Potent inhibitory effect of δ-tocopherol on prostate cancer cells cultured in vitro and grown as xenograft tumors in vivo

In the present study, the effects of δ-tocopherol (δ-T) on growth and Apoptosis of human prostate Cancer cells were determined and compared with that of α-tocopherol (α-T), a commonly used form of vitamin E. Treatment of human prostate Cancer cells with δ-T resulted in strong growth inhibition and Apoptosis stimulation, while the effects of α-T were modest. The strong effects of δ-T on the cells were associated with suppression of Androgen Receptor (AR) activity and decreased level of prostate specific antigen (PSA) that is a downstream target of the AR signaling. In the in vivo study, we found that δ-T had a more potent inhibitory effect on the formation and growth of prostate xenograft tumors than that of α-T. Moreover, δ-T inhibited proliferation and stimulated Apoptosis in the tumors. The present study identified δ-T as a better form of vitamin E than α-T for future clinical studies of prostate Cancer prevention.

AR signaling; apoptosis; prostate cancer; tocopherol; vitamin E; xenograft tumor.