bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 1716: Mechanisms of resistance in carboplatin, docetaxel and dual drug resistant ovarian cancer cell lines
Authors: Lannér Carita , Armstrong Stephen , Kalatskaya Irina , Guo Baoqing , Parissenti Amadeo
Published: June 2012

Carboplatin and docetaxel are two standard chemotherapeutics used to treat ovarian cancer. Patients often exhibit resistance to single agent therapy, and dual agent therapy was developed to overcome this resistance. However, resistance still commonly occurs in dual agent therapy. It is known that specific changes in gene expression occur in single agent resistance, but it is not known whether resistance to combined chemotherapy involves novel gene expression changes or if resistance is only the sum of changes seen in single agent resistant cells.

Using the chemotherapy-naïve A2780 ovarian cancer cell line, we have generated three resistant cell lines including carboplatin and docetaxel single agent resistant lines (A2780CBN, and A2780DXL respectively), and a carboplatin/docetaxel dual resistant line (A2780CBNDXL) by exposing A2780 cells to increasing concentrations of drug until a dose is reached where resistance could no longer be developed. The concentration of drug at which 50% of cells die (IC50) was measured for reach resistant cell line using a clonogenic assay. The IC50 of A2780CBN is 8×10−5 M, 13-fold more resistant than the parent line. The IC50 of A2780DXL is 3×10−7 M, 5000-fold more resistant than the parent line. The IC50 of A2780CBNDXL is 8×10−6 M for carboplatin and 8×10−9 M for docetaxel.

Changes in gene expression associated with the development of resistance in each cell line were identified by microarray analysis on Agilent 4×44k total human genome arrays. In the A2780CBN line there were a total of 1209 significant changes in gene expression, in the A2780DXL line there were 955 changes, and in the A2780CBNDXL line there were 1336 changes. The majority of changes in each cell line (70%) were unique, indicating that novel changes in gene expression occur in the dual line. A Functional Interaction Network-based analysis was conducted on the microarray data identify important gene clusters acting in the drug resistant A2780 ovarian cancer cell lines. Ten major clusters were found in the A2780CBN line, 8 clusters in the A2780DXL line and 10 clusters in the A2780CBNDXL line. Although similar clusters occurred among the lines, the genes in them were different and several unique clusters occurred in the dual line. Functional enrichment analysis will be done for every cluster and the most significant pathways will be taken into further consideration for validation.

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 1716. doi:10.1158/1538-7445.AM2011-1716
Abstract 1724: Inhibition of the PI3K and mTOR pathways reverses gemcitabine resistance in pancreatic cancer
Authors: Chung Vincent , Gaur Shikha , Ann David , Yen Yun
Published: June 2012

BACKGROUND: Despite chemotherapy, survival for most patients with pancreatic cancer is less than one year. These dismal statistics reflect the lack of effective therapy. Understanding the molecular pathways that drive cancer growth may help target our therapy. Over 90% of pancreatic cancers are K-ras mutant which activates the PI3K/AKT pathway and signals downstream to mTOR leading to cell growth, proliferation and survival. We explored the combination of gemcitabine and BEZ235, a novel dual PI3K/mTOR inhibitor, in pancreatic cancer cell lines.

METHODS: Cytotoxicity assays were performed utilizing the CellTiter-96-Aqueous-One-Solution-Cell-Proliferation-Assay-(MTS) from Promega in K-ras mutant MIA PaCa-2 pancreatic cancer cell lines. We generated gemcitabine resistant cell lines by serial passage of cells with increasing concentrations of drug. We utilized the CalcuSyn program by Biosoft to quantify synergism or antagonism with drug combinations. We also collected cells 6 hours after drug treatment for analysis of phosphorylated proteins.

RESULTS: MIA PaCa-2 wild-type and gemcitabine resistant cells were treated with 100, 50 and 25 nM of either gemcitabine, BEZ235 or the combination of both. At the 100 nM dose, cell viability of the wild-type cells was 66%, 55% and 39% respectively. In the gemcitabine resistant cells, cell viability was 84%, 63% and 44%. The combination index was 0.51 in the wild-type cells and 0.46 in the gemcitabine resistant cells indicating synergy in both cell lines. In both cell lines, p-S6K and p-AKT levels increased with gemcitabine treatment which was abrogated by treatment with BEZ-235. Interestingly, in the gemcitabine resistant cells, there appeared to be significantly increased levels of p-MEK1 compared to control.

CONCLUSION: Because pancreatic cancer remains resistant to current therapies despite recent advances in the development of molecular targeted therapies, there is an urgency to understand these pathways. We showed that the combination of gemcitabine and BEZ235 is synergistic in both cell lines but cell viability still remains high at 39% and 44% respectively. Combination with a MEK inhibitor may help to increase cell apoptosis and studies are on-going.

