血浆RASSF1A甲基化检测及其在非小细胞肺癌诊断中的意义

Detection of RASSF1A hypermethylation in plasma DNA from non-small cell lung cancer patients and its value in non-small cell lung cancer diagnosis

目的:分析非小细胞肺癌(non-small cell lung cancer,NSCLC)患者血浆游离DNA和相应的肿瘤组织中RASSF1A启动子甲基化情况,探讨检测血浆中该基因异常甲基化在NSCLC诊断中的意义。方法:应用半巢式MSP法分析了96例NSCLC、12例肺良性病变患者及20例健康人血浆游离DNA,MSP法分析了96例NSCLC患者对应的肿瘤组织DNA,检测RASSF1A的异常甲基化改变。结果:①血浆及相应的肿瘤组织RASSF1A异常甲基化检出率分别为43.75%和48.96%,血浆中该基因甲基化仅发生在相应的肿瘤组织甲基化阳性的NSCLC患者。②血浆RASSF1A异常甲基化只与肿瘤的组织学类型有关,鳞癌组(57.14%)高于腺癌组(33.33%,P<0.05)。但与患者的年龄、性别、是否吸烟,肿瘤的TNM分期、分化程度和有无淋巴结转移无关(P>0.05)。③检测RASSF1A异常甲基化用于诊断NSCLC的敏感性43.75%,特异性100%,阴性预测值41.30%,阳性预测值100%。结论:RASSF1A异常甲基化很可能是NSCLC发生过程中的早期分子事件,检测血浆游离DNA中该基因异常甲基化可能成为NSCLC早期诊断的有效方法之一。

Objective：To explore the promoter hypermethylation of Ras association domain family 1A gene（RASSF1A） in plasma DNA and matched NSCLC tissues DNA from non-small cell lung cancer patients,and its value in non-small cell lung cancer（NSCLC） diagnosis.Methods：A semi-nested methylation-specific PCR（MSP） was used to detect the status of RASSF1A promoter hypermethylation in plasma DNA from 96 NSCLC patients,12 benign lung disease patients and 20 volunteers with no lung disease.Using MSP,the status of hypermethylation of RASSF1A was investigated in 96 matched NSCLC tissues DNA.Results：① Hypermethylation of RASSF1A was identified in 43.75 % of the plasma samples from NSCLC patients,48.96 % of the matched tumor tissues.Only in those patients whose tumor tissues had hypermethelation of RASSF1A,similar changes could be detected in their plasma sampes.② The promoter hypermethylation of RASSF1A in plasma DNA was only correlated with the histological type of the tumor.RASSF1A methylation was more frequently observed in patients with squamous cell carcinomas（57.14 %） than in patients with adenocarcinomas（33.33 %,P0.05）.But hypermethylation of RASSF1A in plasma DNA was not significantly correlated with ages,sexes,smoking or no smoking of the non-small cell lung cancer patients,the TNM stage,lymph node metastasis or non-lymph node metastasis and differentiation of the toume（P0.05） ③ Sensitivity,specificity,negative predictive value and positive predictive value of RASSF1A hypermethylation in plasma DNA for diagnosis of NSCLC were 43.75%,100%,41.30% and 100%,respectively.Conclusion：RASSF1A promoter methylation may occur in early stage in NSCLC.And the identification of hypermethylation of RASSF1A in plasma DNA could be useful for early detection of NSCLC.