bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A47: The LKB1-AMPK pathway mediates the metabolic stress response of dormant ovarian cancer spheroids
Authors: Peart Teresa , Fazio Elena , Ramos-Valdes Yudith , Bertrand Monique , McGee Jacob , Prefontaine Michel , Sugimoto Akira , DiMattia Gabriel E. , Shepherd Trevor G.
Published: August 2014

Metastatic epithelial ovarian cancer (EOC) cells can form multicellular spheroids while in suspension and disperse throughout the peritoneum via ascites to seed secondary lesions. We hypothesize that EOC spheroids are key mediators of metastasis, which use specific signaling pathways to alter cell metabolism for increased survival. Our lab discovered that AKT signaling is reduced during spheroid formation leading to cellular quiescence and autophagy. Given the induction of quiescence and autophagy in EOC spheroids, we are studying the 5′-AMP-activated protein kinase (AMPK) pathway as a master controller of the metabolic stress response and dormant phenotype of EOC spheroids. We demonstrate AMPK activity and its upstream kinase LKB1 are increased in quiescent EOC spheroids compared with proliferating adherent EOC cells. We also show elevated AMPK activity in spheroids isolated directly from patient ascites. Targeted knockdown of STK11, encoding LKB1, reduces cell viability in ovarian cancer cell line spheroids; PRKAA1 (AMPKα1) knockdown has little to no effect on EOC cell or spheroid viability. Combination of STK11 knockdown with carboplatin treatment leads to a synergistic enhancement in EOC spheroid cell death. In contrast, AICAR treatment of proliferating adherent ovarian cancer cell lines and primary EOC cells induces AMPK activity and causes either cytostasis or cell death. In addition, AICAR treatment of spheroids during reattachment decreases the dispersion capacity of migrating EOC cells. These results offer a glimpse of the potential important contributions of LKB1-AMPK pathway in stress signaling related to EOC cell survival during metastasis. In addition, downstream effectors of upregulated LKB1-AMPK signalling may provide additional mechanisms by which EOC evades chemotherapy. It is foreseeable that these findings will allow us to identify new therapeutic targets within this pathway critical to EOC progression for ultimate translation to the clinic.

Citation Format: Teresa Peart, Elena Fazio, Yudith Ramos-Valdes, Monique Bertrand, Jacob McGee, Michel Prefontaine, Akira Sugimoto, Gabriel E. DiMattia, Trevor G. Shepherd. The LKB1-AMPK pathway mediates the metabolic stress response of dormant ovarian cancer spheroids. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr A47.
Abstract A67: Obesity promotes growth of ovarian cancer through adipose stem cells
Authors: Zhang Yan , Solley Travis , Nowicka Aleksandra , Klopp Ann
Published: August 2014

Purpose: Excess visceral adiposity increases the risk of ovarian cancer. Intraperitoneal spread to omental adipose is a frequent event and a major cause of morbidity and mortality in women with ovarian cancer. We have recently described a population of tumor tropic adipose stem cells from omental adipose. We hypothesized that visceral obesity alters the visceral adipose population to enhance the initiation and progression of ovarian cancer.

Results: Intraperitoneally injected ID8 ovarian cancer cells grew significantly faster in mice with diet-induced obesity (p<0.05). To determine if the tumor promoting effects of obesity was due to ASC, ASC were isolated from omental (O-ASC) and subcutaneous adipose (SC-ASC) of mice with and without diet induced obesity. Both O-ASC and SC-ASC from Lean/obese mice expressed same mesenchymal cell surface markers. 106 mouse ovarian cancer cells ID8 were co-injected with equal number of different ASC isolates. ASC from all sources increased the cancer cell proliferation in vitro and increased ovarian cancer cell ID8 survival under the treatment of chemo drug Taxol at different concentrations. There were no significant differences in ASC isolates in migration towards tumor-conditioned media. Tumor growth was accelerated by ASCs, but O-ASC and SC-ASC derived from obese mice more potently promoted tumor progression and produced more ascites.

Conclusions: Obesity promotes ovarian tumor progression and this effect is mediated at least in part by adipose stem cells. We propose that obese derived ASCs, especially O-ASC express specific factors that enhance tumor progression, promoting survival and proliferation of tumor cells.

Citation Format: Yan Zhang, Travis Solley, Aleksandra Nowicka, Ann Klopp. Obesity promotes growth of ovarian cancer through adipose stem cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr A67.
Abstract B28: The stress phenotype makes ovarian cancer cells addicted to CDT2, a substrate receptor of the CRL4 ubiquitin ligase
Authors: Olivero Martina , Dettori Daniela , Arena Sabrina , Zecchin Davide , Lantelme Erica , Renzo Maria Flavia Di
Published: August 2014

