DNA MISMATCH REPAIR FUNCTIONAL GENETIC TESTS

基因组不稳定性在癌细胞和癌前细胞中都得到了很好的证明。遗传性非息肉病性结直肠癌(HNPCC)是由编码DNA错配修复(DMR)相关蛋白的四个基因中的任何一个突变引起的。DMR的缺陷在一些散发性癌症和癌前病变中也被证明，这表明DMR的细胞缺陷可能是癌细胞进化的一个常见的早期步骤。对HNPCC家族的遗传分析显示，在观察到的DMR基因变化中，约有25%预示着蛋白质的微小变化，如氨基酸替换。用目前的基因测试方法，不可能明确地将这些序列变异归类为突变或沉默的多态。这项研究拨款申请提出了发展DNA错配修复的功能遗传学测试。这项新技术将在基础、临床和流行病学癌症研究中具有广泛的实用价值。无论是通过体细胞突变获得的DMR缺陷，还是作为生殖系DMR突变遗传的DMR缺陷，都容易导致癌症的发生。这项研究提案中描述的技术将允许评估DMR基因产物的体内功能，因此将允许对特定DMR基因突变引起的基因组不稳定性进行明确的分子表征。拟议的商业应用：基因组不稳定是癌症、癌前细胞和癌症遗传易感性的标志。DNA错配修复缺陷是基因组不稳定的常见来源，但目前的基因检测方法无法充分表征所观察到的大约25%的基因变异。这项研究将开发的技术与其他方法相结合，将使细胞DNA错配修复能力的最终表征成为可能。

Genomic instability has been well documented in both cancer cells and precancer cells. Hereditary nonpolyposis colorectal cancer (HNPCC) is caused by mutations in any one of four genes encoding proteins involved in DNA mismatch repair (DMR). Defects in DMR have also been demonstrated in several sporadic cancers as well as precancers, indicating that cellular defects in DMR may be a frequent early step in the evolution of a cancer cell. Genetic analyses of HNPCC kindreds reveal that approximately 25% of the observed alterations in DMR genes predict minor changes in the protein, such as amino acid replacements. With current genetic testing methods, it is not possible to unambiguously assign these sequence variations as either mutations or silent polymorphisms. This research grant application proposes development of functional genetic tests of DNA mismatch repair. This novel technology will have broad utility for basic, clinical and epidemiological cancer research. Defects in DMR predispose to cancer development, both when acquired in a precancer cell through somatic mutation or when inherited as a germline DMR mutation. The technology described in this research proposal will allow assessment of the in vivo function of DMR gene products, and will therefore allow definitive molecular characterization of genomic instability caused by mutations in specific DMR genes. PROPOSED COMMERCIAL APPLICATIONS: Genomic instability is a hallmark of both cancers, precancer cells and inherited predispositions to cancer. Defective DNA mismatch repair is a common source of genomic instability, but current genetic testing methods fail to adequately characterize approximately 25% of the gene variants observed. The technology to be developed in this research, in conjunction with other methods, will allow definitive characterization of cellular DNA mismatch repair competence.