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 1724. doi:10.1158/1538-7445.AM2011-1724
Abstract 1725: Activation of the p53 pathway by the MDM2 antagonist nutlin-3 downregulates the DNA repair protein hABH2 and sensitizes glioma cells to chemotherapy
Authors: Johannessen Tor-Christian A. , Prestegarden Lars , Grudic Amra , Tysnes Berit B. , Bjerkvig Rolf
Published: June 2012

Glioblastoma is the most frequent and most malignant primary brain tumor in adults. Standard first line treatment for glioblastoma patients includes surgery followed by focal fractionated radiotherapy with concomitant and adjuvant administration of the alkylating agent temozolomide. During the course of therapy, however, radio- and chemoresistance typically become evident through local tumour recurrence, and median survival time for glioblastoma patients remains around 15 months. In order to improve this poor prognosis, there is a critical need to recognize the molecular basis for the low sensitivity of glioblastomas towards chemotherapeutic treatment. We have previously reported that elevated expression levels of the DNA repair protein hABH2 may provoke temozolomide resistance in glioma cells. In this work, we explored whether activation of the p53 (encoded by TP53) pathway by the MDM2 antagonist nutlin-3 would influence cellular levels of hABH2 and subsequently chemoresistance. Immunoblotting following nutlin-3 exposure for 24 hours showed increased protein levels of p53, MDM2, p21 and PUMA in glioma cell lines expressing wild type p53, but decreased hABH2 levels in a dose-dependent manner. Real-time quantitative PCR confirmed reduced hABH2 mRNA levels after nutlin-3 therapy, suggesting that hABH2 downregulation occurred at a transcriptional level. Combination therapy with nutlin-3 and temozolomide further enhanced activation of the p53 pathway, diminished levels of hABH2 protein and increased cellular cytotoxicity compared to either agent alone. Our results show that levels of hABH2 can be downregulated by activation of the p53 pathway in glioma cells. This suggests that p53 pathway activation may increase glioma sensitivity to chemotherapy not only by increased transcription of pro-apoptotic genes such as PUMA, but also by reducing levels of DNA repair proteins such as hABH2 that would otherwise promote drug resistance.

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 1725. doi:10.1158/1538-7445.AM2011-1725
Abstract 173: Targeted killing of cancer stem-like cells by a novel analogue of curcumin
Authors: Bao Bin , Ali Shadan , Kong Dejuan , Sarkar Sanila H. , Wang Zhiwei , Banerjee Sanjeev , Aboukameel Amro , Padhye Subhash , Philp Philip A. , Sarkar Fazlul H.
Published: June 2012

The existence of cancer stem cells (CSCs) or cancer stem-like cells in a tumor mass is believed to be responsible for tumor recurrence because of their intrinsic and extrinsic drug-resistance characteristics. Therefore, targeted killing of CSCs would be a newer strategy for the prevention of tumor recurrence and/or treatment by overcoming drug-resistance. We have developed a novel synthetic compound-CDF, which showed greater bioavailability in animal tissues such as pancreas, and also induced cell growth inhibition and apoptosis, which was mediated by inactivation of NF-κB, COX-2, and VEGF in pancreatic cancer (PC) cells. In the current study we showed, for the first time, that CDF could significantly inhibit the sphere-forming ability (pancreatospheres) of PC cells consistent with increased disintegration of pancreatospheres, which was associated with attenuation of CSC markers (CD44 and EpCAM), especially in gemcitabine-resistant (MIAPaCa-2) PC cells containing high proportion of CSCs consistent with increased miR-21 and decreased miR-200. Moreover, CDF treatment showed increased protein levels of phospho-β-catenin, and decreased levels of Wnt3a, β-catenin, LEF1, and CD44. In a xenograft mouse model of human PC, CDF treatment significantly inhibited tumor growth, which was associated with decreased NF-κB DNA binding activity, COX-2, Wnt3a, and miR-21 expression, and increased PTEN and miR-200 expression in tumor remnants. These results strongly suggest that the anti-tumor activity of CDF is associated with inhibition of CSC function via down-regulation of CSC-associated signaling pathways. Therefore, CDF could be useful for the prevention of tumor recurrence and/or treatment of PC with better treatment outcome in the future.

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 173. doi:10.1158/1538-7445.AM2011-173
Abstract 1733: Therapeutic significance of ERα—PELP1 axis in blocking endocrine therapy resistance
Authors: Cortez Valerie A. , Suzuki Takayoshi , Miyat Naoki , Sood Anil K. , Vadlamudi Ratna K.
Published: June 2012

Breast cancer therapies target the estrogen receptor-alpha (ERα) with letrozol an aromatase inhibitor or anti-estrogens such tamoxifen to limit circulating estrogen levels and alter ERα functions. Many women suffering from recurrent or advanced disease develop resistance to current targeted endocrine treatments. Emerging data suggests therapeutic resistance is precipitated through dysfunction of ERα coregulatory proteins and crosstalk between ERα and growth factor signaling. Deregulated expression of proline-, glutamic acid- and leucine-rich protein 1 (PELP1), an ERα coregulator, was observed in a subset of human breast tumors. Recently, PELP1 was identified as an independent prognostic biomarker of shorter survival in ERα positive/luminal-like breast cancer patients. Epigenetic changes of target gene promoters are modulated by PELP1 via an interaction with lysine specific demethylase 1 (KDM1). Additionally, PELP1 promotes crosstalk between ERα and Src kinase leading to enhanced activation of extranuclear signaling pathways. Therapeutic potential of targeting the ERα-PELP1 axis in vivo was examined using a pharmacological approach in well-established preclinical models of endocrine therapy resistant breast cancer. We utilized (1) siRNA liposomes to down regulate PELP1 expression; (2) pargyline and NCL-1, KDM1 inhibitors, to block PELP1-mediated epigenetic modifications and (3) dasatinib, a Src kinase inhibitor, to prevent PELP1-mediated extranuclear actions in both pre- and post-menopausal conditions. In xenograft-based assays, treatment of ERα positive breast cancer cells with liposomes containing PELP1-siRNA, dasatinib or KDM1 inhibitors significantly reduced proliferation and tumor growth. Combinatorial therapies of letrozol or tamoxifen with PELP1 axis blockers substantially impeded xenograft tumor growth by blocking both ERα nuclear and extranuclear signaling and promoting apoptosis in therapy resistant cells. Taken together, our results suggest targeting the ERα-PELP1 axis in combination with current endocrine therapies will enhance therapeutic efficacy and may inhibit or delay development of endocrine therapy resistance.

