DAPK基因CpG岛的异常甲基化在人膀胱癌组织中的意义

目的 探讨DAPK基因CpG岛的异常甲基化在膀胱癌组织中的意义.方法 选择临床膀胱癌组织标本24例和癌旁组织标本22例进行研究.用免疫组织化学和Western blot方法分别检测DAPK基因和DNMTl基因在不同组织中的表达情况.采用甲基化特异PCR(MSP)方法检测不同组织标本中DAPK基因的甲基化状态.结合上述结果分析DAPK基因甲基化及其表达状态与肿瘤之间的关系.结果 DAPK基因表达于细胞质及胞膜,在正常膀胱黏膜中强表达,在膀胱癌组织中弱表达或不表达.在膀胱癌组织中有14例(14/24,58.3%)检测到DAPK基因的甲基化改变,而正常组织中未检测到其甲基化.甲基化改变与肿瘤病理分级无显著相关性,但是与肿瘤肌层浸润(P＜0.05)及复发(P＜.05)明显相关.结论 DAPK基因的甲基化改变可能是肿瘤复发的一个重要预测指标.肿瘤组织中DNMTl的高表达提示其在调节肿瘤组织抑癌基因甲基化中发挥重要作用.

Analysis of CpG island methylation of DAPK in tissues of human bladder cancer

Objective To investigate the implications of CpG island methylation of DAPK in tissues of human bladder cancer.Methods Twenty-four fresh bladder cancer samples and 22 cases of normal urothelia were collected.Methylation specific PCR was used to detect the CpG island methylation of DAPK in two groups of samples.Western bloting was performed to detect the protein expression of DAPK and DNMT1 in bladder samples.Results Aberrant methylation of DAPK was observed in 14 (58.3%) of 24 cases of tumor tissues,and no methylation was founded in normal tissues.There was a significant relationship between aberrant mcthylation of DAPK with muscle invasiveness ( P＜0.05 ) and tumor recurrence ( P＜0.05 ).Western blotting and immunohistocbemistry revealed that the protein expression of DAPK in bladder cancer samples was lower than in the normal tissues.Moreover,tbe expression of DNMTl protein was detectable in 18 (75%) of 24 bladder cancer samples but not in tumor tissues.Conclusion The aberrant methylation of DAPK tends to happen in recurrent tumors,which indicates that the methylation of DAPK may present us a useful molecule marker to prognose the recurrence of bladder cancer.Also the present study further implies that DNMT1 plays an important role in the hypermethylation of DAPK.