INHIBITORY EFFECT OF SOME NEW RETINOIDS ON CARCINOGENESIS

Effects of nine retinoids on carinogenesis of the forestomach in mice were studied. RⅠ, RⅡ, RⅢ, RⅥ, and RⅧ showed significaut inhibitory effect. RⅠN-(4-ethoxycarbophenyl) Retinanide appeared to be the most effective, reproducible and has not been reported in the literature. No toxic effect was observed with therapeutic dose of RⅠ, and no sign of hypervitaminosis A was noticed with dosage as high as 6 times the therapeutic dose. However hypervitamnosis A was induced with retinoic acid at the some dose. The toxiciity of RⅡ appeared to the much less than that of retinoic acid.Autoradiography using H³-thymidine showed marked inhibitory effect of RⅡ on DNA synthesis in the forestomach epithelium of mice.