Mutagenicity of cadmium in mammalian cells: implication of oxidative DNA damage
Mutagenicity of cadmium in mammalian cells: implication of oxidative DNA damage
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DOI：
10.1016/j.mrfmmm.2003.11.006
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发表时间：
2004-02-26
影响因子：
2.3
通讯作者：
Hei, TK
中科院分区：
文献类型：
--
作者：
Filipic, M;Hei, TK
镉和镉化合物是公认的人类致癌物，普遍存在于环境中。由于在细菌和标准哺乳动物细胞突变试验中，镉的直接致突变作用较弱，因此镉的致癌机制在很大程度上仍不清楚。在这项研究中，我们表明，当使用人-仓鼠杂交A（L）细胞突变试验进行评价时，基因内和多位点缺失都可以很容易地检测到，氯化镉是一种强诱变剂，主要诱导大的缺失突变。同时用氧自由基清除剂二甲基亚砜处理A（L）细胞显著减少了镉诱导的突变数量。与此相反，预处理的细胞与buthiflavine亚砜亚胺，耗尽细胞内谷胱甘肽，增加细胞毒性和致突变性的镉。这些结果表明，活性氧介导镉诱导的A（L）细胞突变。用激光扫描共聚焦显微镜和荧光探针5-（和-6）-氯甲基-2 '，7'-二氯二氢荧光素二乙酸酯（5-chloromethyl-2 '，7'-dichlorodihydrofluorescein diacetate），我们证明镉诱导细胞内氧自由基的形成具有剂量和时间依赖性。使用免疫过氧化物酶染色加上单克隆抗体特异性的8-OHdG加合物在DNA中，我们证明，镉诱导的8-OHdG加合物的剂量依赖性增加，随着暴露时间的延长而积累。此外，我们发现，在低浓度下，镉，衰减去除过氧化氢诱导8-OHdG加合物。因此，镉的致癌性可以部分地由其致突变活性来解释，该致突变活性由活性氧诱导的DNA损伤以及其对氧化性DNA损伤修复的干扰来介导。(C)2003 Elsevier B. V.保留所有权利。
Cadmium and cadmium compounds are well established human carcinogens and are ubiquitously present in the environment. The carcinogenic mechanism(s) of cadmium remains largely unknown since direct mutagenic effect is weak in bacterial and in standard mammalian cell mutation assays. In this study, we show that when evaluated using the human-hamster hybrid A(L) cell mutation assay in which both intragenic and multilocus deletions can readily be detected, CdCl2 is a strong mutagen that induces predominantly large deletion mutations. Concurrent treatment of A(L) cells with the oxyradical scavenger dimethyl sulfoxide significantly reduced the number of cadmium-induced mutations. In contrast, pre-treatment of cells with buthionine sulfoximine that depletes intracellular glutathione, increased cytotoxicity and mutagenicity of cadmium. These results demonstrate that reactive oxygen species mediate cadmium induced mutations in A(L) cells. With laser scanning confocal microscopy and the fluorescent probe 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, we demonstrated that cadmium induced a dose and time dependent formation of intracellular oxyradicals. Using immunoperoxidase staining coupled with a monoclonal antibody-specific for 8-OHdG adducts in DNA, we demonstrated that cadmium induced a dose dependent increase of 8-OHdG adducts, which accumulated with prolonged exposure. Furthermore, we showed that at low concentration, cadmium, attenuated removal of hydrogen peroxide induced 8-OHdG adducts. Thus, the carcinogenicity of cadmium can, in part, be explained by its mutagenic activity, which is mediated by reactive oxygen species induced DNA damage and by its interference with the repair of oxidative DNA damage. (C) 2003 Elsevier B.V. All rights reserved.