Celli Claudia M, Tran Namphuong, Knox Richard, Jaiswal Anil K
Department of Pharmacology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Biochem Pharmacol. 2006 Jul 28;72(3):366-76. doi: 10.1016/j.bcp.2006.04.029. Epub 2006 May 4.
quinone oxidoreductase 2 (NQO2) is a cytosolic flavoprotein that utilizes NRH as electron donor. The present studies investigate the role of NQO2 in metabolic detoxification/activation of quinones and quinone based anti-tumor drugs. Chinese hamster ovary (CHO) cells stably overexpressing cDNA derived mouse NQO2 and mouse keratinocytes from DMBA-induced skin tumors in wild-type and NQO2-null mice were generated. The CHO cells overexpressing NQO2 and mouse keratinocytes expressing or deficient in NQO2 were treated with varying concentrations of mitomycin C (MMC), CB1954, MMC analog BMY25067, EO9, menadione and BP-3,6-quinone, in the absence and presence of NRH. The cytotoxicity of the drugs was evaluated by colony formation. The CHO cells overexpressing higher levels of mouse NQO2 showed significantly increased cytotoxicity to menadione, BP-3,6-quinone and to the anti-tumor drugs MMC and CB1954 when compared to CHO cells expressing endogenous NQO2. The cytotoxicity increased in presence of NRH. Similar results were also observed with BMY25067 and EO9 treatments, but to a lesser extent. The results on keratinocytes deficient in NQO2 supported the data from CHO cells. The inclusion of NRH had no effect on cytotoxicity of quinones and drugs in keratinocytes deficient in NQO2. Mouse NQO2 protein was expressed in bacteria, purified and used to study the role of NQO2 in MMC-induced DNA cross-linking. Bacterially expressed and purified NQO2 efficiently catalyzed MMC activation that led to DNA cross-linking. These results concluded that NQO2 plays a significant role in the metabolic activation of both quinones and anti-tumor drugs leading to cytotoxicity and cell death.
醌氧化还原酶2（NQO2）是一种胞质黄素蛋白，它利用NRH作为电子供体。本研究调查了NQO2在醌类和基于醌的抗肿瘤药物的代谢解毒/激活中的作用。构建了稳定过表达源自小鼠NQO2的cDNA的中国仓鼠卵巢（CHO）细胞，以及来自野生型和NQO2基因敲除小鼠的经二甲基苯并蒽（DMBA）诱导的皮肤肿瘤的小鼠角质形成细胞。在有和没有NRH的情况下，用不同浓度的丝裂霉素C（MMC）、CB1954、MMC类似物BMY25067、EO9、甲萘醌和BP - 3,6 - 醌处理过表达NQO2的CHO细胞以及表达或缺乏NQO2的小鼠角质形成细胞。通过集落形成评估药物的细胞毒性。与表达内源性NQO2的CHO细胞相比，过表达较高水平小鼠NQO2的CHO细胞对甲萘醌、BP - 3,6 - 醌以及抗肿瘤药物MMC和CB1954的细胞毒性显著增加。在有NRH存在时细胞毒性增加。用BMY25067和EO9处理也观察到了类似结果，但程度较小。NQO2缺陷的角质形成细胞的结果支持了来自CHO细胞的数据。添加NRH对NQO2缺陷的角质形成细胞中醌类和药物的细胞毒性没有影响。小鼠NQO2蛋白在细菌中表达、纯化，并用于研究NQO2在MMC诱导的DNA交联中的作用。细菌表达和纯化的NQO2有效地催化了导致DNA交联的MMC激活。这些结果得出结论，NQO2在醌类和抗肿瘤药物的代谢激活中起重要作用，导致细胞毒性和细胞死亡。
