bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 3016: Roles of histone deacetylase inhibitors in the regulation of DNA methyltransferase 1
Authors: Takashima Asami , Faller Douglas V.
Published: June 2012

DNA methylation and histone deacetylation are the two major classes of genomic modifications which can contribute to transcriptionally-repressive chromatin structure.Tumor suppressor genes are hypermethylated in their promoter regions in certain cancers, which leads to transcriptional repression of these genes, and histone deacetylases (HDACs) cooperate with DNA methyltransferases (DNMTs) in this process, by their subsequent recruitment to methylated DNA. HDAC inhibitors, which can variably induce differentiation, apoptosis and/or cell cycle arrest in tumor cells, are known to alter gene expression patterns by disrupting the transcriptional regulatory complexes with which DNMT1 and HDAC1 or HDAC2 associate. Surprisingly, a series of recent studies by our group and others, using HDAC inhibitors, suggests that HDAC activity may influence DNA methylation, in addition to the established and reciprocal ability of CpG methylation to influence HDAC recruitment and transcriptional repression. HDAC inhibitors appear to influence DNA methylation by regulating the expression of DNMT1, although the molecular pathway mediating this regulation has not been fully elucidated. We have documented DNMT1 downregulation at the level of mRNA and protein abundance in human cancer cell lines, following exposure to any of several structurally-different HDAC inhibitors, suggesting that HDAC inhibitors decrease DNMT1 expression at the level of mRNA. We determined at which level, transcription or RNA degradation, DNMT1 mRNA is affected by HDAC inhibition, by measuring the time course of RNA degradation using real-time PCR following treatment of Actinomycin D, an inhibitor of de novo transcription. In spite of their ability to upregulate AUF1, a known regulator of DNMT1 mRNA stability, HDAC inhibitors did not significantly alter DNMT1 mRNA half-life in comparison to vehicle-treated controls. In agreement with this finding, specific knockdown of AUF1 by siRNA did not abrogate the decrease in DNMT1 protein expression caused by HDAC inhibition. Exposure to HDAC inhibitors in the presence of cycloheximide, an inhibitor of de novo protein synthesis, prevented the downregulation of DNMT1 mRNA, suggesting that new protein synthesis is required for the effect of HDAC inhibitors on DNMT1 expression. Thus, the downregulation of DNMT1 expression by HDAC inhibitor treatment is induced at the transcriptional level in LNCap cells, possibly in an indirect manner. These findings begin to elucidate the mechanism whereby HDACs and their inhibitors may influence DNA methylation, in addition to the established and reciprocal ability of CpG methylation to influence HDAC recruitment and transcriptional repression.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3016. doi:10.1158/1538-7445.AM2011-3016
Abstract 3019: Demethylation of RB regulator MYPT1 by histone demethylase LSD1 promotes cell cycle progression in cancer cells
Authors: Cho Hyun-Soo , Nakamura Yusuke , Hamamoto Ryuji
Published: June 2012

Histone demethylase LSD1 (also known as KDM1 and AOF2) is active in various cancer cells, but its biological significance in human carcinogenesis is unexplored. In this study, we explored hypothesized interactions between LSD1 and MYPT1, a known regulator of RB1 phosphorylation. We found that MYPT1 was methylated in vitro and in vivo by histone lysine methyltransferase SETD7 and demethylated by LSD1, identifying Lys 442 of MYPT1 as a target for methylation/demethylation by these enzymes. LSD1 silencing increased MYPT1 protein levels, decreasing the steady-state level of phosphorylated RB1 (Ser 807/811) and reducing E2F activity. MYPT1 methylation status influenced the affinity of MYPT1 for the ubiquitin-proteasome pathway of protein turnover. MYPT1 was unstable in murine cells deficient in SETD7, supporting the concept that MYPT1 protein stability is physiologically regulated by methylation status. LSD1 overexpression could activate RB1 phosphorylation by inducing a destabilization of MYPT1 protein. Taken together, our results comprise a novel cell cycle regulatory mechanism mediated by methylation/demethylation dynamics, and they reveal the significance of LSD1 overexpression in human carcinogenesis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3019. doi:10.1158/1538-7445.AM2011-3019
Abstract 3020: Transcriptional repressive H3K9 and H3K27 methylations are essential for DNMT1-mediated DNA methylation recovery
Authors: Wong Chun-Ming , Ng Irene Oi-Lin
Published: June 2012

