The Synergistic effect and Mechanism of Arsenic on Chromium (VI) Carcinogenesis

砷对六价铬致癌的协同作用及机制

• 批准号: 8289847
• 负责人: Hong Xie
• 金额: $ 41.5万
• 依托单位: UNIVERSITY OF SOUTHERN MAINE
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8289847
• 关键词: Area; Arsenic; Biological; Biological Assay; Cancer Etiology; Carcinogen exposure; Carcinogens; Cells; Chromosome abnormality; Chromosomes; Comet Assay; Complex; Cytogenetics; DNA; DNA Damage; DNA Double Strand Break; DNA Repair; DNA Repair Inhibition; DNA repair protein; Data; Double Strand Break Repair; Environmental Hazards; Exposure to; Gene Expression; Gene Silencing; Human; Immune; Immunofluorescence Immunologic; Lead; Lesion; Lung; Malignant neoplasm of lung; Measures; Metal exposure; Metals; Modeling; Molecular Cytogenetics; NBS1 gene; Neoplastic Cell Transformation; Play; Process; Production; Proteins; Public Health; Publishing; Reporting; Research; Research Proposals; Reverse Transcriptase Polymerase Chain Reaction; Risk; Role; Techniques; Testing; Transfection; Western Blotting; Zinc; carcinogenesis; carcinogenicity; chromium hexavalent ion; design; interest; plasmid DNA; protein complex; protein expression; repaired; response; wasting

DESCRIPTION (provided by applicant): Hexavalent chromium (Cr(VI)) and arsenic are both major environmental concern, because they are known human lung carcinogens and exposure is widespread. It is likely that humans with co- exposure to Cr(VI) and arsenic could have even greater risks of lung cancers. The proposed research focuses on mechanisms of metal-induced carcinogenesis and investigates the hypothesis that arsenic synergistically increases Cr(VI) carcinogenicity as a consequence of interference with the repair of DNA double strand breaks. Our data show that arsenic synergistically increases Cr(VI)-induced chromosome damage and DNA double strand breaks in human lung cells. Arsenic inhibits the repair of this DNA damage and the expression of Mre11, a protein which plays an essential role in the repair of double strand breaks. Our studies also show that Mre11 deficiency leads to Cr(VI)-induced neoplastic transformation. We will test our hypothesis through three interrelated specific aims: 1) characterize the effect of arsenic on Cr(VI)-induced chromosome aberration, DNA double strand breaks and their repair; 2) determine how arsenic inhibits DNA double strand break repair; 3) determine if arsenic-induced modulation of MRN contribute to Cr(VI) and arsenic-induced neoplastic transformation. These three aims will use a combination of established and state-of-the-art toxicological, cytogenetic, and molecular biological techniques and with the following approach: 1) Cr(VI)-induced chromosome damage and DNA double strand breaks will be measured by cytogenetic assay and comet assay as well as the production of gamma-H2A.X foci, respectively; 2) Gene expression, immune-localization, protein expression studies and gene silencing will determine the mechanisms of arsenic synergistic effect; and 3) DNA transfection and transformation assays will determine how double strand break repair protects cells from arsenic and Cr(VI)-induced neoplastic transformation. This is the only study investigating the carcinogenicity of co-exposure of Cr(VI) and arsenic, which is a critical area of study as people are exposed to these metals simultaneously under most conditions. Our results will lead to the first reports of detailed information on the effect of arsenic on DNA double stran break repair machinery and the first identification of DNA double strand break repair proteins targeted by arsenic. This research is significant because it will provide: 1) An understanding of Cr(VI) and arsenic's carcinogenic mechanism; 2) Essential information to better assess the risk of exposure to these metals; and 3) A mechanistic approach for further study of arsenic, Cr(VI), other metals, and lung cancer in general. PUBLIC HEALTH RELEVANCE: Both Hexavalent chromium (Cr(VI)) and arsenic are major environmental hazards and are associated with human lung cancer. Despite that people are exposed to these metals simultaneously under most conditions, little is known about the potential co- exposure impact. This research will investigate how arsenic disrupts DNA damage repair which results in enhancement of Cr(VI)-induced lung cancer.

描述（由申请人提供）：六价铬（Cr(VI)）和砷都是主要的环境问题，因为它们是已知的人类肺癌致癌物，并且暴露范围很广。同时暴露于铬（六）和砷的人患肺癌的风险可能更大。本研究的重点是金属致癌的机制，并探讨了砷通过干扰DNA双链断裂的修复而协同增加Cr（VI）致癌性的假设。我们的数据表明，砷协同增加Cr（VI）诱导的人肺细胞染色体损伤和DNA双链断裂。砷抑制这种DNA损伤的修复和Mre11的表达，Mre11是一种在双链断裂修复中起重要作用的蛋白质。我们的研究还表明，Mre11缺乏导致Cr（VI）诱导的肿瘤转化。我们将通过三个相互关联的特定目标来验证我们的假设：1)表征砷对Cr（VI）诱导的染色体畸变、DNA双链断裂及其修复的影响；2)确定砷如何抑制DNA双链断裂修复；3)确定砷诱导的MRN调节是否有助于Cr（VI）和砷诱导的肿瘤转化。这三个目标将结合现有的和最先进的毒理学、细胞遗传学和分子生物学技术，并采用以下方法：1)Cr（VI）诱导的染色体损伤和DNA双链断裂将通过细胞遗传学试验和彗星试验以及γ - h2a的产生来测量。分别为X个焦点；2)基因表达、免疫定位、蛋白表达研究和基因沉默将决定砷协同效应的机制；3) DNA转染和转化试验将确定双链断裂修复如何保护细胞免受砷和Cr（VI）诱导的肿瘤转化。这是唯一一项研究Cr（VI）和砷共同暴露致癌性的研究，这是一个关键领域