Abstract 1479: Modulating AKT induced epithelial mesenchymal transition (EMT) for prevention and treatment of colon cancer.

Activation of serine threonine kinase-AKT transduces signals that regulate multiple biological processes including cellular proliferation, survival, apoptosis, gene expression, angiogenesis, migration and EMT in many cancer types. Recent studies have shown oncogenic activation of AKT has emerged as a central feature of EMT, endowing the cancer cells with migratory and invasive capability. In our results over expression of AKT in HCT-116 (AKT/HCT-116) (express low levels of pAKT as compared to the other colon cancer cell lines) showed significantly higher cell proliferation and aggressive phenotype with increase in migration and invasion when compared to the vector transfected control cells (pCMV/HCT-116). Further in vivo studies revealed highly aggressive, angiogenic with large tumor volume in AKT/HCT-116 xenografts compared to the control tumors. Down-regulating constitutively active Akt (by a PI3 kinase inhibitor, such as wortmannin or LY 294002) reverses both cell survival and resistance to chemotherapeutic agents, however, these inhibitors causes severe toxicity in animal models. Hence, it is exigent to identify novel molecules, to inhibit Akt signaling, which could be developed as a new therapeutics, as well as preventive agents for colon cancer. Our small molecules screening studies revealed, Withaferin-A (WA) as a potent molecule which significantly inhibited AKT activity that resulted in inhibition of cell proliferation in AKT over expressing HCT-116 cells. At molecular level inhibition of AKT resulted in suppression of its downstream pro-survival signaling such as NFκB and BCL-2 in AKT/HCT-116 cells and pCMV/HCT-6 cells. Oral treatment of WA significantly suppressed AKT-induced tumor growth, invasion and migration in cell culture and xenograft models. These results correlated well at molecular level with significant inhibition of the important EMT markers i.e. snail, slug, β-catenin, MMP-2 and MMP-9. Immunohistochemistry of tumor tissues showed WA treatment resulted in increase in E-cadherin expression with concomitant decrease in the expression and nuclear localization of β-catenin in AKT overexpressing tumors. Decreased levels of pAKT, NFkB, Snail, Slug, vimentin expression were seen in WA treated both pCMV/HCT-116 and AKT/HCT-116 tumors. Interestingly, significant inhibition of micro-vessel formation and length of vessels were evident in WA-treated tumors which correlated with low expression of angiogenic markers like Factor VIII and RETIC. In conclusion, the present study underscores the crucial role of AKT activation in inducing cell proliferation, angiogenesis and EMT in colon cancer cells and WA could be a potent compound for the chemoprevention and/or chemotherapy of colon cancer. Citation Format: Suman Suman, Vittal Kurisetty, Trinath P. Das, Aditi Vadodkar, Ramadevi Subramani Reddy, Rajkumar Lakshmanaswamy, Chendil Damodaran. Modulating AKT induced epithelial mesenchymal transition (EMT) for prevention and treatment of colon cancer. [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 1479. doi:10.1158/1538-7445.AM2013-1479