【摘要】 目的:分析胃癌组织微卫星不稳定性、hMLH1蛋白表达以及两者的关系。方法:选取65例胃癌组织标本,常规酚-氯仿法提取DNA,选取基因组上的五个微卫星位点BAT26、BAT25、D5S346、D2S123和D17S250,进行PCR扩增,扩增产物加入GeneScan 500size standard共同热变性后,用60g/L的SLPA添加8mol/L尿素做筛分递质的毛细管电泳进行分析。被检测的5个微卫星位点如出现≥2个位点的不稳定,定为微卫星的高度不稳定(MSI-H),1个位点出现不稳定定为微卫星的低度不稳定(MSI-L),没有位点出现不稳定定为微卫星稳定(MSS),石蜡切片常规免疫组织化学SP方法检测hMLH1蛋白的表达。结果65例胃癌组织中,有21例(32.3%)表现为MSI-H,20例(30.8%)有hMLH1蛋白表达的缺失。在21例MSI-H的胃癌组织中,18例(85.7%)有hMLH1蛋白表达的缺失。44例MSI-L/MSS的胃癌组织中仅2例(4.5%)有hMLH1表达的缺失。胃癌的MSI-H与hMLH1蛋白表达的缺失高度相关,P<0.01。其中,25例高分化腺癌有7例(28.0%)表现为MSI-H,6例(24.0%)有hMLH1表达的缺失;40例中低分化腺癌14例(35.0%)表现为MSI-H,12例(30.0%)有hMLH1蛋白表达的缺失。26例早期癌有1例(3.8%)表现为MSI-H,2例(7.7%)有hMLH1蛋白表达的缺失;39例中晚期癌20例(51.3%)表现为MSI-H,17例(43.6%)有hMLH1蛋白表达的缺失。微卫星不稳定在中晚期胃癌明显高于早期胃癌(P<0.01),但在不同分化程度的胃癌间差异无统计学意义;hMLH1蛋白表达缺失与分化程度无关,但在早期与中晚期的胃癌间差异有统计学意义,P<0.05。结论:由hMLH1基因所致细胞修复功能缺陷与部分胃癌的发生有关,而与胃癌的生物学行为无关;胃癌的微卫星不稳定性随着肿瘤的演进而增加。更多还原

【Abstract】 OBJECTIVE:To detect the microsatellite instability(MSI) and expression of hMLH1 gene in gastric cancinoma tissues,and explore the molecular biological mechanism underlying the carcinogenesis of gastric cancinoma.METHODS:A total of 65 cases of gastric cancinomas tissues from surgical excision samples were collected.The microsatellite locus of BAT-26,BAT25,D5S346,D2S123 and D17S250 were amplified by PCR after DNA abstraction.Then PCR products were mixed together with GeneScan 500 size standard followed by heat denaturation.Microsatellites were analyzed by capillary electrophoresis with 60 g/L SLPA and 8 mol/L urea as sieving medium.Carcinoma were characterized as high MSI(MSI-H) if they manifested instability at two or more markers,low MSI(MSI-L) if unstable at only one marker,and microsatellite stable(MSS) if they showed no instability at any marker.Expression of hMLH1 gene hMLH1 was detected by immunohistochimical staining.RESULTS:Of the 65 cases of gastric carcinomas,21 cases(32.3%) showed MSI-H and 20 cases(30.8%) showed loss of hMLH1.In the 21 cases of the MSI,18 cases(85.7%) were accompanied by loss of hMLH1 expression,whereas in the 44 cases of the MSI-L/MSS,only 2 cases(4.5%) were accompanied by loss of hMLH1 expression.MSI was significantly related with hMLH1 deficiency(P<0.01).Of the 25 cases of well-differentiated carcinomas,7 cases(28.0%) manifested MSI-H and 6 cases(24.0%) showed protein defection of hMLH1.Comparatively,14 cases(35.0%) manifested MSI-H and 12 cases(30.0%) showed protein defection of hMLH1 in 40 cases poorly-differentiated carcinomas.Of the 26 cases early stage carcinomas,only 1 cases(3.8%) manifested MSI-H and 2 cases(7.7%) showed protein defection of hMLH1,whereas 20 cases(51.3%) manifested MSI-H and 17 cases(43.6%) showed protein defection of hMLH1 in 39 cases advanced carcinomas.The MSI frequency was higher in advanced stage than that in early stage of gastric carcinoma and the difference was significant(P<0.01),but no difference between well and poorly differentiated gastric carcinoma.The loss frequency of hMLH1 expression was higher in advanced stage than that in early stage of gastric carcinoma and the difference was significant(P<0.05),but no difference between well and poorly differentiated gastric carcinoma.CONCLUSIONS:The defect of hMLH1 may be involved in the carcinogenesis of a subset of gastric cancer but not in the biologic behavior.MSI frequency increases with the progression of gastric carcinoma.更多还原