CDT2/L2DTL/RAMP is one of the substrate receptors that binds the CRL4 ubiquitin ligase and confers it specificity for a number of substrates, such as CDT1, p21 and CHK1. Previously, we reported that in ovarian cancer cell lines increased susceptibility to cisplatin is associated to the down-regulation of the CDT2 gene. Here we show that CDT2 depletion was alone able to induce the apoptotic death not only in ovarian cancer cell lines but also in 10/10 other human cancer cell lines from different tissues, irrespective of p53, ATM and ATR status and CDT2 expression level. Conversely, CDT2 depletion did not affect non-transformed human cells, such as immortalized kidney, lung and breast cell lines, and primary cultures of endothelial cells and osteoblasts. After CDT2 suppression, all cancer cells underwent rereplication associated to the inability to destroy CDT1 and to cell death. The ectopic over-expression of an activated oncogene, such as the mutation-activated RAS or the amplified MET in non-transformed immortalized breast cell lines and primary human osteoblasts, respectively, made cells transformed in vitro, tumorigenic in vivo, and susceptible to CDT2 loss. Conversely, the knock-down of the tumor suppressor genes PTEN or RB1 did not transform immortalized breast cells and did not sensitize them to CDT2 loss. These data show that transformation makes cells “addicted” to CDT2. The widespread effect of CDT2 depletion in different cancer cells suggests that CDT2 is not in a synthetic lethal interaction to another specific gene or pathway but becomes dominant in these cells because of their stress phenotype, due to DNA damage, replication and mitotic stress.

Citation Format: Martina Olivero, Daniela Dettori, Sabrina Arena, Davide Zecchin, Erica Lantelme, Maria Flavia Di Renzo. The stress phenotype makes ovarian cancer cells addicted to CDT2, a substrate receptor of the CRL4 ubiquitin ligase. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B28.
Abstract B41: Proteomic characterization of carboplatin resistance in ovarian cancer cells
Authors: Wrzeszczynski Kazimierz O. , Fan Gaofeng , Fu Cexiong , Pappin Darryl J. , Lucito Robert , Tonks Nicholas K.
Published: August 2014

The analysis of quantitative protein expression is necessary for the determination of actual biochemical protein concentrations that can lead to a more accurate description of cellular function. A knowledgebase of cancer function founded on cellular protein levels can more directly implicate potential gene candidates for the detection and treatment of disease. Therefore, we analyzed iTRAQ (Isobaric tag for relative and absolute quantification) data from 11 serous ovarian cancer cell lines and 2 normal ovarian surface epithelial cell lines. We profiled cellular protein abundance in over 2600 proteins with 746 proteins common to all 13 cell lines. Of the 746, 52 proteins exhibited elevated expression and 46 proteins had diminished expression in the cancerous cells when compared to the two normal cell lines. We identified the 300 most variable iTRAQ expressed proteins based on median absolute deviation within 8 carboplatin sensitive and resistant cell lines. Using iTRAQ protein expression profiles from these 300 we successfully segregated the cell lines based on carboplatin sensitivity and resistance measurements. Next, we further examined correlations among iTRAQ protein expression, individual gene RNA expression and DNA methylation data. There was no substantial correlation between protein abundance and RNA expression or epigenetic data. Furthermore RNA expression and DNA methylation data alone did not show any significant discrimination for chemosensitivity or resistance. Our clustering proteomics-based profile used to identify chemotherapy response contained proteins involved in homologous recombination and repair, specifically RPA, MCM2/MCM5 and PALB2. We therefore present the potential of proteomics based discovery for carboplatin response in ovarian cancer and also identify putative gene candidates that may be functionally responsible for chemotherapy response which otherwise would not have been predicted by other singular whole genome data sources.

Citation Format: Kazimierz O. Wrzeszczynski, Gaofeng Fan, Cexiong Fu, Darryl J. Pappin, Robert Lucito, Nicholas K. Tonks. Proteomic characterization of carboplatin resistance in ovarian cancer cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B41.
Abstract B67: IG-001: A non-biologic nanoparticle paclitaxel for the treatment of ovarian cancer
Authors: Hwang Larn , Cheng Catherine , Trieu Vuong
Published: August 2014

Introduction: IG-001(Genexol-PM), like nab-paclitaxel, is a polymer bound nanoparticle paclitaxel. IG-001 utilizes biodegradable di-block copolymer composed of methoxy poly (ethylene glycol)-poly (lactide) to form nanoparticles with Paclitaxel containing hydrophobic core and a hydrophilic shell. IG-001 is being developed for difficult to perfuse hypoxic tumors such as pancreatic cancer and ovarian cancer. Methods: Clinical efficacy was evaluated across multiple cancer indications including metastatic breast cancer (MBC), non small cell lung cancer (NSCLC), pancreatic cancer and ovarian cancer. Phase I ovarian trial design: six patients/dose level were treated with IG-001 at 220, 260, and 300 mg/m2. Phase II ovarian trial design: randomized, two-arm trial, primary advanced epithelial ovarian cancer consisting of 100 pts (50/each arm). Control Arm: Solvent based paclitaxel 175mg/m2 IV + Carboplatin 5 AUC IV, 3 weeks, 6 cycles and Experimental Arm: IG-001 260mg/m2 IV + Carboplatin 5 AUC IV 3 weeks, 6 cycles. Phase III ovarian trial design- planning phase to consist of therapeutic drug monitoring and biomarker testing. Results: Clinical trials conducted with IG-001 demonstrated significant antitumor activities comparable to historical data for Abraxane. Across three cancer indications (MBC, NSCLC, and Pancreatic Cancer), IG-001 was more active than historical Taxol. Since Pancreatic Cancer is known to be poorly-perfused, IG-001 activity in this indication is consistent with it being able to penetrate poorly-perfused tumors. Conclusions: IG-001 is effective across multiple cancer indications. Clinical development of IG-001 in ovarian cancer is ongoing. Phase I data was encouraging and phase II data forthcoming. IG-001 could be considered to be superior to Cremophore based paclitaxel because of the possibilities of delivering higher paclitaxel dose without additional toxicities. Phase III trial design incorporating therapeutic drug monitoring and biomarker testing should further improve on IG-001 clinical activities.