DNA methylation and histone modifications are two major epigenetic events regulating gene expression and chromatin structure, and their alterations are linked to human carcinogenesis. DNA methylation plays an important role in tumor suppressor gene inactivation, and can be revised by DNA methylation inhibitors. The reversible nature of DNA methylation forms the basis of epigenetic cancer therapy. However, it has been reported that DNA re-methylation and gene re-silencing could occur after removal of demethylation treatment and this may significantly hamper the therapeutic value of DNA methylation inhibitors. In this study we have provided detailed evidence demonstrating that mammalian cells possess a bona fide DNA methylation recovery system. We have also shown that DNA methylation recovery was mediated by the major human DNA methyltransferase, DNMT1. Moreover, the DNA methylation recovery function of DNMT1 was cell division-independent and likely to be distinct from its conventional “maintenance” DNA methyltransferase function. In addition, we found that H3K9-tri-methylation and H3K27-tri-methylation were closely associated with this DNA methylation recovery. These persistent transcriptional repressive histone modifications may have a crucial role in regulating DNMT1-mediated DNA methylation recovery. Our findings may have important implications towards a better understanding of epigenetic regulation and future development of epigenetic therapeutic intervention.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3020. doi:10.1158/1538-7445.AM2011-3020
Abstract 3043: FXR1 promotes lung cancer cell growth by regulating oncogenic targets in the 3q26-3q28 amplicon
Authors: Qian Jun , Zou Yong , Rahman Jamshedur , Hassanein Mohamed , Massion Pierre
Published: June 2012

Gain of chromosome 3q26-28 is one of the most common genomic imbalances in non-small cell lung cancer (NSCLC), particularly in squamous cell carcinomas (SCC). A comprehensive approach combining array CGH, mircroarray expression and shotgun proteomics data analysis reveals amplification, overexrpession of a candidate gene on 3q26, fragile-X-mental-retardation-related protein 1 (FXR1) in lung cancer. FXR1 is amplified and overexpressed in NSCLC tumors and highly correlated with several 3q26-28 targets including epithelial cell transforming sequence 2 (ECT2), protein kinase C iota (PKCi) and eukaryotic translation initiation factor 4 gamma 1 (EIF4G1) measured by Real time-PCR and immunohistochemistry. We hypothesized that FXR1 is associated with these oncogenes and plays a critical role in lung cancer progression. ECT2 is known to promote lung cancer by binding to PKCi and activating MAPK signaling pathway. We found that overexpressing FXR1 in an immortalized human bronchial epithelial cell line (HBEC3KT) leads to upregulated expression of ECT2, PKCi and ERK1/2 activity. Downregulation of FXR1 using siRNA in lung cancer cell lines H520 and HCC95 induces the decreased expression of ECT2, PKCi and EIF4G1. Immunoprecipitation confirms that FXR1 binds to PKCi and EIF4G1 in NSCLC cells. Loss of FXR1 using siRNA treatment inhibits cell growth and survival of NSCLC cells that harbor 3q26-28 amplicon. Our results demonstrate the oncogenic potential of FXR1 and supports the concept that amplified targets on 3q26-28 are genetically and functionally associated to drive lung cancer cell growth.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3043. doi:10.1158/1538-7445.AM2011-3043
Abstract 3045: Dual functions of NDRG1 in cell growth and invasion
Authors: Li Hsiao-Fang , Cheng Ann-Joy
Published: June 2012

Head neck cancer (HNC) is a top ten leading cancers in Taiwan. Since this cancer usually occurs in the middle age male, at the high peak of life responsibility, it has tremendous impact of family and society. Previously through differential display analysis, we have identified several genes associated with HNC including NDRG1 (N-myc downstream-regulated gene-1), which is over-expression in HNC. In the present study, we further investigate cellular function of this gene leads to cancer development. NDRG1 expression was modulated by shRNA and full-length plasmid transfection and the potential alterations of cellular phenotypes were examined. Results showed that NDRG1 suppressed cell growths by 14% to 55%. This phenomenon was confirmed by colony formation. However, by using wound healing assay the cell migration increased (17% ∼ 43%) and by using matrigel invasion assay the invasion increased (7 ∼ 12 folds). Both migration and invasion were significantly enhanced. These results suggest that NDRG1 plays dual functions in tumorigenesis with multiple aspects

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3045. doi:10.1158/1538-7445.AM2011-3045
Abstract 305: EphB4 and EphrinB2 regulates ovarian cancer progression
Authors: Tan Wei , Yang Suijin , Looper David , Nowlin Dawn , Huang Zhongdong , Los Gerrit , Jani Jitesh P.
Published: June 2012

EphB4 belongs to the Eph Receptor Tyrosine Kinase family. EphB4 regulates angiogenesis, neuron migration and breast morphogenesis. Overexpression of EphB4 has been observed in numerous cancer types, including breast, ovarian and prostate cancers. How EphB4 regulates cancer progression is still largely unknown. EphrinB2 is the unique ligand for EphB4. EphrinB2 triggers phosphorylation, activation and down-regulation of EphB4. We analyzed various ovarian cancer cell lines and patient derived xenograft samples by in vitro and in vivo assays including siRNA knockdown and gene expression profiling. A large portion of ovarian cancer models express both EphB4 and ephrinB2. SiRNA targeting of EphB4 induced growth inhibition and induction of apoptosis in several cell lines. Serous ovarian carcinoma cell line, Ovcar-3 which expresses both EphB4 and ephrinB2 was most sensitive to siRNA targeting. Non ephrinB2 expressing cell lines were less sensitive suggesting that sensitivity to EphB4 siRNA targeting is not only dependent on the levels of EphB4 but also the status of ephrinB2. Gene expression profiling studies showed that EphB4 is implicated in signaling transduction, cell attachment and growth. Currently, we are examining how ephrinB2 expression modulates EphB4 signaling and the down-stream effectors of EphB4 signaling pathway.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 305. doi:10.1158/1538-7445.AM2011-305
Abstract 3051: The vitamin D2 analog 19-nor-1,25-dihydroxyvitamin D2: antitumor activity against gastric cancer cells
Authors: Bae Woo Kyun , Park Myung Suk , Lee Ji Hee , Hwang Jun Eul , Yoon Joo Young , Shim Hyun Jeong , Cho Sang Hee , Lee Jae Hyuk , Chung Ik Joo
Published: June 2012

