Induction of oxyradicals by arsenic: Implication for mechanism of genotoxicity
Induction of oxyradicals by arsenic: Implication for mechanism of genotoxicity
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DOI：
10.1073/pnas.98.4.1643
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发表时间：
2001-02-13
影响因子：
11.1
通讯作者：
Hei, TK
中科院分区：
文献类型：
--
作者：
Liu, SX;Athar, M;Hei, TK
虽然砷是一种公认的人类致癌物质，但其致癌机制仍然知之甚少。我们先前证明亚砷酸盐在人-仓鼠杂交种(A(L))细胞中是一种有效的诱变剂，并且它主要诱导多位点缺失。在这里，我们用荧光探针5‘.6’-chloromethyl-2‘.7’-dichlorodihydrofluorescein二乙酸酯的共聚焦扫描显微镜显示，亚砷酸盐在治疗后5分钟内诱导细胞内氧自由基的产生随剂量的增加而增加3倍。同时用亚砷酸盐和自由基清除剂DMSO处理细胞，使荧光强度降低到控制水平。以4-hydroxy-2，2.6，6-tetramethyl-1-hydroxypiperidine(TEMPOL-H)为探针，结合超氧化物歧化酶和过氧化氢酶分别猝灭超氧阴离子和过氧化氢的电子自旋共振光谱表明，亚砷酸盐增加了这些细胞中超氧阴离子驱动的羟基自由基水平。此外，用丁硫氨酸S-R-亚磺胺降低A(L)细胞内非蛋白巯基(主要是谷胱甘肽)的水平，亚砷酸盐的诱变潜力增加了5倍以上。这些数据与我们之前对自由基清除剂DMSO的研究结果一致，DMSO降低了砷在这些细胞中的致突变性，并提供了令人信服的证据，表明活性氧物种，特别是羟基自由基，在砷化合物对哺乳动物细胞的遗传毒性中起着重要的因果作用。
Although arsenic is a well-established human carcinogen, the mechanisms by which it induces cancer remain poorly understood. We previously showed arsenite to be a potent mutagen in human-hamster hybrid (A(L)) cells, and that it induces predominantly multilocus deletions. We show here by confocal scanning microscopy with the fluorescent probe 5'.6'-chloromethyl-2'.7'-dichlorodihydrofluorescein diacetate that arsenite induces, within 5 min after treatment, a dose-dependent increase of up to 3-fold in intracellular oxyradical production. Concurrent treatment of cells with arsenite and the radical scavenger DMSO reduced the fluorescent intensity to control levels. ESR spectroscopy with 4-hydroxy-2,2.6,6-tetramethyl-1-hydroxypiperidine (TEMPOL-H) as a probe in conjunction with superoxide dismutase and catalase to quench superoxide anions and hydrogen peroxide, respectively, indicates that arsenite increases the levels of superoxide-driven hydroxyl radicals in these cells. Furthermore, reducing the intracellular levels of nonprotein sulfhydryls (mainly glutathione) in A(L) cells with buthionine S-R-sulfoximine increases the mutagenic potential of arsenite by more than 5-fold. The data are consistent with our previous results with the radical scavenger DMSO, which reduced the mutagenicity of arsenic in these cells, and provide convincing evidence that reactive oxygen species, particularly hydroxyl radicals, play an important causal role in the genotoxicity of arsenical compounds in mammalian cells.