Citation Format: Larn Hwang, Catherine Cheng, Vuong Trieu. IG-001: A non-biologic nanoparticle paclitaxel for the treatment of ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B67.
Abstract B74: Elafin drives poor outcome in high-grade serous ovarian cancers and basal-like breast tumors
Authors: Labidi-Galy Intidhar , Clauss Adam , Ng Vivian , Duraisamy Sekhar , Elias Kevin M. , Bilal Erhan , Davidowitz Rachel A. , Lu Yiling , Badalian-Very Gayane , Piao Hui-Ying , Kang Un-Beom , Ficarro Scott , Ganesan Shridar , Mills Gordon B. , Marto Jarrod , Drapkin Ronny
Published: August 2014

High grade serous ovarian carcinoma (HGSOC) and basal-like breast cancer (BLBC) share many features including TP53 mutations, genomic instability and poor prognosis. We recently reported that Elafin is overexpressed by HGSOC and is associated with poor overall survival. Here, we confirmed that Elafin overexpression is associated with shorter survival in 1000 HGSOC patients. Elafin confers a proliferative advantage to tumor cells through activation of the MAP kinase pathway. This mitogenic effect can be neutralized by RNA interference, specific antibodies, and a MEK inhibitor. Elafin expression in patient-derived samples was also associated with chemoresistance and strongly correlates with bcl-xL expression. We translated these findings into examination of 1100 primary breast tumors and 6 breast cancer cell lines. We observed that Elafin is overexpressed and secreted specifically by BLBC tumors and cell lines, leading to a similar mitogenic effect through activation of the MAP kinase pathway. Here too, Elafin overexpression is associated with shorter overall survival, suggesting that it may serve as a biomarker or therapeutic target in this setting.

Citation Format: Intidhar Labidi-Galy, Adam Clauss, Vivian Ng, Sekhar Duraisamy, Kevin M. Elias, Erhan Bilal, Rachel A. Davidowitz, Yiling Lu, Gayane Badalian-Very, Hui-Ying Piao, Un-Beom Kang, Scott Ficarro, Shridar Ganesan, Gordon B. Mills, Jarrod Marto, Ronny Drapkin. Elafin drives poor outcome in high-grade serous ovarian cancers and basal-like breast tumors. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B74.
Abstract IA11: Using publicly available databases for the functional characterization of cancer genes
Authors: Cheon Dong-Joo , Beach Jessica , Tong Yunguang , Cui Xiaojiang , Tighiouart Mourad , Liu Zhenqiu , Walts Ann E. , Karlan Beth Y. , Orsulic Sandra
Published: August 2014

It is now known that tumors are complex ‘organs’ consisting of multiple malignant and nonmalignant cells, blood vessels, and many other cell types, which are frequently lumped together as tumor stroma because their individual characteristics and roles in tumor progression and metastasis are not well defined. Despite the universal presence of cancer-associated stroma in solid tumors and wide clinical use as a prognostic marker, the origin of stromal cells in tumors is still the subject of extensive debate. The dynamic bi-directional interaction between the cancer cells and stroma is also not well understood although it is becoming increasingly apparent that the stroma can modify the aggressiveness of tumor cells and that tumor cells re-program the stroma to generate a nurturing microenvironment that is crucial for tumor survival, progression, and metastasis. Because of the prominent role of stroma in most aspects of tumor progression, it is believed that rational anticancer therapy design should not only target the cancer cells but also the stroma. Therefore, a better understanding of the cancer-stroma interaction and the identification of molecular events whose disruption may undermine tumor progression are required steps toward successful anticancer therapy.

Most public expression profile databases contain information from tumors with variable amounts of stroma. Thus, a snapshot of cross-signaling between cancer and stroma is captured in such transcription profiles although it is difficult to deconvolve the source and direction of the signals. The intensities of the signals are also difficult to determine because analysis of total mRNA from tissues dampens signals from rare cell types, such as cancer stem cells and activated fibroblasts. Expression profile databases that contain laser capture-microdissected samples or single-cell samples provide more information about specific cell types but typically suffer from a small number of patient samples. Through integration of multiple expression profile databases, we identified a set of highly co-regulated genes that are associated with poor patient survival. These genes are induced as a result of the epithelial-stromal interaction and define a microenvironment that serves as a favorable niche for ovarian cancer stem cells, thereby leading to chemotherapy resistance and metastasis and, ultimately, poor overall survival.

