家族背景大肠癌微卫星不稳定性、错配修复基因表达的研究

Study on Microsatellite Instability、MMR Gene Expression And Proliferation Kinetics In Colorectal Cancer With Familial Predisposition

目的:了解具有家族背景大肠癌微小卫星 DNA 不稳定性(MIN)、MMR 基因(hMLH1、hMSH2)表达及细胞增殖活性特征。方法:应用银染聚合酶链反应-单链构相多态性(PCR-SSCP)分析技术、免疫组化 SP 法和流式细胞术(FCM),对46例大肠癌进行研究。结果:与无家族史的原发性大肠癌相比,具有家族背景大肠癌 MIN 的表达增高(P<0.05);癌家族史、MIN 与大肠癌发病年龄轻、右半大肠癌、大肠外癌及低分化癌的发生率高均有明显关系(P<0.01,P<0.05);癌组织 hMLH1 表达阴性率及其切缘“正常”腺体 hMLH1 和 hMSH2 表达阴性率明显增高(P<0.05);而其 PCNA 标记指数、DNA 异倍体率则显著减低(P<0.01,P<0.05).hMLH1和 hMSH2表达阴性与 MIN 有显著的相关性(P<0.05).结论.MIN 在具有家族背景大肠癌中起着明显的作用。具有家族背景及 MIN阳性大肠癌肿瘤细胞及切缘“正常”腺体 hMLH1和 hMSH2突变率的增高,其增殖指标有所降低.

Objective:To evaluate the microsatellie instability (MIN)、expression of MMR gene(hMLH1、hMSH2) and proliferation kinetics in colorectal cancer (CRC) with familial predis- position.Methods:46 cases of CRC were studied using silver staining polymerase chain reaction- single strand conformation polymorphism (PCR-SSCP) technique、SP immunohistochemical method and flow cytometry.Results:In CRC with familial prediposition,the incidence of MIN- positive was higher than sporadic CRC(P<0.05).Familial predisposition and MIN-positive re- lated strongly with early age of cancer onset,the proclivity for proximal colonic,poor differentiat- ed and extracolorectal malignancy (P<0.01,P<0.05).The incidence of expression negative of hMLH1 in tumor tissue and hMLH1、hMSH2 in the margin mucosa resected was higher signifi- cantly (P<0.05).Its LI of PCNA and heteroploid rate of DNA decreased obviously (P<0.01,P <0.05).The expression negative of hMLH1 together with hMSH2 was corelated with MIN-posi- tive(P<0.05).Conclusions:In CRC with familial predisposition,MIN might be an important contributor.The rate of hMLH1 and hMSH2 mutation increased in tumor and the margin mucosa resected.And the proliferation activity of their cancer cell was lower.