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.

铬已被确认为一种“主要的危险物质” 很大比例的超级基金危险废物场地。流行病学 研究表明，在工作场所接触铬化合物 增加罹患肺癌的风险。此外，一定 各种形式的铬已被证明对动物和 在细菌和哺乳动物细胞系统中具有致突变性。尽管这一过程 致癌机制是复杂的，很明显，诱变激活 原癌基因在其中起着重要的作用。这项研究的目的 在这里提出是为了了解铬引起 在哺乳动物细胞中的突变和提供诱变剂之间的联系 和铬的致癌活性。我们使用的是穿梭载体 在培养的哺乳动物细胞和酵母中鉴定诱变前DNA损伤 铬化合物的诱变作用及致突变特异性的测定 造成的损害。我们还使用了哺乳动物的体外DNA复制 研究细胞DNA复制设备如何响应的系统 对铬诱导的模板损伤以及DNA复制的保真度 受铬对DNA复制因子的直接影响。 此外，我们正在寻找铬的突变和 利用转基因小鼠检测诱变效应的致癌作用 吸入的铬酸钙粉尘在肺中-靶器官 铬致癌。 这项工作的重点将是理解 细胞内铬的生物转化在诱变中起作用 化合物的活化。显然，铬以一种 铬(VI)，其中它可以还原为活性物种铬(V)、铬(VI)和 铬(III)。尽管一些细胞大分子已经被 与这些转变有关，看起来细胞内 谷胱甘肽可能在铬还原和诱变中起关键作用。 我们建议检验以下假设：细胞内还原 谷胱甘肽对铬的作用是产生铬的主要途径 导致铬致突变的活性中间体 完整的细胞和动物体内铬的致癌作用。通过比较 铬致突变靶基因的突变谱 体外处理质粒DNA并在酵母中复制时的化合物 或哺乳动物细胞，当酵母或哺乳动物细胞含有质粒时 用铬处理，并在小鼠肺部的转基因中 在吸入铬之后，我们希望确定 诱变前DNA损伤在铬诱变和 确定突变特异性是如何由特定的 细胞内铬还原的途径。加深了解 铬的诱变机制，应该会增强我们的能力 评估与人类接触环境有关的风险 危害，并可能提出干预和预防的方法 暴露对健康的不利影响。