Hypoxia, Genetic Instability and DNA Mismatch Repair

缺氧、遗传不稳定性和 DNA 错配修复

• 批准号: 6573292
• 负责人: PETER M GLAZER
• 金额: $ 32.19万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-30 至 2008-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6573292
• 关键词: DNA damage; DNA repair; DNA replication; acetylation; cell line; colon neoplasms; disease /disorder model; flow cytometry; gel mobility shift assay; gene expression; gene mutation; genetic promoter element; hypoxia inducible factor 1; immunocytochemistry; laboratory mouse; mass spectrometry; methylation; microarray technology; neoplasm /cancer genetics; neoplastic process; nuclear magnetic resonance spectroscopy; p53 gene /protein; protein structure function; reporter genes; transcription factor

DESCRIPTION (provided by applicant): Genetic instability is a hallmark of cancer. In previous work, we had found that the hypoxic tumor microenvironment is one cause of this genetic instability. Recently, we have found that hypoxia specifically causes decreased expression of the DNA mismatch repair (MMR) factors, MLH1 and PMS2, with MLH1 but not PMS2 down-regulated at the mRNA level. These factors are critical for maintaining genomic integrity by correcting DNA replication errors, and they also play a role in response to DNA damage. Mutations in these and other genes associated with MMR have been linked to hereditary colon cancer.In this renewal application, we propose to explore the mechanism(s) by which the MMR factors MLH1 and PMS2 are down-regulated by hypoxia and potentially by other cell stresses. Transcription regulatory pathways, including histone deacetylation and promoter hypermethylation, will be examined, and critical Mlhl promoter regions will be mapped. The putative roles of p53 and HIF-1, two transcription factors regulated by hypoxia, will be tested, and experiments will be performed to identify other possible trans-acting factors. Using experimental tumor models in mice, we will determine the extent to which hypoxia in vivo can be correlated with reduced MMR gene expression and with increased genetic instability.These studies will provide insight into how the hypoxic tumor microenvironment may contribute to genetic instability and thereby to tumor progression. In addition, the down-regulation of MMR factors detected in response to hypoxia may be a feature of a more general stress response in mammalian cells by which cell mutation rates may be increased under adverse conditions, even if such conditions are not directly genotoxic. Elucidation of this pathway would have important implications for our understanding of the cellular response to a variety of environmental insults and so may bear on pathways of carcinogenesis and aging.

描述（由申请人提供）：遗传不稳定性是癌症的标志。在先前的工作中，我们发现低氧肿瘤微环境是这种遗传不稳定的原因之一。最近，我们发现缺氧特异性导致DNA不匹配修复（MMR）因子MLH1和PMS2的表达降低，而MLH1则在mRNA水平下下调了PMS2。这些因素对于通过纠正DNA复制误差来维持基因组完整性至关重要，并且它们在响应DNA损伤方面也起作用。这些与MMR相关的基因的突变与遗传性结肠癌有关。在这种更新应用中，我们建议探索MMR因子MLH1和PMS2通过低氧下调并可能由其他细胞应力下调的机制。将检查转录调节途径，包括组蛋白脱乙酰化和启动子高甲基化，并将映射关键的MLHL启动子区域。将测试由缺氧调节的两个转录因子p53和HIF-1的推定作用，并将进行实验以识别其他可能的跨性别因素。使用小鼠的实验性肿瘤模型，我们将确定体内缺氧与MMR基因表达降低相关的程度以及遗传不稳定性的增加。这些研究将提供有关低氧肿瘤微环境可能如何有助于遗传不稳定性的，从而有助于遗传性不稳定和肿瘤进展。此外，即使在不良条件下，哺乳动物细胞中发现细胞突变率可能会增加的哺乳动物细胞中更普遍的压力反应的MMR因子的下调，即使这种情况不是直接的遗传毒性。 阐明这一途径将对我们对各种环境侮辱的细胞反应的理解具有重要意义，因此可能会遵循致癌和衰老的途径。