Abstract 4114: Chemopreventive and chemotherapeutic effect of Withaferin-A on in vivo models of prostate cancer

Several groups have emphasized on the functional role of phytochemicals in chemoprevention and chemotherapy of prostate cancer (CaP). In this study we have focused on Withaferin A (WA) a bioactive compound derived from Withania somnifera, which has been extensively used in Asian and African traditional medicine system. In our in vitro studies, WA inhibits the growth of CRPC cells by targeting AKT mediated pro-survival signaling and simultaneously activating FOXO3a dependent apoptosis in CaP cell lines. The objective of the present study was to evaluate the in vivo efficacy of WA on both xenograft and transgenic adenocarcinoma of mouse prostrate (TRAMP) models. DU-145 and C4-2B CaP cells stably overexpressing AKT were xenografted in nude mice and WA (5mg/kg body weight) was orally administered along with control groups fed with oil alone for 4-5 weeks. AKT-overexpressing tumors showed 2-3-fold faster growth than pCMV-expressing tumors and oral administration of WA significantly reduced AKT-induced tumor growth. Immunohistochemistry of tumor sections revealed high expression of AKT, pAKT and down regulation of nuclear FOXO3a in tumor sections derived from AKT-overexpressing tumors. On the contrary, WA treated controls as well as AKT over expressed tumor sections clearly revealed that WA reverted FOXO3a mediated apoptotic signaling by down regulating AKT activation. In addition, activation of AKT has emerged as a central feature of epithelial-mesenchymal transition (EMT). Our results also revealed elevated expression of important EMT related transcription factors and genes such as snail, slug, β-catenin, vimentin, and MMPs and decrease in the expression of E-cadherin expression in AKT overexpressing tumors. Simultaneously, WA treatment of pCMV and AKT-overexpressing tumors showed decrease in the expression of these EMT markers and increase in the expression of E-cadherin. Similarly, TRAMP mice were randomized into controls and WA (oral gavage-3mg/kg body weight) for 31 weeks. Control and WA-treated mice were sacrificed periodically at 11, 20, 27 and 31 weeks. Histopathological examination revealed both the groups (control and WA-treated) showed prostatic hyperplasia with no signs of metastasis up to 20 weeks. However, 58.3% mice in the control group showed metastasis to lungs, liver or kidneys, whereas in the treatment group 16.6% mice showed metastasis in 31 weeks. Molecular analysis showed higher expression of phosphorylated AKT, FOXO3a, along with EMT markers like β-catenin, snail, vimentin and down regulation of E-cadherin expression in control-TRAMP tumors. On the other hand, WA-treated tumor tissues revealed low expression of pAKT and pFOXO3a in WA treated mice. Also, low expression of β-catenin; snail, vimentin and upregulation of E-cadherin in WA treated mice was observed. These results potentiate the chemopreventive and chemotherapeutic effects of WA in CaP and steers the clinical translation of this biomolecule. Citation Format: Suman Suman, Trinath P. Das, Murali K. Ankem, Chendil Damodaran. Chemopreventive and chemotherapeutic effect of Withaferin-A on in vivo models of prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4114. doi:10.1158/1538-7445.AM2015-4114