Background: The active metabolite of vitamin D, 1, 25-dihydroxyvitamin D3 (calcitriol), inhibits the growth of several types of human cancer cells in vitro, but its therapeutic use is limited because it causes hypercalcemia. Among its analogs, 19-nor-1, 25-dihydroxyvitamin D2 (paricalcitol) induces fewer calcemic effects and exhibits an activity that is equipotential to that of calcitriol in several in vivo and in vitro systems. We investigated the antitumor activity and mechanism of action of paricalcitol in gastric cancer cells.

Methods: We examined the effects of paricalcitol on cell proliferation, cell cycle, apoptosis, and inflammation/immunity in the human gastric cancer cell lines AGS, SNU719, and MKN45.

Results: In vitro treatment with paricalcitol was associated with the following: (1) a dose-dependent increase in vitamin D receptor (VDR) protein expression; (2) inhibited gastric cell growth and induced apoptosis in AGS, SNU719, and MKN45 cell lines; (3) increased expression of p21 and p27 and decreased expression of CDK2; (4) increased expression of the caspase-3 cleaved protein and decreased expression of the anti-apoptotic Bcl-2 and Bax proteins; (5) promotion of early and late apoptosis; and (6) decreased expression of STAT-3, JAK2, COX2, and NF-κB.

Conclusion: The low-calcemic vitamin D analog, paricalcitol, exhibits anticancer activity against gastric cancer cells, and its mechanism of action may be mediated through the VDR. Paricalcitol is a promising agent for the prevention and treatment of gastric cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3051. doi:10.1158/1538-7445.AM2011-3051
Abstract 3056: Amplification of the BP1 homeobox gene in familial breast cancer with BRCA1/2 mutations
Authors: Pereira Silma R. , Oliveira Marcia M.C. , Haddad Bassem R. , Berg Patricia E. , Cavalli Luciane R.
Published: June 2012

Background: BP1 is a homeobox gene which was reported to be amplified and overexpressed in breast tumors with poor clinical outcome. Its exact role and function in breast tumorigenesis is not known and no studies have investigated its role in familial breast cancer cases. BP1 is located on 17q21, a chromosomal region that is altered in a high percentage of breast tumors; CGH analysis of the 17q region demonstrated gains in 50% and 85% of BRCA1 and BRCA2 mutated familial breast tumors, respectively. BP1 has been found to be overexpressed in breast cancer cells defective in double-strand break repair by homologous recombination (BRCA defective) and has been shown to directly regulate BRCA1 expression. The above information formed our rationale to evaluate the amplification of BP1 in familial breast cancer patients with known BRCA1/2 mutation status. We hypothesized that BP1 would be preferentially amplified in BRCA1/2 mutations carriers and correlated with poor clinical prognostic factors.

Methods: Three tissue microarrays, containing tumor tissues of a total of 67 familial breast cancer patients, with known BRCA1/2, ER and PR status and full clinical data, were obtained from the Familial Cancer Registry from Georgetown University. FISH analysis was performed using a specific BP1 FISH probe developed in our lab.

Results: FISH scoring in 100 cells was performed in 87% of the patients. Amplification of BP1 was observed in 26% of the cases and was significantly correlated with the presence of mutations in the BRCA1/2 genes, as opposed to patients with full negative (FN), Jewish panel negative (JPN) and variant with unknown significance (VUS). BP1 amplification was also significantly correlated with large tumor size (>1.5cm) and poorly differentiated tumors. Upon stratification of the samples by histological type, a total of 173 lesions (from cores containing different lesions from the same patients) were analyzed. Similar frequencies of BP1 amplification were observed in invasive (24%) and ductal carcinoma in situ (23.6%) lesions.

Conclusions: Our findings demonstrate that the BP1 homeobox gene is amplified in familial breast cancer patients and its amplification is correlated with the presence of mutations in the BRCA1/2 genes as well as poor clinical prognostic factors, such as large tumor size and poorly differentiated tumors. Studies evaluating the expression of BRCA1 and BP1 proteins in these samples are in progress, in order to identify possible mechanism of interactions and related pathways between BP1 positive and BRCA1 mutant tumors in familial breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3056. doi:10.1158/1538-7445.AM2011-3056
Abstract 3057: Identification and characterization of SPOCK1 in HCC development
Authors: Li Yan , Chan Hon Man , Chen Leilei , Guan Xin-Yuan
Published: June 2012

EIF5A2 is a recently identified oncogene in HCC which can enhance cell motility and promote tumor metastasis. To explore its oncogenic mechanisms, an mRNAs profiling microarray was carried out to identify downstream targets. Among the genes differentially regulated by EIF5A2, SPOCK1 was further investigated. The protein encoded by SPOCK1 is a component of the extracellular matrix, which is predicted to be involved in cell adhesion and migration. Overexpression of SPOCK1 was detected in approximately 70% of human HCC samples analyzed and positively correlated with EIF5A2 expression. Functional studies found that ectopic expression of SPOCK1 could promote cell proliferation, anchorage-dependent growth, anchorage-independent growth and invasion in HCC cells. In vivo, SPOCK1 over-expressed stable clones formed bigger tumors when compared to controls. Silencing SPOCK1 expression by shot-hairpin knock-down approach effectively abolished the tumorigenic and metastatic abilities of HCC cell line.

