Abstract 2178: Growth inhibition of the crude extracts of Musa basjoo in human colon carcinoma cells

Abstract

Abstract Musa basjoo (MB) is a tropical evergreen tree growing mainly in subtropical or tropical countries. MB has been used globally as a folk medicine such as antipyretic, diuretic, and hemostatic drugs for centuries but evidence-based biological activities and molecular mechanism of action of MB are unknown. Therefore, in the current study we examined whether the crude extracts of MB exert anticancer activity in HT29 and HCT116 human colon carcinoma cell lines. Dried leaves of MB samples were extracted with acetone or methanol. Crude extracts of MB were then dissolved in dimethylsulfoxide (DMSO) and used for the following experiments. Growth inhibition was determined by colony or MTT assays in these cell lines. Cells were treated with increasing concentrations (12.5 to 200 μg/mL in colony assays, 25 to 400 μg/mL in MTT assays) of acetone/methanol extracts of MB in DMEM/5%FBS. Untreated control cells were treated with DMSO alone. Crude extracts of MB inhibited the growth of cells with IC50 values of 118 µg/mL (acetone extract, HT29), 75 µg/mL (acetone extract, HCT116), >200 µg/mL (methanol extract, HT29), 141 µg/mL (methanol extract, HCT116) in colony assays, and with IC50 values of 137 µg/mL (acetone extract, HT29), 73 µg/mL (acetone extract, HCT116), 240 µg/mL (methanol extract, HT29), 248 µg/mL (methanol extract, HCT116) in MTT assays. Acetone extract was used in the flowcytometry and western blot analyses because it showed stronger growth inhibition than methanol extract in both cell lines. Flowcytometry analysis indicated that when HT29 and HCT116 cells were treated with 100 µg/mL acetone extract of MB for 96h, the percentage of cells in G1 increased by 5.4% and this was associated with a concomitant decrease of cells in the S and G2-M phases of the cell cycle. Acetone extract of MB did not cause subG1 fraction in either HT29 or HCT116 cell lines. The results indicate that acetone extract of MB causes carcinoma cells to arrest in the G1 phase. We then performed western blot analysis to determine whether treatment of carcinoma cells with acetone extract of MB alters cellular levels of the G1 cell cycle control proteins cyclin D1, cdk4 and the cell cycle inhibitor protein p21CIP1. When HT29 and HCT116 cells were treated with 50 and 100 µg/mL acetone extract of MB for 96h, there was a marked decrease in the levels of expression of the cyclin D1 and cdk4 proteins and a marked increase in the levels of expression of the p21CIP1 protein. Thus, a decrease in cyclin D1 may cooperate with the induction of p21CIP1 to arrest cells in G1 and thereby further contribute to MB-induced growth inhibition. Taken together, the crude extracts of MB contain active component(s) that exert growth inhibition of human colon carcinoma cells. The current study is the first systematic examination of the anticancer activity of MB and may provide a novel approach to the chemoprevention and/or chemotherapy of human colon carcinoma. Citation Format: Harutoshi Matsumoto, Saeko Ando, Katsumi Fukamachi, Mitsuru Futakuchi, Kazunori Kimura, Naoki Yoshimi, Masumi Suzui. Growth inhibition of the crude extracts of Musa basjoo in human colon carcinoma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2178. doi:10.1158/1538-7445.AM2017-2178