Abstract 3783: Co-treatment of metastasis-derived colon cancer cells with bromoethyl indole (BEI) enhances camptothecin or TNF alpha-induced cell death

Abstract

Abstract Colorectal cancer is still the third most deadly cancer in the United States. Currently, there are limited choices of targeted anticancer agents that are durably effective against colorectal cancer. Therefore, chemotherapeutic regimens containing the drugs Camptothecin (CPT), 5-FU and Oxaliplatin remain the mainstays for the treatment of advanced colorectal cancer. We recently found that the indole-derivative small compound Bromoethyl Indole (BEI) potently inhibits the proliferation of colon cancer cells and also suppresses NF-kB activation. In this study, we investigated if the combination of BEI with either CPT or TNFα would enhance cell death in vitro. Metastasis-derived parental or engineered NF-kB-reporter colon cancer cells were used to examine 1) the activation of NF-kB signaling by clinically used drugs, 2) the potential for BEI to inhibit drug-induced NF-kB activation, and 3) the potential for combination treatment to enhance cell death in vitro. Cells were treated with either the drugs alone or in combination with BEI at varying concentrations. NF-kB-inducing concentration of CPT (0.6 to 2.5 μM), TNFα (25 to 50 ng/ml), and BEI concentrations of 1 to 50 μM range were tested. Cell cycle profiles and cell death markers were assessed to determine the effects of single or co-treatments. The expressions of Bcl-xL and cIAP2 (BIRC3) proteins were examined to monitor the targets of NF-kB activation. Our results show that 1) both TNFα and CPT induce NF-kB signaling in metastasis-derived colon cancer cells, 2) combination of BEI and TNFα or CPT inhibits such a drug-induced NF-kB activation and reduces the expression of NF-kB responsive genes, 3) sequential treatment of the cells with CPT and BEI delivers the best outcome, increasing cell death by up to 3-fold compared to either CPT or BEI alone, and 4) co-treatment of the cells with TNFα and BEI increases cell death by up to 2-fold compared to either TNFα or BEI alone, 5) BEI is most effective in inducing cell death at concentrations between 2 and 10 μM. We anticipate that BEI will improve the therapeutic index of some chemotherapeutic drugs. Therefore, the potential benefit for combination of BEI with NF-kB activating drugs needs to be evaluated in vivo. Citation Format: Rupak Chowdhury, Sonni A. Miller, Dominique Gales, Jason White, Upender Manne, Temesgen Samuel. Co-treatment of metastasis-derived colon cancer cells with bromoethyl indole (BEI) enhances camptothecin or TNF alpha-induced cell death. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3783.