慢传输性便秘患者结肠黏膜DNA甲基转移酶表达显著增高

Expression of DNA methyltransferase is significantly increased in the colonic mucosa of patients with slow transit constipation

目的研究DNA甲基转移酶(DNA methyltransferase,Dnmt)在慢传输性便秘(slow transit constipation,STC)结肠黏膜中的表达。方法收集2015年9月至2017年6月我科收治的8例STC患者乙状结肠标本,采用免疫组织化学染色、Western blot检测Dnmt1、Dnmt3a、Dnmt3b蛋白在结肠黏膜的表达情况,real-time qRT-PCR检测结肠黏膜Dnmt1、Dnmt3a、Dnmt3b mRNA相对表达量。对照组标本采用直肠癌患者术中切除的远离癌灶的近端乙状结肠。结果免疫组织化学染色结果显示:对照组Dnmt1、Dnmt3a、Dnmt3b IOD值分别为(705±362)、(538±206)、(359±238),STC组Dnmt1、Dnmt3a、Dnmt3b IOD值分别为(4 077±1 219)、(4 214±1 858)、(3 026±1 619),两组比较差异有统计学意义(P<0.05);Western blot检测结果显示:对照组Dnmt1、Dnmt3a、Dnmt3b蛋白相对表达量分别为(0.663±0.349)、(0.250±0.159)、(0.330±0.195),STC组Dnmt1、Dnmt3a、Dnmt3b蛋白相对表达量分别为(1.475±0.372)、(1.035±0.362)、(0.977±0.258),两组比较差异有统计学意义(P<0.05);Real-time qRT-PCR结果显示:对照组Dnmt1、Dnmt3a、Dnmt3b mRNA相对表达量分别为(0.285±0.121)、(0.069±0.021)、(0.512±0.112),STC组Dnmt1、Dnmt3a、Dnmt3b mRNA相对表达量分别为(0.563±0.172)、(0.340±0.083)、(0.964±0.219),两组比较差异有统计学意义(P<0.05)。结论 STC患者结肠黏膜Dnmt1、Dnmt3a、Dnmt3b表达显著增高,可能是STC发病的重要环节。

Objective To investigate the expression of DNA methyltransferase（ Dnmt） in the colonic mucosa of patients with slow transit constipation（ STC）. Methods Surgical specimens of the sigmoid colon were collected from 8 patients with STC and 8 patients with rectal cancer admitted in our hospital between September,2015 and June,2017. Only the adjacent colon tissues（ at least 10 cm from the tumor margin）from the rectal cancer patients were used to serve as the control. The expressions of Dnmt1,Dnmt3 a and Dnmt3 b proteins in the colonic mucosa were detected using immunochemistry and Western blotting,and their mRNA expressions were quantified with real-time qRT-PCR. Results The results of immunochemical staining showed that the integral optical densities（ IOD） of Dnmt1,Dnmt3 a and Dnmt3 b expressions in the control group were 705 ± 362,538 ± 206,and 359 ± 238,respectively,significantly lower than those in STC group（ 4 077 ± 1 219,4 214 ± 1 858,and 3 026 ± 1 619,respectively; P〈0. 05）. Western blotting also showed significantly lower relative expressions of Dnmt1,Dnmt3 a and Dnmt3 b proteins in the control group than in STC group（ 0. 663 ± 0. 349,0. 250 ± 0. 159,and 0. 330 ± 0. 195 vs 1. 475 ± 0. 372,1. 035 ± 0. 362,and 0. 977 ± 0. 258,respectively; P〈0. 05）. Real-time qRT-PCR yielded consistent results of the relative expressions of Dnmt1,Dnmt3 a and Dnmt3 b mRNAs in the control and STC groups（ 0. 285 ± 0. 121,0. 069 ±0. 021,and 0. 512 ± 0. 112 vs 0. 563 ± 0. 172,0. 340 ± 0. 083,and 0. 964 ± 0. 219,respectively; P〈0. 05）. Conclusion High expressions of Dnmt1,Dnmt3 a and Dnmt3 b in the colonic mucosa may be an important factor in the pathogenesis of STC.