上尿路尿路上皮癌中RASSF1A基因启动子区域的甲基化状态及其临床意义

目的：通过检测上尿路尿路上皮癌(upper tract urothelial carcinoma，UTUC)组织中RAS相关结构域家族蛋白1异构体A(RAS-association domain family protein 1 isoform A，RASSF1A)基因启动子区域的甲基化状态，探讨RASSF1A基因异常甲基化与患者临床病理特征以及术后复发的关系。方法： 采用回顾性分析方法，共入选687例在北京大学第一医院泌尿外科接受手术的UTUC患者，通过甲基化特异性聚合酶链反应的方法对RASSF1A基因启动子区域的甲基化状态进行检测。结果： UTUC组织中RASSF1A基因的甲基化率为26.6%（183/687）,RASSF1A基因异常甲基化与患者年龄、性别、肿瘤多发、术前输尿管镜检查、根治性手术、肿瘤直径及合并原位癌均无相关性(P＞0.05)，但分别与患者吸烟史(P=0.044)、患侧肾积水(P＜0.001)、肿瘤位置(P＜0.001)、肿瘤形态(P=0.013)、肿瘤分期(P=0.001)、肿瘤分级(P=0.007)以及淋巴结转移(P=0.001)相关，而且后四项均为提示肿瘤恶性程度高和预后不良的病理特征。RASSF1A基因的异常甲基化状态是患者术后膀胱复发(P＜0.001, HR=0.471)和对侧上尿路复发(P=0.030, HR=0.269)的独立危险因素。RASSF1A基因启动子高甲基化组的UTUC患者术后的膀胱无复发生存时间和对侧无复发生存时间均比低甲基化组长，其无复发生存时间较长和累积无复发生存率较高，此外，肿瘤多发(P =0.002,HR=1.538)和术前输尿管镜检(P =0.001, HR=1.725)分别是UTUC患者术后膀胱复发的独立危险因素。结论： RASSF1A基因启动子区域的甲基化状态是与UTUC肿瘤恶性程度显著相关的表观遗传学生物标记物和尿路复发的预后因素。

Methylation status of RASSF1A gene promoter in upper tract urothelial carcinoma and its clinical significance

Objective:To investigate the methylation status of the RASSF1A gene promoter in upper tract urothelial carcinoma (UTUC)tissues and its correlation with clinicopathologic characteristics and postoperative recurrence of primary UTUC.Methods:In a retrospective design,a total of 687 patients who underwent surgeries for primary UTUC in the urology department of Peking University First Hospital were enrolled.The methylation status of the RASSF1A gene promoter was analyzed using methylation-sen-sitive polymerase chain reaction on tumor specimens.Results:Aberrant methylation for the RASSF1A gene promoter was detected in 183 (26.6%) DNA samples in total.Aberrant methylation of the RASSF1A gene was strongly associated with tobacco consumption (P =0.044),ipsilateral hydronephrosis (P <0.001 ),tumor location (P <0.001 ),tumor stage (P =0.001 ),tumor grade (P =0.007), lymph node metastasis (P =0.001 )and growth pattern (P =0.013).The methylated RASSF1A gene promoter was an independent risk factor for bladder recurrence (P <0.001,HR =0.471)and contrala-teral recurrence (P =0.030,HR =0.269)of UTUC after surgery.Hypermethylated RASSF1A was pre-dictive for improved bladder recurrence-free survival (BRFS)(P <0.001)and contralateral recurrence-free survival (CRFS)(P =0.021)in the UTUC patients.Compared with the patients with unmethylated RASSF1A,the patients containing tumors with hypermethylated RASSF1A had tendency toward longer re-currence-free survival time (114.4 ±3.9)months vs.(84.0 ±3.2)months for BRFS,(138.1 ±1.8) months vs.(132.9 ±1.9)months for CRFS]and higher estimated cumulative recurrence-free survive rates (five-year survival rate for example,79.8% ±3.4% vs.57.4% ±2.6% for BRFS,98.9% ± 0.8% vs.93.0% ±1.4% for CRFS).Additionally,tumor multifocality (P =0.002,HR =1.538), and ureteroscopy before surgery (P =0.001,HR =1.725)were independent risk factors for bladder re-currence in postoperative UTUC patients.Conclusion:The methylation status of the RASSF1A gene pro-moter appears to be a promising epigenomic biomarker for assessing the aggressiveness of UTUC and a predictor predicting the urinary tract recurrence after surgery.