Citation Format: Dong-Joo Cheon, Jessica Beach, Yunguang Tong, Xiaojiang Cui, Mourad Tighiouart, Zhenqiu Liu, Ann E. Walts, Beth Y. Karlan, Sandra Orsulic. Using publicly available databases for the functional characterization of cancer genes. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr IA11.
Abstract IA25: Immunotherapy opportunities and challenges in ovarian cancer
Authors: Coukos George
Published: August 2014

Epithelial ovarian cancer (EOC) cells are antigenic and express a multitude of proteins that have been validated as known tumor-associated antigens (TAAs) including Her-2/neu, p53, NY-ESO-1, cdr2, hTERT, mesothelin, survivin, SP-17, WT1 and others. Clinical data indicate that the immune system affects the outcome of patients with EOC; the presence of intraepithelial tumor-infiltrating lymphocytes correlates with improved progression-free and overall survival, as shown by numerous correlative studies conducted on hundreds of ovarian cancer samples. Tumor infiltrating lymphocytes (TILs) isolated from ovarian cancers are oligoclonal, recognize autologous tumor, are specific to known TAAs ex vivo, and exhibit tumor-specific cytolytic activity. Tumor-specific T-cell precursors can also be detected in the blood of patients with advanced ovarian carcinoma. These observations suggest that activation of antitumor immunity could be feasible and could produce clinical results in patients with EOC. To date, immunotherapy investigations with intraperitoneal IL-2 infusion, CTLA-4 antibody, vaccines using NY-ESO-1 peptide, virus-modified autologous tumor cells, or dendritic cells (DCs) pulsed with whole autologous tumor lysate have yielded limited but encouraging results in EOC. We will review lessons from previous studies and will discuss various opportunities and challenges in the development of effective immunotherapy for EOC.

Citation Format: George Coukos. Immunotherapy opportunities and challenges in ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr IA25.
Abstract IA5: Discovering the distal fallopian tube as the origin for high-grade serous ovarian cancer
Authors: Drapkin Ronny
Published: August 2014

Recent developments in the study of epithelial ovarian cancer have called into question the traditional views regarding the site of tumor initiation. Histopathologic studies and genomic analyses suggest that extra-ovarian sites, like the fallopian tube (FT) epithelium, may harbor the coveted cell of origin and could therefore contribute significantly to the development of high-grade serous ovarian carcinoma (HGSOC). Our ability to validate these emerging genomic and pathologic observations and characterize the early transformation events of HGSOC hinges on the development of novel model systems.

The tubal hypothesis of serous tumorigenesis has led us to develop a number of experimental platforms. These platforms provide us with a unique view into the susceptibilities of the FT epithelium to neoplastic transformation and provide a vehicle to query the contribution of any given genetic alteration to tumor development in vitro and in vivo. These models include the ex-vivo bioanalytical platform of benign FT epithelium, the in vitro FT secretory cell transformation model, a series of patient-derived primary tumor xenograft (PDX) models that retain the phenotypic and genotypic properties of the original patient tumors, and a genetically-engineered mouse model (GEMM) that specifically targets the FT epithelium in vivo.

Our GEM model specifically targets the Müllerian secretory cell. It uses the Pax8 promoter to drive expression of the Cre recombinase in the fallopian tube (FT) secretory cells. Pax8 is a lineage marker for the Müllerian system. It is necessary for the development of the female reproductive tract and its expression is retained in the adult FT secretory cell and in nearly all HGSOCs. By crossing our Pax8-Cre deletor mouse with mice carrying floxed alleles of BRCA genes, TP53 (or mutant) and/or PTEN, we could specifically manipulate the expression of these genes in the FT secretory cell. Using this approach, in collaboration with the laboratory of Daniela Dinulescu, we showed that HGSOC can originate in secretory cell of the FT and also established that serous tubal intraepithelial carcinoma (STIC) is the precursor lesion to high-grade serous ovarian and peritoneal carcinomas. Importantly, the tumors that arise in this model not only look like high-grade serous carcinomas but they also retain the genomic complexity that is a hallmark of human HGSOC. In addition to providing mechanistic insight into the origin and pathogenesis of HGSC, this model provides a platform to explore HGSOC sensitivity to novel therapeutic strategies and to develop better detection strategies for early tumor diagnosis in high-risk women.