Furthermore, as detected by the functional studies, over-expression of SPOCK1 increased MMP9 level in HCC cells. Western blotting analysis revealed an increase of sheared fibronectin as the result of full-length fibronectin degradation. As SPOCK1 belongs to a matricellular glycoprotein family that mediates interactions between cells and their microenvironment, the above results suggest it may promote invasion by regulating matrix deposition and turnover.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3057. doi:10.1158/1538-7445.AM2011-3057
Abstract 3062: A comparative analysis of phosphothioated DNA and peptide nucleic acid molecular beacons targeting specific K-ras mutation
Authors: Kam Yossi , Rubinstein Abraham , Nissan Aviram , Halle David , Yavin Eylon
Published: June 2012

Introduction: Early detection of gastrointestinal malignancies may improve disease-related outcome. In vivo, real time imaging using hybridization of fluorescently-labeled complementary transcripts to intracellular RNA sequences may facilitate early detection of malignant and pre-malignant lesions

Methods: Using K-ras oncogene as a model target, and adapting the molecular beacon technology, we performed an hybridization kinetics and hybridization specificity comparison of two types of molecular beacons (MBs) based on either phosphothioated DNA (PS-DNA-MB) or peptide nucleic acid (PNA-TO-MB, where thiazole orange [TO] was used as the fluorescent molecule) both in vitro and in a variety of cell lines. In order to determine the sequence-specificity of MB's at a single base resolution, a codon 12 K-ras oncogene mutation (GGT→GAT) was used as target in different cell lines. Both PS-DNA and PNA-TO MB's were designed to target this specific K-ras point mutation. We studied the hybridization of the two MBs to wild-type K-ras (HT-29 colon cancer cell line) and two cell lines, one harboring this K-ras point mutation (PANC-1) and SW-480 harboring a different (GGT→GTT) mutation.

Results: Hybridization kinetics of PNA-TO-MB to target DNA or RNA was faster compared to PS-DNA-MB highlighting the advantage of such probes to be developed into diagnostic kits for the early detection of cancer. However, in solution, using synthetic DNA oligomers as targets, PS-DNA-MB demonstrated higher specificity to its complementary target (3-to 4.6-fold increase in fluorescence in comparison to DNA with a single mismatch) compared to the PNA-TO-MB (only 1.3- to 2.2-fold increase). Yet, incubation of PNA-TO-MB with total RNA (isolated from these cell lines) and with fixed cells, resulted in a significantly higher fluorescent signal (p < 0.001) detected for target (fully complement, PANC-1) compared to single mismatch mRNA transcript in HT29 and SW-480. In contrast, the PS-DNA-MB showed poor discrimination in total RNA and no fluorescent signal with all cell lines after 5 minutes incubation.

Conclusions: Based on the fast hybridization kinetics and based on the single mismatch discrimination found for PNA-TO-MB in fixed cells and with total RNA, it is speculated that such PNA-TO-MB's are promising candidates for the early detection of cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3062. doi:10.1158/1538-7445.AM2011-3062
Abstract 3071: Accurate and sensitive detection of KRAS mutations in heterogeneous cancer specimens
Authors: Bao Yun , Merrill David , Corre Delphine Le , Sproul Scott , Ching Bonnie , Casuga Iris , Sapinoso Lorenzo , Desai Sejal , Petraroli Rosella P. , Deng David , Brzoska Pius , Blons Helene , Laurent-Puig Pierre , Chen Caifu
Published: June 2012

