Metabolism of tRNA in rats with aflatoxin B1-induced hepatomas.

This study describes effects of aflatoxin B1-induced hepatomas on RNA metabolism in rats. At 4 and 24 hours after the administration of L-(14CH3)-methionine, tRNA was isolated from the livers and hydrolyzed enzymatically to nucleosides which were quantitatively measured by HPLC. Radioactivity of the nucleosides was also determined. The data indicate that although tRNA methylation may be more rapid in livers with hepatomas, catabolism of tRNA in tumorous tissue is slower than in control livers. The large increase in some radioactive methylated nucleosides and bases by the tumor-bearing rats during the 24-hour period following the administration of labeled methionine indicates increased turnover of mRNA and rRNA as well as tRNA. Since degradation of tumor tRNA appears to be delayed, the excessive amounts of the urinary methylated nucleosides must be derived from RNA in nonneoplastic tissue.