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微卫不稳定(microsatellite instbility,MSI)又称复制错误(replication error,RER),其意义是肿瘤细胞与同一个体的正常组织细胞DNA相比,肿瘤细胞的基因组DNA中单个、二个、三个或四个核苷酸组成的重复序列长度发生了改变[1-2]。最初的研究认为,MSI是遗传性非息肉病性结直肠癌(hereditary nonpolyposis colorectal cancer,HNPCC)特征性的分子变化,与人类错配修复基因(mismatch repair,MMR)的种系突变有关。而后续研究发现一小部分的散发性大肠癌也存在着MSI现象,但这种MSI大都与hMLH1基因的启动子区高甲基化状态有关。
Microsatellite instability (MSI), also known as replication error (RER), is defined as a single, two, or three genomic DNA in tumor cells compared to normal tissue cells in the same individual Or four nucleotide repeats length has changed [1-2]. Initial studies suggest that MSI is a characteristic molecular change in hereditary nonpolyposis colorectal cancer (HNPCC) and is associated with germline mutations in human mismatch repair (MMR) genes. Follow-up study found that a small part of sporadic colorectal cancer also exists MSI phenomenon, but most of this MSI hMLH1 gene promoter hypermethylation state.