Vitamins A and E do protect against oral carcinoma.

Tumorigenesis requires accelerated polyamine biosynthesis, and elevated levels of ornithine decarboxylase, the rate-limiting enzyme in this reaction chain. The primary goal of this study was to determine whether induction of oral cavity carcinoma by dimethylbenzanthracene was accompanied by increased ornithine decarboxylase. It has previously been demonstrated in an oral carcinogenesis model that cotreatment with vitamins A or E delayed tumor development. The second goal of this study was to determine whether this chemoprotective effect was associated with a decrease in ornithine decarboxylase activity. We found that dimethylbenzanthracene did stimulate ornithine decarboxylase. Vitamins A and E alone also stimulate ornithine decarboxylase, and this effect is additive with dimethylbenzanthracene. Use of both vitamins together prevents the additive effect of either, alone, and vitamin A inhibits the late-phase ornithine decarboxylase response to dimethylbenzanthracene in all animals. We conclude that pretreatment with vitamins A, or A and E together protects against the carcinogenic action of dimethylbenzanthracene, and that the mechanism of this protection is early truncation of the ornithine decarboxylase response to dimethylbenzanthracene.