Particulate Cr(VI) Toxicology in Human Lung Epithelial Cells and Fibroblasts

受资助家长助学金项目摘要 肺癌仍然是美国癌症死亡的主要原因。防治肺癌的关键战略之一 这是为了更好地了解其原因。六价铬[Cr(VI)]是人类肺癌的主要致癌物 健康问题，因为在工作场所和一般环境中接触这种物质是很常见的。我们的研究 重点研究铬(VI)诱导的致癌机制，目前尚不清楚。在……里面 特别是，这项工作集中在颗粒铬(VI)化合物，因为它们是最有效的铬(VI) 致癌物质。最近的研究表明，微粒铬(VI)会导致染色体不稳定，并导致细胞 避免DNA双链断裂修复，这是人类肺癌的标志。因此，本研究的重点是 微粒铬(VI)诱导细胞逃避DNA双链断裂修复导致染色体 不稳定和致癌。我们的数据显示，长期暴露在颗粒铬(VI)中会特别影响 同源重组效应臂(HR修复)，破坏RAD51核蛋白细丝形成，丢失 这可能会导致染色体不稳定。因此，这项研究的目标是描述这种影响对 人力资源修复和潜在的变化，以了解所涉及的机制。我们的假设是： 颗粒铬(VI)破坏RAD51核蛋白细丝形成失活的潜在机制 HR修复铬(VI)诱导的DNA断裂，导致CIN和肿瘤转化。我们将对此进行测试 通过三个相互关联的具体目标进行假设。目标1将确定铬(VI)如何影响BRCA2、DSS1、 RAD51B、RAD51C、RAD51D、RPA和XRCC2干扰人RAD51核蛋白细丝形成 肺细胞。目的2确定被破坏的RAD51丝形成的持久性和细胞遗传性 铬(VI)诱发人肺细胞癌变及BRCA2、DSS1、RAD51B、 RAD51C、RAD51D、RPA和XRCC2在铬(VI)作业工人肺肿瘤中的表达目标3决定了影响 铬(VI)对肺组织中BRCA2、DSS1、RAD51B、RAD51C、RAD51D、RPA和XRCC2蛋白水平的影响 铬(VI)染毒动物的肺肿瘤。结果将导致第一次报告详细的信息 铬(VI)与HR修复效应臂在细胞和分子水平的相互作用 肿瘤结局中这些方面的特征，包括接触铬(VI)工人的肿瘤。 结果还将显示哪些变化是暂时的，取决于暴露情况，哪些变化在细胞中持续存在 逃脱了细胞死亡，并进展为肿瘤结果。这项研究具有重要意义，因为它提供了：1) 对铬(VI)S致癌机理的理解；2)更好地评估暴露风险的基本信息 3)进一步研究铬(VI)、其他金属和一般肺癌的机理方法。

PROJECT SUMMARY OF THE FUNDED PARENT GRANT Lung cancer continues to be the leading cause of cancer death in the U.S. One of the key strategies to combating it is to better understand its causes. Hexavalent chromium [Cr(VI)] is a human lung carcinogen of major public health concern because exposure to it is common in the workplace and in the general environment. Our study focuses on investigating the mechanisms of Cr(VI)-induced carcinogenesis, which are currently unknown. In particular, this work focuses on the particulate Cr(VI) compounds, because they are the most potent Cr(VI) carcinogens. Recent studies indicate particulate Cr(VI) induces chromosome instability and causes cells to evade DNA double strand break repair, which are hallmarks of human lung cancer. Thus, this research focuses on how particulate Cr(VI) induces cells to evade DNA double strand break repair leading to chromosome instability and carcinogenesis. Our data show prolonged exposure to particulate Cr(VI) specifically impacts the effector arm of homologous recombination (HR repair), disrupting RAD51 nucleoprotein filament formation, loss of which can cause chromosome instability. Therefore, the goal of this research is to characterize this impact on HR repair and the underlying changes in order to understand the mechanisms involved. Our hypothesis is: particulate Cr(VI) disrupts the underlying mechanisms of RAD51 nucleoprotein filament formation inactivating HR repair of Cr(VI)-induced DNA breaks resulting in CIN and neoplastic transformation. We will test this hypothesis through three interrelated specific aims. Aim 1 will determine how Cr(VI) impacts BRCA2, DSS1, RAD51B, RAD51C, RAD51D, RPA, and XRCC2 to disrupt RAD51 nucleoprotein filament formation in human lung cells. Aim 2 determines the persistence and cellular heritability of disrupted RAD51 filament formation in human lung cells neoplastically transformed by Cr(VI), and the protein levels of BRCA2, DSS1, RAD51B, RAD51C, RAD51D, RPA, and XRCC2 in lung tumors from human Cr(VI) workers. Aim 3 determines the impact of Cr(VI) on protein levels of BRCA2, DSS1, RAD51B, RAD51C, RAD51D, RPA, and XRCC2 in the lungs and lung tumors of Cr(VI)-exposed animals. Results will lead to the first reports of detailed information of the interactions of Cr(VI) with the effector arm of HR repair at a cellular and molecular level and the first characterizations of these aspects in neoplastic outcomes including tumors from Cr(VI)-exposed workers. Results will also show which changes are transient and depend on exposure and which changes persist in cells that escape cell death and progress to neoplastic outcomes. This research is significant because it provides: 1) An understanding of Cr(VI)’s carcinogenic mechanism; 2) Essential information to better assess exposure risk to particulates; and 3) A mechanistic approach for further study of Cr(VI), other metals and lung cancer in general.