胰腺癌组织和细胞系中DNA错配修复基因的甲基化和异常表达

Hypermethylation and aberrant expression of DNA mismatch repair gene in pancreatic cancer

目的:检测错配修复基因hMLH1、hMSH2和hMLH3在胰腺癌中的甲基化和表达状态,探讨错配修复缺陷在胰腺癌发病中的作用.方法:采用甲基化特异性PCR(MSP)检测hMLH1、hMSH2和hMLH3的甲基化状态,逆转录PCR(RT-PCR)检测hMLH1、hMSH2和hMLH3的表达状态.结果:在胰腺癌组织中hMLH1、hMSH2和hMLH3的甲基化频率分别为28.6%、46.4%和39.3%;在癌旁正常组织中分别为3.6%、10.7%和12.5%,上述各基因在胰腺癌中的甲基化频率均显著高于癌旁正常组织(hMLH1:χ2=12.97,P<0.01;hMSH2:χ2=17.50,P<0.01;hMLH3:χ2=10.47,P<0.01).在胰腺癌组织中分别有25.0%、50.0%和33.9%没有检出hMLH1、hMSH2和hMLH3表达.在癌旁正常组织中分别有7.1%、8.9%和16.1%,各基因在胰腺癌中的表达缺失频率均显著高于癌旁正常组织(hMLH1:χ2=6.62,P<0.05;hMSH2:χ2=22.73,P<0.01;hMLH3:χ2=4.76,P<0.05).hMLH1在胰腺癌细胞系PANC-1和CFPAC-1检出甲基化和表达消失.hMSH2在PC-3检出甲基化和表达消失.hMLH3在PC-3和PANC-1检出甲基化和表达亦消失.结论:在胰腺癌错配修复基因缺陷较普遍参与了部分胰腺癌的发病过程.

AIM： To determine the methylation and expression status of mismatch repair genes hMLH1, hMSH2 and hMLH3 and explore the role of mismatch repair defect in pancreatic cancer. METHODS： Methylation status of hMLH1, hMSH2 and hMLH3 was detected by methylation-specific polymerase chain reaction （MSP）, and the expression of hMLH1, hMSH2 and hMLH3 were determined by reverse-transcription PCR （RT-PCR）.RESULTS： The frequencies of methylation for hMLH1, hMSH2 and hMSH3 were 28.6%, 46.4% and 39.3%, respectively in pancreatic cancer tissues, and 3.6%, 10.7% and 12.5% in cancer-adjacent normal tissues, and there were significant differences between cancer and normal tissues （hMLHI： χ^2= 12.97, P 〈 0.01; hMSH2： χ^2 = 17.50, P 〈 0.01; hMLH3：χ^2 = 10.47, P 〈 0.01）. The frequencies of expression loss for hMLH1, hMSH2 and hMSH3 were 25.0%, 50.0% and 33.9%, respectively in pancreatic cancer tissues, and 7.1%, 8.9% and 16.1% in cancer-adjacent normal tissues, and there were also marked differences between cancer and normal tissues （hMLHI： χ^2 = 6.62, P 〈 0.05; hMSH2： χ^2= 22.73, P 〈 0.01; hMLH3： χ^2 = 4.76, P 〈 0.05）. Methylations of hMLH1, hMSH2 and hMLH3 were found in PANC-1, PC-3 and CF- PAC-1 cell lines, while expression loss of hMLH1 was observed in PANC-1 and CFPAC-1 cell lines, that of hMSH2 in PC-3 cell line and hMLH3 was observed in PC-3 and PANC-1 cell lines. CONCLUSION： Mismatch repair defect is common in pancreatic cancer and plays a role in pancreatic carcinogenesis.