The discovery of pivotal genetic alterations and the understanding of their role in cancer is leading to remarkable successes in therapeutics and patient care. Molecular diagnosis methods such as DNA sequencing and conventional genotyping of tumor biopsies have advanced research in this field, but are limited in sensitivity due to stromal contamination and by genetic heterogeneity in cancer. We have recently developed competitive allele specific TaqMan® PCR (castPCR) assays assays for detecting cancer-associated sequence variations. CastPCR not only maintains the wide dynamic range, high sensitivity and reproducibility of TaqMan® assays but also greatly improves the specificity. The technology enables detection, of as little as 1 mutant allele molecule in 10,000,000 wild type molecules. We report here sensitive and accurate detection of cancer-associated KRAS mutations within formalin-fixed paraffin-embedded (FFPE) heterogeneous cancer specimens. Eight FFPE model cell lines were initially used to validate the assays (NCI-H2009:p.G12A; SW1463:p.G12C; PANC-1:p.G12D; PSN-1: p.G12R; A549:p.G12S; SW480:p.G12V; DLD-1:p.G13D; Jurkat:Wild Type). Mutant FFPE cell line DNAs were titrated in the FFPE wild type cell line DNAs from 100% to 0.1%. Mutations were easily identified at the level of 0.1% with high reproducibility. 24 anonymous tumor tissues and 12 non-tumor tissues from FFPE specimens were also examined. No positive samples were found in non-tumor tissues. The results obtained by castPCR for the 24 tumor tissues were concordant to those previously reported by three different methods (Taqman® PCR, Taqman® PCR + PNA and Sequencing). Our results demonstrate that castPCR, as a new rare mutation detection technology, has greater sensitivity, specificity and can thereby facilitate accurate molecular diagnosis of heterogeneous cancer specimens and enable patient selection for targeted cancer therapies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3071. doi:10.1158/1538-7445.AM2011-3071
Abstract 3082: Exploring LIN28 mRNA targets in breast cancer cells
Authors: Yang Jun , Kinyamu Harriet H. , Archer Trevor K.
Published: June 2012

LIN28 is a RNA binding protein and a pluripotency factor. It represses tumor suppressing microRNA let-7 and thus derepresses let-7 oncogene targets such as HMGA2, K-Ras and c-Myc. In addition, LIN28 binds and enhances translation of IGF-2 mRNA a known mitogen. Recent reports show that LIN28 overexpression promotes tumor cell migration and cellular transformation through repression of let-7, and that overexpression is associated with advanced stages of disease, including breast cancer. Despite the apparent critical role in cancer, the molecular function and mode of action of LIN28 is not yet elucidated. To further understand the function of LIN28, we explored LIN28 mRNA targets in breast cancer cells using RNA-protein immunoprecipitation (RIP-Chip) followed by RNA sequencing. Using RIP-Chip and RNA sequencing we have identified a number of novel LIN28 targets in MCF-7 breast cancer cells. Therapeutic drugs inhibiting LIN28 could be promising in treatment of cancer. Our experiments also demonstrate that MG132, a proteasome inhibitor, inhibits LIN28 expression and modulates expression of LIN28 mRNA targets in breast cancer cells. The mechanism by which LIN28 regulates its targets is unknown; however, a number of the new targets are important in cancer. Previous studies suggest that LIN28 acts through translational mechanisms. Studies are ongoing to reveal the mechanisms by which LIN28 regulates bound targets and how proteasome inhibitors impact this regulation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3082. doi:10.1158/1538-7445.AM2011-3082
Abstract 3083: The RNA stability factor HuR promotes an angiogenic switch in colon cancer
Authors: Young Lisa E. , Dixon Dan A.
Published: June 2012

The initiation and progression of colorectal tumorigenesis is characterized by alterations in gene expression that allow for the overexpression of oncogenic and tumor-promoting factors. In normal cells, the mRNA transcripts of these cancer-associated genes are targeted for rapid decay through AU-rich elements (ARE) present in the mRNA 3’ untranslated region (3′UTR). However, growing evidence reveals that the loss of ARE-mediated mRNA decay is a characteristic feature contributing to pathogenic gene expression in colorectal cancer. Our prior work identified enhanced expression of the RNA-binding protein HuR to occur during colon tumorigenesis and HuR overexpression is correlated with poor clinical prognosis. In this capacity, HuR promotes overexpression of many cancer-associated factors by binding to their ARE and interfering with subsequent rapid mRNA decay. To determine the functional significance of HuR overexpression in vivo, a tissue-specific HuR-transgenic mouse (HuR-Tg) was created that overexpresses HuR in the epithelium of the small intestine and colon. HuR-Tg mice displayed normal growth and did not reveal any morphological changes in the gastrointestinal tract. To test if HuR overexpression can impact tumorigenesis downstream a tumor initiating event, crosses between HuR-Tg mice and the APCMin/+ mouse, a genetic model of gastrointestinal tumorigenesis, were performed. As early as 12 weeks of age, HuR-Tg/APCMin/+ lines display a 2- to 4-fold increase in tumor burden and size in both the colon and small intestine compared to APCMin/+control mice. Based on HuR's ability to bind various ARE-containing mRNAs associated with angiogenesis, vascular density was assayed in tissue derived from HuR-Tg/APCMin/+ mice. Micro-vessel density was 2-fold greater in the tumors and surrounding tissue in APCMin/+ mice overexpressing HuR. Angiogenic mRNA array analysis of tumors derived from HuR-Tg/APCMin/+ mice showed enhanced expression of multiple ARE-containing angiogenic genes including the HuR target genes vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2). Furthermore, dietary treatment of HuR-Tg/APCMin/+ mice with celecoxib attenuated HuR-dependent tumor formation and suppressed micro-vessel density and VEGF expression. These findings indicate that HuR functions during colon tumorigenesis downstream of a tumor-initiating event to stabilize ARE-containing mRNAs associated with tumor vascularization and identify this mRNA stability factor as a new molecular target for therapeutic intervention in controlling angiogenic gene expression.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3083. doi:10.1158/1538-7445.AM2011-3083
Abstract 3089: The role of p63 regulation during epithelial to mesenchymal transition (EMT) and subsequent accumulation of malignant features of primary immortalized prostate cells
Authors: Olsen Jan Roger , Ke Xi-Song , Qu Yi , Rostad Kari , Hellem Margrete R. , Lorens James B. , Micklem David R. , Haugen Hallvard , Gravdal Karsten , Halvorsen Ole Johan , Rotter Varda , Akslen Lars A. , Oyan Anne Margrete , Kalland Karl H.
Published: June 2012