This study is funded by Komen grant KG090447 and NIH grant CA095681.

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 1733. doi:10.1158/1538-7445.AM2011-1733
Abstract 1796: The impact of adjuvant immunochemotherapy using protein-bound polysaccharide-K on overall survival of gastric cancer
Authors: Tanaka Hiroaki , Ohira Masaichi , Muguruma Kazuya , Kubo Naoshi , Nagahara Hisashi , Kimura Kenjiro , Amano Ryosuke , Noda Eiji , Yamada Nobuya , Yashiro Masakazu , Maeda Kiyoshi , Onoda Naoyoshi , Sawada Tetsuji , Nakata Bunzo , Ishikawa Tetsuro , Hirakawa Kosei
Published: June 2012

Protein-bound polysaccharide (PSK) has been approved as an anti-cancer agent to be used in combination with chemotherapeutic drug for adjuvant therapy against gastric cancer. Several clinical studies have demonstrated that PSK has antitumor and immunomodulating properties. However, there is little evidence about the effectiveness of PSK in clinical practice. The aim of this study was to evaluate the impact of PSK on overall survival of patients with gastric cancer and predict the suitable case selection for postoperative adjuvant immunochemotherapy. The patients with stage II/III gastric cancer who underwent surgical curative resection between 2000 and 2007 at Deptarment of Surgical Oncology, Osaka City University were included in this retrospective study. All patients received oral fluorinated pyrimidine anti-metabolites with or without PSK after surgical operation. We analyzed clinicopathological features and evaluated the impact of PSK on postoperative survival rate of resectable gastric cancer. We identified 254 patients with a median follow-up of 33 months (range, 7-110 months). 138 patients received oral anti-metabolized alone (control group) and 115 patients received anti-metabolites plus PSK (PSK group). 139 patients of the cohort experienced postoperative recurrence. No significant difference between control and PSK group in overall survival or relapse free survival was detected over the 8-year period. In patients with early tumor recurrence, PSK group increased overall survival significantly (p<0.023). Among patients with pN3 lymph nodes metastasis, PSK group had better median overall survival of 28 months compared with 22 months with oral chemotherapeutics alone. After multivariate Cox regression analysis, duration of PSK administration was associated with an increased overall survival (p=0.002, HR 0.964, 95%CI 0.942 to 0.987). Our results suggested that adjuvant immunochemotherapy with PSK increased overall survival for patients with pN3 and early tumor recurrence. A population with lymph nodes metastasis might be a suitable to combine PSK with oral chemotherapeutic agents for postoperative adjuvant therapy against 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 1796. doi:10.1158/1538-7445.AM2011-1796
Abstract 1798: Effective lymphoma and leukemia therapy with epratuzumab (anti-CD22 IgG) conjugated to SN-38 (Emab-SN-38), with enhanced activity in combination with veltuzumab (anti-CD20 IgG)
Authors: Sharkey Robert M. , Cardillo Thomas M. , Govindan Serengulam V. , Goldenberg David M.
Published: June 2012

A number of B-cell malignancies, including lymphomas (NHL) and leukemia (ALL), can be treated effectively with antibodies, but these usually are combined with chemotherapy to enhance efficacy. We conjugated SN-38, a topoisomerase I inhibitor with nanomolar potency, to an anti-CD22 IgG (6:1 SN-38:IgG) by coupling to the tert-hydroxy group on the lactone ring of SN-38. This inhibits formation of the inactive carboxylate, a common problem with irinotecan, its prodrug, but the linker allows the active SN-38 to be released slowly from the IgG (∼50% decouples every 1 to 1.5 days) in serum or in the acidic environment of the lysosome. In vitro, Emab-SN-38 had nanomolar potency against a number of human NHL and ALL cell lines. Specific (as compared to an irrelevant anti-CEACAM5-SN-38 conjugate) and enhanced anti-tumor activity were demonstrated in mice bearing Ramos (Burkitt NHL), WSU-FSCCL (follicular NHL), or 697 (ALL) when compared to the unconjugated antibody (anti-CD22 or anti-CD20) alone or when combined with irinotecan. For example, animals bearing 0.3 to 0.8 cm3 Ramos xenografts treated with 3.75 mg/kg of an irrelevant immunoconjugate (54.5 µg/kg SN-38 equivalents) progressed to 3.0 cm3 in 1.0 week (median), while Emab-SN-38-treated animals had a median time to progression (TTP) of 4.05 weeks (P = 0.003) and 3/10 cures. Increasing the Emab-SN-38 dose to 12.5 mg/kg improved TTP to >12 weeks with 7/10 cures, while the irrelevant conjugate's TTP was just 3.5 wk (P = 0.023). Improvements in TTP and cures were also found for the Emab-SN-38 in FSCCL and 697. Additionally, in Ramos and FSCCL, the anti-tumor response was enhanced by co-treating animals with veltuzumab. For example, median survival in animals treated 5 days after IV implantation of FSCCL was >161 days for Emab-SN-38 + veltuzumab vs. 63 days and 91 days for Emab-SN-38 alone and veltuzumab alone, respectively (untreated, 42 days). Importantly, these treatments were tolerated without toxicity, with other studies showing tolerability in mice at doses of 1500 mg/kg. These data suggest the Emab-SN-38 is a potent, minimally toxic therapeutic in both NHL and ALL, with the added value when combined with anti-CD20 antibody therapy for enhanced responses.

