Hepatocarcinogen-induced tRNA methylase activity in rat liver.

Dimethylaminoazobenzene, carbon tetrachloride, and ethionine, which can induce cancer cells in rat liver, were found to increase rat liver tRNA methylase activity. Other chemicals (aminoazobenzene, acetylaminofluorene, alpha-naphthylisothiocyanate, beta-naphthylisothiocyanate, dimethyl and diethylnitrosamine, and methylcholanthrene), which may be hepatotoxic or carcinogenic, produced either no increase or only slight increases in liver tRNA methylase activity of rat liver tissue. Although no increase was observed with the powerful hepatocarcinogen aflatoxin, others have recently reported an increase in tRNA methylase activity using larger doses than those reported here. Ethionine was able to increase liver tRNA methylase activity in guinea pigs as well as rats, as previously described, but not in chicks.