A family of transcription factors is constituted by p53, p63 and p73. Unlike p53, which is expressed in response to environmental stress, p63 (TP73L) is constitutively expressed at high levels in a variety of epithelial tissues including prostate. Our genome-wide gene expression analysis identified p63 as one of the most consistently under-expressed genes in prostate cancer samples compared to matched benign prostate tissue. All benign prostate samples including benign prostate hyperplasias (BPH) exhibited high p63 expression.

Two alternative p63 promoters generate two different N-terminal variants, TA or ΔN which contains and lacks the transactivating domain, respectively. Differential splicing generates multiple additional isoforms. The activity and interactions of the different isoforms remain unresolved.

Using isoform-specific TaqMan real-time quantitative PCR assays, we have found that ΔNp63α is the predominant isoform in prostate tissues, but the other isoforms are detectable.

Our group has established a new experimental cell culture model based upon primary, immortalized prostate epithelial cells (EP156T cells), where p63 was found to be shut-down as EP156T cells underwent epithelial-to-mesenchymal transition (EMT) to become EPT1 cells. Subsequently, EPT2 cells were derived from EPT1 cells and p63 stayed shut-down. EPT2 cells had acquired several malignant features in contrast to the progenitors, including anchorage independent growth in soft agar and ability to grow at much higher density in monolayers.

To dissect the role of p63 in EMT and in gene expression modules associated with carcinogenesis, we have stably re-expressed the predominant isoform ΔNp63α in both EPT1 and EPT2 cells using retroviral vector transductions.

Microarray analysis shows that p63 re-expression leads to re-expression of genes participating in several cell-junction components, such as hemidesmosomes, focal adhesions and gap junctions. These genes were down-regulated during EMT. There were also morphological changes and a decreased ability to migrate following p63 re-expression. This indicates that ΔNp63α re-expression might result in a partial mesenchymal-to-epithelial transition (MET).

The present focus is to identify co-factors that may act complementary or synergetically with p63 to induce a complete MET in EPT1 cells and to identify p63 target genes and regulatory cross-talk with relevance for anti-cancer strategies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3089. doi:10.1158/1538-7445.AM2011-3089
Abstract 3100: HOX transcription factors promote cell survival in breast cancer
Authors: Morgan Richard , Michael Agnieszka , Bhatt Aagna , Harrington Kevin , Boxall Angela , Annels Nicola , Pandha Hardev
Published: June 2012

The HOX genes are a family of closely related transcription factors that help to define the identity of cells and tissues during embryonic development and which are also frequently deregulated in a number of malignancies, including breast cancer. Whilst relatively little is known about the roles that individual HOX genes play in cancer, it is however clear that these roles can be both contradictory, with some members acting as oncogenes and some as tumour suppressors, and also redundant, with several genes essentially having the same function. Here we have attempted to address this complexity by using the HXR9 peptide to target the interaction between HOX proteins and PBX, a second transcription factor that serves as a common co-factor for many HOX proteins. We show that HXR9 causes apoptosis in a number of breast cancer-derived cell lines and that sensitivity to HXR9 is directly related to the averaged expression of HOX genes HOXB1 through to HOXB9, providing a potential biomarker to predict the sensitivity of breast tumours to HXR9 or its derivatives. Furthermore, we show that whilst HXR9 blocks the oncogenic activity of HOX genes, it does not affect the known tumour-suppressor properties of a subset of HOX genes in breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3100. doi:10.1158/1538-7445.AM2011-3100
Abstract 3103: Transducin β-like protein 1 promotes cancer cell invasion by recruiting nuclear factor-κB to target gene promoter for transcriptional activation
Authors: Ramadoss Sivakumar , Li Jiong , Ding Xiangming , Wang Cun-Yu
Published: June 2012