Citation Format: Ronny Drapkin. Discovering the distal fallopian tube as the origin for high-grade serous ovarian cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr IA5.
Prostate Cancer Cell Response to Paclitaxel Is Affected by Abnormally Expressed Securin PTTG1
Authors: Castilla Carolina , Flores M. Luz , Medina Rafael , Pérez-Valderrama Begoña , Romero Francisco , Tortolero María , Japón Miguel A. , Sáez Carmen
Published: August 2014

PTTG1 protein, the human securin, has a central role in sister chromatid separation during mitosis, and its altered expression has been reported in many tumor types. Paclitaxel is a widely used chemotherapeutic drug, whose mechanism of action is related to its ability to arrest cells in mitosis and the subsequent induction of the intrinsic apoptotic pathway. By using two prostate cancer cell lines with different responses to paclitaxel treatment, we have identified two situations in which PTTG1 influences cell fate differentially. In slippage-prone PC3 cells, both PTTG1 downregulation and overexpression induce an increase in mitotic cells that is associated with diminished apoptosis after paclitaxel treatment. In LNCaP cells, however, PTTG1 downregulation prevents mitotic entry and, subsequently, inhibits mitosis-associated, paclitaxel-induced apoptosis. In contrast, PTTG1 overexpression induces an increase in mitotic cells and apoptosis after paclitaxel treatment. We have also identified a role for Mcl-1 protein in preventing apoptosis during mitosis in PC3 cells, as simultaneous PTTG1 and Mcl-1 silencing enhances mitosis-associated apoptosis after paclitaxel treatment. The finding that a more efficient mitotic arrest alone in PC3 cells is not enough to increase apoptosis was also confirmed with the observation that a selected paclitaxel-resistant PC3 cell line showed an apoptosis-resistant phenotype associated with increased mitosis upon paclitaxel treatment. These findings could contribute to identify putative responsive and nonresponsive cells and help us to approach incomplete responses to paclitaxel in the clinical setting. Mol Cancer Ther; 13(10); 2372–83. ©2014 AACR.
Lipid Catabolism via CPT1 as a Therapeutic Target for Prostate Cancer
Authors: Schlaepfer Isabel R. , Rider Leah , Rodrigues Lindsey Ulkus , Gijón Miguel A. , Pac Colton T. , Romero Lina , Cimic Adela , Sirintrapun S. Joseph , Glodé L. Michael , Eckel Robert H. , Cramer Scott D.
Published: August 2014

Prostate cancer is the most commonly diagnosed malignancy among Western men and accounts for the second leading cause of cancer-related deaths. Prostate cancer tends to grow slowly and recent studies suggest that it relies on lipid fuel more than on aerobic glycolysis. However, the biochemical mechanisms governing the relationships between lipid synthesis, lipid utilization, and cancer growth remain unknown. To address the role of lipid metabolism in prostate cancer, we have used etomoxir and orlistat, clinically safe drugs that block lipid oxidation and lipid synthesis/lipolysis, respectively. Etomoxir is an irreversible inhibitor of the carnitine palmitoyltransferase (CPT1) enzyme that decreases β oxidation in the mitochondria. Combinatorial treatments using etomoxir and orlistat resulted in synergistic decreased viability in LNCaP, VCaP, and patient-derived benign and prostate cancer cells. These effects were associated with decreased androgen receptor expression, decreased mTOR signaling, and increased caspase-3 activation. Knockdown of CPT1A enzyme in LNCaP cells resulted in decreased palmitate oxidation but increased sensitivity to etomoxir, with inactivation of AKT kinase and activation of caspase-3. Systemic treatment with etomoxir in nude mice resulted in decreased xenograft growth over 21 days, underscoring the therapeutic potential of blocking lipid catabolism to decrease prostate cancer tumor growth. Mol Cancer Ther; 13(10); 2361–71. ©2014 AACR.
Abstract A25: Systematic analysis of gene-drug interactions in isogenic cells reveals novel unexpected dependencies in lung cancer cells
Authors: Smida Michal , Cruz Ferran Fece de la , Uras Iris , Nijman. Sebastian MB
Published: August 2014

Lung cancer is the leading cause of cancer-related deaths worldwide, killing more people than colon, breast and prostate cancer together. Although the majority of genes that cause lung cancer have been identified, the translation of this knowledge into effective treatments has proven challenging. Thus, an interrogation of functional gene-drug interactions and identification of cancer vulnerabilities for approved or experimental drugs can help bridge the gap between cancer genomics and effective treatments. We constructed a genetically tractable and flexible lung cancer model consisting of a panel of isogenic cell lines that captures parts of the molecular heterogeneity and complexity of lung adenocarcinoma. This panel was screened against a collection of drugs, mainly kinase inhibitors and lung cancer chemotherapeutics. The screen revealed several known or expected gene-drug interactions, thus providing the proof of principle for our approach. For instance, RAS mutant cells were resistant to p38 inhibitors, presumably as RAS is able to activate p38 MAPK. Also the resistance of RAS mutant cells to VEGFR inhibitors can be assigned to the fact that RAS is a downstream effector of VEGFR. On the other hand, we observed that DNA-PK(cs)-deficient cells display hypersensitivity to the DNA-damaging agents etoposide and doxorubicin. Interestingly, we also found strong sensitivity of ATM loss-of-function cells to CHK1/2 inhibitor. As CHK activates DNA-PK(cs) and this substrate was shown to be synthetically lethal with ATM, this may provide plausible explanation for the mechanism. Importantly, we have identified several unexpected vulnerabilities to multiple protein kinase inhibitors that are currently in clinical trials. These sensitivities were consequently reproduced in a panel of patient derived lung cancer cell lines and the physiological relevance was demonstrated. Currently, we are investigating the mechanisms responsible for the exquisite dependency observed. Overall, these data may provide a direct and testable rational to apply these kinase inhibitors in stratified lung cancer patient cohorts with the relevant genetic makeup.

