DNA Mismatch Repair Functions in Tumor Suppression

DNA 错配修复在肿瘤抑制中的作用

• 批准号: 6774719
• 负责人: ANDREW B BUERMEYER
• 金额: $ 20.16万
• 依托单位: OREGON STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-16 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6774719
• 关键词: DNA damage; DNA repair; DNA replication; carcinogenesis; cell death; cell growth regulation; cell line; clinical research; gene mutation; genetic mapping; human genetic material tag; neoplasm /cancer genetics; tumor suppressor genes

DESCRIPTION (provided by applicant): Heterozygous germline deficiencies in DNA mismatch repair (MMR) genes cause hereditary non-polyposis colorectal cancer (HNPCC), one of the most common inherited cancer syndromes, whereas homozygous deficiency causes severe hematological malignancy. Defects in MMR also are detected in other sporadic cancers, suggesting that loss of MMR is a common etiologic factor in human tumorigenesis. At the cellular level, MMR ensures the stability of the genome through the correction of errors made during DNA replication and the recognition of several types of DNA damage, leading to growth arrest and cell death. The precise mechanism of these different functions is unknown. Particularly poorly defined are the MMR-dependent responses to DNA damage. Cells lacking MMR demonstrate an elevated rate of spontaneous mutation and resistance to cell killing induced by DNA damaging agents. However, the extent to which the different phenotypes associated with MMR deficiency contribute to cancer risk is not known. To elucidate the mechanisms and importance of MMR functions in the prevention of cancer, we propose a functional characterization of the MMR gene MLH1. We will define the phenotypic consequences of specific mutations in MLH1 through the analysis of isogenic cell lines expressing MLH1 variants (Aim 1). We will elucidate the mechanism underlying genetic deficiencies identified in Aim 1 using biochemical assays of mismatch-directed excision, error correction, and DNA damage processing (Aim 2). Finally, we will identify and characterize novel mutations in MMR genes using a unique genetic selection for dominant-acting mutations that interfere with MMR-dependent responses to DNA damage (Aim 3). Our analyses will increase understanding of the mechanisms of MMR, the consequences of specific MMR gene mutations, and the importance of different MMR functions for the prevention of cancer. Such knowledge will facilitate more rationally designed intervention strategies for the treatment and/or prevention of cancer associated with MMR deficiency.

描述（由申请人提供）：DNA不匹配修复（MMR）基因中的杂合种系缺乏引起遗传性非型型结肠直肠癌（HNPCC），这是最常见的遗传性癌症综合征之一，而纯粹的缺乏症会导致严重的血压恶性肿瘤。 在其他零星癌症中也发现了MMR中的缺陷，这表明MMR的丧失是人类肿瘤发生的常见病因。 在细胞水平上，MMR通过纠正DNA复制过程中犯错的错误以及对几种DNA损伤的识别，从而确保基因组的稳定性，从而导致生长停滞和细胞死亡。 这些不同功能的确切机制尚不清楚。 尤其定义的是MMR依赖对DNA损伤的反应。 缺乏MMR的细胞表明自发突变的速度升高和对DNA损害剂诱导的细胞杀伤的抗性。 但是，与MMR缺乏症相关的不同表型在多大程度上导致癌症风险。 为了阐明MMR功能在预防癌症中的机制和重要性，我们提出了MMR基因MLH1的功能表征。 我们将通过分析表达MLH1变体的等源细胞系（AIM 1）来定义MLH1中特异性突变的表型后果。 我们将使用错配导向切除，误差校正和DNA损伤处理的生物化学测定在AIM 1中鉴定出的遗传缺陷的基本机制（AIM 2）。 最后，我们将使用独特的遗传选择来识别并表征MMR基因中的新型突变，用于主导作用突变，这些突变会干扰MMR依赖对DNA损伤的反应（AIM 3）。 我们的分析将增加对MMR机制，特定MMR基因突变的后果以及不同MMR功能在预防癌症的重要性的理解。 这些知识将促进更合理设计的干预策略，以治疗和/或预防与MMR缺乏相关的癌症。