遗传性非息肉性结直肠癌患者腺瘤和癌组织微卫星基因型分析

背景：遗传性非息肉性结直肠癌（HNPCC）是一种由错配修复基因种系突变引起的常染色体显性遗传病，高度微卫星不稳定（MSI—H）为其分子生物学特征之一。目的：利用5个微卫星位点建立正常结直肠黏膜、结直肠腺瘤和癌组织的微卫星基因型，探讨HNPCC的MSI发生情况和MSI检测的临床意义。方法：纳入源自33个HNPCC家系的腺瘤28例和腺癌14例，其中4例为同步腺瘤-癌；以32例散发性结直肠腺瘤和24例散发性结直肠癌作为对照。选用BAT25、BAT26、D2S123、D5S346、D17S250五个微卫星位点行荧光标记聚合酶链反应（PCR），以GeneMapper软件分析PCR产物。通过与正常黏膜微卫星序列PCR片段长度进行比较，判定腺瘤和癌组织的MSI情况。结果：HNPCC腺瘤和癌组织MSI-H发生率分别显著高于散发性结直肠腺瘤和结直肠癌（64-3％对3．1％，71.4％对12．5％，P〈0．05）。4例同步腺瘤-癌均表现为MSI—H．其腺瘤和癌组织的MSI类型不同。结论：HNPCC腺瘤和癌组织MSI—H发生率高。同步腺瘤一癌来源于不同克隆。MSI检测可作为HNPCC的临床初筛方法。

Microsatellite Genotyping of Adenoma and Adenocarcinoma in Patients with Hereditary Nonpolyposis Colorectal Cancer

Background：Hereditary nonpolyposis colorectal cancer （HNPCC） is an autosomal dominant inherited disease caused by germ line mutation of mismatch repair gene. High-degree microsatellite instability （MSI-H） is one of the molecular biological characteristics of HNPCC. Aims： To investigate the MSI status in HNPCC and the clinical significance of MSI detection by genotyping of five microsatellite loci in normal colorectal mucosa, colorectal adenoma and adenocarcinoma. Methods： Twenty-eight adenomas, 14 adenocarcinomas from 33 HNPCC families were collected, among them, 4 were synchronous adenoma and adenocarcinoma. Thirty-two sporadic colorectal adenomas and 24 sporadic colorectal adenocarcinomas served as controls. BAT25, BAT26, D2S123, D5S346 and D17S250 microsatellite loci were amplified by polymerase chain reaction （PCR） with fluorescent primers, and the PCR products were analyzed by GeneMapper software. The MSI status of adenoma and adenocarcinoma was identified by comparing the microsatellite genotypes between neoplastic and normal tissues. Results： The incidence of MSI-H was significantly higher in HNPCC adenoma and adenocarcinoma than that in sporadic colorectal adenoma and adenocarcinoma （64.3% vs. 3.1%, 71.4% vs. 12.5%, respectively, P〈0.05）. MSI-H was present in all 4 synchronous adenoma and adenocarcinoma, and the microsatellite genotypes of adenoma and adenocarcinoma were different. Conclusions： The incidence of MSI-H in HNPCC adenoma and adenocarcinoma is high. The synchronous adenoma and adenocarcinoma are generated from different clones. MSI detection can be used as a preliminary clinical screening method for HNPCC.