Background and Purpose: Nuclear factor-kappaB (NF-κB) signaling controls a wide range of cellular functions such as tumor progression and invasion by inducing gene expression. Although significant progress has been made in understanding NF-κB-mediated gene transactivation, little is known about how NF-κB is recruited to its target gene promoters. Therefore the purpose of the study is to determine the role of transducin β-like protein 1 (TBL1) in the recruitment of NF-κB to target gene promoter. Methods:TBL1 knock down breast and squamous cell carcinoma cells were used to asses the significance of TBL1 depletion on NF-κB recruitment to target gene promoter and its consequence on the invasion of cancer cells. Results: Our results revealed that transducin β-like protein 1 (TBL1) controlled the expression of NF-κB target genes by directly binding with NF-κB and facilitating its recruitment to target gene promoters. TNF-α stimulation triggered the formation of NF-κB and TBL1 complex and subsequent target gene promoter binding. Knock-down of TBL1 impaired the recruitments of NF-κB to its target gene promotes. Interestingly, the mRNA microarray studies available from Oncomine revealed that TBL1 expression levels were higher in invasive breast cancer tissues than in breast adenocarcinoma. Consistently, TBL1 knockdown significantly reduced the invasive potential of breast cancer cells by inhibiting NF-κB. Conclusions: Our results unravel a new mechanism for the regulation of NF-κB activation, with important implications in the development of novel strategies for cancer therapy by targeting NF-κB.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3103. doi:10.1158/1538-7445.AM2011-3103
Abstract 3106: Intestinal mesenchymal fibroblasts promote early epithelial tumorigenesis through activation of integrin beta4 and receptor tyrosine kinases, bypassing common mutational mechanisms
Authors: Woo Janghee , Morikawa Teppei , Ogino Shuji , Gilliland D. Gary , Shivdasani Ramesh A.
Published: June 2012

Cancer cells communicate extensively with their stroma, exchanging signals that influence growth and metastasis. Intestinal sub-epithelial myofibroblasts (ISEMFs) direct organogenesis and constitute the colorectal cancer (CRC) microenvironment. ISEMFs from the mouse small intestine and colon express regional characteristics and different cytokines. In line with these regional patterns, ApcMin mice develop adenomas principally in the small intestine but not in the colon; conversely, humans develop tumors mainly in the colon and rarely in the small bowel. We hypothesize that intestinal ISEMFs influence tumor regionality through cell-cell communication. Murine ileal ISEMFs supported growth of human CRC cells markedly better than those originating in the colon in NOD/SCID xenografts and in vitro. We traced this effect to a single secreted factor, matrix metalloproteinase 9 (MMP9), which is exclusively mesenchymal in expression and substantially enriched in native ileal over colonic ISEMFs. Actively cycling intestinal epithelial progenitors and Lgr5+ stem cells showed selectively reduced bromodeoxyuridine uptake in Mmp9-/- mouse ileum, revealing that Mmp9 deficiency impairs epithelial self-renewal. Moreover, ApcMin mice developed fewer ileal adenomas upon treatment with an Mmp9 inhibitor or on the Mmp9-/- genetic background. MMP9 immunohistochemistry revealed expression in 106 of 642 (16.5%) human CRC samples; expression was confined to stromal fibroblasts and considerably enriched among CRCs that lack characteristic KRAS mutations and harbor the CpG island methylator phenotype. Gene expression in epithelial cells interacting with ileal fibroblasts pointed to activation of cytoskeletal remodeling and integrin ß4 signaling pathways, signatures absent in cells cultured with colonic ISEMFs. Biochemical assays verified that stromal MMP9 activates epithelial integrin ß4 and, in turn, ErbB and c-Met receptor tyrosine kinases (RTKs) in adjoining epithelial, including human CRC, cells. This activation is mediated by MMP9 cleavage of the integrin ligand laminin alpha4. Activation of epithelial integrin ß4 and RTKs and the paucity of KRAS mutations in CRCs with stromal MMP9 expression together suggest that potent MMP9-mediated microenvironment signals can help bypass common mutational mechanisms of constitutive growth factor pathway activation in CRC. These results define a novel and therapeutically tractable pathway of tumor-stromal interaction in early CRC pathogenesis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3106. doi:10.1158/1538-7445.AM2011-3106
Abstract 3111: Normal breast epithelial architecture and breast-cancer cell metabolism are altered by adipocytes and inflammatory fatty acids: Implications for postmenopausal breast cancer
Authors: Siriwardhana Nalin , Layman Rhett , Patel Shiwani , Karwandyar Ayub , Clark Matthew Mitchell , Tatge Blair Blair , Lampley Jessica , Zou Ming-Hui Ming-Hui , Wang Qilong , Moustaid-Moussa Qilong Moustaid-Moussa Naima , Wimalasena Jay
Published: June 2012

Alteration of organized breast epithelial ductal architecture accompanies neoplastic transformation. Obesity and chronic inflammation are associated with increased risk of postmenopausal breast cancer (BC). Further, omega 6 arachodonic acid (AA) significantly increases the secretion of pro-inflammatory cytokines by adipocytes compared to omega 3 eicosapentaenoic acid (EPA), therefore, we compared the effect of adipocytes and these two fatty acids on primary breast epithelial cell growth and formation of acini-like spheroid architecture. We used three dimensional (3D) MatrigelTM cultures of both basal and luminal primary breast cells and a novel 3D co-culture system with primary breast epithelial cells (basal/luminal) and adipocytes from lean or obese women. Effects of adipocytes as well as fatty acids on cellular architecture were assessed. Culture of basal or luminal epithelial cells with obese adipocytes/AA showed a significant increase in the irregularity of acini-like spheroid formation compared to normal spheroid formation in the absence of adipocytes or AA. Conditioned media transfer from lean/obese adipocytes into growing breast cell cultures showed remarkably different effects on LKB1/AMPK/mTOR metabolic signaling systems specifically in invasive MDA MB 321 cells. Obese adipocyte media decreased the activation of LKB1, AMPK, Acetyl-CoA carboxylase (ACC) and mTOR levels compared to lean adipocyte media. Further the expression of LKB1, pLKB1, pACC and mTOR were significantly higher in MDA MB 231 cells compared to less invasive MCF7 or epithelial MCF10A cells. Our data highlights the regulatory influence of adipocytes and inflammatory fatty acids on breast cellular architecture as well as metabolism and such alterations may underlie the effects of obesity on transformation of normal breast cells to BC cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3111. doi:10.1158/1538-7445.AM2011-3111
Abstract 3113: M402, a novel heparan sulfate mimetic, modulates the desmoplastic response in an orthotopic pancreatic cancer model in mice
Authors: Chu Chia Lin , Long Alison , Honan Christopher M. , Duffner Jay , Avery William , D'Alessandro Josephine , Kishimoto Takashi K. , Schultes Birgit C.
Published: June 2012

