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Hypoxia, DNA repair, and gene silencing

缺氧、DNA 修复和基因沉默

基本信息

批准号：
8813923
负责人：
PETER M GLAZER
金额：
$ 37.46万
依托单位：
YALE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1992
资助国家：
美国
起止时间：
1992-09-30 至 2019-10-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8813923
关键词：
Address Apoptosis Apoptotic Arsenic BCL2 gene BCL2L11 gene BRCA1 gene Biological Assay CHEK2 gene Cancer Biology Carcinogens Cell Death Cells Chemicals DNA DNA Damage DNA Repair DNA Repair Gene Down-Regulation Environmental Carcinogens Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Epigenetic Process Equilibrium Exposure to Funding Gefitinib Gene Expression Gene Silencing Gene Silencing Pathway Genes Genetic Goals Grant Growth Growth Factor Receptors Heavy Metals Histones Human Hypoxia Hypoxia Pathway Lead Link Lysine MLH1 gene Malignant Neoplasms Malignant neoplasm of lung Mediating Mediator of activation protein MicroRNAs Mismatch Repair Molecular Neoplasm Metastasis Nickel Oncogenes Pathway interactions Post-Translational Protein Processing Process Publishing Radiation Receptor Inhibition Regulation Regulatory Element Research Resistance Role Solid Neoplasm Stress Testing Tumor Suppressor Genes Work angiogenesis base cancer cell cancer chemoprevention cancer prevention cancer therapy carcinogenesis cell growth cell killing gene repair in vivo inhibitor/antagonist kinase inhibitor mimetics novel novel strategies outcome forecast prevent promoter public health relevance radiation resistance resistance gene response restoration small hairpin RNA small molecule tumor growth tumor microenvironment tumor progression tumor xenograft

项目摘要

DESCRIPTION (provided by applicant): Hypoxia, DNA repair, and gene silencing. Hypoxia is a key feature of solid tumors that confers radiation resistance, stimulates angiogenesis, promotes metastasis, and is linked to poor prognosis. With the support of this grant, we have shown that hypoxia is also a driver of genetic instability via down-regulation of critical DNA repair genes. In the past funding period, we have discovered that hypoxia can also induce durable silencing of the BRCA1 and MLH1 promoters via specific epigenetic factors. In recent preliminary studies, we have further determined that hypoxia can lead to silencing of the pro-apoptotic BIM gene and resistance to the EGFR inhibitor, gefitinib, in lung cancer cells. The broad, long-term goal of this renewal application is to elucidate the impact of hypoxic stress on carcinogenesis and cancer biology, with a focus on DNA repair and gene silencing. In Aim 1, we will dissect the molecular mechanisms by which hypoxic stress drives epigenetic change to cause gene silencing, with a focus on the MLH1 promoter. We will determine promoter elements and regulatory factors that mediate silencing, and we will use a facile selection-based shRNA screen to identify key targets for reversal of this process. We will also assay for the impact of the hypoxic tumor microenvironment on gene silencing during tumor growth in vivo. Next, since heavy metals are known human carcinogens that can induce hypoxia-related pathways, in Aim 2 we will ask whether exposure to heavy metals can also drive gene silencing and/or down-regulate DNA repair. In Aim 3, we will build on novel preliminary results suggesting that growth of lung cancer cells in hypoxia can promote resistance to the epidermal growth factor receptor (EGFR) inhibitor, gefitinib, in conjunction with silencing of the pro-apoptotic factor, BIM. We wil test specific hypotheses regarding the underlying mechanisms, and, guided by Aim 1, we will identify strategies to prevent or reverse this resistance. The proposed work will elucidate key pathways of gene silencing and DNA repair regulation in response to hypoxia (and possibly to carcinogenic heavy metals) that may underlie critical steps in carcinogenesis, genetic instability, tumor progression, and resistance to radiation and other cancer therapies. Identification of strategies to prevent or reverse these pathways may provide the basis for new approaches to cancer prevention and therapy.

描述（由申请人提供）：缺氧、DNA 修复和基因沉默。缺氧是实体瘤的一个关键特征，它赋予放射抗性、刺激血管生成、促进转移，并与不良预后相关。在这笔资助的支持下，我们发现缺氧也是通过下调关键 DNA 修复基因而导致遗传不稳定的一个因素。在过去的资助期间，我们发现缺氧还可以通过特定的表观遗传因子诱导 BRCA1 和 MLH1 启动子的持久沉默。在最近的初步研究中，我们进一步确定缺氧可以导致肺癌细胞中促凋亡BIM基因的沉默以及对EGFR抑制剂吉非替尼的耐药性。这一更新应用的广泛、长期目标是阐明缺氧应激对致癌和癌症生物学的影响，重点是 DNA 修复和基因沉默。在目标 1 中，我们将剖析缺氧应激驱动表观遗传变化导致基因沉默的分子机制，重点关注 MLH1 启动子。我们将确定介导沉默的启动子元件和调控因子，并且我们将使用基于简单选择的 shRNA 筛选来识别逆转该过程的关键靶标。我们还将测定缺氧肿瘤微环境对体内肿瘤生长过程中基因沉默的影响。接下来，由于重金属是已知的人类致癌物，可以诱导缺氧相关途径，因此在目标 2 中，我们将询问接触重金属是否也可以驱动基因沉默和/或下调 DNA 修复。在目标 3 中，我们将基于新的初步结果，表明肺癌细胞在缺氧条件下的生长可以促进对表皮生长因子受体 (EGFR) 抑制剂吉非替尼的耐药性，并结合促凋亡因子 BIM 的沉默。我们将测试有关潜在机制的具体假设，并在目标 1 的指导下，确定预防或扭转这种阻力的策略。拟议的工作将阐明基因沉默和 DNA 修复调节的关键途径，以响应缺氧（可能还有致癌重金属），这可能是致癌、遗传不稳定性、肿瘤进展以及对放射和其他癌症疗法的抵抗力。确定预防或逆转这些途径的策略可能为癌症预防和治疗的新方法提供基础。