应用二维DNA电泳检测大肠癌错配修复基因hMLH1突变

Detection of mismatching repair gene hMLH1 mutation in colorectal cancer by two-dimentional DNA electrophoresis

目的 探讨大肠癌错配修复基因hMLH1突变与微卫星不稳 (MSI)的关系。方法 采用二维DNA电泳和DNA测序技术检测hMLH1突变 ;采用PCR为基础的方法检测MSI。结果 76例大肠癌中检出hMLH1基因突变 8例 ,突变率为 10 .5% ,检出MSI 2 0例 ,检出率为 2 6 .3%。右侧大肠癌hMLH1突变和MSI的检出率显著高于左侧大肠癌 (P <0 .0 5 ) ,hMLH1突变与肿瘤大小、分化程度、组织学类型、浸润深度、淋巴结转移和临床病理分期无显著相关。将MSI分为高频率MSI(MSI H ,≥ 2个位点 ) 10例、低频率MSI(MSI L ,仅为 1个位点 ) 10例和MSI阴性 (MSS) 5 6例 3组 ,8例hMLH1基因突变均发生于MSI H组 ,而MSI L和MSS组未见有突变者。结论 hMLH1基因突变与MSI多发生于右侧大肠癌 。

Objective To evaluate the role of hMLH1 mutation in colorectal carcinogenesis and to correlate hMLH1 mutation with microsatellite instability (MSI) in colorectal carcinomas. Methods hMLH1 mutation was measured by two dimentional DNA electrophoresis and DNA sequencing;MSI was analyzed by PCR based methods.Results Seventy six cases of sporadic colorectel carcinoma were studied for hMLH1 mutation and MSI. hMLH1 mutaions were detected in 8(10.5 %). By using five microsatellite markers, MSI in at least one locus was detected in 20 of 76(26.3 %)of the tumors analyzed. Frequences of hMLH1 mutation and MSI in the right colorectal cancer were significantly higher than those in the left colorectal cancer ( P <0.05). No association was observed between hMLH1 mutation or MSI and tumor size, differentiation, histological type, depth of invasion, metastasis or stages( P >0.05). Eight hMLH1 mutations were all detected in high frequence MSI (≥2 loci, n =10), but no mutation was found in low frequence MSI (only one locus, n =9) or MSS(tumor lacking MSI or stable, n =51). Conclusions hMLH1 mutation and MSI are related to the right colorectal cancer and hMLH1 mutation is involved in carcinogenesis of some gastric cancer with high frequence MSI.