Low-level self-tolerance to arsenite in human HepG2 cells is associated with a depressed induction of micronuclei
Low-level self-tolerance to arsenite in human HepG2 cells is associated with a depressed induction of micronuclei
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DOI：
10.1016/s1383-5718(01)00343-6
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发表时间：
2002-02-15
影响因子：
1.9
通讯作者：
Hirsch-Ernst, K
中科院分区：
文献类型：
--
作者：
Gebel, TW;Leister, M;Hirsch-Ernst, K
砷（As）是全球最重要的环境毒物之一。有证据表明，人类可能会对砷的毒性产生耐受性。例如，已知摄取少量As会导致获得对该元素急性毒性的提高的抗性。此外，有人建议，作为暴露的土著安第斯妇女的阿塔卡梅诺种族可能已获得抵抗皮肤癌。目前还不知道这种适应如何可以机械地赋予。在这种情况下，生物学选择和克隆的人类细胞耐受As提供了一个有价值的方法来研究这个问题。用递增剂量的砷培养12周的方法，从人肝癌细胞系HepG 2中筛选出三个不同的抗砷克隆。这三个克隆对亚砷酸盐的急性毒性具有相似的大约两倍的抗性（在65 μ M对115 μ M时中性红（NR）摄取减少50%; HepG 2对照分别对克隆HepG 2 K1、HepG 2 K11和HepG 2 K14）。此外，在微核阻断试验中，这些克隆显示出显著降低的微核诱导（MNi），表明对As遗传毒性的抗性也有所提高（例如，在25 μ M亚砷酸盐浓度下的平均MNi率：分别为28.5（对照）对21.6（HepG 2 K1）、18（HepG 2 K11）和16（HepG 2 K14），每个P < 0.05）。这种耐受性既不与puC 1As-挤出膜转运蛋白多药耐药相关蛋白1（MRP 1）、2或3的mRNA诱导相关，也不与普遍表达的哺乳动物ABC半转运蛋白UMAT（ABCB 6）的mRNA诱导相关。未检测到As代谢甲基化的变化。当比较克隆和亲本系时，GSH的细胞水平没有差异。综上所述，数据表明，在人HepG 2细胞中，对As介导的细胞毒性的低水平耐受性也与对As诱导的DNA损伤的增强的抗性相关。(C)2002 Elsevier Science B. V.保留所有权利。
Arsenic (As) is one of the most important global environmental toxicants. There is evidence that humans may develop tolerance to As's toxicity. For instance, it is known that uptake of small amounts of As leads to an acquisition of elevated resistance to the element's acute toxicity. Moreover, it was suggested that As-exposed native Andean females of Atacameno ethnicity may have acquired resistance to skin cancer. It is not known how such adaptation could be mechanistically conferred. In this context, the biological selection and cloning of human cells tolerant to As provides a valuable approach to investigate this question. By the means of a 12 weeks culture with increasing doses of As, three different As-resistant clones of the human hepatoma cell line HepG2 were selected. These three clones were similarly and roughly two-fold resistant to the acute toxicity of arsenite (50% reduction of neutral red (NR) uptake at 65 muM versus 115 muM; HepG2 control versus clones HepG2 K1, HepG2 K11 and HepG2 K14, respectively). Moreover, in the cytokinesis-block micronucleus test, these clones showed a significantly reduced induction of micronuclei (MNi) indicating elevated resistance to As genotoxicity as well (e.g. mean MNi rates at a concentration of 25 muM arsenite: 28.5 (control) versus 21.6 (HepG2 K1), 18 (HepG2 K11), and 16 (HepG2 K14), respectively, each P < 0.05). The tolerance was neither associated with mRNA induction of putatively As-extruding membrane transporters multidrug resistance-associated protein 1 (MRP1), 2, or 3 nor to mRNA induction of the ubiquitously expressed mammalian ABC half-transporter UMAT (ABCB6). Changes in the metabolic methylation of As could not be detected. There were no differences in the cellular levels of GSH when comparing the clones and the parental line. Taken together the data showed that low-level tolerance to As-mediated cytotoxicity in human HepG2 cells was associated with enhanced resistance to As-induced DNA damage as well. (C) 2002 Elsevier Science B.V. All rights reserved.