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 1798. doi:10.1158/1538-7445.AM2011-1798
Abstract 1807: Tumor-infilitrating lymphocytes derived from pancreatic adenocarcinoma exhibit an activated, pro-inflammatory phenotype
Authors: Hall MacLean S. , Centeno Barbara , Malafa Mokenge , Hodul Pamela J. , Weber Jeffrey S. , Pilon-Thomas Shari , Sarnaik Amod A.
Published: June 2012

Contrary to current dogma, which maintains that pancreatic adenocarcinoma (PA) is infiltrated by predominantly inhibitory, regulatory CD4+ T cells (Treg), we demonstrate expansion of activated, pro-inflammatory tumor-infiltrating lymphocytes (TILs) from PA that could be used for adoptive cell therapy. TILs were grown in vitro in high-dose IL-2 from fragments of primary or metastatic PA. Pancreatic TILs were successfully expanded in 9 of 10 tumors and were phenotyped by flow cytometry. CD3+ TILs were predominantly CD4+ (mean frequency 76%, range 37-97%). CD4+ TILs were assessed for Treg frequency by CD25 and FoxP3 co-expression as a percent of total CD3+ TILs. Tregs were found to comprise the minority of CD3+ TILs (mean=3.1%, range=0.36-6.6%). We assessed CD4+ TIL expression of CD69, a known marker of T cell activation, and found a relatively high percentage of CD4+ TILs expressed CD69 (mean=25%, range=9-46%), which was significantly higher than the mean percent of Treg (p=0.0006). To confirm pro-inflammatory function, bulk TILs were stimulated in vitro by PMA/ionomycin, and expression of the pro-inflammatory cytokine IFNγ and the cytolytic marker CD107a was assessed. CD4+ TILs demonstrated a relatively high level of expression of IFNγ (mean=35%, range=20-47%) and CD107a (mean=19%, range=10-26%). Despite a low relative frequency, CD8+ TILs (mean=17%, range=1.8-41%) also expressed CD69 (mean=46%, range=17-83%) and exhibited a pro-inflammatory function upon stimulation as demonstrated by IFNγ (mean=43%, range=31-61%) and CD107a (mean=42%, range=22-69%) expression. After CD4 depletion, CD8-enriched TILs were effectively expanded with α-CD3 and maintained an activated, pro-inflammatory phenotype. This is the first report demonstrating that CD4+ TILs derived from PA have a predominantly pro-inflammatory phenotype. CD8+ TILs, though in the minority, also displayed an activated phenotype and preserved this phenotype throughout selective expansion. Further work is ongoing to support a phase I clinical trial involving adoptive TIL therapy in PA.

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 1807. doi:10.1158/1538-7445.AM2011-1807
Abstract 1826: Obesity as a therapeutic target for preventing recurrence and mortality in prostate cancer survivors: A meta-analysis of 29 cohort studies
Authors: Song Yong Sang , Kim Hee Seung , Kim Mi-Kyung , Lee Sangchul , Gong Seung Pyo , Kim Yong Beom , Lee Eunsik
Published: June 2012

Objective: The role of body mass index (BMI) remains unclear for disease recurrence and survival in patients with prostate cancer. To evaluated the role of BMI in prostate cancer survivors, we performed a meta-analysis for comparing biochemical recurrence-free survival (BCRFS), progression-free survival (PFS) and overall survival (OS) among normal weight (BMI <25 kg/m2), overweight (BMI 25 – 29.9 kg/m2) and obesity (BMI ≥30 kg/m2).

Methods: After the extensive literature search till July 2010, we analyzed 29 relevant cohort studies where the role of BMI was investigated for BCRFS, PFS and OS in prostate cancer survivors. We used the fixed-effect model for the meta-analysis because of no observed heterogeneity among all relevant studies (Higgins I2 ≤50%).

Results: Although there was no difference in BCRFS between BMI <25 kg/m2 and ≥25 kg/m2 (HR, 1.02, 95% CI, 0.98 to 1.09), BMI ≥30 kg/m2 showed poor BCRFS when compared with BMI <30 kg/m2 (HR, 1.56, 95% CI, 1.48 to 1.65). In sub-analyses for BCRFS, BMI 25 – 29.9 kg/m2 showed poor BCRFS, compared with BMI <25 kg/m2 (HR, 1.08; 95% CI, 1.03 to 1.14), and BMI ≥30 kg/m2 was also associated with poor BCRFS, compared with BMI 25 – 29.9 kg/m2 (HR, 1.20; 95% CI, 1.12 to 1.29). Furthermore, BMI ≥30 kg/m2 was related with PFS (HR, 1.65; 95% CI, 1.43 to 1.91) and OS (HR, 1.73; 95% CI, 1.63 to 1.97) when compared with BMI <30 kg/m2, whereas there were no differences in them between BMI <25 kg/m2 and ≥25 kg/m2 (PFS and OS; HR, 1.01 and 1.05; 95% CI, 0.85 to 1.20 and 0.88 to 1.26). In sub-analyses for PFS and OS, BMI ≥30 kg/m2 also decreased PFS (HR, 1.45; 95% CI, 1.23 to 1.71) and OS (HR, 1.49; 95% CI, 1.29 to 1.72) when compared with BMI 25 – 29.9 kg/m2 in spite of no differences in them between BMI <25 kg/m2 and BMI 25 – 29.9 kg/m2 (PFS and OS; HR, 1.05 and 0.99; 95% CI, 0.88 to 1.26 and 0.88 to 1.11). Finally, these meta-analytic results showed no publication bias among all relevant studies.

