Abstract 4964: High-throughput genomic analysis of platinum and taxane resistance in ovarian cancer cells

Abstract

Abstract Ovarian cancer is the fifth-leading cause of death from cancer in women. The five-year survival rate for ovarian cancer remains low at approximately 45%. Ovarian cancer patients are often treated with a combination of a platinum agent plus a taxane and despite initial success, up to 75% of responders relapse within 18-28 months. We have previously utilized high-throughput siRNA screening to identify gene modulators of cisplatin resistance in ovarian cancer cell lines. Here, we identify genomic characteristics of paclitaxel-resistant and cisplatin-resistant ovarian cancer cells. Combined with our previous cisplatin-resistance studies, we hope to obtain a more complete picture of platinum/taxane resistance in ovarian cancer. We have developed a variant of the A2780 cell line (A2780-pacli) that exhibits a four-log increase in paclitaxel IC50. Array based comparative genomic hybridization (aCGH) has demonstrated a small number of focal chromosomal aberrations between the parent and isogenic derivative cell lines suggesting drug-specific evolutionary changes to the A2780 genome. We also utilized expression microarrays to identify genes that may contribute to drug-resistant phenotypes. cRNA probes generated from A2780-pacli cells or a commercial cisplatin-resistant A2780 cell line (A2780-cis) and were hybridized against cRNA from wild-type A2780 cells (A2780-WT). Differential gene expression analysis identified overlapping and individual drug-specific patterns of gene expression, including 1519 genes over- or under-expressed in both the cis- and pacli-resistant lines. Additionally, we have completed a high-throughput RNA interference (HT-RNAi) screen on A2780-pacli cells involving 572 kinase genes in order to determine mediators of paclitaxel resistance in this cell line. The HT-RNAi assay was developed to quantify the growth inhibition of A2780-pacli cells transfected with siRNA and treated with an EC50 dose of paclitaxel. Cell viability was assessed after 72 hours of drug exposure. The HT-RNAi screening data was normalized and log 2 ratios of drug-treated/vehicle-treated wells were determined to show drug potentiation. Following data analysis, we generated a list of gene targets that, upon silencing, lead to potentiation of cell viability in response to paclitaxel. Validation of these genes will identify potential therapeutic targets for novel paclitaxel combinations in order to improve clinical efficacy. These findings further demonstrate the effectiveness of using HT-RNAi as a tool for identifying sensitizing targets to chemotherapeutic agents. Taken together, the integrated application of genomic survey methods provides insight into mechanisms of drug resistance in ovarian cancer 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 4964. doi:10.1158/1538-7445.AM2011-4964