Abstract 5128: Different effect of irinotecan induced apoptosis in k-Ras wild and mutant type colon cancer cell lines

Abstract

Abstract Irinotecan(IRI) prevents DNA from unwinding by inhibition of topoisomerase I. Its main use is in colon cancer, in particular, in combination with other chemotherapy agents. Recent studies, those with Irinotecan treatment has a synergistic effect appears. However, there is no study on the effect of the Irinotecan mono-treatment. In addition their roles and the underlying mechanism in anti-tumorigenic function of solid tumor, especially kras wild and mutant type colon cancer, are not yet known. Bax protein is a key mediator of apoptosis and might be related to chemosensitivity. In this work, we evaluated the anti-tumorigenic action of these Irinotecan anti-cancer agent with especially k-ras wild and mutant type colon cancer cell lines, and investigated their apoptosis-inducing effects as the potential mechanism in this process. The results show that the growth inhibitory effects of 5-fuorouracil (5-FU), Oxaliplatin(OX) produced a dose- and time dependent fashion in k-ras wild(HT29, Colo205) and mutant type(HCT116, DLD-1) colon cancer cell lines. Otherwise, Irinotecan(IRI) produced a cell growth of k-ras wild type cell lines were resistant versus that shown in the sensitive k-ras mutant type cell lines. Cell cycle analysis by FACS indicated that IRI-treated cell lines showed an increase in the proportion of cells in sub-G1 phase, compared to untreated cells. Exposure of colon cancer cells to IRI also resulted in the increase in the percentage of annexin V- positive and PI-negative cells. The results by multiple in vitro experimental model, showed that IRI induce these k-ras mutant type colon cancer cells to undergo apoptosis with increased the Bax protein and a release of cytochrome C from mitochondria, the activation of caspase9, the cleavage of PARP. But Bax protein was inactivation in k-ras wild type colon cancer cell lines. Importantly, inhibition of ERK kinase activity demonstrated that IRI-induced apoptotic pathway was regulated by the ERK signaling cascade. These data indicate that Anti-cancer agent, Irinotecan, promotes Bax-mediate apoptosis of colon cancer cell lines by sequential activation of the ERK signaling pathway followed by the up-regulation of intrinsic pathway of caspase 9. Citation Format: Myoung Hee Kang, Jung Lim Kim, Bo Ram Kim, Yoo Jin Jang, Sun Il Lee, Jun Suk Kim, Sang cheul Oh. Different effect of irinotecan induced apoptosis in k-Ras wild and mutant type colon cancer cell lines. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5128. doi:10.1158/1538-7445.AM2014-5128