Objective: To investigate the prognostic stratification value of MLH1 promoter methylation in a mismatch repair deficiency (dMMR)-type endometrioid endometrial carcinoma (EEC). Methods: A total of 338 patients with confirmed diagnosis of dMMR EEC at Third Hospital of Peking University Health Science Center, from July 2005 to June 2023 were analyzed. Based on the promoter methylation, they were classified into a dMMR methylated (dMMR MET) group (177 cases) and a dMMR nonmethylated (dMMR nonMET) group (127 cases). Somatic mutations were analyzed by targeted sequencing (196/425-gene panel), and transcriptomic differences were assessed by RNA sequencing (Master panel). We compared the clinicopathological characteristics, gene mutation/expression profiles, and molecular pathway activities systematically between the two groups. Results: Compared with the dMMR nonMET group, patients of the dMMR MET group were older significantly [(56.89±8.85) vs. (53.76±9.45) years, P=0.003] and had tumor size of larger diameters [(3.39±1.78) vs. (2.71±1.31) cm, P=0.014]. The menopausal proportion (66.9% vs. 48.8%, P=0.002) and the proportion with tumor buddings (47.5% vs. 30.4%, P=0.036) were higher. No significant differences were identified in FIGO stage, histologic grade, depth of myometrial invasion, lymphovascular invasion, or rate of lymph node metastasis (P>0.05). Mutational profiling revealed that the nonMET group had significantly higher mutation frequencies in CHD4, NF1, SMARCA4, and RET (P<0.05). Transcriptomic analysis demonstrated upregulation of immune-related genes (CCL21, CXCL2) in the MET group, and downregulation of epithelial-mesenchymal transition (EMT)-associated genes (SOX2, FOXA1). Both GO and KEGG enrichment analyses of different gene expression in the MET group demonstrated an association with the MAPK pathway. However, Hallmark pathway analysis showed no significant differences in overall pathway activity between the two groups. Survival analysis revealed no significant differences in progression-free survival (P=0.206) or overall survival (P=0.813) between the groups. Conclusions: The methylation status of the MLH1 promoter has limited value in predicting the prognosis of dMMR EEC. Molecular pathways heterogeneity between the methylated and nonmethylated subgroups suggests the necessity of integrate multi-dimensional indicators to optimize stratification strategies, instead of relying on a single epigenetic marker.
目的： 探讨MLH1启动子甲基化在错配修复缺陷（mismatch repair deficiency，dMMR）型子宫内膜样癌（endometrioid endometrial carcinoma，EEC）中的预后分层价值。 方法： 收集北京大学第三医院2005年7月至2023年6月338例经严格分子分型验证的dMMR型EEC患者，根据MLH1启动子甲基化状态分为dMMR甲基化组（177例）和dMMR非甲基化组（127例）。采用靶向测序（196/425基因Panel）分析体细胞突变，并基于RNA测序（Master panel）评估转录组差异，系统比较两组病例的临床病理、基因突变/表达谱特征及分子通路活性的差异。 结果： 甲基化组患者相较于非甲基化组患者，年龄［（56.89±8.85）岁比（53.76±9.45）岁，P=0.003］及肿瘤最大径［（3.39±1.78）cm比（2.71±1.31）cm，P=0.014］更大，绝经比例（66.9%比48.8%，P=0.002）及伴有肿瘤出芽比例（47.5%比30.4%，P=0.036）更高，两组在FIGO分期、组织学分级、肌层浸润深度、淋巴血管间隙侵犯及淋巴结转移率方面差异无统计学意义（P>0.05）。基因突变谱显示，非甲基化组CHD4、NF1、SMARCA4及RET突变频率显著升高（P<0.05）。转录组分析表明，甲基化组上调免疫调节基因（CCL21、CXCL2），下调EMT相关基因（SOX2、FOXA1）；根据差异表达基因对甲基化组行GO及KEGG富集分析均显示与MAPK通路相关。Hallmark通路分析显示两组间各通路活性差异无统计学意义。生存分析显示两组无进展生存期（P=0.206）及总生存期（P=0.813）差异无统计学意义。 结论： MLH1启动子甲基化状态对dMMR EEC预后预测价值有限。甲基化与非甲基化亚组的分子通路异质性提示需整合多维度指标优化分层策略，而非依赖单一表观遗传标志。.