大肠癌微卫星不稳定性及其临床意义

Study of microsatellite instability of colotectal cancer and its clinical significance

目的 了解大肠癌微卫星不稳定性（ｍｉｃｒｏｓａｔｅｌｌｉｔｅｉｎｓｔａｂｉｌｉｔｙ， ＭＩ） 情况。方法 用６ 个微卫星位点检测ＰＣＲ扩增所选位点ＰＣＲ产物用８％ 变性聚丙烯酰胺凝胶电泳、银染。结果 ６０ 例大肠癌中，２０ 例表现ＭＩ，其中１１ 例为复制错误（ｒｅｐｌｉｃａｔｉｏｎ ｅｒｒｏｒｓ，ＲＥＲ）阳性。ＲＥＲ阳性与ＲＥＲ阴性大肠癌患者相比，发病年龄较年轻，一级亲属有恶性肿瘤病史者明显高于ＲＥＲ阴性，倾向位于结肠，呈浸润性生长，Ⅲ～Ⅳ期比例高。５ 例大肠癌伴大肠腺瘤病例中，４ 例腺瘤有ＭＩ。结论 中国人大肠癌ＭＩ发生率介于文献报道之间，ＭＩ为大肠癌形成过程中的早期分子事件，ＲＥＲ为肿瘤易感指标之一。

Objective To evaluate microsatellite instability (MI) of colorectal cancer in China. Method Replication error (RER) status was examined by using 6 microsatellite loci D2S123, D2S119, D13S160, D8S282, D3S1293 and D18S58. The loci were amplified by PCR technique. The PCR products were separated on denatured polyacrylamide gel and then silver stained. Results Of the 60 cases of colorectal cancer studied, 20 (33.3%) showed MI, 11 cases (18.3%) were RER positive. In 11 RER positive cases, 4(36.4%) had family history of malignant tumor, while only 8.2% had positive family history in RER negative cases ( P <0.05). The RER positive patients were younger, and their cancer occurred more frequently in the colon with invasive type of growth. There were more cancers in Dukes III and IV in the RER positive patients. In 5 colorectal cancer cases associated with adenoma, MI was detectable in 4 adenomas. Conclusion MI phenotype might be present ubiquitously in sporadic colorectal cancers in China. Its frequency is comparable to that of other reports. MI is a relatively early molecular event in the genesis of colorectal cancers. RER is a useful sign of susceptibility to the development of colorectal cancer.