膀胱移行细胞癌尿沉渣RASSF1A基因启动子的甲基化状况及意义

Detection of methylated promoter of RASSF1A gene in urine sediments of bladder cancer patients

目的 探讨膀胱癌患者尿沉渣细胞中RASSF1A基因启动子CpG岛的甲基化状况及其临床意义.方法 选取病理确诊的39例膀胱癌标本,采用甲基化特异PCR方法检测膀胱癌肿瘤组织和配对的尿沉渣RASSF1A基因启动子CpG岛的甲基化异常频率,同时以45例非肿瘤性泌尿系疾病患者及14例健康志愿者的相关检测情况作为对照,分析膀胱肿瘤患者RASSF1A基因异常甲基化的情况.结果 膀胱癌组RASSF1A基因启动子甲基化阳性率（61.5%,24/39）显著高于非肿瘤组（4.4%,2/45）（P〈0.01）,非肿瘤组与志愿组间（阳性率为0）并无明显差异（P＞0.05）;尿沉渣RASSF1A基因甲基化对膀胱癌诊断的敏感性为61.5%（24/39）,特异性为95.6%（43/45）.性别、年龄、病理分级及临床分期与RASSF1A基因甲基化均无明显相关性（均P＞0.05）.膀胱癌肿瘤组织RASSF1A基因启动子甲基化阳性率为69.2%（27/39）.膀胱癌肿瘤组织和配对的尿沉渣同时出现RASSF1A基因甲基化为20例,同时仅出现非甲基化为8例,两者明显相关（P〈0.05）.结论 RASSF1A基因异常甲基化可能是膀胱癌的早期事件,其异常甲基化状态可能成为非侵入性诊断膀胱癌的分子标志物之一.

Objective To detect methylated promoter of RASSF1A gene in urine sediments of bladder cancer patients and to evaluate its clinical significance. Methods Thirty nine patients with bladder transitional cell carcinoma were included in this study. The methytation status of RASSF1A gene in cancer tissues and urine sediments was examined by MSP method. Results The frequency of methytation of RASSF1A gene in cancer tissues and urine sediments was 69.2%（27/39）and 61.5% （24/39）, which were correlated with each other （r=0.387,P=0.015）.The frequency of methylation of RASSF1A gene in urine sediments with bladder cancers was significantly higher than that in patients with noncancerous urinary conditions（X2=31.87, P=0.000）. No hypermetylation of RASSF1A was detected in normal health individuals . No association between methylation status and grading or muscle invasiveness was demonstrated （P〉0.05）. The sensitivity and specificity of aberrant methylation of RASSF1A gene in urine sediments for detecting bladder cancer was 61.5%（24/39）and 95.6% （43/45） respectively, Conclusion Methylation of RASSF1A gene may be an early event in the tumorigenesis of bladder cancer. Hypermethylation of RASSF1A in urine sediments might be a potential biomarker for detecting bladder cancer.