The Role of Microsatellite Instability in Cancer

描述(由申请人提供)：虽然上皮源性癌症的完整病因尚不清楚，但已经确定了几个相关的遗传和环境因素。作为肿瘤发生的标记和促成因素，一类特定的遗传事件受到越来越多的关注，涉及微卫星长度突变，表现为微卫星改变(MA)和微卫星不稳定性(MSI)(Forgacs等人，2001年；Woerner等人，2001年)。微卫星重复序列在哺乳动物基因组中很常见，而且经常是多态的。我们已经开发并验证了预测微卫星的算法，这些微卫星最有可能受到频繁突变的影响(Fondon等人，1998年)。体细胞微卫星长度突变通常在结肠癌、子宫内膜癌、乳腺癌和胃癌中观察到，并已被证明是一些肺癌的一个显著特征(Girard等人，2001；Forgacs等人，2001；Wistuba等人，2000)。MSI已被证明是DNA错配修复基因缺陷的一种表现，也是一种有用的DNA错配修复缺陷的指示物。我们推测，体细胞和生殖系微卫星突变可能在某些癌症的发生和发展中发挥重要的病因学作用，了解它们的突变频率、复杂性和在不同类型的上皮性癌症中的多样性以及了解它们在不同正常遗传背景下的变化是至关重要的。我们已经检查了基因组中与基因相关的微卫星，并在可能经历扩张和/或收缩突变的基因的转录区域中确定了10,000多个座位。其中许多是在编码区，其中8%预测在改变时会导致移码变异，一些是在肿瘤抑制基因中(Wren等人，2001年)。在目标1中，我们将改进预测与癌症进展相关的微卫星突变事件的方法，扫描最近完成的人类基因组，在已知或怀疑在肿瘤发生中起作用的基因中预测重复多态，并在来自肺、乳腺、卵巢和结直肠癌细胞系的一组DNA中选择150个这些座位进行基因分型(目标2)，其中包括许多除了原发肿瘤和正常血液DNA外还有匹配的B淋巴细胞DNA的DNA。我们还将(目标3)通过将目标2中确定的这些突变与剪接异构体的全球定量调查结果相关联，来研究它们对剪接的影响。

DESCRIPTION (provided by applicant): While the complete etiology of epithelial-derived cancers is not yet known, several correlative genetic and environmental factors have been identified. One specific class of genetic events receiving increasing attention as both a marker and a contributing factor of oncogenesis involves microsatellite length mutations, manifested as microsatellite alteration (MA) and microsatellite instability (MSI) (Forgacs et al., 2001; Woerner et al., 2001). Microsatellite repeats are common and often polymorphic in mammalian genomes. We have developed and verified algorithms for predicting microsatellites, which are most likely to be subject to frequent mutation (Fondon et al., 1998). Somatic microsatellite length mutations are commonly observed in colon, endometrial, breast, and stomach cancers, and have been shown to be a prominent feature of some lung cancers (Girard, et al., 2001; Forgacs, et al., 2001; Wistuba et al., 2000). MSI has been shown to be a manifestation of defects in DNA mismatch repair genes, and is a useful indicator of a class of defects in DNA mismatch repair. We hypothesize that both somatic and germline microsatellite mutation may play an important etiological role in the development and progression of some cancers, and it is critical to have knowledge of their mutational frequency, complexity, and diversity among types of epithelial-derived cancers, as well as an understanding of how they vary in different normal genetic backgrounds. We have inspected the genome for gene-associated microsatellites, and have identified over 10,000 loci within transcribed regions of genes that are likely to experience expansion and/or contraction mutations. Many of these are in coding regions, with 8% of these predicted to result in frame-shifting variants when altered and some are in tumor suppressors (Wren et al., 2001). In Aim 1 we will refine methods for predicting microsatellite mutation events associated with cancer progression, scan the recently completed human genome for predicted repeat polymorphisms in genes known or suspected to have a role in tumorigenesis, and select -150 of these loci for genotyping (Aim 2) in a panel of DNAs from lung, breast, ovarian and colorectal cancer cell lines, including many with matched B lymphocyte DNAs in addition to primary tumor and normal blood DNAs. We will also (Aim 3) investigate the effects of these mutations identified in Aim 2 on splicing by correlating them with the results of a quantitative global survey of splicing isoforms.