Abstract 4470: Kevetrin™, a novel small molecule, activates p53, enhances expression of p21, induces cell cycle arrest and apoptosis in a human cancer cell line

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL We have previously shown that Kevetrin, a small molecule currently under development, has potent antitumor activity in human multi-drug resistant carcinoma xenograft models while being well tolerated. To investigate the mechanism of action for its potent antitumor activity, we assessed Kevetrin's effect on apoptosis, cell cycle progression, including underlying molecular mechanisms. Here we report that Kevetrin strongly induced cell cycle arrest and apoptosis in a human lung adenocarcinoma cell line (A549) using the TUNEL assay and FACS analysis; similar results were observed using a human breast carcinoma cell line (MDA-MB-231). Treatment of A549 cells with 400 µM of Kevetrin for 48 hours resulted in G2/M phase cell cycle arrest that was associated with a marked decline in levels of G2/M regulatory proteins, including CDK1 and cdc25B, and increased expression of Wee1. Further, Kevetrin-mediated growth inhibition of A549 correlated with apoptosis induction that was characterized by cleavage of procaspase-3 and poly (ADP-ribose) polymerase (PARP). The p53 tumor suppressor is a well characterized transcription factor controlling cell growth and apoptosis during times of cellular stress. The tumor suppressor p53 inhibits tumor growth primarily through its ability to induce apoptosis. In cancer development, the resistance of cells to apoptosis is one of the crucial steps. The reactivation of p53 in tumor cells should trigger massive apoptosis and eliminate the tumor. Interestingly, Kevetrin treatment caused enhanced activated p53 levels in A549 cells. Activation of p53 can lead to cell cycle arrest and apoptosis. Western blotting revealed a concentration dependent increase in phosphorylation of p53 at serine 15. The phosphorylation of p53 at serine 15 leads to reduced interaction between p53 and its negative regulator, the oncoprotein MDM2. We also found that Kevetrin increased expression of p53 target genes such as p21 (Waf1). The tumor suppressor protein p21 (Waf1) acts as inhibitor of cell cycle progression. Finally, we also found that p53 induced apoptosis by inducing the expression of PUMA. Our study shows that Kevetrin activates p53 functions in tumor cells. Thus Kevetrin is a strong candidate as an anticancer drug that targets p53. Based on our studies we plan to initiate a Phase I clinical trial in 2011. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4470. doi:10.1158/1538-7445.AM2011-4470