title: Role of NAD(P)H:quinone oxidoreductase 1 (DT diaphorase) in protection against quinone toxicity.
abstract: NQO1-/- mice, along with Chinese hamster ovary (CHO) cells, were used to determine the in vivo role of NAD(P)H:quinone oxidoreductase 1 (NQO1) in cellular protection against quinone cytotoxicity, membrane damage, DNA damage, and carcinogenicity. CHO cells permanently expressing various levels of cDNA-derived P450 reductase and NQO1 were produced. Treatment of CHO cells overexpressing P450 reductase with menadione, benzo[a]pyrene-3,6-quinone (BPQ), and benzoquinone led to increased cytotoxicity as compared with CHO cells expressing endogenous P450 reductase. In a similar experiment, overexpression of NQO1 significantly protected CHO cells against the cytotoxicity of these quinones. Knockout (NQO1-/-) mice deficient in NQO1 protein and activity had been generated previously in our laboratory and were used in the present studies. Wild-type (NQO1+/+) and knockout (NQO1-/-) mice were given i.p. injections of menadione and BPQ, followed by analysis of membrane damage and DNA damage. Both menadione and BPQ induced lipid peroxidation in hepatic and non-hepatic tissues, indicating increased membrane damage. Exposure to BPQ also resulted in increased hepatic DNA adducts in NQO1-/- mice as compared with NQO1+/+ mice. The skin application of BPQ alone and BPQ + 12-O-tetradecanoylphorbol-13-acetate (TPA) failed to induce papillomas, or other lesions, for up to 50 weeks in either NQO1+/+ or NQO1-/- mice. The various results from CHO cells and NQO1-/- mice indicated that NQO1 protects against quinone-induced cytotoxicity, as well as DNA and membrane damage. The absence of BPQ-induced skin carcinogenicity in NQO1-/- mice may be related to the strain (C57BL/6) of mice used in the present study and/or due to poor BPQ absorption into the skin and/or due to detoxification of BPQ by cytosolic NRH:quinone oxidoreductase 2 (NQO2).
authors.affiliation: Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: P
authors.initials: P
authors.lastname: Joseph
authors.forename: D J
authors.initials: DJ
authors.lastname: Long
authors.forename: A J
authors.initials: AJ
authors.lastname: Klein-Szanto
authors.forename: A K
authors.initials: AK
authors.lastname: Jaiswal
mesh_terms: D000818:Animals; D001580:Benzopyrenes / Q000633:toxicity*; D016227:Benzoquinones / Q000633:toxicity; D016466:CHO Cells; D015197:Carcinogenicity Tests; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics / Q000378:metabolism*; D020011:Protective Agents / Q000378:metabolism; D014812:Vitamin K / Q000633:toxicity
chemical_list: D001580:Benzopyrenes; D016227:Benzoquinones; D020011:Protective Agents; D014812:Vitamin K; C018003:benzo(a)pyrene-3,6-quinone; D016660:NAD(P)H Dehydrogenase (Quinone)