目的:通过研究结直肠锯齿状病变组织中h-MLH1基因启动子区CpG岛甲基化及蛋白表达,探讨h-MLH1启动子甲基化状态与蛋白表达相关性及在锯齿状癌变通路中的作用,并分析h-MLH1基因在不同年龄层段甲基化程度。方法:收集北京军区总医院病理科2007-01-01-2012-12-31诊断为锯齿状病变标本225例,其中包括96例增生性息肉(hyperplastic polyp,HP)、61例广基(无蒂)锯齿状腺瘤/息肉(sessile serrated adenoma/polyp,SSA/P)和68例传统锯齿状腺瘤(traditional serrated adenoma,TSA);同时收集同院同期的54例管状腺瘤(tubular adenoma,TA)、69例结直肠癌(colorectal cancer,CRC)和42例正常结直肠黏膜组织作为对照。应用Taqman探针qPCR(MethyLight)方法检测各组织中h-MLH1基因CpG岛甲基化状态,同时采用免疫组织化学方法检测其蛋白表达水平,其中随机抽取锯齿状病变116例(HP 52例、SSA/P 41例、TSA 23例)、TA 20例、CRC 24例和正常结直肠黏膜组织24例,并将其甲基化状态与相应的蛋白表达水平及临床病理学资料进行统计学分析。结果:正常、TA、HP、SSA/P、TSA和CRC组织中,h-MLH1基因启动子CpG岛甲基化阳性表达率分别为9.24%(4/42)、40.74%(22/54)、22.92%(22/96)、45.90%(28/61)、61.76%(42/68)和52.17%(36/69)。HP组与正常、SSA/P、TSA及CRC组之间比较,正常组与SSA/P及TSA组之间比较,差异均有统计学意义,P<0.05;其余各组之间比较,差异均无统计学意义,P>0.05。正常、TA、HP、SSA/P、TSA和CRC组织中,h-MLH1蛋白阳性表达率分别为100%(24/24)、80.00%(16/20)、98.08%(51/52)、75.61%(31/41)、69.57%(16/23)和70.83%(17/24)。正常组与HP、SSA/P、TSA、TA、CRC组之间比较,差异均有统计学意义,P<0.05;其余各组之间比较,差异均无统计学意义,P>0.05。TA、SSA/P和TSA组中,h-MLH1基因甲基化与其蛋白表达差异均有统计学意义(P<0.05),且呈负相关,相关系数γ分别为-0.553、-0.497、和-0.473。TA、HP、SSA/P和TSA组中,h-MLH1基因甲基化与年龄差异均有统计学意义(P<0.05),且呈正相关,相关系数γ分别为0.475、0.289、0.450和0.575。结论:结直肠锯齿状病变组织中h-MLH1基因甲基化可能导致其蛋白表达下调,与锯齿状病变的发生和发展密切相关,同时,h-MLH1基因甲基化又可能与年龄相关,随年龄增长,甲基化程度越高。 OBJECTIVE: To investigate the relationship between the methylation status and protein expression of h-MLH1 promoter and its role in serrated carcinogenesis through the study of CpG island methylation and protein expression of h-MLH1 promoter in the serrated lesion of colorectal Role, and analysis of h-MLH1 gene methylation in different age groups. METHODS: Totally 225 cases of serrated lesions were collected from Department of Pathology, Beijing Military Region General Hospital from January 2007 to January 31, 2012. 96 cases of hyperplastic polyp (HP), 61 cases of broad base ), Sessile serrated adenoma / polyp (SSA / P) and 68 cases of traditional serrated adenoma (TSA). At the same time, 54 cases of tubular adenoma (TA) , 69 cases of colorectal cancer (CRC) and 42 cases of normal colorectal mucosa as a control. The methylation status of CpG island of h-MLH1 gene in each tissue was detected by Taqman probe qPCR (MethyLight) method. Meanwhile, the protein expression level of hCGH1 gene was detected by immunohistochemical method. Among them, 116 cases of serrated lesions (HP 52 cases, SSA / P 41 cases, TSA 23 cases), TA 20 cases, CRC 24 cases and normal colorectal mucosa tissue 24 cases, and their methylation status and the corresponding protein expression levels and clinicopathological data were statistically analyzed. Results: The positive rates of CpG island methylation in promoter region of h-MLH1 gene in normal, TA, HP, SSA / P, TSA and CRC tissues were 9.24% (4/42) and 40.74% (22/54) 22.92% (22/96), 45.90% (28/61), 61.76% (42/68) and 52.17% (36/69). There was significant difference between HP group and normal group, SSA / P, TSA and CRC group, there was significant difference between normal group and SSA / P group and TSA group, P <0.05; among the other groups, the difference was No statistical significance, P> 0.05. The positive rates of h-MLH1 protein in normal, TA, HP, SSA / P, TSA and CRC tissues were 100% (24/24), 80.00% (16/20), 98.08% (51/52), 75.61 % (31/41), 69.57% (16/23) and 70.83% (17/24). The difference between the normal group and the group of HP, SSA / P, TSA, TA and CRC was statistically significant (P <0.05). There was no significant difference between the other groups (P> 0.05). The methylation of h-MLH1 gene and its protein expression in the TA, SSA / P and TSA groups were statistically significant (P <0.05), and negatively correlated, the correlation coefficients γ were -0.553, -0.497, 0.473. There was a significant positive correlation between h-MLH1 gene methylation and age in TA, HP, SSA / P and TSA groups (P <0.05), and the correlation coefficients γ were 0.475,0.289,0.450 and 0.575 respectively. Conclusion: The methylation of h-MLH1 gene in colorectal serrated lesions may result in the down-regulation of its protein expression, which is closely related to the occurrence and development of serrated lesions. Meanwhile, the methylation of h-MLH1 gene may be related to age, with With age, the higher the degree of methylation.