Virosecurinine induces apoptosis by affecting Bcl-2 and Bax expression in human colon cancer SW480 cells

Virosecurinine, the major alkaloid isolated from Securinega suffruticosa Pall Rehd was found to exhibit growth inhibition and cytotoxicity against huaman colon cancer SW480 cells via the microculture tetrazolium (MTT) assay. Due to its greater cytotoxic potency and selectivity towards SW480 cells, flow cytometry was used to analyze the cell cycle distribution of control and treated SW480 cells whereas Annexin V-FITC/PI flow cytometry analysis was carried out to confirm apoptosis induced by virosecurinine in SW480 cells. Apoptotic regulatory genes were determined by RT-PCR analysis. Virosecurinine was found to induce G1/S cell cycle arrest which led to predominantly apoptotic mode of cell death. Mechanistically, virosecurinine was found to up-regulated the Bax gene expression and down-regulated the Bcl-2 expression in SW480, The ratio of Bcl-2 to Bax was significantly decreased. Hence, we suggest that virosecurinine induced apoptosis in SW480 cells by affecting the expression of bcl-2 and bax.