Halobenzoquinones (HBQs) are frequently detected disinfection byproducts (DBPs) in treated water. Recent studies have demonstrated that HBQs are highly cytotoxic and capable of inducing the generation of reactive oxygen species (ROS) and depleting cellular glutathione (GSH). Multidrug resistance proteins (MRPs/ABCCs) are known to play a critical role in the elimination of numerous drugs, carcinogens, toxicants, and their conjugated metabolites. In general, little is known about the roles of transporters in DBP toxicity. Here, we hypothesize that MRPs may play roles in the detoxication of HBQs. To test this hypothesis, we used human embryonic kidney 293 (HEK293) cells stably expressing MRPs (MRP1, 3, 4, and 5) and HEK293 cells with empty vector (HEK-V) to examine the comparative cytotoxicity of four HBQs: 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ), 2,6-dibromo-1,4-benzoquinone (2,6-DBBQ), 2,6-dichloro-3-methyl-1,4-benzoquinone (DCMBQ), and 2,3,6-trichloro-1,4-benzoquinone (TriCBQ). The cytotoxicity (IC₅₀) of the four HBQs in HEK-MRP1, -MRP3, -MRP4, and -MRP5 cells and the control HEK-V cells clearly showed that MRP4 had the most significant effect on reducing the toxicity of the four HBQs. To further support MRP4-mediated detoxication of HBQs, we examined the HBQ-induced ROS levels in HEK-MRP4 and HEK-V cells. ROS levels were significantly reduced in HEK-MRP4 cells compared with HEK-V cells after HBQ treatment. Furthermore, it was found that MRP4-mediated detoxication of the HBQs was GSH dependent, as the cytotoxicity of the HBQs was increased in GSH-depleted HEK-MRP4 cells in comparison to HEK-MRP4 cells. The GSH-dependent protection of cells from HBQs supports the possibility of HBQ–GSH conjugate efflux by MRP4. This study demonstrates a role for MRP4 in cellular protection against HBQ DBP-induced toxicity and oxidative stress.

中文翻译：

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多重耐药蛋白4（MRP4 / ABCC4）保护细胞免受卤代苯醌的毒性作用

卤代苯醌（HBQ）是经常在处理过的水中检测到的消毒副产物（DBP）。最近的研究表明，HBQ具有高度的细胞毒性，能够诱导活性氧（ROS）生成并消耗细胞内的谷胱甘肽（GSH）。已知多药抗性蛋白（MRP / ABCC）在消除众多药物，致癌物，毒物及其结合的代谢物方面起着至关重要的作用。通常，关于转运蛋白在DBP毒性中的作用知之甚少。在这里，我们假设MRP可能在HBQ的解毒中起作用。为了验证这一假设，我们使用稳定表达MRP（MRP1、3、4和5）的人胚胎肾293（HEK293）细胞和带有空载体（HEK-V）的HEK293细胞来检查四种HBQ的比较细胞毒性：2， 6-二氯-1,4-苯醌（2,6-DCBQ），2，6-二溴-1,4-苯醌（2,6-DBBQ），2,6-二氯-3-甲基-1,4-苯醌（DCMBQ）和2,3,6-三氯-1,4-苯醌（TriCBQ）。细胞毒性（IC₅₀）HEK-MRP1，-MRP3，-MRP4和-MRP5细胞中的四个HBQs和对照HEK-V细胞清楚地表明，MRP4对降低这四个HBQs的毒性具有最显着的作用。为了进一步支持MRP4介导的HBQ脱毒，我们检查了HEK-MRP4和HEK-V细胞中HBQ诱导的ROS水平。与HBQ处理后的HEK-V细胞相比，HEK-MRP4细胞中的ROS水平显着降低。此外，发现MRP4介导的HBQs的解毒是GSH依赖性的，因为与HEK-MRP4细胞相比，在耗尽GSH的HEK-MRP4细胞中HBQs的细胞毒性增加了。细胞对HBQ的依赖GSH的保护支持了MRP4引起HBQ-GSH结合物流出的可能性。这项研究证明了MRP4在针对HBQ DBP诱导的毒性和氧化应激的细胞保护中的作用。