Objective To investigate the methylation status of the CpG island of tumor suppressor gene PCDH 8 and its clinical significance in bladder cancer tissues .Methods 79 cases of primary bladder transitional cell carcinoma and 20 cases of normal blad-der mucosa tissue were collected ,and then the promoter methylation status of PCDH8 gene was examined by methylation specific PCR (MSP) ,and correlated with clinical pathological data for statistical analysis .Results We found that no PCDH8 gene methyla-tion was detected in 20 normal bladder mucous tissues ,while PCDH8 promoter methylation was found in 44 cases of total 79 prima-ry bladder transitional cell carcinoma tissues ,the methylation rate was 55 .7% ,and the difference was statistical significant between normal bladder mucous group and bladder cancer group (P<0 .01) .The promoter methylation of PCDH8 gene in bladder transi-tional cell carcinoma tissues did not correlate with patient′s age ,gender ,tumor number (P>0 .05) ,the methylation rate of PCDH8 gene in tumors whose diameter more than 3 cm was 72 .7% ,while the methylation rate of PCDH8 gene in tumors whose diameter less than 3 cm was 43 .5% ,and the difference was significant(P< 0 .05) .The methylation rate of PCDH8 gene in the papillary tumor was 48 .2% ,while the methylation rate of PCDH8 gene in the unpapillary tumor was 73 .9% ,and the difference was signifi-cant(P<0 .05) .The methylation rate of PCDH8 gene in recurrent tumors was 71 .1% ,while the methylation rate of PCDH8 gene in primary tumors was 35 .3% ,and the difference was significant(P<0 .05) .The methylation rate of PCDH8 gene in tumors with G1 ,G2 phase was 43 .4% ,while the methylation rate of PCDH8 gene in tumors with G3 was 80 .8% ,and the difference was signifi-cant(P<0 .05) .The methylation rate of PCDH8 gene in the tumors with Ta T1 phase was 43 .7% ,while the methylation rate of PCDH8 gene in tumors with T2 T4 was 74 .2% ,and the difference was significant(P<0 .05) .Our result suggested that PCDH8 gene methylation was associated with tumor growth ,morphology ,recurrence ,poor differentiation and tumor invasion (P<0 .05) . Conclusion The promoter methylation of tumor suppressor gene PCDH8 is closely correlated with the occurrence and development of primary bladder transitional cell carcinoma .The promoter methylation of PCDH8 gene could be used as molecular markers of ear-ly diagnosis ,monitoring and prognosis biomarker in bladder cancer .%目的：研究膀胱癌组织中抑癌基因PCDH8（原钙黏蛋白8，protocadherin 8）启动子区CPG岛甲基化状态及临床意义。方法收集79例原发性膀胱移行细胞癌组织和20例正常膀胱黏膜组织，应用甲基化特异性PCR（MSP）检测PCDH8基因启动子区CPG岛的甲基化状态，并结合临床病理资料进行分析。结果20例正常膀胱黏膜组织中均未检测到PCDH8基因甲基化，79例膀胱癌组织中44例检测到PCD H8基因启动子区甲基化，甲基化率为55．7％，两组相比差异有统计学意义（ P＜0．01）；膀胱癌组织中PCDH8基因CPG岛启动子区甲基化与患者的年龄、性别、肿瘤数目无关（P＞0．05）；直径小于或等于3 cm的肿瘤组织中PCDH8基因甲基化率为43．5％，＞3 cm的肿瘤组织中PCDH8基因甲基化率为72．7％，差异有统计学意义（P＜0．05）；乳头状肿瘤中PCDH8基因的甲基化率为48．2％，非乳头状肿瘤中PCDH8基因的甲基化率为73．9％，差异有统计学意义（P＜0．05）；复发性肿瘤中PCDH8基因甲基化率为71．1％，原发性肿瘤中 PCDH8基因的甲基化率为35．3％，差异有统计学意义；G1～G2膀胱癌PCDH8基因的甲基化率为43．4％，G3膀胱癌的甲基化率为80．8％，差异有统计学意义（P＜0．05）；PCDH8基因在Ta～T1期肿瘤的PCDH8基因甲基化率为43．7％，T2～ T4期肿瘤中的甲基化率为74．2％，差异有统计学意义（P＜0．05）。结论抑癌基因PCDH8启动子区CPG岛甲基化与膀胱移行细胞癌的发生、发展相关，PCDH8基因启动子区CPG岛的甲基化有可能成为膀胱癌早期诊断、监测复发和判断预后的分子标志物。
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