Citation Format: Michal Smida, Ferran Fece de la Cruz, Iris Uras, Sebastian MB Nijman. Systematic analysis of gene-drug interactions in isogenic cells reveals novel unexpected dependencies in lung cancer cells. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr A25.
Abstract A28: Identification of HDAC inhibitor potentiating targets in acute myeloid leukemia cells by large-scale RNA-interference
Authors: Bogenberger James M. , Rudd James E. , Chow Donald , Kassner Michelle , Yin Holly , Greene Casey S. , Tibes Raoul
Published: August 2014

The lysine deacetylase inhibitor suberoylanilide acid (SAHA) has shown promising but limited activity in the treatment of acute myeloid leukemia (AML). To identify potential targets for rational combination therapies that increase the efficacy of SAHA in AML, we used a functional RNA-interference (RNAi) screening approach to identify genes, that when inhibited, potentiate the in vitro anti-leukemic activity of SAHA. A total of 901 kinase, phosphatase and associated signaling genes were silenced, with four different siRNA sequences per gene, in combination with SAHA treatment. Log2 values of the ratio [(siRNA + SAHA)/(siRNA alone)] were calculated, with median and standard deviation determined on a per-plate basis. Hits were defined as ≥ 2 standard deviations from the log2 ratio median. Hit lists for each cell line were over-laid on an integrated functional relationship network. We applied a community detection algorithm to this sub-network and identified siRNA sensitive modules. Each module represents a highly connected set of genes in the integrated network. To identify the pathways represented by each module, we evaluated enrichment using the National Cancer Institute (NCI) Protein Interaction Database (PID) pathways. Several novel sensitizing targets, grouped into a small number of pathways, emerged from these screens. Some hits exhibit little to no anti-leukemic activity when silenced alone, indicative of synthetic lethal interaction with SAHA treatment. Initial validation experiments with siRNA and novel small molecule inhibitors confirm RNAi screen results and pharmacological sensitization is observed. The first reported large-scale HDAC inhibitor RNAi screen in leukemias has identified a novel rational combination that can be translated into design of a clinical trial.

Citation Format: James M. Bogenberger, James E. Rudd, Donald Chow, Michelle Kassner, Holly Yin, Casey S. Greene, Raoul Tibes. Identification of HDAC inhibitor potentiating targets in acute myeloid leukemia cells by large-scale RNA-interference. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr A28.
Abstract B01: Nonsteroidal anti-inflammatory drugs selectively kill colon cancer cells through a synthetic lethal interaction
Authors: Leibowitz Brian , Moyer Mary P. , Yu Jian , Zhang Lin
Published: August 2014

Colorectal tumorigenesis is initiated by genetic alterations in the APC tumor suppressor pathway. Nonsteroidal anti-inflammatory drugs (NSAIDs) can inhibit tumorigenesis by eliminating APC-deficient early pre-malignant cells. However, how and why NSAIDs selectively kill APC-deficient cells while leaving normal cells unharmed has remained elusive. We demonstrate that the NSAID sulindac sulfide initiates death receptor signaling in both colon cancer cells and NCM356 normal colonic epithelial cells, but only induces apoptosis in colon cancer cells and APC-deficient NCM356 cells. Loss of APC leads to down-regulation of c-FLIP, largely due to increased expression of c-Myc. Sulindac sulfide treatment further enhanced down-regulation of c-FLIP. Loss of c-FLIP allows death receptor signaling to progress through caspase-8 and BID cleavage, leading to amplified apoptotic signaling via the mitochondria. Depleting APC in NCM356 cells recapitulates this pathway, and is sufficient to lead to sulindac sulfide-induced apoptosis. Based on these data, we conclude that NSAIDs selectively kill colon cancer cells through a synthetic lethal interaction between death receptor signaling and APC deficiency. These findings potentially open a door to development of more effective colon cancer prevention and treatment strategies.

Citation Format: Brian Leibowitz, Mary P. Moyer, Jian Yu, Lin Zhang. Nonsteroidal anti-inflammatory drugs selectively kill colon cancer cells through a synthetic lethal interaction. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr B01.
Abstract B24: Using KRAS synthetic lethality to design novel therapeutic approaches to cancer
Authors: Costa-Cabral Sara , Marinari Eliana , Aarts Marieke , Riffell Jenna L. , Torrence Christopher , Lord Christopher L. , Ashworth Alan
Published: August 2014

Background: KRAS is among the most commonly mutated human cancer genes, and is mutated in approximately 20% of human tumors. In colorectal cancer KRAS mutation is a predictor of anti-EGFR treatment resistance and different KRAS mutations can lead to different anti-EGFR treatment responses. Despite this, KRAS has proven difficult to target with small molecule inhibitors. Identifying synthetic lethal interactions that occur only in the context of tumor specific KRAS mutations represents one approach that could be used to target tumor cells.

