摘要
目的探讨微卫星不稳定性（MSI）与3号染色体短臂杂合性缺失（LOH）在乳腺癌发生机制中的作用及其临床病理学意义。方法采用PCR—SSLP及银染方法检测41例乳腺癌和13例癌前病变中MSI状态以及3p上11个微卫星位点LOH发生情况；应用免疫组化SP法检测错配修复（MMR）基因hMLH1、hMSH2和3p上相关基因的表达情况。结果（1）乳腺癌MSI发生率为36．6％，低分化乳腺癌MSI发生率明显高于高中分化组；癌前病变的发生率为15．4％；良性增生均表现微卫星稳定。（2）乳腺癌中微卫星异常主要分布于D3S1766、D2S2739和TP533个位点，癌前病变和乳腺癌具有相同的高频不稳定位点D3S1766和D2S2739。（3）97．0％乳腺癌患者发生3pLOH，检出率较高的位点分别是D3S1295、D3S1029和D3S1038。癌前病变患者3pLOH发生率为41．7％，缺失率较高的位点是D3S1295和D3S1029。（4）hMLHl和hMSH2蛋白在乳腺癌中阳性表达率分别为45．0％和40．0％，在癌前病变中分别为61．5％和76．9％，均明显低于良性增生组（P〈0．05）。乳腺癌中两种蛋白阳性率与组织学分级相关（P〈0．05），高分化组明显高于低中分化组。MSI＋乳腺癌和癌前病变均表现MMR蛋白表达缺失。结论错配修复基因表达缺陷和MSI是乳腺癌多步骤发展过程的早期事件，在进展阶段MSI与乳腺癌低分化相关；D3S1766和D2S2739可能是检测乳腺癌与癌前病变MSI较敏感的位点。3p最小共同缺失区位于3p14-p25，提示该区域有与乳腺肿瘤发生发展相关并影响其生物学行为的候选抑癌基因。
Objective To investigate the incidence and clinicopathologic significance of MSI and LOH on 3P in breast carcinoma and its precancerous lesions, intraductal papillary adenoma and ductal carcinoma in situ. Methods 41 paired sporadic invasive breast carcinomas, 13 archival precancerous lesion specimens of the breast and 14 couples of benign hyperplasia were collected. Twelve microsatellites on chromosomes 2p, 3p, 5% 6q, 16q, 17q, eleven markers on chromosome 3p were amplified for MSI and LOH, respectively, by polymerase chain reaction （PCR） with designed primers and detecting after polyacrylamide gel electrophoresis. In addition, the expression of protein of hMSH2, hMLH1, FHIT, ER, and PR were detected by immunohistochemistry. Results MSI was observed, at least two microsatellite markers, in 15 out of 41 （36. 6% ） of the carcinomas, almost all belonging to poorly or intermediately differentiated carcinoma. Instability was shown in 9 of the 13 cases of precancerous lesions, but only 2 among them had more than 2 MSI sites. There was no MSI in benign hyperplasia. MSI was targeted predominately at D3S1766, D2S2739 in both carcinomas and precancerous lesions. Of the 11 loci examined, D3S1295, D3S1029 and D3S1038 were identified as the locus with most frequent LOH which were all correlated significantly with some clinicopathological parameters such as histological type, lymph node metastasis in breast cancer, while D3S1295 and D3S1029 were the most frequent markers in precancerous lesions. LOH of D3S1295 had significant correlation with negative expression of FHIT. Positive expression of hMLH1 and hMSH2 protein was detected in breast carcinomas in scattered distribution and their positive rate was 45% and 40%, respectively. In precancerous lesions, hMLH1 and hMSH2 protein showed diffuse expression and their positive rate was 61.54% and 76.92%, respectively, significantly lower than that in the control tissues. Conclusion Defective expression of MMR genes is closely associated with the development of breast cancer. Genomic instability might play a role in the early stage during multi-step mammary carcinogenesis. MSI indicates poor histological differentiation in breast carcinoma. D3S1766 and D2S2739 might be the sensitive sites to detect MSI in breast carcinoma and precancerous lesions. The smallest common LOH deletion regions seem likely to be situated between 3p14 and 3p25, indicating the existence of breast tumor related genes in those regions and some of them might affect tumor development.
出处
《中华肿瘤杂志》
CAS
CSCD
北大核心
2007年第1期34-40,共7页
Chinese Journal of Oncology
基金
浙江省自然科学基金资助项目（302698）
关键词
乳腺肿瘤
癌前病变
微卫星不稳定性
杂合性缺失
DNA错配修复基因
Breast neoplasms
Precancerous lesion
Microsatellite instability（MSI）
Loss of beterozygosity（LOH）
Mismatch repair gene（MMR）
