: Diagnosing prostate cancer with image fusion (MRI, PET, CT, US)
Authors: Choyke Peter L.
Published: May 2013

The localization of cancer within the prostate is important for diagnosis, staging, biopsy guidance, focal therapy and active surveillance. Among the available imaging methods ultrasound offers real time monitoring but poor sensitivity, MRI offers higher sensitivity but is not real time, PET has the highest sensitivity but poor resolution and CT offers high resolution with poor sensitivity. Thus, no single imaging modality is ideal for this challenging application. This talk will focus on how we can use image fusion to combine the best aspects of each modality into a “hybrid scan” that is more than additive in its value.

MRI is the best current modality for localizing prostate cancer. MRI depends on the use of multiple parameters such as T2 weighting, diffusion weighting, spectroscopy and dynamic contrast enhancement. Since each of these methods are slightly different in their acquisition parameters, these images must first be fused to create a composite multiparametric MRI. However, having localized a suspicious area on MRI, it is necessary to direct a biopsy into it. Unfortunately, doing this under MR is a tedious and imperfect process. Thus, MRI can be fused to transrectal Ultrasound for purposes of biopsy. Under ultrasound (with MR guidance), real time biopsies and even focal therapies can be performed. One disadvantage of this approach is that with focal therapies the ability to perform real time MR thermometry is lost.

PET scanning has the highest sensitivity among the available modalities. To date, however, there is no ideal PET agent for localizing prostate cancer while it is still confined to the gland. However, there are a growing number of exciting PET agents that will be useful in the setting of local recurrence and advanced disease. For instance, agents such as Sodium Fluoride (F18 NaF), Dihydrotestosterone (F18-DHT), Prostate Specific Membrane Antigen (F18 DCFBC) and synthetic leucine analogs (F18-FACBC) are among the promising agents available for advanced prostate cancer. Unfortunately, PET suffers from poor spatial resolution, however fusion with CT is now commonplace. Newer scanners combine PET and MRI, thus completing the circle of possible fusions between MRI, PET, CT and Ultrasound. Such hybrid imaging promises great dividends for the management of patients with prostate cancer.

Citation Format: Peter L. Choyke. Diagnosing prostate cancer with image fusion (MRI, PET, CT, US) [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr IA23.
Abstract IA24: Molecular imaging agents for prostate cancer: Focus on PSMA
Authors: Pomper Martin G.
Published: May 2013

Although most clinical diagnostic imaging studies employ anatomic techniques such as computed tomography and magnetic resonance imaging, much of radiology research currently focuses on adapting these conventional methods to physiologic imaging as well as on introducing new techniques and probes for studying processes at the cellular and molecular levels in vivo, i.e. molecular imaging. Molecular imaging promises to provide new methods for the detection of minimal disease and support for personalized therapy. This summary will focus on experimental and near-term translational molecular imaging agents and methods for prostate cancer, with a focus on radiopharmaceuticals and optical agents, the former primarily for staging and the latter for surgical guidance.

Citation Format: Martin G. Pomper. Molecular imaging agents for prostate cancer: Focus on PSMA [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr IA24.
Abstract IA3: Functional implications of relocation of regulated transcription units in prostate cancer
Authors: Yang Liuqing , Lin Chunru , Nunez Esperanza , Li Wenbo , Destici Eugin , Rosenfeld Michael G.
Published: May 2013

Despite the long-standing recognition of distinct subnuclear architectural features and the recent discovery of noncoding RNAs (ncRNAs), their potential interacting roles in gene regulation remain elusive. We have found that two ncRNAs, TUG1 and NEAT2, located in Polycomb body (PcGs) and interchromatin granules, respectively, control relocation of growth control genes required for regulation of cell cycle between these two subnuclear structures, depending on the status of Polycomb 2 protein (Pc2) methylation in response to growth signals. These ncRNAs direct the assembly of multiple transcriptional co-repressor/coactivator complexes and, surprisingly, can alter “reading” of the histone tail marks by the Pc2 chromodomain, thereby specifying growth control gene expression and cell proliferation in a spatially organized manner. Binding of NEAT2 to demethylated Pc2, which promotes the SUMOylation of E2F1, which culminates in activation of the growth control gene program. These observations provide a molecular logic integrating actions of transcription factor/co-regulators, non-histone protein methylation, and ncRNAs resident in distinct subnuclear architectural structures to achieve coordinated programs of regulated gene expression in the three-dimensional space of the nucleus. We also will present data linking these strategies to mechanisms of ligand-induced activation of AR target genes in prostate cancer cells.

