Apoptosis induction by γ-tocotrienol in human hepatoma Hep3B cells

We evaluated the antitumor activity of tocotrienol (T3) on human hepatoma Hep3B cells. At first, we examined the effect of T3 on the proliferation of human hepatoma Hep3B cells and found that γ-T3 inhibited cell proliferation at lower concentrations and shorter treatment times than α-T3. Then, we examined the effect of γ-T3 apoptosis induction and found that γ-T3 induced poly (ADP-ribose) polymerase (PARP) cleavage and stimulated a rise in caspase-3 activity. In addition, γ-T3 stimulated a rise in caspase-8 and caspase-9 activities. We also found that γ-T3-induced apoptotic cell death was accompanied by up-regulation of Bax and a rise in the fragments of Bid and caspase-8. These data indicate that γ-T3 induced apoptosis in Hep3B cells and that caspase-8 and caspase-9 were involved in apoptosis induction. Moreover, these results suggest that Bax and Bid regulated apoptosis induction by γ-T3.