Specific accumulation of γ- and δ-tocotrienols in tumor and their antitumor effect in vivo

In contrast to extensive studies on tocopherols, very little is understood about tocotrienols (T3). We evaluated the antitumor activities of γ-T3 and δ-T3 in murine hepatoma MH134 cells in vitro and in vivo. We found that δ-T3 inhibited the growth of MH134 cells more strongly than γ-T3 by inducing apoptosis. In C3H/HeN mice implanted with MH134, it was found that γ-T3 and δ-T3 feeding significantly delayed tumor growth. On the other hand, both T3 had no significant effect on body weight, normal-tissue weight and immunoglobulin levels. Intriguingly, we found that T3 was detected in tumor, but not in normal tissues. These results, to our knowledge, are the first demonstration of specific accumulation of γ-T3 and δ-T3 in tumors and suggest that T3 accumulation is critical for the antitumor activities of T3.