诱导痰RASSF1A， p16和DAPK基因启动子区 甲基化在肺癌诊断中的价值

目的：探讨诱导痰中RASSF1A, p16和DAPK基因启动子区异常甲基化及其联合检测在肺癌诊断中的价值。方法：采用甲基化特异性PCR（MSP）技术，检测82例肺癌患者诱导痰和对应肿瘤组织以及25例肺部良性病变组织中RASSF1A, p16和DAPK 3种基因启动子区甲基化改变，并分析三者与临床病理资料的关系。结果：肺癌病理组织中RASSF1A, p16和DAPK基因启动子区甲基化检出率分别为63.4％，59.8％和58.5％, 对应的诱导痰三者甲基化检出率分别为54.9％，48.8％和51.2%；肺部良性病变组织中甲基化检出率均为零，两组间比较差异有统计学意义(P＜0.05）。RASSF1A基因甲基化检出率在中高分化和无淋巴结转移的肺癌中明显低于低分化和未分化及有淋巴结转移者（P＜0.05），与年龄、性别、吸烟指数、临床分期及病理类型无关，而p16和DAPK基因甲基化检出率与上述因素均无明显相关性（P＞0.05）；联合检测3种基因甲基化的检出率为73.2％。结论：联合检测诱导痰中RASSF1A, p16和DAPK基因启动子区高甲基化有可能作为诊断肺癌及评估预后的简便有效的指标，并能提高检出率。

Value of promoter methylation of RASSF1A, p16, and DAPK genes in induced sputum in diagnosing lung cancers

Objective To determine the aberrant methylation status of RASSF1A,p16 and DAPK gene promoter region in induced sputum from lung cancer patients and the value of their combined detection in diagnosing lung cancers. Methods Methylation-specific PCR (MSP) was used to detect the promoter methylation status of RASSF1A,p16, and DAPK genes in induced sputum and pathological tissues from 82 patients with lung cancers and 25 patients with pulmonary benign lesion.We also analyzed the relation between methylation status and clinical pathological data.Results The positive rates of promoter methylation of RASSF1A,p16, and DAPK genes in pathological tissues from patients with lung cancers were 63.4%,59.8%, and 58.5%, respectively,and those in induced sputum were 54.9%,48.8%,and 51.2%, respectively. The promoter methylation of RASSF1A,p16, and DAPK genes were not detected in patients with pulmonary benign lesion.There was a significant difference between the lung cancer group and pulmonary benign lesion group (P＜0.05). The methylation rate of RASSF1A gene was significantly lower in the middle and high differentiation and non-metastastic lymph node of lung cancer tissues than that in the poor differentiation and the metastatic lymph node of lung cancer tissues(P＜0.05), and was not correlated with age, sex, smoking index, clinical stage, and pathological types.The methylation rate of p16, and DAPK genes was not significantly correlated with all the above mentioned factors (P＞0.05). The methylation rate of joint detecting RASSF1A, p16, and DAPK genes was 73.2%. Conclusion Joint detection for promoter hypermethylation of RASSF1A, p16, and DAPK genes in induced sputum may be used as a simple and effective index of the diagnosis and prognose of lung cancers, and can improve the positive rate.