Abstract 1451: Lipid-based Akt inhibitors preferentially kill lung cancer cells with mesenchymal features

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Most solid tumors are epithelial in origin. A loss of epithelial-cell markers and gain of mesenchymal-cell markers (epithelial mesenchymal transition, EMT) has been observed in patient tumor samples, particularly at the leading edge or invasive front of solid tumors such as non-small cell lung cancer (NSCLC). Pathological EMT is often associated with tumor metastasis and can confer a poor prognosis. EMT is promoted by Akt activation, which contributes to the formation, maintenance, and therapeutic resistance of cancer. In this study, we found that lipid-based Akt inhibitors (LBAI) such as phosphatidylinositol ether lipid analogues (PIAs) and alkylphospholipids (perifosine and miltefosine) preferentially kill tumor cells with mesenchymal features. NSCLC cell lines that exhibited epithelial, intermediate and mesenchymal phenotypes (H322, A549 and H157, respectively) were increasingly sensitive to the cytotoxic effects of LBAI. Prolonged treatment of A549 cells with TGFbeta induced a mesenchymal phenotype and increased sensitivity to LBAI. Because EMT can be controlled by the tumor suppressor RhoB, which we previously showed was transcriptionally activated by LBAI, we investigated the role of RhoB in these cell lines. An inverse relationship between Akt activation and RhoB expression was observed in the parental cell lines as well as A549 cells treated with TGFbeta, which correlated with LBAI cytotoxicity. Stable knockdown of RhoB in A549 cells induced features of EMT including loss of E-cadherin expression, induction of vimentin expression and Akt activation, and increased cellular migration. Stable knockdown of RhoB also increased sensitivity to LBAI. These studies show that lung cancer cells with a mesenchymal phenotype are preferentially sensitivity to LBAI, and that RhoB is a critical mediator of EMT. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1451.