Trouba Kevin J, Geisenhoffer Kristen M, Germolec Dori R
National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
Environ Health Perspect. 2002 Oct;110 Suppl 5(Suppl 5):761-6. doi: 10.1289/ehp.02110s5761.
Arsenic is a carcinogen that poses a significant health risk in humans. Based on evidence that arsenic has differential effects on human, rodent, normal, and transformed cells, these studies addressed the relative merits of using normal human epidermal keratinocytes (NHEK) and immortalized human (HaCaT) and mouse (HEL30) keratinocytes when examining stress-induced gene expression that may contribute to carcinogenesis. We hypothesize that redox-related gene expression is differentially modulated by arsenic in normal versus immortalized keratinocytes. To test the hypothesis, we exposed keratinocytes to sodium arsenite for 4 or 24 hr, at which time serine threonine kinase-25 (stk25) and nicotine adenine dinucleotide phosphate [nad(p)h] quinone oxidoreductase gene expression were measured. The effect of glutathione reduction on arsenite-induced cytotoxicity and gene expression in NHEK also was evaluated by addition of l-buthionine-[S,R]-sulfoximine (BSO) to culture media. Results indicate the term LC(50) for arsenite is approximately 10-15 microM in NHEK and HEL30 keratinocytes and 30 microM in HaCaT keratinocytes. Compared with HaCaT and HEL30 keratinocytes, a nontoxic concentration of arsenite (2.5 microM) increases stk25 and nad(p)h quinone oxidoreductase gene expression in NHEK, an effect partially attenuated by BSO. These data indicate that NHEK and HaCaT/HEL30 keratinocytes have similar sensitivities toward arsenite-induced cytotoxicity but unique gene expression responses. They also suggest that arsenite modulates gene expression in NHEK involved in cellular signaling and other aspects of intermediary metabolism that may contribute to the carcinogenic process.
砷是一种致癌物，对人类健康构成重大风险。基于砷对人类、啮齿动物、正常细胞和转化细胞有不同影响的证据，这些研究探讨了在检测可能导致致癌作用的应激诱导基因表达时，使用正常人表皮角质形成细胞（NHEK）、永生化人角质形成细胞（HaCaT）和小鼠角质形成细胞（HEL30）的相对优点。我们假设，在正常角质形成细胞与永生化角质形成细胞中，氧化还原相关基因表达受砷的调节存在差异。为验证该假设，我们将角质形成细胞暴露于亚砷酸钠中4小时或24小时，此时检测丝氨酸苏氨酸激酶-25（stk25）和烟酰胺腺嘌呤二核苷酸磷酸[nad(p)h]醌氧化还原酶基因的表达。通过向培养基中添加L-丁硫氨酸-[S,R]-亚砜亚胺（BSO），还评估了谷胱甘肽还原对亚砷酸盐诱导的NHEK细胞毒性和基因表达的影响。结果表明，亚砷酸盐在NHEK和HEL30角质形成细胞中的半数致死浓度（LC(50)）约为10 - 15微摩尔，在HaCaT角质形成细胞中为30微摩尔。与HaCaT和HEL30角质形成细胞相比，无毒浓度的亚砷酸盐（2.5微摩尔）可增加NHEK中stk25和nad(p)h醌氧化还原酶基因的表达，BSO可部分减弱这种作用。这些数据表明，NHEK和HaCaT/HEL30角质形成细胞对亚砷酸盐诱导的细胞毒性具有相似的敏感性，但基因表达反应独特。它们还表明，亚砷酸盐可调节NHEK中参与细胞信号传导及中间代谢其他方面的基因表达，这可能有助于致癌过程。
