非小细胞肺癌组织中RASSF_(1A)和p16基因启动子甲基化研究

目的:研究肺癌新型侯选抑癌基因Ras相关结构域家族基因1A(RASSF1A)和p16基因在非小细胞肺癌(NSCLC)中的甲基化情况,揭示两基因表达失活的机制,为NSCLC的基因诊断和治疗寻找新途径。方法:用甲基化特异性PCR(MSP)方法对96例NSCLC患者癌组织及相应的远癌正常肺组织中RASSF1A和p16基因启动子甲基化状态进行检测。结果:(1)96例NSCLC组织RASSF1A甲基化率48.96%,p16基因34.38%,96例远癌正常肺组织均未发现此两基因甲基化。(2)RASSF1A甲基化率鳞癌组(64.29%)高于腺癌组(37.04%,P<0.05);p16基因甲基化率50岁以上组(44.93%)高于50岁以下组(7.41%,P<0.05),鳞癌(61.90%)高于腺癌(12.96%,P<0.05),有淋巴结转移组(46.67%)高于无淋巴结转移组(13.89%,P<0.05)。(3)RASSF1A与p16基因启动子CPG岛甲基化呈正相关(r=0.256,P<0.05)。结论:RASSF1A和p16在NSCLC尤其是鳞癌中频繁甲基化,可能是两基因表达失活的主要原因。

Detection of promoter hypermethylation of RASSF1A and p16 gene in non-small-cell lung cancer

Objective: To explore the promoter hypermethylation of Ras association domain family 1A gene(RASSF1A) and p16 gene, and the major mechanisms for silencing of these two genes in non-small cell lung cancer(NSCLC). Methods: Methylation-specific PCR(MSP) was used to detect the frequency of aberrant methylation of RASSF1A and p16 gene in 96 human NSCLC tissues and matched 96 normal lung tissues far from cancer area. Results: (1) Of the 96 NSCLC samples, methylation was detected in 48.96% for RASSF1A, 34.38% for p16. But no methylation was found in 96 cancer-free tissues. (2) RASSF1A methylation was more frequently observed in patients with squamous cell carcinomas (64.29%) than in patients with adenocarcinomas(37.04%, P<0.05); The frequency of p16 aberrant methylation was remarkably higher in >50 group(44.93%),squamous cell carcinoma group (61.90%) and lymph node metastasis group (46.67%) than in <50 group(7.41%), adenocarcinoma group (12.96%) and non- lymph node metastasis group (13.89%, all P<0.05). (3) The positive correlation between the aberrant methylation of RASSF1A and that of p16 gene was identified in 96 NSCLC tissues( r=0.256,P<0.05). Conclusion: The promoter hypermethylation of RASSF1A and p16 gene is a frequent event in patients with NSCLS especially in squamous cell carcinoma, which may be the major mechanisms for silencing of these two genes in NSCLC.