Butylhydroquinone protects cells genetically deficient in glutathione biosynthesis from arsenite-induced apoptosis without significantly changing their prooxidant status
Butylhydroquinone protects cells genetically deficient in glutathione biosynthesis from arsenite-induced apoptosis without significantly changing their prooxidant status
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DOI：
10.1093/toxsci/kfi253
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发表时间：
2005-10-01
影响因子：
3.8
通讯作者：
Puga, A
中科院分区：
文献类型：
--
作者：
Kann, S;Estes, C;Puga, A
砷是最具环境危害的物质之一，与皮肤癌、肺癌、肝癌、肾癌、前列腺癌和膀胱癌有关。砷还是一种心血管和中枢神经系统毒物，具有遗传毒性和免疫毒性作用。矛盾的是，三氧化二砷被成功地用于治疗急性早幼粒细胞白血病和多发性骨髓瘤。砷诱导氧化应激，其毒性因游离硫醇的减少而降低，而因谷胱甘肽的耗竭而增加。为了进一步研究谷胱甘肽和氧化应激在砷毒性中的作用，我们使用了来自Gclm(-/-)小鼠的胎儿成纤维细胞，这种细胞缺乏谷氨酸-半胱氨酸连接酶的修饰亚基，谷氨酸-半胱氨酸连接酶是谷胱甘肽合成的限速酶。GCLM(-/-)小鼠胚胎成纤维细胞(MEF)对亚砷酸盐诱导的凋亡死亡的敏感度是对照组的8倍。由于谷胱甘肽水平的显著降低，Gclm(-/-)MEF具有高度的促氧化状态，而酚类抗氧化剂TBHQ并不能显著缓解这种状态；然而，TBHQ阻止了亚砷酸盐诱导的Gclm(+/+)和Gclm(-/-)细胞的凋亡，尽管它只在Gclm(+/+)细胞中提高了显著的抗氧化反应。全球基因表达谱显示，TBHQ在逆转亚砷酸盐诱导的Gclm(+/+)MEF基因失控方面显著有效，但在Gclm(-/-)MEF中无效。这种作用在金属蛋白酶和伴侣蛋白的表达，以及与DNA损伤和修复、蛋白质生物合成、细胞生长和维持、细胞凋亡和细胞周期调节有关的基因的表达上都是明显的。这些结果表明，GCLM对谷胱甘肽水平的调节决定了细胞对砷诱导的细胞凋亡的敏感性，这是通过设定细胞建立有效抗氧化反应的总体能力来实现的。
Arsenic, first among the top environmentally hazardous substances, is associated with skin, lung, liver, kidney, prostate, and bladder cancer. Arsenic is also a cardiovascular and a central nervous system toxicant, and it has genotoxic and immunotoxic effects. Paradoxically, arsenic trioxide is used successfully in the treatment of acute promyelocytic leukemia and multiple myeloma. Arsenic induces oxidative stress, and its toxicity is decreased by free thiols and increased by glutathione depletion. To further characterize the role of glutathione and oxidative stress in the toxicity of arsenic, we have used fetal fibroblasts from Gclm(-/-) mice, which lack the modifier subunit of glutamate-cysteine ligase, the rate-limiting enzyme in glutathione biosynthesis. Gclm(-/-) mouse embryo fibroblasts (MEFs) are eight times more sensitive to arsenite-induced apoptotic death. Because of a dramatic decrease in glutathione levels, Gclm(-/-) MEFs have a high prooxidant status that is not significantly relieved by treatment with the phenolic antioxidant tBHQ; however, tBHQ blocks arsenite-induced apoptosis in both Gclm(+/+) and Gclm(-/-) cells, although it raises a significant antioxidant response only in Gclm(+/+) cells. Global gene expression profiles indicate that tBHQ is significantly effective in reversing arsenite-induced gene deregulation in Gclm(+/+) but not in Gclm(-/-) MEFs. This effect of tBHQ is evident in the expression of metalloproteases and chaperones, and in the expression of genes involved in DNA damage and repair, protein biosynthesis, cell growth and maintenance, apoptosis, and cell cycle regulation. These results suggest that regulation of glutathione levels by GCLM determines the sensitivity to arsenic-induced apoptosis by setting the overall ability of the cells to mount an effective antioxidant response.