Conclusion: These findings suggest that overweight (BMI 25 – 29.9 kg/m2) and obesity (BMI ≥30 kg/m2) may be associated with early biochemical recurrence, whereas obesity (BMI ≥30 kg/m2) may influence on clinical poor prognosis such as PFS and OS in prostate cancer survivors.

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 1826. doi:10.1158/1538-7445.AM2011-1826
Abstract 1842: Vitamin D compounds induce BRCA1 expression and inhibit breast stem cells
Authors: Kakarala Madhuri , Dubey Shiv K. , Dobry Craig J. , Peng Xinjian , Murillo Genoveva , Parikh Satyam R. , Amarasinghe Chintaka , Mehta Rajendra , Brenner Dean E.
Published: June 2012

Background: Basal breast cancer which occurs in women with BRCA1 mutations has been suggested to arise from arrested differentiation of stem/luminal progenitor cells, whose gene profile includes Vitamin D receptor prominently. In addition to DNA repair, BRCA1 enhances luminal differentiation of breast stem cells. Vitamin D compounds have long been known to have differentiating function. We hypothesized that Vitamin D receptor exists on stem cells and that vitamin D treatment induces differentiation of stem/progenitor cells, in part due to increased BRCA1 expression.

Methods: We treated normal human breast epithelial cells and MCF-7 breast cancer cells with 10 or 100 nM 1, 25 dihydroxyvitamin D3 or the less hypercalcemic vitamin D5 analogue (1alpha(OH)D5) in suspension culture in stem cell media to assess: 1) stem cell self renewal using the mammosphere assay; 2) inhibition of stem cell percentage; 3) induction of BRCA1 mRNA and 4) induction of BRCA1 protein.

Results: Teatment with 100nM 1alpha(OH)D5 inhibited stem cell self renewal as assessed by mammosphere formation assay from 23spheres/high power field (HPF) to 1 per HPF at 7 days; inhibited of percentage of stem cells from 17% in vehicle control to 7% with vitamin D5. Both vitamin D3 and D5 caused an 8 fold induction of vitamin D target CYP24 gene expression; 4 fold increase in BRCA1 mRNA by real time PCR; and 4 fold increase in BRCA1 protein expression by western blot compared to actin control.

Conclusion: Vitamin D3 and D5 analogue induce BRCA1 expression and inhibit stem cell percentage in normal breast 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 1842. doi:10.1158/1538-7445.AM2011-1842
Abstract 2155: The origins and functional consequences of ETS gene fusions in prostate cancer
Authors: Mani Ram S. , Tomlins Scott A. , Brenner Chad J. , Wang Lei , Iyer Matthew , Yu Jindan , Cao Qi , Callahan Kaitlin , Ghosh Aparna , Nyati Mukesh K. , Varambally Sooryanarayana , Palanisamy Nallasivam , Chinnaiyan Arul M.
Published: June 2012

The purpose of this study is to unravel the cellular mechanisms underlying the oncogenic ETS gene fusions, which are a hallmark of prostate cancer development. Recurrent gene fusions involving the 5’untranslated region of the androgen-regulated gene TMPRSS2 and the ETS family genes are observed in a majority of prostate cancers. Among the ETS family gene fusions, the TMPRSS2-ERG fusions involving the 5’untranslated region of TMPRSS2 with the ERG gene are the most common and found in approximately 50% of prostate cancers. However, the origins and functional consequences of ETS gene fusions are not clear. Using dual color fluorescence in situ hybridization (FISH), we demonstrate that stimulation with dihydrotestosterone (DHT) induces proximity between TMPRSS2 and ERG genomic loci in LNCaP cells, which are androgen sensitive and lack the TMPRSS2-ERG gene fusions. This effect was dependent on androgen receptor (AR). Importantly, androgen did not induce proximity between the TMPRSS2 and ERG loci in DU145 human prostate cancer cells, which are androgen insensitive. Further, a combination of androgen signaling and genotoxic stress that induces DNA double strand breaks results in the formation of TMPRSS2-ERG gene fusions in LNCaP cells. Interestingly, we observe that the ERG protein formed as a result of gene fusion binds to the promoter of wild type ERG and activates its transcription. The VCaP cell line that endogenously harbors the TMPRSS2-ERG gene fusion has high levels of wild type ERG. Treatment with androgens induces the expression of both the TMPRSS2-ERG and wild type ERG transcripts in VCaP cells. Lenti virus mediated stable over expression of TMPRSS2-ERG in PC3 cells results in an increase in the expression levels of wild type ERG. This auto-activation of wild type ERG is observed in about 50% of clinically localized and 25% of metastatic prostate cancers harboring the TMPRSS2-ERG gene fusions, but not in ETS negative prostate cancers. Taken together, our studies provide a mechanistic framework for the up-regulation of ERG transcription in prostate 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 2155. doi:10.1158/1538-7445.AM2011-2155
Abstract 2158: Increased expression of NuSAP gene in recurrent prostate cancer is mediated by E2F
Authors: Gulzar Zulfiqar G. , Brooks James D.
Published: June 2012

