Vitamin E and the Y4 agonist BA-129 decrease prostate cancer growth and production of vascular endothelial growth factor.

BACKGROUND

A biologically active form of vitamin E, alpha-tocopherol succinate (ATS), has been shown to induce apoptosis of hormone-refractory prostate cancer in vitro and inhibit cell growth in vivo. The gastrointestinal hormone peptide YY (PYY) has growth inhibitory activity against multiple cancer cell lines and is synergistic with ATS against breast and pancreatic cancer growth. BA-129, a specific Y4 receptor agonist, has growth inhibitory effects on pancreatic cancer in vitro. We investigated the effects of BA-129 and ATS on prostate cancer growth and evaluated their effects on vascular endothelial growth factor (VEGF) production.

METHODS

A hormone-refractory human prostate cancer cell line, PC-3, was treated with ATS alone at 10 pg/ml, PYY or BA-129 alone at doses of 75 and 500 pmol/ml, or a combination of the two agents. Cell growth was measured by MTT assay and hemocytometry using trypan blue. Quantitative measurement of VEGF was performed by ELISA. Statistical analysis was achieved by ANOVA.

RESULTS

ATS exhibited significant (P < 0.05) growth inhibitory effects in prostate cancer cells. PYY also inhibited growth (P < 0.05). ATS treatment reduced VEGF production (P < 0.05). PYY treatment increased VEGF. When ATS was given in combination with BA-129, VEGF production was further reduced (P < 0.05).

CONCLUSIONS

Both PYY and ATS inhibit growth in hormone-refractory prostate cancer, with augmentation when used in combination. VEGF production is inhibited by vitamin E, but increased by PYY. ATS abolishes the augmented VEGF response to PYY. Our data suggest that PYY is involved in the regulation of VEGF production and prostate cancer growth.