Preventive role of vitamin a in colon carcinogenesis in rats

Abstract

Recent literature reviews (Cancer Res. 35:3295, Cancer Res. 35:3427, 1975) have re‐emphasized the importance of vitamin A in the differentiation and maintenance of integrity of epithelium and increasing resistance to some forms of cancer. We have observed an increased incidence of colon carcinoma (100% vs. 60%) in rats deficient in vitamin A and exposed to dimethylhydrazine (Cancer Res. 33:1003, 1973). Other studies have shown that a marginal dietary level of vitamin A not only enhanced liver cancer in rats exposed to aflatoxin B1 but resulted in a 29% incidence of colon cancer as well (J. Natl. Cancer Inst. 50:439, 1973). Recent unpublished results with DMH‐induced colon tumors indicated a significant protection from increased dietary levels of vitamin A analog, 13‐Cis retinoic acid (20/20 vs. 8/20 animals with tumors, 3.1 vs. 2.3 average tumors/animal). These data correlate with depressed glycopeptide synthesis by the gut epithelium (J. Biol. Chem. 245:4551, 1970). Results of these studies indicate that a deficiency of dietary vitamin A can increase susceptibility to DMH‐induced colon tumors in rats, resulting in colon tumors as well as liver tumors in rats exposed to aflatoxin B1 and that that the retinoid, 13 Cis‐retinoic acid can inhibit colon tumor induction by DMH. These findings further substantiate the importance of adequate vitamin A and the potential for the therapeutic use of 13‐Cis retinoic acid. Copyright © 1977 American Cancer Society