The modulation effect of vitamin E on prostaglandin E2 level and ornithine decarboxylase activity at the promotion phase of lung tumorigenesis in mice.

The present study was undertaken to investigate a mechanism of the inhibitory effect of vitamin E in urethane-induced lung tumorigenesis in mice. We assayed ornithine decarboxylase (ODC) activity and the prostaglandin E2 (PGE2) level in lung at 8 weeks after urethane injection (promotion phase). Excessive vitamin E feeding or indomethacin treatment suppressed the urethane-induced increase in ODC activity, while exogenous PGE2 overcame the effect of vitamin E on ODC activity. Furthermore, the amount of PGE, and the level of ODC activity were well correlated. These results indicate that the vitamin E-induced decrease in PGE2 level probably contributes to the inhibition of ODC induction and the prevention of tumor development in the lung.