Effects of ethionine on the replicational fidelity in V79 chinese hamster cells

The possibility that ethionine, the ethyl analog of methionine and potent liver carcinogen, exerts its action by blocking the methylation of DNA and thereby rendering the post-replicative methylation instructed error-avoidance system inoperative was investigated. While the results are not directly supportive for the existence of such a repair system in V79 Chinese hamster cells, effects of ethionine were found. Following the exposure of ethionine-treated cells to EMS an increase in cell killing and a decrease in mutation induction was observed. The base analog, 6-hydroxyaminopurine, was shown to be clearly mutagenic in the mammalian cells and in the presence of ethinine a drastic decrease in mutant frequency was observed. Ethionine itself did not appear mutagenic over the entire dose range tested (1-1000 micrograms/ml).