title: Transfer RNA methylase activity and capacity during aflatoxin B1-induced hepatocellular carcinogenesis.
abstract: Transfer RNA methylase (tRNA methylase) activity and capacity were monitored in whole-rat-liver preparations during the induction of hepatocellular carcinomas by an 8-week aflatoxin B1 dosing regimen that produced minimal toxic effects. Significant phases of elevated tRNA methylase capacity occurred at 6 to 9 weeks (20%) and 24 to 29 weeks (40%). No significant change in tRNA methylase activity was noted over the course of the 55-week experiment. Higher aflatoxin B1 doses, producing acute toxic liver damage, resulted in elevated tRNA methylase activity (50%) and capacity (30%) at least as early as 1 week after dosing. Experiments with individual nodular lesions excised from livers of rats continuously fed a diet containing 2 ppm aflatoxin B1 demonstrated similarly elevated tRNA methylase activities and capacities in hyperplastic (preneoplastic)nodules, with and without histological evidence of carcinoma.
mesh_terms: D000348:Aflatoxins; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000139:chemically induced / Q000201:enzymology*; D008099:Liver / Q000201:enzymology / Q000473:pathology; D008113:Liver Neoplasms / Q000139:chemically induced / Q000201:enzymology*; D008297:Male; D009374:Neoplasms, Experimental / Q000139:chemically induced / Q000201:enzymology; D011230:Precancerous Conditions / Q000201:enzymology / Q000473:pathology; D051381:Rats; D012359:tRNA Methyltransferases / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000348:Aflatoxins; D012359:tRNA Methyltransferases