The Chinese herb Norcantharidin (NCTD) has been used in traditional Chinese medicine for more than two thousand years. The first recorded use of cantharidin as an anti-cancer agent was in 1264[2]. Currently, multiple studies in vitro and in vivo have shown that NCTD was cytotoxic to various types of tumor cells.The

significant apoptotic effects was also observed in tumor cells treated by NCTD. Apoptosis can be initiated via two alternative signaling pathways: the death receptor-mediated extrinsic apoptotic pathway and see more the mitochondrion-mediated intrinsic apoptotic pathway[13–15]. Mitochondria play critical roles in the regulation of various apoptotic processes including drug-induced apoptosis[16].The mitochondrial death pathway is controlled by members of the Bcl-2 family, which play a central regulatory role to decide the fate of the cells via the interaction between pro- and anti-apoptotic members[17, 18].The Bcl-2 family consists of pro-apoptotic and anti-apoptotic members[19].During apoptosis, Bcl-2 family pro-apoptotic proteins including Bim, Bax and Bid can translocate to the outer membrane of mitochondria, promote the release of pro-apoptotic factors, and induce apoptosis. On the other hand, Bcl-2 family anti-apoptotic proteins including Bcl-2 and Bcl-XL,

sequestered in mitochondria, inhibit the release of pro-apoptotic factors and prevent apoptosis. When interacting with activated pro-apoptotic proteins, SB431542 research buy the anti-apoptotic proteins lose inhibiting ability of pro-apoptotic factors’ release, and again promote apoptosis. Alteration in the levels of anti- and pro-apoptotic Bcl-2 family proteins influences apoptosis[20]. In

this study, the NCTD-induced apoptosis in HepG2 cells was accompanied by up-regulation FER of Bax and the selleck chemical down-regulation of Bcl-2, suggesting that NCTD induced apoptosis in HepG2 cells by modulating Bcl-2 family proteins. Recent data indicate that caspases play a key role in the initiation of apoptosis[21, 22]. In the present study, NCTD treatment caused the activation of caspase-3 and -9 in a dose-dependant manner that is consistent with the results of PARP activation and cell apoptosis. These results demonstrated that NCTD-induced apoptosis may involve a caspase-3-mediated mechanism and activation of caspase-9 may act upstream of caspase-3 activation. Mitochondria have been reported to play a critical role in the regulation of apoptosis[23, 24]. Consistent with these results, in the cytosol of NCTD -treated HepG2 cells, cyto c was detected after a 24 h treatment period. Once released into the cytosol, cyto c binds with procaspase-9 in the presence of ATP and Apaf-1 to form the apoptosome. This complex activated caspase-9, which, in turn, cleaves, and thereby activates, caspase-3.