Increasing evidence suggests prostate cancer is over diagnosed and over treated. Identification of prognostic biomarkers would aid in treatment selection. To define prognostic biomarkers for aggressive prostate cancer, we carried out gene expression profiling of 100 prostate tumors and normal prostate tissue samples with detailed clinical annotation and a median follow up of 5 years. Using Significance Analysis of Microarrays (SAM) we identified 28 transcripts significantly associated with recurrence after radical prostatectomy, including several that have been reported previously. Several transcripts were noted to function in mitotic assembly including NuSAP, which encodes for a protein that binds DNA to the mitotic spindle. NuSAP was found highly prognostic in 3 independent datasets. To characterize the role and regulation of NuSAP in prostate cancer, we studied the expression of NuSAP in the LNCaP and PC3 human prostate cancer cell lines. Using siRNA, we found that post transcriptional silencing of the NuSAP gene severely hampers the ability of PC3 to invade and proliferate in vitro. We cloned 431bp of human NuSAP promoter to understand its regulation. Sequence analysis of the promoter region suggests that NuSAP promoter contains 2 CCAAT boxes, Sp1 box and binding sites for several proteins including proliferation master regulator E2F. E2F has previously been shown to be over-expressed during prostate cancer progression. Transient transfection of E2F and the NuSAP promoter with a luciferase reporter construct identify E2F as a powerful regulator of NuSAP expression. Promoter deletion experiments demonstrate that E2F directly binds to NuSAP promoter at nt -243 to drive expression. Deletion of the E2F binding site negates the effects of E2F on NuSAP expression. NuSAP is a novel biomarker for prostate cancer recurrence after surgery and its over-expression might be largely driven by E2F activation.

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 2158. doi:10.1158/1538-7445.AM2011-2158
Abstract 2169: The effect of WT1 on E-cadherin expression in prostate cancer cells
Authors: Brett Adina , Fraizer Gail , Eisermann Kurtis
Published: June 2012

Prostate carcinoma is the most common malignancy and second leading cause of death among American men. The molecular mechanisms that control the progression of this type of cancer are still poorly understood. One of the genes expressed in prostate cancer epithelium is the zinc finger transcription factor Wilms’ Tumor 1, WT1. Previous studies in our lab have shown WT1 protein in a majority of high grade prostate tumor sections with little or no WT1 staining in non-neoplastic or benign prostatic hyperplasia (BPH) tissues. However, a mechanistic role for WT1 in prostate cancer has not been established. Recently, WT1 has been associated with the regulation of cell adhesion molecules such as E-cadherin in NIH 3T3 cells and epicardial cells. Loss of E-cadherin expression is frequently associated with increased cellular motility and tumor invasion. Several regulatory mechanisms controlling E-cadherin gene expression have been proposed in breast cancer cells, however the mechanisms of regulation of E-cadherin gene expression in prostate cancer cells are not yet understood. The objective of this study was to determine whether WT1 might regulate E-cadherin expression and contribute to cancer progression in prostate cancer cells. First, potential WT1 binding sites were identified in the promoter of the E-cadherin gene using a bioinformatics approach. Chromatin Immunoprecipitation (ChIP) showed direct in vivo binding of WT1 to the E-cadherin promoter in the chromatin of LNCaP and PC3 cells. The effect of transfection of prostate cancer cells with a GFP/WT1 expression construct was then tested by quantitative real-time PCR (QRT-PCR). QRT-PCR results showed a decrease in E-cadherin transcripts in GFP/WT1 transfected prostate cancer cells. Conversely, knockdown of WT1 mRNA in siWT1 transfected LNCaP cells, showed increased levels of E-cadherin mRNA. Moreover, co-transfection of WT1 expression construct with an E-cadherin promoter reporter construct showed that WT1 decreased the activity of the proximal E-cadherin promoter in PC3 cells. Overall these results demonstrated that WT1 modulated E-cadherin expression in prostate cancer cells and suggests a novel mechanism whereby WT1 may increase migration by decreasing E-cadherin levels, a novel role for WT1 mediated prostate cancer progression.

This work was supported by NIHR15CA11360 and Ohio Board of Regents.

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 2169. doi:10.1158/1538-7445.AM2011-2169
Abstract 217: Functional analysis of the protein citrullination through p53/PADI4 network in carcinogenesis
Authors: Tanikawa Chizu , Matsuda Koichi , Nakamura Yusuke
Published: June 2012

Upon a wide range of cellular stresses, p53 is activated and inhibits malignant transformation through the transcriptional regulation of its target genes related to apoptosis, cell cycle arrest, and DNA repair. However, its involvement in posttranslational modifications of proteins has not yet been well characterized. We recently reported the novel role of p53 in the regulation of protein citrullination through the transactivation of peptidylarginine deiminase type 4 (PADI4). The PADI4 gene encodes an enzyme catalyzing the citrullination of arginine residues in proteins, and ectopic expression of p53 or PADI4 induced protein citrullination. In addition, various proteins were citrullinated in response to DNA damage, but knockdown of PADI4 or p53 remarkably inhibited their citrullination. Here we generated the Padi4-deficient mice and examined the role of protein citrullination in vivo. When mice were exposed to X-ray (3 Gy), Padi4 expression was induced in thymus of irradiated wild type mice but not in p53-/- and Padi4-/- mice. Interestingly, TUNEL-positive cells in irradiated thymus were significantly decreased in Padi4-/- mice. Gene expression analysis using irradiated thymus tissues revealed several genes related to the immune response were regulated by Padi4. To further investigate the molecular mechanism whereby PADI4 regulates apoptotic pathway, we surveyed PADI4 substrates and found that various proteins such as core histones were citrullinated in response to DNA damage. These findings demonstrated the significance of PADI4-mediated protein citrullination in the p53 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 217. doi:10.1158/1538-7445.AM2011-217
Abstract 2178: Survivin appears to act as a transcription factor or co-factor to transcriptionally downregulate p21 gene expression via a p53 status-dependent manner
Authors: Tang Lei , Ling Xiang , Liu Wensheng , Das Gokul M. , Li Fengzhi
Published: June 2012

