The initiator tRNA acceptance assay as a short-term test for carcinogens. 1. A standardized procedure.
A short-term test for carcinogens has been developed based on the interaction of chemical carcinogens with tRNA(FMet) in vitro. Transfer RNA from rat or rabbit liver is pre-treated with compounds to be tested in the presence of microsomal enzymes and NADPH. Re-isolated tRNA is then charged with L-methionine by aminoacyl-tRNA synthetases from E. coli B. Carcinogens induce a stimulation of tRNA charging whereas chemically similar non-carcinogenic compounds do not show this effect. Experiments with model substances N-methyl-N'-nitro-N-nitrosoguanidine (strong carcinogen) and aflatoxin G1 (weak carcinogen) revealed some differences in dose effect relationships. It is advisable to test unknown compounds at three different concentrations (10(-5), 10(-7) and 10(-9) mg/ml) with at least two different quantities of microsomal enzymes. Tests on greater than 150 different compounds performed so far indicate that the evaluation of results as % of stimulation (when compared with the control value obtained with the charging of tRNA treated with the solvent only) may allow a quantitative discrimination between weak and intermediate, and strong carcinogens. The procedure is rapid, well reproducible and relatively inexpensive and may be used to complement the other short-term tests for carcinogenicity.
Hradec
J
J
Department of Molecular Biology, Research Institute for Tuberculosis and Respiratory Diseases, Prague, Czechoslovakia.
D000818:Animals; D002273:Carcinogens / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D008715:Methionine / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology; D009152:Mutagenicity Tests / Q000379:methods*; D009249:NADP / Q000494:pharmacology; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D002273:Carcinogens; D009249:NADP; D012343:RNA, Transfer; D008715:Methionine