Citation Format: Liuqing Yang, Chunru Lin, Esperanza Nunez, Wenbo Li, Eugin Destici, Michael G Rosenfeld. Functional implications of relocation of regulated transcription units in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr IA3.
Abstract PR1: Oncogenic ETS over-expression mimics RAS/MAPK signaling in prostate cells
Authors: Hollenhorst Peter C. , Ferris Mary W. , Hull Megan A. , Chae Heejoon , Kim Sun , Graves Barbara J.
Published: May 2013

The aberrant expression of an oncogenic ETS transcription factor is implicated in the progression of the majority of prostate cancers. The prostate cancer chromosomal rearrangements that drive over-expression are associated with one of four ETS genes, ERG, ETV1, ETV4 and ETV5. It is not clear how these four oncogenic ETS genes differ from the numerous other ETS genes expressed in normal prostate. We report that these oncogenic ETS proteins, but not other ETS factors, enhance prostate cell migration. Genome-wide binding analysis matched this specific biological function to occupancy of a unique set of genomic sites highlighted by the presence of ETS and AP-1 binding sequences. ETS/AP-1 binding sequences are prototypical RAS-responsive elements, but oncogenic ETS proteins activated a RAS/MAPK transcriptional program in the absence of MAPK activation. Thus, overexpression of oncogenic ETS proteins can replace RAS/MAPK pathway activation in prostate cells. The genomic description of this ETS/AP-1 regulated, RAS-responsive, gene expression program provides a resource for understanding the role of ETS factors in both prostate cancer and other cancers with either ETS or RAS pathway mutations.

This abstract is also presented as Poster B26.

Citation Format: Peter C. Hollenhorst, Mary W. Ferris, Megan A. Hull, Heejoon Chae, Sun Kim, Barbara J. Graves. Oncogenic ETS overexpression mimics RAS/MAPK signaling in prostate cells [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr PR1.
Abstract PR5: Therapeutic targeting of oncogene-specific tyrosine kinase networks during prostate cancer progression
Authors: Drake Justin M. , Huang Jiaoti , Graeber Thomas G. , Witte Owen N. , Graham Nicholas A. , Stoyanova Tanya , Sedghi Amir , Goldstein Andrew S. , Cai Houjian , Smith Daniel A. , Zhang Hong , Evangelia Komisopoulou
Published: May 2013

Dominant activating mutations or DNA amplification of tyrosine kinases are not readily observed despite the numerous oncogenic alterations implicated in prostate cancer. We demonstrate that castration resistant prostate cancer (CRPC) exhibits increased tyrosine phosphorylation, raising the question of whether enhanced tyrosine kinase activity is observed in this disease in the absence of specific tyrosine kinase mutations. We generated a mouse model of prostate cancer progression using combinations of commonly perturbed non-tyrosine kinase oncogenes and pathways, including myristoylated Akt (Akt), androgen receptor (AR), Erg, and activated Kras (KrasG12V). We recapitulated the different stages of prostate cancer ranging from prostatic intraepithelial neoplasia (PIN) (Akt) to low grade cancer (Akt+Erg) to highly aggressive prostatic adenocarcinoma (Akt+AR or Akt+KrasG12V). We detected a significant upregulation of tyrosine phosphorylation at the advanced adenocarcinoma stage. Phosphotyrosine peptide enrichment and quantitative mass spectrometry identified oncogene-specific tyrosine kinase signatures, including activation of Egfr Y1172 (Akt+Erg), EphA2 Y595 (Akt+KrasG12V), and Jak2 Y1007/08 (Akt+AR). Kinase:substrate relationship analysis of the phosphopeptides also revealed Abl Y245 and Src Y416 tyrosine kinase activation in Akt+AR tumors; known targets of the tyrosine kinase inhibitor Dasatinib. We are currently evaluating the efficacy of tyrosine kinase inhibitors Dasatinib or Erlotinib on non-tyrosine kinase driven tumors Akt+AR or Akt+Erg, respectively. In summary, the observation of elevated phosphotyrosine signaling in advanced prostate cancer and identification of specific tyrosine kinase pathways from genetically-defined tumor models points to new therapeutic approaches using tyrosine kinase inhibitors for advanced prostate cancer.

This abstract is also presented as Poster C35.

Citation Format: Justin M. Drake, Jiaoti Huang, Thomas G. Graeber, Owen N. Witte, Nicholas A. Graham, Tanya Stoyanova, Amir Sedghi, Andrew S. Goldstein, Houjian Cai, Daniel A. Smith, Hong Zhang, Evangelia Komisopoulou. Therapeutic targeting of oncogene-specific tyrosine kinase networks during prostate cancer progression [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr PR5.