Survivin, a unique member of the inhibitor of apoptosis (IAP) family proteins, is highly expressed in cancers but undetectable in most normal adult tissue. Survivin shows both inhibition of apoptosis and promotion of cell division. It plays a central role in cancer cell signaling network. Recent studies indicate that survivin may also play an important role in G1/S transition during cell cycle regulation. However, the underlying mechanism is unclear. Furthermore, although upregulation of p21WAF1/CIP1 (p21) expression by p53 plays an important role in p53-mediated cell G1 arrests in response to various distressing stimuli, it is unknown whether survivin plays a role in the regulation of p21 expression. Here, we report that forced expression of survivin in p53-wild type MCF-7 breast cancer cells inhibits the expression of the cell cycle inhibitor p21 protein, mRNA and promoter activity, while the survivin C84A mutant and survivin antisense failed to do so. Cotransfection experiments in the p53 mutant H1650 lung cancer cell line showed that exogenous survivin expression neutralizes p53-induced p21 expression and promoter activity. Both p53 and survivin interacts on two p53 binding sites in the p21 promoter (−2313 to -2212; -1452 to -1310), and survivin protein physically interacts with p53 protein in cancer cells. Additionally, we identified a PKC phosphorylation site at T127 that plays a critical role in inhibition of p21 promoter activity by survivin. Together, we propose that survivin acts as a transcription factor or cofactor to interact with p53 on the p21 promoter leading to transcriptional inhibition of p21 expression at least in part by neutralizing p53-mediated transcriptional activation of the p21 gene.

*LT was a pre-doctoral Chinese fellowship student (Second West China Hospital, Sichuan University, Sichuan 610041, China) at the time this work was performed in the Li laboratory

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 2178. doi:10.1158/1538-7445.AM2011-2178
Abstract 2179: Bile acids downregulate the squamous differentiation program of esophageal cells
Authors: Reveiller Marie , Ghatak Sayak , Kalatskaya Irina , Toia Liana , DSouza Mary , Zhou Zhongren , Bandla Santhoshi , Godfrey Tony E. , Peters Jeffrey
Published: June 2012

Background: The lumen of the normal esophagus is covered by a nonkeratinized, stratified squamous epithelium. However, in individuals with prolonged gastroesophageal reflux disease the squamous epithelium is gradually replaced by a more acid-resistant metaplastic columnar epithelium known as Barrett's Esophagus (BE). BE is the strongest known risk factor for development of esophageal adenocarcinoma. Understanding the molecular mechanisms underlying the formation of BE is fundamental to the development of new and effective prevention and treatment strategies for patients with BE.

Methods: We performed a global analysis of gene expression in normal squamous esophageal cells in response to bile acids or acid exposure. Differentially expressed genes were classified into major biological functions based on analysis using pathway and interaction network software programs. Array data were verified by quantitative PCR and western blot both in-vitro and in human biopsies from esophageal normal squamous and columnar epithelia.

Results: Bile acids modulated expression of 218 genes (153 up and 65 down) and acid 112 genes (31 up and 81 down). Interestingly, genes involved in squamous differentiation formed the largest functional group of differentially expressed genes and consisted of 40 genes downregulated by bile acids exposure. Bile acids decreased expression of key squamous differentiation genes such as KRT10, KRTDAP and GRHL1 which was confirmed at both the mRNA and protein level as was increased expression of CDX2, a transcription factor key to the intestinal epithelial phenotype. Bile acids induced expression changes were also seen in genes involved in the pathways of cell adhesion, DNA repair, oxidative stress, cell cycle, Wnt signaling and lipid metabolism. Expression of DSG1, a target gene of GRHL1, and DKK1, a Wnt inhibitor, were confirmed to be respectively downregulated and upregulated by bile acids. Further, expression data from human columnar epithelial biopsies revealed low or no expression of KRT10, KRTDAP, DSG1 and GRHL1 compared to squamous epithelia. Finally, network analysis suggested that bile acids exposure modulated the transcription activity of CREB and bile acids induced phosphorylation of CREB was confirmed experimentally.

Conclusion: We report for the first time that bile acids inhibit the squamous differentiation program of esophageal cells while inducing columnar differentiation via CDX2 expression possibly via CREB and Wnt signaling.

