DNA MISMATCH REPAIR GENES AND TUMORIGENESIS

DNA 错配修复基因与肿瘤发生

• 批准号: 6633274
• 负责人: TOMAS ALBERTO PROLLA
• 金额: $ 22.2万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2004-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6633274
• 关键词: DNA repair; DNA replication; cell line; chemical carcinogenesis; gene targeting; genetic markers; genetic susceptibility; laboratory mouse; neoplasm /cancer genetics; point mutation

Mutations in the DNA mismatch repair genes hMLH1, hPMS2 and hPMS1 are involved in human hereditary colon cancer. Lack of MMR activity, as determined by the presence of microsatellite instability, is also a common feature in a significant fraction of sporadic tumors from a variety of tissues, and is associated with the development of resistance to several chemotherapeutic agents. We have recently generated and characterized mice deficient for the Mlh1, Pms2 and Pms1 DNA mismatch repair gene. Our analysis has demonstrated that mice carrying mutations in these genes differ in tumor susceptibility, and that there is no obvious correlation between intestinal tumorigenesis and the frequency of DNA replication errors in the intestinal epithelium. These findings imply that individual DNA mismatch repair genes have unique biological roles, and that poorly characterized factors play a role in tumorigenesis associated with DNA mismatch repair deficiency. The broad goal of this proposal is to define the mechanism(s) of tumor formation due to defects in DNA mismatch repair. We hypothesize that different tumor susceptibility in Mlh1, Pms2 and Pms1 deficient mice is due to gene-specific roles in either spontaneous or chemically induced mutagenesis. In order to examine this hypothesis, we propose to construct isogenic cell lines carrying mutations in Mlh1, Pms2 and Pms1 through homologous recombination (Aim 1). These cell lines will be used in conjunction with previously generated Msh2-/-cell lines in a number of assays that will allow us to systematically determine the relative contribution of different MMR genes to spontaneous mutation, mutation spectra at defined loci, instability of simple-repeat tracts, and genetic recombination between diverged DNA elements (Aim 2). Additionally, we will determine if mismatch repair genes affect chemically induced mutagenesis, and if base modifying agents can affect tumor development in mismatch repair deficient mice (Aim 3). The proposed research program will define the role of different mismatch repair genes in several aspects of mutagenesis at the cellular level, and results will be applied in the study of tumor formation at the organismal level in DNA mismatch repair deficient mice. Elucidation of novel and specific roles of DNA mismatch repair genes will provide new strategies for cancer prevention in families carrying mismatch repair gene mutations, and will suggest new therapeutic avenues for treatment of DNA mismatch repair deficient tumors.

DNA错配修复基因hMLH 1、hPMS 2和hPMS 1的突变与人类遗传性结肠癌有关。 MMR活性的缺乏，如通过微卫星不稳定性的存在所确定的，也是来自各种组织的散发性肿瘤的显著部分中的共同特征，并且与对几种化疗剂的耐药性的发展相关。 我们最近产生和表征小鼠缺陷的Mlh 1，Pms 2和Pms 1 DNA错配修复基因。我们的分析表明，携带这些基因突变的小鼠在肿瘤易感性方面存在差异，并且肠道肿瘤发生与肠道上皮中DNA复制错误的频率之间没有明显的相关性。这些研究结果表明，个别DNA错配修复基因具有独特的生物学作用，并不充分的特点的因素发挥作用，与DNA错配修复缺陷相关的肿瘤发生。该提案的广泛目标是定义由于DNA错配修复缺陷导致的肿瘤形成机制。 我们推测，不同的肿瘤易感性Mlh 1，Pms 2和Pms 1缺陷小鼠是由于基因特异性的作用，无论是自发或化学诱导的诱变。 为了检验这一假设，我们建议通过同源重组构建携带Mlh 1，Pms 2和Pms 1突变的等基因细胞系（目的1）。 这些细胞系将与先前生成的Msh 2-/-细胞系一起用于许多试验，这些试验将使我们能够系统地确定不同MMR基因对自发突变的相对贡献、定义基因座的突变谱、简单重复序列的不稳定性以及分歧DNA元件之间的遗传重组（目的2）。 此外，我们将确定错配修复基因是否影响化学诱导的诱变，以及碱基修饰剂是否可以影响错配修复缺陷小鼠的肿瘤发展（目的3）。 拟议的研究计划将定义不同的错配修复基因在细胞水平诱变的几个方面的作用，其结果将应用于DNA错配修复缺陷小鼠在生物体水平上的肿瘤形成研究。 阐明DNA错配修复基因的新的和特定的作用将为携带错配修复基因突变的家庭的癌症预防提供新的策略，并将为治疗DNA错配修复缺陷型肿瘤提供新的治疗途径。