Hepatic DNA methylation and liver tumor formation in male C3H mice fed methionine- and choline-deficient diets. JNCI

ABSTRACT-The effects of the chronic administration of methyl-deficient, amino acid-defined diets on liver tumor formation were examined in male weanling C3H/HeN mice previously treated with a single ip injection of 0 or 150 mg diethylnitrosamine/kg body weight [(DENA) CAS: 55-18-5). Five diets were used: diet 1, ade-quate; diet 2, devoid of both methionine and choline; diet 3, devoid of methionine only; diet 4, devoid of choline only; and diet 5, devoid of methionine, choline, folic acid, and vitamin B,2. Equi-molar homocystine replaced methionine in all methionine-devoid diets. All diets were administered for 1 year. No hepatocellular carcinomas and only 3 liver adenomas were seen among the 129 animals at risk in the 5 groups that had received no DENA. Among the DENA-treated groups fed diets 1-4, the incidence of hepatocel-lular carcinomas in the mice at risk averaged 40%, with no signifi-cant differences noted among groups. A relatively low incidence o