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 2179. doi:10.1158/1538-7445.AM2011-2179
Abstract 2180: Antagonistic relationship between the tumor suppressor ING4 and estrogen signaling in breast cancer
Authors: Whitsett Timothy G. , Kim Suwon
Published: June 2012

ING4 is a tumor suppressor that plays a role in many cancer-related cellular processes, including cell proliferation, apoptosis, contact inhibition and cell migration. Our lab found ING4 is deleted in 15% of estrogen receptor (ER)-positive breast cancers, implicating a role for ING4 as a tumor suppressor in estrogen-driven breast cancer. Estrogen is a tumor promoter in breast cancer, causing cell proliferation, cell survival and cell migration. We hypothesize that estradiol (E2) exposure suppresses ING4, and conversely that the expression of ING4 modulates estrogen-induced phenotypes in breast cancer cells. We employed qPCR to test whether E2 suppressed ING4 in a time-, dose- and ER-dependent manner. By over-expressing or knocking down the expression of ING4 in MCF-7 breast cancer cells, we determined whether ING4 affected E2-induced cell proliferation. Physiological levels of E2 (100pM-10nM) suppressed the expression of ING4 in MCF-7 cells by more than 50% at early time points (6-24 hours). The suppression of ING4 by E2 was dependent on ER, as blocking ER with a pure anti-estrogen completely abrogated the suppression of ING4 by E2. Having shown that E2 suppressed ING4, we next tested whether the expression level of ING4 could affect E2-induced cell proliferation in breast cancer cells. The knockdown of ING4 by shRNA in MCF-7 cells resulted in a hyper-proliferation in response to E2 exposure. Conversely, the over-expression of ING4 in MCF-7 cells completely abolished the proliferative response to E2 seen in MCF-7 pMIG (vector alone) cells. In hormone-depleted media, MCF-7 cells over-expressing ING4 underwent apoptosis as demonstrated by the cleavage of caspase-7 and PARP. Estradiol exposure did not rescue the apoptotic phenotype. The over-expression of ING4 in MCF-7 cells suppressed the protein expression of Bcl-2, facilitating cell death. The suppression of Bcl-2 was necessary for cell death as the ectopic expression of Bcl-2 rescued the apoptotic phenotype induced by ING4 over-expression in hormone-depleted media. This work demonstrates an antagonistic relationship between E2 signaling and the tumor suppressor ING4 in breast cancer cells. The suppression of ING4 by E2 may indicate a novel mechanism of E2 action in breast cancer. This work also suggests that the expression of ING4 in estrogen-driven breast cancer may determine the magnitude of response to estrogen and anti-estrogen therapeutics.

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 2180. doi:10.1158/1538-7445.AM2011-2180
Abstract 2183: Tumor suppressor LZAP regulates cell cycle progression and doming during zebrafish epiboly
Authors: Liu Dan , Yarbrough Wendell G. , Kanpik Ela W. , Wang Wen-Der
Published: June 2012

Initial stages of embryonic development rely on rapid, synchronized cell divisions of the fertilized egg followed by a set of morphogenetic movements collectively called epiboly and gastrulation. Lzap is a putative tumor suppressor whose expression is lost in 30% of head and neck squamous cell carcinomas. Lzap activities include regulation of cell cycle progression and response to therapeutic agents. Here we explore developmental roles of the lzap gene during zebrafish morphogenesis. Lzap is highly conserved among vertebrates and is maternally deposited. Expression is initially ubiquitous during gastrulation, and later becomes more prominent in the pharyngeal arches, digestive tract and brain. Antisense morpholino-mediated depletion of Lzap resulted in delayed cell divisions during blastomere formation, resulting in fewer, larger cells. Furthermore, the Lzap-deficient embryos failed to initiate epiboly – the earliest morphogenetic movement in animal development – which has been shown to be dependent on cell adhesion and migration of epithelial sheets. Our results strongly implicate Lzap in regulation of cell cycle progression, adhesion and migratory activity of epithelial cell sheets during early development. These functions provide further insight into Lzap activity that may contribute not only to development, but also to tumor formation.

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 2183. doi:10.1158/1538-7445.AM2011-2183
Abstract 2199: SOX1 functions as a tumor suppressor through antagonizing WNT/β-catenin signaling pathway in hepatocellular carcinoma
Authors: Tsao Chun-Ming , Lin Wen-Chi , Yu Pei-Ning , Shih Yu-Lueng , Hsieh Tsai-Yuan , Hsieh Chung-Bao , Lai Hung-Cheng , Yan Ming-De , Lin Ya-Wen
Published: June 2012

Oncogenic activation of the Wnt/β-catenin signaling pathway is common in hepatocellular carcinoma (HCC). Aberrant hypermethylation of tumor suppressor genes in their promoter regions is frequently found in human cancers. Our previous works have demonstrated that SOX1 gene was hypermethylated in HCCs as well as cervical and ovarian cancers. A growing number of papers suggest that SOX family proteins, such as SOX9, SOX17, SOX4 and SOX2, serve as either tumor suppressors or oncoproteins through manipulating Wnt signaling pathway in different types of cancer. However the molecular mechanism is not well understood.

In this study, we established an inducible system to overexpress SOX1 in HCC cell lines and checked whether SOX1 have tumor suppressor function in vitro and in vivo. We found that overexpression of SOX1 could inhibit cell proliferation and colony formation in HCC cells and suppress tumor growth in xenograft mice. Next we used GST pull-down, co-immunoprecipitation (co-IP), immunocytochemistry and luciferase reporter assay to study whether SOX1 could interact with β-catenin to regulate Wnt/β-catenin signaling. Our data showed that SOX1 is physically associated with β-catenin/ TCF complex and could inhibit the TCF-dependent transcriptional activity. Furthermore, SOX1 was co-localized with β-catenin in nucleus by confocal microscopy. These results suggest that SOX1 functions as a tumor suppressor through interfering Wnt/β-catenin signaling in HCC.

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 2199. doi:10.1158/1538-7445.AM2011-2199