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目的 探讨幽门螺杆菌 (H .pylori)感染与hMLH1和APC突变及甲基化异常的关系。方法 采用改良的Giemsa染色和PCR方法检测H .pylori;采用二维DNA电泳、DGGE电泳和DNA测序技术检测hMLH1和APC突变 ;采用甲基化特异性PCR检测hMLH1启动子区的甲基化状态 ;采用以PCR为基础的方法检测微卫星DNA不稳 (MSI)。结果 6 8例胃癌中检出hMLH1基因突变 3例 ,突变率为 4 4 %。APC基因突变 15例 ,突变率为 2 2 1%。hMLH1突变与肿瘤大小、分化程度、组织学类型、浸润深度和临床病理分期无显著相关。APC突变率在肠型胃癌显著高于弥漫型胃癌 (P <0 0 5 )。正常胃黏膜未见hMLH1高甲基化。 6 8例胃癌中检出hMLH1高甲基化 11例 ,占 16 2 % ,均为去甲基化和高甲基化并存。将MSI分为高频率MSI(MSI H ,≥ 2个位点 ) 8例、低频率MSI(MSI L ,仅为 1个位点 ) 9例和MSI阴性 (MSS) 5 1例三组 ,结果 3例hMLH1基因突变均发生于MSI H组 ,而MSI L和MSS组未见 ;APC突变均发生于MSI L和MSS组 ,而MSI H组未发现有APC突变者 ;MSI H组hMLH1高甲基化的检出率显著高于MSI L和MSS组 (P <0 0 1)。hMLH1和APC基因突变及hMLH1甲基化在H pylori阳性组和H pylori阴性组及CagA+ 组和CagA-组检出率差异均无统计学意义 (P>0 0 5 )。结论 hMLH1突变和
Objective To investigate the relationship between H. pylori infection and the mutation and methylation of hMLH1 and APC. Methods The H.pylori was detected by modified Giemsa staining and PCR. The mutations of hMLH1 and APC were detected by two-dimensional DNA electrophoresis, DGGE electrophoresis and DNA sequencing. The methylation status of hMLH1 promoter region was detected by methylation-specific PCR. Microsatellite DNA destabilization (MSI) was detected using a PCR-based approach. Results Three cases of hMLH1 gene mutation were found in 68 cases of gastric cancer, the mutation rate was 44%. APC gene mutation in 15 cases, the mutation rate was 22.1%. The hMLH1 mutation had no significant correlation with tumor size, differentiation, histological type, depth of invasion and clinicopathologic stage. The mutation rate of APC in intestinal type gastric cancer was significantly higher than that in diffuse type gastric cancer (P <0.05). Normal gastric mucosa no hMLH1 hypermethylation. Eleven cases (16.2%) of hMLH1 hypermethylation were detected in 68 cases of gastric cancer, both of which were demethylated and hypermethylated. MSI was divided into high frequency MSI (MSI H, ≥ 2 loci) in 8 cases, low frequency MSI (MSI L, only 1 locus) and MSI negative MSS 51 cases in three groups, the results of 3 Cases of hMLH1 gene mutations occurred in the MSI H group, and MSI L and MSS group was not seen; APC mutation occurred in the MSI L and MSS group, MSI H group was not found APC mutation; MSI H group hMLH1 hypermethylation The rates were significantly higher than those in MSI L and MSS groups (P <0.01). The mutation rates of hMLH1 and APC and methylation of hMLH1 in H pylori positive group, H pylori negative group, CagA + group and CagA - group were not significantly different (P> 0.05). Conclusions hMLH1 mutations and