Material and methods: To identify KRAS synthetic lethal interactions we have generated functional profiles of constitutively activated KRAS mutant cancers, using an integrated approach that involves cell viability screening. We used a panel of isogenic tumor cell lines carrying different KRAS mutations (G12D, G12S, G12V and G13D) where we performed siRNA screens using a library targeting kinases and kinase-related and tumor suppressor genes. The validation of the siRNA hits was performed in a panel of non-isogenic colorectal and pancreatic cell lines to assess the generality of the effect. By determining the effect on cell viability of each siRNA in each cell model we were able to identify KRAS mutation specific effects.

Results: By using high throughput functional viability profiling in KRAS mutant models we have been able to identify a series of genetic dependencies specific for tumor cells with oncogenic KRAS mutations. We have also some exciting preliminary results with small molecule inhibitors, which target some of the genes that we identified as being critical for the survival of KRAS mutant cancers.

Conclusion: Using functional viability profiling of a series of KRAS isogenic cell lines we have now identified and confirmed several KRAS synthetically lethal candidate genes. Our subsequent work will focus on dissecting of the molecular mechanisms responsible for these KRAS mutant selective effects, and possible combinations with other drugs clinically available.

Citation Format: Sara Costa-Cabral, Eliana Marinari, Marieke Aarts, Jenna L. Riffell, Christopher Torrence, Christopher L. Lord, Alan Ashworth. Using KRAS synthetic lethality to design novel therapeutic approaches to cancer. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr B24.
Abstract B32: Patient-derived tissue slice grafts of high-risk primary prostate cancer: An authentic preclinical model for synthetic lethality-based therapy
Authors: Zhao Hongjuan , Thong Alan , Nolley Rosie , Reese Stephen , Santos Jennifer , Ingels Alexandre , Peehl Donna
Published: August 2014

Background: Effective eradication of high-risk primary prostate cancer (HRPCa) could significantly decrease mortality from prostate cancer. Drugs exploiting synthetic lethality have gained attention as novel anticancer agents. However, the discovery of such therapies for HRPCa is hampered by the lack of authentic preclinical models.

Methods: We improved upon tumorgraft models that have been shown to predict drug response in other cancer types by implanting thin, precision-cut slices of HRPCa under the renal capsule of immunodeficient mice. Tissue slice grafts (TSGs) from 6 cases of HRPCa were established in mice. Following androgen deprivation by castration, TSGs were recovered and the presence and phenotype of cancer cells were evaluated.

Results: High-grade cancer in TSGs generated from HRPCa displayed characteristic Gleason patterns and biomarker expression. Response to androgen deprivation therapy (ADT) was as in humans, with some cases exhibiting complete pathologic regression and others showing resistance to castration. As in humans, ADT decreased cell proliferation and prostate-specific antigen expression in TSGs. Adverse pathological features of parent HRPCa were associated with lack of regression of cancer in corresponding TSGs after ADT. Castration-resistant cancer cells remaining in TSGs showed upregulated expression of androgen receptor target genes, as occurs in castration-resistant prostate cancer (CRPC) in humans. Finally, a rare subset of castration-resistant cancer cells in TSGs underwent epithelial-mesenchymal transition, a process also observed in CRPC in humans.

Conclusions: Our study demonstrates the feasibility of generating TSGs from multiple patients and of generating a relatively large number of TSGs from the same HRPCa specimen with similar cell composition and histology among control and experimental samples in an in vivo setting. The authentic response of TSGs to ADT, which has been extensively characterized in humans, suggests that TSGs can serve as a surrogate model for clinical trials to achieve rapid and less expensive screening of synthetic lethality based therapeutics for HRPCa and primary CRPC.

Citation Format: Hongjuan Zhao, Alan Thong, Rosie Nolley, Stephen Reese, Jennifer Santos, Alexandre Ingels, Donna Peehl. Patient-derived tissue slice grafts of high-risk primary prostate cancer: An authentic preclinical model for synthetic lethality-based therapy. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr B32.
Abstract IA13: Targeting the dependence of N-Myc on interaction with Aurora-A with small molecules
Authors: Brockmann Markus , Poon Evon , Chesler Louis , Eilers Martin
Published: August 2014

Multiple proof-of-principle experiments suggest that targeting members of the Myc family of oncoproteins will have significant therapeutic benefit in human tumors. Deregulated expression of MYCN, one of the three family members implicated in human tumors, is prevalent in both pediatric and adult neuroendocrine tumors. We have shown previously that MYCN-amplified neuroblastoma cells depend on high levels of Aurora-A expression for maintaining N-Myc function. Similarly, Aurora-A and N-Myc bind each other and together drive an oncogenic gene expression program in neuroendocrine prostate tumors. Although stabilization of N-Myc does not require the catalytic activity of Aurora-A, we found that two inhibitors of Aurora-A disrupt the Aurora-A/N-Myc complex and promote degradation of N-Myc via the Fbxw7 ubiquitin ligase. Disruption of the Aurora-A/N-Myc complex inhibits N-Myc-dependent transcription, correlating with tumor regression and prolonged survival in a mouse model of MYCN-driven neuroblastoma, suggesting that Aurora-A is an accessible target that makes destabilization of N-Myc a viable therapeutic strategy.

