Joseph P, Long D J, Klein-Szanto A J, Jaiswal A K
Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA.
Biochem Pharmacol. 2000 Jul 15;60(2):207-14. doi: 10.1016/s0006-2952(00)00321-x.
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).
NQO1基因敲除小鼠以及中国仓鼠卵巢（CHO）细胞被用于确定NAD(P)H:醌氧化还原酶1（NQO1）在细胞抵御醌类细胞毒性、膜损伤、DNA损伤和致癌性方面的体内作用。构建了稳定表达不同水平cDNA来源的P450还原酶和NQO1的CHO细胞。与表达内源性P450还原酶的CHO细胞相比，用甲萘醌、苯并[a]芘-3,6-醌（BPQ）和苯醌处理过表达P450还原酶的CHO细胞会导致细胞毒性增加。在一项类似实验中，NQO1的过表达显著保护CHO细胞免受这些醌类的细胞毒性。本实验室之前已培育出缺乏NQO1蛋白和活性的基因敲除（NQO1-/-）小鼠，并将其用于本研究。对野生型（NQO1+/+）和基因敲除（NQO1-/-）小鼠进行腹腔注射甲萘醌和BPQ，随后分析膜损伤和DNA损伤。甲萘醌和BPQ均诱导肝组织和非肝组织中的脂质过氧化，表明膜损伤增加。与NQO1+/+小鼠相比，NQO1-/-小鼠暴露于BPQ后肝DNA加合物也增加。单独涂抹BPQ以及BPQ + 12-O-十四酰佛波醇-13-乙酸酯（TPA）在NQO1+/+或NQO1-/-小鼠中长达50周均未能诱导乳头状瘤或其他病变。来自CHO细胞和NQO1-/-小鼠的各种结果表明，NQO1可抵御醌类诱导的细胞毒性以及DNA和膜损伤。NQO1-/-小鼠中未出现BPQ诱导的皮肤致癌性可能与本研究中使用的小鼠品系（C57BL/6）有关，和/或由于BPQ经皮肤吸收不良，和/或由于胞质NRH:醌氧化还原酶2（NQO2）对BPQ的解毒作用。
