Induction of cell cycle arrest and apoptosis by tubeimoside I isolated from Bolbostemma paniculatum in HeLa cells

AIM: To study the antitumor mechanism of tubeimoside I (TBMS1), and to investigate its effects on cell division cycle and cell death in HeLa cells. METHODS: Cell growth inhibition of TBMS1 was measured by MTT assay; the induction of cell cycle arrest and apoptosis by TBMS1 was determined by flow cytometry, light, fluorescence and electron microscopies, and gel electrophoresis of fragmented DNA. Western blotting was performed for detecting the apoptosis related genes. RESULTS: TBMS1 displayed strong growth inhibitory effect against HeLa cells with estimated IC 50 values of 35.7 , 23.6 , and 17.4 μmol·L -1 . HeLa cells underwent G 2/M arrest with exposure to TBMS1, and had typical morphologic and biochemical evidence of apoptosis. Western blot analysis of TBMS1 treated cells revealed downregulation of bcl 2, and overexpression of bax. CONCLUSION: TBMS1 induced cell cycle arrest and apoptosis may play an important role in antitumor effect of TBMS1, and TBMS1 induced apoptosis is closely related to downregulation of bcl 2 and overexpression of bax.