Citation Format: Markus Brockmann, Evon Poon, Louis Chesler, Martin Eilers. Targeting the dependence of N-Myc on interaction with Aurora-A with small molecules. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr IA13.
Abstract IA7: Chromosome instability and synthetic lethality in yeast and cancer
Authors: Hieter Philip , Bailey Melanie , O'Neil Nigel , Pel Derek van , Stirling Peter
Published: August 2014

Genes that maintain chromosome stability (CIN genes) are conserved in eukaryotes and are often somatically mutated in cancer. We have been identifying synthetic lethal partner genes, in yeast synthetic lethal (SL) interaction networks, that are highly connected with sets of CIN genes somatically mutated in cancer. This identifies hub proteins and processes that are candidate targets for synthetic lethal killing of cancer cells with defined CIN gene somatic mutations. One hub process in these networks is DNA replication. The protein product of FEN1 (encoding flap endonuclease) was used as a target for small-molecule inhibitor screening using a fluorescence-based assay for enzyme activity. Inhibitors of FEN1 activity in vitro were shown to selectively inhibit the proliferation of cultured cancer cells carrying inactivating mutations in CDC4, or knockdown or inhibition of MRE11A, two genes frequently mutated in a variety of cancers. Analysis of synthetic lethal interactions with cohesin gene mutations, a class of somatic mutation found in several tumor types, found that cohesin mutants require the function of genes that mediate replication fork progression. PARP1 has roles in the DNA damage response but also the restart of stalled replication forks. We found that cohesin mutants exhibited synthetic lethal interactions with PARP mutants in C. elegans, and demonstrated that this interaction is conserved in human cells by showing that PARP inhibitors reduce the viability of cultured human cells depleted for cohesin components. Solomon, Waldman et al (Science 333:1039-43, 2011) have shown that the cohesin subunit gene, STAG2, is recurrently mutated in glioblastoma, Ewing's sarcoma, and melanoma tumors. Using matched glioblastoma cell lines containing either a truncated STAG2 or wild-type STAG2 knock-in, we found that STAG2 mutants undergo significantly decreased proliferation in the presence of PARP inhibition, suggesting that PARP inhibitors may be effective in treating cancers carrying somatic mutations in cohesin genes.

Citation Format: Philip Hieter, Melanie Bailey, Nigel O'Neil, Derek van Pel, Peter Stirling. Chromosome instability and synthetic lethality in yeast and cancer. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr IA7.
Abstract PR10: A cyclic AMP-regulated melanocyte lineage program confers resistance to MAP kinase pathway inhibition
Authors: Johannessen Cory M. , Johnson Laura A. , Piccioni Federica , Townes Aisha , Frederick Dennie T. , Flaherty Keith T. , Wargo Jennifer A. , Root David E. , Garraway Levi A.
Published: August 2014

BRAFV600E-mutant malignant melanomas depend on RAF/MEK/ERK (MAP kinase) signaling for tumor cell growth. RAF and MEK inhibitors show remarkable clinical efficacy in BRAFV600E melanoma; however, resistance to these agents remains a formidable challenge. Systematic characterization of resistance mechanisms may inform the development of more effective therapeutic combinations. To chart the landscape of potential resistance mechanisms, we performed systematic gain-of-function resistance studies by expressing >15,500 genes individually in a BRAFV600E melanoma cell line treated with RAF, MEK, ERK, or combined RAF/MEK inhibitors. These studies revealed a cyclic AMP-dependent melanocytic signaling network not previously associated with drug resistance, including G-protein coupled receptors, adenyl cyclase, protein kinase A and cAMP response element binding protein (CREB). In biopsies from BRAFV600E melanoma patients, phosphorylated (active) CREB was suppressed by RAF/MEK-inhibition but restored in relapsing tumors. Expression of transcription factors activated downstream of MAP kinase and cAMP pathways also conferred resistance, including c-FOS, NR4A1, NR4A2 and MITF. While direct small-molecule inhibition of transcription factors is a current challenge, MITF expression can be suppressed with histone deacetylase (HDAC) inhibitors. Combined treatment with MAP kinase pathway and a panel of HDAC inhibitors suppressed MITF expression and cAMP-mediated resistance. Collectively, these data suggest that oncogenic dysregulation of a melanocyte lineage dependency can cause resistance to RAF/MEK/ERK inhibition, which may be overcome by combining signaling- and chromatin-directed therapeutics.

This abstract is also presented as Poster B23.

Citation Format: Cory M. Johannessen, Laura A. Johnson, Federica Piccioni, Aisha Townes, Dennie T. Frederick, Keith T. Flaherty, Jennifer A. Wargo, David E. Root, Levi A. Garraway. A cyclic AMP-regulated melanocyte lineage program confers resistance to MAP kinase pathway inhibition. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Synthetic Lethal Approaches to Cancer Vulnerabilities; May 17-20, 2013; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(5 Suppl):Abstract nr PR10.