Abstract 526: Combined inhibition of mTOR and AKT activity induces potent apoptosis in epithelial ovarian cancer cells .

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Abstract Mammalian target of rapamycin (mTOR) and Phosphatidylinositol 3-kinase (PI3K) are two key components of the PI3K/Akt/mTOR signaling pathway. These two signal transduction cascades regulate a number of physiological cell functions including differentiation, proliferation, apoptosis and autophagy. Dysregulation of these pathways have been found in many cancers including DLBCL, thyroid cancer, breast cancer, prostate cancer and lung cancer. mTOR has been shown to activate the PI3-kinase/AKT survival pathway and understanding the interplay among signaling molecules in the PI3K/Akt/mTOR pathway is of utmost importance. Two distinct mTOR complexes; mTORC1 and mTORC2, have been identified. mTORC1 is downstream of Akt, sensitive to rapamycin inhibition, and controls cap-dependent protein translation. In contrast, mTORC2 is directly upstream of Akt and is resistant to rapamycin. In this study, we investigated the effect of mTOR inhibition on cell viability and induction of apoptosis in epithelial ovarian cancer (EOC) cells, either alone or in combination with PI3-kinase/AKT inhibitor. We found that Torin2, an mTOR inhibitor, decreased cell viability and induced apoptosis in EOC cell lines in a dose dependent manner. Torin2 also inactivated mTOR1 and mTOR2 as well as downstream targets of mTOR; 4E-BP1 and p70S6. Torin2 treatment of EOC cell lines also induced mitochondrial dependent apoptosis via activation and cleavage of caspases. Finally, combination treatment of EOC cells with Torin2 and LY294002, a PI3-kinase/AKT inhibitor induced a synergistic apoptotic response via inactivation of AKT, mTOR1 and mTOR2 and activation of caspases. These studies will give us an insight on the molecular relationship between these survival pathways and suggest that simultaneous inhibition of mTOR and PI3-kinase/AKT pathways may be beneficial for the management of EOC. Citation Format: Azhar R. Hussain, Shahab Uddin, Maqbool Ahmed, Khawla S. Al-Kuraya. Combined inhibition of mTOR and AKT activity induces potent apoptosis in epithelial ovarian cancer cells . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 526. doi:10.1158/1538-7445.AM2013-526