title: Monoclonal antibody-directed analysis of cytochrome P-450-dependent monooxygenases and mutagen activation in the livers of DBA/2 and C57BL/6 mice.
abstract: Monoclonal antibodies (MAb 1-7-1 and Mab 2-66-3) specific for cytochrome P-450 (cyt. P-450) isozymes inhibited the metabolism of carcinogens, other xenobiotics, and endogenous compounds in two strains of mice. Postmitochondrial liver supernatant (S9) was prepared from untreated, 3-methylcholanthrene-treated, phenobarbital-treated, and pregnenolone 16 alpha-carbonitrile-treated C57BL/6 (B6) and DBA/2 (D2) mice. The modifying effect of two types of MAb to a 3-methylcholanthrene-induced cyt. P-450 and a phenobarbital-induced cyt. P-450 was investigated for: (a) S9-mediated mutagenicity of aflatoxin B1, benzo(a)pyrene 7,8-dihydrodiol, 2-acetylaminofluorene, and N-nitrosomorpholine in Salmonella typhimurium strains; and (b) the activity of aryl hydrocarbon hydroxylase, ethoxycoumarin O-deethylase, ethoxyresorufin O-deethylase, aminopyrine N-demethylase, and testosterone 6 beta-, 7 alpha-, and 16 beta-hydroxylases. With certain S9s, MAb-1-7-1 inhibited only those cytochrome P-450 isozymes involved predominantly in activity of aryl hydrocarbon hydroxylase, ethoxyresorufin O-deethylase, and ethoxycoumarin O-deethylase and mutagenicity of 2-acetylaminofluorene and benzo(a)pyrene 7,8-dihydrodiol; MAb 2-66-3 inhibited only those involved in aminopyrine N-demethylase and testosterone 6 beta-, 7 alpha, and 16 beta-hydroxylase activity and aflatoxin B1 mutagenicity. Both Mab 1-7-1 and MAb 2-66-3 inhibited cytochrome P-450 isozyme(s) implicated predominantly in testosterone 7 alpha-hydroxylation in S9 from pregnenolone 16 alpha-carbonitrile-treated B6 mice. MAb 1-7-1 did not inhibit N-nitrosomorpholine mutagenicity and MAb 2-66-3 increased it by 2- to 6-fold depending on the source of S9. Using these MAbs, it is thus possible to identify the contribution of the epitope-defined single or class of cyt. P-450 to specific metabolic reactions in S9 from untreated and inducer-treated mice.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D001711:Biotransformation; D002273:Carcinogens / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000276:immunology / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D007527:Isoenzymes / Q000378:metabolism; D008099:Liver / Q000201:enzymology*; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D009152:Mutagenicity Tests; D010634:Phenobarbital / Q000494:pharmacology; D011285:Pregnenolone Carbonitrile / Q000494:pharmacology; D012486:Salmonella typhimurium / Q000235:genetics
chemical_list: D000911:Antibodies, Monoclonal; D002273:Carcinogens; D007527:Isoenzymes; D011285:Pregnenolone Carbonitrile; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010634:Phenobarbital