On the mechanism of Cr (VI)-induced carcinogenesis: Dose dependence of uptake and cellular responses
On the mechanism of Cr (VI)-induced carcinogenesis: Dose dependence of uptake and cellular responses
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DOI：
10.1023/a:1017938918686
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发表时间：
2001-06-01
影响因子：
4.3
通讯作者：
Shi, XL
中科院分区：
文献类型：
--
作者：
Liu, KJ;Husler, J;Shi, XL
铬(VI)化合物是广泛使用的工业化学品，也是公认的人类致癌物。与这些化合物相关的致癌机制仍有待研究。本研究着重于铬(VI)诱导的摄取和细胞反应的剂量依赖关系。结果表明，低浓度的铬(VI)能进入人肺上皮细胞系A549细胞，并表现为饱和转运和被动扩散的结合。电子自旋共振(ESR)捕捉测量表明，在铬(VI)刺激下，A549细胞能够产生活性氧(ROS)。ROS的生成量取决于Cr(VI)的浓度。ROS的产生涉及依赖NADPH的黄素酶。铬(VI)以剂量依赖的方式影响下列细胞参数：(A)核转录因子NF-kappaB和P53的激活，(B)DNA损伤，(C)诱导细胞凋亡，(D)抑制细胞增殖。用凝胶迁移率改变分析和免疫印迹分析检测转录因子的活性，用单细胞凝胶电泳法检测DNA损伤，用DNA片段分析检测细胞凋亡，用非放射性试剂盒检测细胞增殖。在本研究使用的浓度范围内，在所有这些细胞对铬(VI)的反应中没有发现阈值。这些结果可能会指导进一步的研究，以更好地了解和评估低水平暴露下铬(VI)诱发致癌的风险。
Cr (VI) compounds are widely used industrial chemicals and are recognized human carcinogens. The mechanisms of carcinogenesis associated with these compounds remain to be investigated. The present study focused on dose-dependence of Cr (VI)-induced uptake and cellular responses. The results show that Cr (VI) is able to enter the cells (human lung epithelial cell line A549) at low concentration (< 10 muM) and that the Cr (VI) uptake appears to be a combination of saturable transport and passive diffusion. Electron spin resonance (ESR) trapping measurements showed that upon stimulation with Cr (VI), A549 cells were able to generate reactive oxygen species (ROS). The amount of ROS generated depended on the Cr (VI) concentration. ROS generation involved NADPH-dependent flavoenzymes. Cr (VI) affected the following cellular parameters in a dose-dependent manner, (a) activation of nuclear transcription factors NF-kappaB, and p53, (b) DNA damage, (c) induction of cell apoptosis, and (d) inhibition of cell proliferation. The activation of transcription factors was assessed by electrophoretic mobility shift assay and western blot analysis, DNA damage by single cell gel electrophoresis assay, cell apoptosis by DNA fragmentation assay, and cell proliferation by a non-radioactive ELISA kit. At the concentration range used in the present study, no thresholds were found in all of these cell responses to Cr (VI). The results may guide further research to better understand and evaluate the risk of Cr (VI)-induced carcinogenesis at low levels of exposure.