[Expression and clinical significance of MMR protein and MLH1 promoter methylation testing in endometrial cancer].

Objective: To explore the expression and clinical significance of mismatch repair (MMR) protein and MLH1 promoter methylation testing in endometrial cancer (EC) . Methods: A total of 420 cases with EC diagnosed by the surgical pathology examination from the Department of Pathology of PLA General Hospital, MLH1, MSH2, MSH6 and PMS2 protein in EC were detected by immunohistochemistry and methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) testing. Results: (1) Of the 420 tumor cases, the total expression loss rate of MMR protein was 34.5% (145/420) , the expression loss rates of MLH1, MSH2, MSH6 and PMS2 protein were respectively 17.1% (72/420) , 8.1% (34/420) , 7.4% (31/420) , 26.2% (110/420) and loss rates of MLH1 and PMS2, MSH2 and MSH6 were16.7% (70/420) , 6.2% (26/420). When there was a loss of MMR protein expression, any one or more protein expression deletions in MLH1, PMS2, MSH2 and MSH6, it could be Lynch syndrome related endometrial carcinoma (LS-EC). The expression loss rate of MMR protein in the poorly differentiated endometrioid adenocarcinoma was higher than that in the well differentiated endometrioid adenocarcinoma (P<0.05). (2) The expression loss rate of MMR and PMS2 protein had statistically significant between the endometrioid adenocarcinoma and non-endometrioid adenocarcinoma (P<0.01). The expression loss rate of MSH2 protein had statistically significant in the stage Ⅲ (P<0.01). Moreover, there were also significant differences in depth of myometrial invasion and lymph node metastasis between the expression loss rate of MMR protein (P<0.05). (3) The expression loss rate of MLH1 protein was 72 cases and 57 cases had MLH1 promoter methylation testing (excluding those who were not qualified for DNA testing). The positive rate was 47.4% (27/57). Therefore, these patients were sporadic endometrial cancer, not non-LS-EC. Conclusions: MMR protein may be play an important role in the development of endometrial cancer and be indicated poor prognosis. Immunohistochemical staining and MLH1 promoter methylation detection may be play an important role in the screening of the LS-EC.目的： 探讨子宫内膜癌组织中错配修复（MMR）基因包括MLH1、MSH2、MSH6、PMS2基因的蛋白表达及MLH1甲基化的临床意义。 方法： 收集2007—2016年10年间解放军总医院病理科确诊为子宫内膜癌的组织蜡块共420份，采用免疫组化EnVision二步法检测子宫内膜癌组织中MLH1、MSH2、MSH6、PMS2蛋白的表达并分析其临床意义，当出现MMR蛋白表达缺失（即MLH1、PMS2、MSH2及MSH6中的任何1个或多个蛋白表达缺失）则高度疑为Lynch综合征相关子宫内膜癌（LS-EC）；进一步采用甲基化特异性多重连接探针扩增（MS-MLPA）技术检测其中MLH1蛋白表达缺失（72份）的子宫内膜癌组织中MLH1基因的甲基化状态，当出现MLH1基因甲基化阳性时，可判定该患者为散发性子宫内膜癌，而非LS-EC。 结果： （1）420份子宫内膜癌组织中，MMR蛋白总缺失率为34.5%（145/420），其中MLH1、MSH2、MSH6、PMS2蛋白缺失率分别为17.1%（72/420）、8.1%（34/420）、7.4%（31/420）、26.2%（110/420）；MLH1和PMS2蛋白的联合缺失率为16.7%（70/420）、MSH2和MSH6蛋白的联合缺失率仅为6.2%（26/420）。（2）病理类型为子宫内膜样癌与非子宫内膜样癌组织中MMR蛋白总缺失率（分别为32.4%、58.8%）、PMS2蛋白缺失率（分别为23.6%、55.9%）分别比较均有明显差异（P<0.01）。不同病理分化程度的子宫内膜样癌组织中MMR蛋白总缺失率及MLH1、MSH2、MSH6、PMS2蛋白缺失率分别比较均有明显差异（P<0.05）。不同手术病理分期的子宫内膜癌组织中MSH2蛋白缺失率（Ⅰ、Ⅱ、Ⅲ期分别为5.5%、10.6%、18.6%）比较有明显差异（P<0.01）。不同浸润深度的子宫内膜癌组织中MMR蛋白总缺失率（黏膜内、浅肌层、深肌层浸润分别为35.0%、30.8%、48.1%）比较有明显差异（P<0.05）。有、无淋巴结转移的子宫内膜癌组织中MMR蛋白总缺失率及MSH2、MSH6蛋白缺失率分别比较均有明显差异（P<0.05）。（3）72份MLH1蛋白表达缺失的子宫内膜癌组织中57份DNA质量检测合格，其中MLH1基因甲基化阳性27份，甲基化阳性率为47.4%（27/57）。 结论： 子宫内膜癌组织中MMR蛋白表达缺失可能提示患者预后不良。免疫组化方法及进一步的MLH1基因甲基化检测可作为初步筛查LS-EC的方法。.