Pancreatic ductal adenocarcinoma (PDAC), currently the fourth leading cause of cancer-related deaths in the US, is one of the most lethal cancers due in part to its resistance to or poor delivery of existing chemotherapeutics (such as gemcitabine). One of the hallmarks of this deadly disease is extensive desmoplasia in the surrounding tumor microenvironment. Recent advances in pancreatic cancer research implicate the involvement of several heparin-binding growth factors that control tumor-stroma interactions (including sonic hedgehog (shh), HB-EGF, TGFs, PDGF and HGF). We have rationally designed a heparan sulfate mimetic, M402, that has previously been shown in animal studies to reduce metastatic seeding through disruption of multiple heparin-binding growth factor-mediated pathways. We hypothesized that M402, alone or in combination with gemcitabine, could potentially modulate tumor-stroma interactions in an orthotopic pancreatic cancer model (Capan-2 cell line) which displays moderate desmoplasia in vivo. Capan-2 human adenocarcinoma cells (∼1×106 cells) were injected into the pancreases of immunodeficient mice (Nu/Nu CD-1, female, 8 weeks old). M402 (40 mg/kg/day) or saline treatment commenced on day 4 (via osmotic pump). Gemcitabine (30-60 mg/kg, twice weekly, IP) treatment commenced between weeks 3-6. At the termination of each study (week 8), gross anatomical observations were made of the primary pancreatic tumor and metastatic lesions in the surrounding tissues including the spleen, intestines and liver. The primary pancreatic tumor was weighed and further processed for immunohistochemistry and mRNA expression of fibrotic matrix markers (fibronectin and COLI) and shh signaling (shh and Gli1). Gemcitabine was increasingly less effective when started at later time points, but still reduced the primary tumor weight by 60-70% (30-45 mg/kg) when treatment was started at week 5. M402 was also effective as monotherapy. The addition of M402 to gemcitabine showed only marginally more activity on primary tumor burden; however, metastasis, invasion, and surrounding fibrotic lesions appeared more impacted by the combination treatment than either agent alone. Immunohistochemical and qPCR analyses showed reduced shh and Gli1 with M402 and gemcitabine combination treatment. These results show that M402 can modulate tumor-stroma interactions involved in the desmoplastic response in a murine model of pancreatic cancer. These results provide a rationale for the clinical investigation of M402 as a potential anti-desmoplastic agent in pancreatic cancer patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3113. doi:10.1158/1538-7445.AM2011-3113
Abstract 3119: SIDT1 is a mediator of pro-desmoplastic pancreatic stellate-adenocarcinoma intercellular communication
Authors: Duxbury Mark S. , Christie Jennifer
Published: June 2012

Introduction: Pancreatic adenocarcinoma is characterized by extensive collagen-rich but hypovascular desmoplasia that impairs drug delivery. Desmoplasia is driven by complex tumor-stromal interactions. Anti-desmoplastic strategies may improve therapeutic responses to existing agents. We examined the role of the membrane protein SIDT1 in mediating pro-desmoplastic signaling between tumor and stromal cells.

Methods: Pancreatic stellate cells (PSC) and adenocarcinoma cells were isolated from surgical patients, characterised and maintained in culture. SIDT1 and collagen I expression was quantified by realtime PCR and Western blotting. SIDT1 fluorescence immunocytochemistry and immunohistochemistry was performed. Collagen I production was quantified in direct and indirect adenocarcinoma/PSC coculture. The effects of SIDT1 gene silencing on collagen I expression were examined using doxycycline-inducible shRNA generating vectors and compared to non-silencing control transfectants

Results: SIDT1 is expressed at relatively high levels in PSC. Adenocarcinoma cells and patient specimens show heterogeneity in SIDT1 expression. Adenocarcinoma/PSC coculture enhances collagen I expression. SIDT1 gene silencing, but not control shRNA, attenuates collagen I production in direct but not indirect coculture.

Conclusions: SIDT1 is abundant in PSC and variably expressed in patient samples. SIDT1 gene silencing limits collagen I production driven by contact dependent tumour-stromal intercellular communication. Disruption of SIDT1-dependent adenocarcinoma/PSC communication may represent a means of limiting desmoplasia.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3119. doi:10.1158/1538-7445.AM2011-3119