MOLECULAR MECHANISMS OF CHROMIUM MUTAGENESIS

铬诱变的分子机制

• 批准号: 6271078
• 负责人: Kathleen Dixon
• 金额: $ 15.46万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 1999-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6271078
• 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.

铬已被认定为“主要有害物质” 超级基金危险废物场的很大一部分。 流行病学 研究已将工作场所接触铬化合物联系起来 增加患肺癌的风险。 此外，某些 多种形式的铬已被证明对动物具有致癌性 细菌和哺乳动物细胞系统中的致突变性。 虽然过程 致癌作用很复杂，很明显，诱变激活 原癌基因发挥着重要作用。 研究目的 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诱变之间的联系 和铬的致癌活性。 我们正在使用穿梭载体 在培养的哺乳动物细胞和酵母中鉴定诱变前 DNA 损伤 由铬化合物诱导并确定诱变特异性 这种损害。 我们还使用哺乳动物体外 DNA 复制 研究细胞 DNA 复制装置如何反应的系统 铬诱导的模板损伤以及 DNA 复制保真度是否 受到铬对 DNA 复制因子的直接影响。 此外，我们正在寻找铬诱变与 使用转基因小鼠检查诱变效应的致癌作用 吸入铬酸钙粉尘进入肺部——目标器官 铬致癌。 这项工作的重点是了解 铬在细胞内的生物转化在诱变中发挥作用 化合物的活化。 显然，铬进入细胞的方式是 Cr(VI) 可被还原为活性物质 Cr(V)、Cr(VI) 和 Cr(III)。 尽管许多细胞大分子已被 与这些转化有关，似乎细胞内 谷胱甘肽可能在铬还原和诱变中发挥关键作用。 我们建议检验以下假设：细胞内减少 谷胱甘肽转化铬是产生铬的主要途径 负责铬诱变的反应中间体 完整细胞和铬在动物中的致癌作用。 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产生化合物 或哺乳动物细胞，当酵母或哺乳动物细胞含有质粒时 经过铬处理，并在小鼠肺部的转基因中 吸入铬后，我们希望确定以下类型： 诱变前 DNA 损伤对于铬诱变很重要 确定诱变特异性是如何由特定的 细胞内铬还原的途径。 加深了解 铬诱变机制的研究应该增强我们的能力 评估与人类暴露于环境相关的风险 危害，并可能提出干预和预防的方法 接触对健康的不利影响。