Abstract A2: miR-10a regulation of PIK3CA and response to taxol in non small cell lung cancer

Abstract

Abstract Phosphatidylinositol 3-kinases (PI3Ks) are a family of enzymes involved in diverse cellular functions including cell growth, proliferation, differentiation, motility, survival and apoptosis. PI3K allows for the transmission of extracellular cues to an intracellular response via its activation through receptor tyrosine kinase or k-ras. Activation of this pathway is antagonized by the phosphatase PTEN. This signaling pathway is under extremely tight regulation and even slight perturbations can lead to aberrant pathway activation, as is the case in a majority of cancers. We are interested in whether PIK3CA is regulated by one or more microRNAs and whether those miRNAs have a therapeutic effect on cancer cell viability and drug response in PI3K-driven oncogenesis. In a systematic approach to identifying miRNA inhibitors with significant effects on cell viability and response to paclitaxel in NSCLC, we performed a high-throughput screen and identified several candidate microRNAs. Regulatory targets of candidate miRNAs were identified through a combination of in vitro and in silico approaches. Targets were then validated using qRT-PCR, protein quantification, and luciferase reporter assays. The response of cancer cells to perturbations of the candidate miRNA was assessed through flow cytometric analysis of cell cycle phase distribution, colony formation and caspase activation assays. The inhibitor screen revealed that inhibition of miR-10a increased cellular growth rate and resistance to paclitaxel. Further validation demonstrated a 10-fold increase in cell viability in the presence of miR-10a inhibitor, and a 10-fold decrease in the presence of miR-10a mimic. Manipulation of miR-10a levels in either direction resulted in significant changes in both mRNA and protein levels of its predicted target, the catalytic subunit of phosphatidylinositol 3-kinase (PI3K), which was confirmed to be a direct target by luciferase reporter assay. Increasing miR-10a levels inhibited the ability to form colonies, while decreasing miR-10a levels increased colony formation. To assess the prognostic value of miR-10a we assessed expression in NSCLC patients and observed that high miR-10a levels correlate with longer overall survival. The identification of a miR-10a as a modulator of cellular response to taxanes, and PI3K as a regulatory target which mediates that response, define a novel regulatory pathway modulating paclitaxel sensitivity in lung cancer, which may provide novel adjuvant strategies along with paclitaxel in the treatment of lung cancer and may also provide biomarkers for predicting paclitaxel response in NSCLC. Ultimately this study will provide new insights into the molecular basis of lung cancer and a new set of potential therapeutic targets for this devastating disease. Citation Format: Chris DeSevo, Liqin Du, Carmen Behrens, Ignacio I. Wistuba, John Minna, Alexander Pertsemlidis. miR-10a regulation of PIK3CA and response to taxol in non small cell lung cancer [abstract]. In: Proceedings of the AACR Special Conference on Noncoding RNAs and Cancer; 2012 Jan 8-11; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(2 Suppl):Abstract nr A2.