Hamadeh Hisham K, Trouba Kevin J, Amin Rupesh P, Afshari Cynthia A, Germolec Dori
Intramural Microarray Center, Laboratory of Molecular Toxicology, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, NC 27709, USA.
Toxicol Sci. 2002 Oct;69(2):306-16. doi: 10.1093/toxsci/69.2.306.
Human exposure to arsenic, a ubiquitous and toxic environmental pollutant, is associated with an increased incidence of skin cancer. However, the mechanism(s) associated with AsIII-mediated toxicity and carcinogenesis at low levels of exposure remains elusive. Aberrations in cell proliferation, oxidative damage, and DNA-repair fidelity have been implicated in sodium arsenite (AsIII)-mediated carcinogenicity and toxicity, but these events have been examined in isolation in the majority of biological models of arsenic exposure. We hypothesized that the simultaneous interaction of these effects may be important in arsenic-mediated neoplasia in the skin. To evaluate this, normal human epidermal keratinocytes (NHEK) were exposed to nontoxic doses (0.005-5 micro M) of AsIII and monitored for several physiological endpoints at the times when cells were harvested for gene expression measurements (1-24 h). Two-fluor cDNA microarray analyses indicated that AsIII treatment decreased the expression of genes associated with DNA repair (e.g., p53 and Damage-specific DNA-binding protein 2) and increased the expression of genes indicative of the cellular response to oxidative stress (e.g., Superoxide dismutase 1, NAD(P)H quinone oxidoreductase, and Serine/threonine kinase 25). AsIII also modulated the expression of certain transcripts associated with increased cell proliferation (e.g., Cyclin G1, Protein kinase C delta), oncogenes, and genes associated with cellular transformation (e.g., Gro-1 and V-yes). These observations correlated with measurements of cell proliferation and mitotic measurements as AsIII treatment resulted in a dose-dependent increase in cellular mitoses at 24 h and an increase in cell proliferation at 48 h of exposure. Data in this manuscript demonstrates that AsIII exposure simultaneously modulates DNA repair, cell proliferation, and redox-related gene expression in nontransformed, normal NHEK. It is anticipated that data in this report will serve as a foundation for furthering our knowledge of AsIII-regulated gene expression in skin and other tissues and contribute to a better understanding of arsenic toxicity and carcinogenesis.
人类接触砷这种普遍存在的有毒环境污染物与皮肤癌发病率增加有关。然而，低水平接触三价砷（AsIII）介导的毒性和致癌作用的机制仍不清楚。细胞增殖异常、氧化损伤和DNA修复保真度与亚砷酸钠（AsIII）介导的致癌性和毒性有关，但在大多数砷暴露生物模型中，这些事件是单独研究的。我们假设这些效应的同时相互作用可能在砷介导的皮肤肿瘤形成中起重要作用。为了评估这一点，将正常人表皮角质形成细胞（NHEK）暴露于无毒剂量（0.005 - 5微摩尔）的AsIII，并在收获细胞进行基因表达测量时（1 - 24小时）监测几个生理终点。双荧光cDNA微阵列分析表明，AsIII处理降低了与DNA修复相关的基因（如p53和损伤特异性DNA结合蛋白2）的表达，并增加了指示细胞对氧化应激反应的基因（如超氧化物歧化酶1、NAD(P)H醌氧化还原酶和丝氨酸/苏氨酸激酶25）的表达。AsIII还调节了某些与细胞增殖增加相关的转录本（如细胞周期蛋白G1、蛋白激酶Cδ）、癌基因以及与细胞转化相关的基因（如Gro - 1和V - yes）的表达。这些观察结果与细胞增殖和有丝分裂测量结果相关，因为AsIII处理在24小时时导致细胞有丝分裂呈剂量依赖性增加，在暴露48小时时细胞增殖增加。本手稿中的数据表明，AsIII暴露同时调节未转化的正常NHEK中的DNA修复、细胞增殖和氧化还原相关基因表达。预计本报告中的数据将为加深我们对AsIII在皮肤和其他组织中调节基因表达的了解奠定基础，并有助于更好地理解砷的毒性和致癌作用。
