title: NAD(P)H:quinone oxidoreductase expression in Cyp1a-knockout and CYP1A-humanized mouse lines and its effect on bioactivation of the carcinogen aristolochic acid I.
abstract: Aristolochic acid causes a specific nephropathy (AAN), Balkan endemic nephropathy, and urothelial malignancies. Using Western blotting suitable to determine protein expression, we investigated in several transgenic mouse lines expression of NAD(P)H:quinone oxidoreductase (NQO1)-the most efficient cytosolic enzyme that reductively activates aristolochic acid I (AAI). The mouse tissues used were from previous studies [Arlt et al., Chem. Res. Toxicol. 24 (2011) 1710; Stiborova et al., Toxicol. Sci. 125 (2012) 345], in which the role of microsomal cytochrome P450 (CYP) enzymes in AAI metabolism in vivo had been determined. We found that NQO1 levels in liver, kidney and lung of Cyp1a1⁻/⁻, Cyp1a2⁻/⁻ and Cyp1a1/1a2⁻/⁻ knockout mouse lines, as well as in two CYP1A-humanized mouse lines harboring functional human CYP1A1 and CYP1A2 and lacking the mouse Cyp1a1/1a2 orthologs, differed from NQO1 levels in wild-type mice. NQO1 protein and enzymic activity were induced in hepatic and renal cytosolic fractions isolated from AAI-pretreated mice, compared with those in untreated mice. Furthermore, this increase in hepatic NQO1 enzyme activity was associated with bioactivation of AAI and elevated AAI-DNA adduct levels in ex vivo incubations of cytosolic fractions with DNA and AAI. In conclusion, AAI appears to increase its own metabolic activation by inducing NQO1, thereby enhancing its own genotoxic potential.
authors.affiliation: Department of Biochemistry, Faculty of Science, Charles University, Prague, Czech Republic.
authors.forename: Katerina
authors.initials: K
authors.lastname: Levova
authors.forename: Michaela
authors.initials: M
authors.lastname: Moserova
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Nebert
authors.forename: David H
authors.initials: DH
authors.lastname: Phillips
authors.forename: Eva
authors.initials: E
authors.lastname: Frei
authors.forename: Heinz H
authors.initials: HH
authors.lastname: Schmeiser
authors.forename: Volker M
authors.initials: VM
authors.lastname: Arlt
authors.forename: Marie
authors.initials: M
authors.lastname: Stiborova
mesh_terms: D000818:Animals; D034341:Aristolochic Acids / Q000493:pharmacokinetics* / Q000633:toxicity; D001449:Balkan Nephropathy / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D002460:Cell Line; D019363:Cytochrome P-450 CYP1A1 / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D018736:DNA Adducts / Q000378:metabolism; D005260:Female; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D034341:Aristolochic Acids; D018736:DNA Adducts; C000228:aristolochic acid I; D019363:Cytochrome P-450 CYP1A1; D019388:Cytochrome P-450 CYP1A2; D016660:NAD(P)H Dehydrogenase (Quinone)