MOLECULAR MECHANISMS OF CHROMIUM MUTAGENESIS

铬诱变的分子机制

• 批准号: 6340904
• 负责人: Kathleen Dixon
• 金额: $ 17.11万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2001-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6340904
• 关键词: DNA damage; DNA replication; chemical carcinogen; chromium; environmental contamination; gene mutation; genetically modified animals; glutathione; hazardous substances; industrial waste; laboratory mouse; molecular pathology; mutagens; neoplasm /cancer genetics; protooncogene; tissue /cell culture; transfection /expression vector

Chromium has been identified as a "primary hazardous substance" at a large proportion of the Superfund Hazardous Waste Sites. Epidemiological studies have linked the exposure to chromium compounds in the work place to increased risk for development of lung cancer. Furthermore, certain forms of chromium have been shown to be carcinogenic in animals and mutagenic in bacteria and mammalian cell systems. Although the process of carcinogenesis is complex, it is clear that mutagenic activation of proto-oncogenes plays an important role. The purpose of the research proposed here is to understand the mechanisms by which chromium causes mutations in mammalian cells and to provide a link between the mutagenic and carcinogenic activities of chromium. We are using shuttle vectors in cultured mammalian cells and yeast to identify premutagenic DNA damage induced by chromium compounds and to determine the mutagenic specificity of this damage. We are also using a mammalian in vitro DNA replication system to investigate how the cellular DNA replication apparatus responds to chromium-induced template damage and whether DNA replication fidelity is affected by direct effects of chromium on DNA replication factors. In addition, we are seeking a link between chromium mutagenesis and carcinogenesis by using transgenic mice to examine the mutagenic effects of inhaled calcium chromate dust in the lung - the target organ for chromium carcinogenesis. The focus of this work will be to understand the role that biotransformation of chromium within the cell plays in the mutagenic activation of the compound. Apparently, chromium enters the cells as Cr(VI) where it can be reduced to reactive species Cr(V), Cr(VI) and Cr(III). Although a number of cellular macromolecules have been implicated in these transformations, it appears that intracellular glutathione may play a key role in chromium reduction and mutagenesis. We propose to test the following hypothesis: The intracellular reduction of chromium by glutathione is a major pathway for the generation of reactive intermediates that are responsible for chromium mutagenesis in the intact cell and for chromium carcinogenesis in animals. By comparing the spectra of mutations induced in a mutagenesis target gene by chromium compounds when plasmid DNA is treated in vitro and replicated in yeast or mammalian cells, when yeast or mammalian cells that contain plasmid are treated with chromium, and in the transgene in the lungs of mice following chromium inhalation, we hope to identify the types of premutagenic DNA damage that are important in chromium mutagenesis and determine how the mutagenic specificity is determined by the specific pathway for chromium reduction in the cell. An increased understanding of the mechanisms of chromium mutagenesis, should enhance our ability to evaluate the risks associated with human exposure to the environmental hazard, and perhaps suggest methods for intervention and prevention of adverse health effects of exposure.

铬已被确定为“主要危险物质”， 大部分的超级基金危险废物场地。 流行病学 研究表明工作场所接触铬化合物 增加患肺癌的风险。 此外，某些 铬的形式已被证明是致癌的动物， 在细菌和哺乳动物细胞系统中具有诱变性。 虽然过程 致癌作用是复杂的，很明显， 原癌基因起着重要的作用。 研究的目的 这里提出的是了解铬引起的机制， 哺乳动物细胞中的突变，并提供突变之间的联系 铬的致癌活性。 我们使用穿梭载体 在培养的哺乳动物细胞和酵母中鉴定诱变前DNA损伤 铬化合物诱导的突变，并确定其致突变特异性 这种损害。 我们也在用哺乳动物的体外DNA复制 系统来研究细胞DNA复制装置如何响应 铬诱导的模板损伤以及DNA复制保真度 受铬对DNA复制因子的直接影响。 此外，我们正在寻找铬致突变和 用转基因小鼠检测致癌作用 吸入铬酸钙粉尘在肺-的目标器官， 铬致癌作用 这项工作的重点将是了解的作用， 铬在细胞内的生物转化在诱变中起作用。 激活化合物。 很明显，铬进入细胞 Cr（VI），可还原为反应性物质Cr（V）、Cr（VI）和 Cr（III）。 尽管许多细胞大分子已经被 在这些转化中，似乎细胞内 谷胱甘肽可能在铬还原和诱变中起关键作用。 我们建议测试以下假设： 铬的谷胱甘肽是一个主要的途径， 反应性中间体，负责铬诱变， 完整的细胞和铬致癌作用的动物。 通过比较 铬在诱变靶基因中诱导的突变谱 当质粒DNA在体外处理并在酵母中复制时， 或哺乳动物细胞，当含有质粒的酵母或哺乳动物细胞 用铬处理，在小鼠肺部的转基因中， 在吸入铬后，我们希望能确定 在铬诱变中重要的预诱变DNA损伤， 确定致突变特异性如何由特异性 细胞中铬还原的途径。 人民进一步了解 铬致突变的机制，应该提高我们的能力， 评估与人类接触环境相关的风险 危害，并可能提出干预和预防 暴露对健康的不良影响。