人大肠癌癌旁不同部位组织中DNA甲基转移酶的表达差异

DNMTs are differentially expressed in tissues at different distances from colorectal cancer lesions

目的:检测D N A甲基转移酶(D N A methyltransferase,DNMT)在距大肠癌病灶不同距离组织中的表达差异,以探讨其表达在大肠癌癌变早期的意义.方法:实验共取25例中分化结肠癌标本,从距离大肠癌病灶近端10、5、2 cm获取组织样本,并分别命名为1、2、3号位组织样本,用免疫组织化学以及Western blot检测3个部位组织中DNMT的表达及分布情况.结果:免疫组织化学实验显示DNMT1在1、2、3号位中的校正吸光度值(c o r r e c t e d absorbance,CA)分别为0.359484±0.037511、0.460941±0.032146、0.498767±0.021143,呈递增趋势(P<0.05).Western blot实验结果也显示DNMT1在1、2、3号位中的表达依次增加,其在3个部位的相对表达量分别为0.7173、0.7418、0.8296.DNMT3A在2、3号位的表达均高于1号位(P<0.05),但在2、3号位之间的表达差异无统计学意义(P>0.05).DNMT3B的表达变化与DNMT3A相同.结论:DNMTs在1、2、3号位表达增加,说明DNMTs在大肠癌的启动及演进过程中发挥了重要作用.

AIM： To detect the expression of DNA methyltransferases （DNMTs） in tissues at different distances from colorectal cancer lesions. METHODS： Immunohistochemistry and Western blot were used to detect the expression of DNMTs in 25 colorectal cancer specimens and matched tumor-adjacent tissues （〉 5 cm apart from the tumor and 2 cm apart from the tumor） and normal tissues （〉 10 cm apart from the tumor）. None of the patients received preoperative treatments such as radiotherapy or chemotherapy. RESULTS： The corrected absorbance of DNMT1 detected by immunohistochemistry in tissues 〉 10, 〉 5 and 2 cm apart from the tumor was 0.359484 ± 0.037511, 0.460941 ± 0.032146 and 0.498767 ± 0.021143, respectively, showing an upward-trend （P 〈 0.05）. The corresponding relative expression levels of DNMT1detected by Western blot were 0.7173, 0.7418 and 0.8296. Expression of DNMT3A in tissues 〉 5 and 〉 10 cm apart from the tumor was significantly higher than that in tissues 2 cm apart from the tumor （both P 〈 0. 05）, although expression of DNMT3A showed no significant difference between tissues 〉 5 and 〉 10 cm apart from the tumor （P 〉 0. 05）. Expression of DNMT3B in the above tissues was similar to that of DNMT3A. CONCLUSION： Up-regulation of DNMT1, DNMT3A and DNMT3B may play a significant role in the occurrence of colorectal carcinoma.