痰液脱落细胞中p16基因和RASSF1A基因甲基化与周边型非小细胞肺癌关系的研究

Methylation of P16 and RASSF1A Genes in Sputum Samples Associated with Peripheral Non-Small Cell Lung Cancer

目的:探讨p16基因和RASSF1A基因甲基化与肺癌发生发展的关系和应用于诊断的意义。方法:采用甲基化特异性PCR(Methylation Specific PCR,MSP)检测120例周边型非小细胞肺癌患者癌组织、痰液脱落细胞和120例非肺癌人群的痰液脱落细胞中p16基因和RASSF1A基因甲基化,分析它们与临床特征的关系以及非肺癌人群与肿瘤患者之间的差异。结果:(1)120例周边型非小细胞肺癌组织中,p16基因甲基化率46.7%(56例),RASSF1A基因甲基化率53.3%(64例)。P16和RASSF1A基因甲基化与吸烟程度、肿瘤大小和临床分期正相关(P<0.05)。(2)肺癌痰液脱落细胞中有28例p16基因出现甲基化(23.3%),20例RASSF1A基因出现甲基化(16.7%),其中32例至少存在一个基因的甲基化(26.7%);66例重度吸烟者中只有4例痰液脱落细胞出现p16基因甲基化(6%),4例出现RASSF1A基因甲基化(6%);54例非重度吸烟正常人中仅有2例出现p16基因甲基化(3.7%),RASSF1A基因无甲基化。(3)液基痰细胞病理学检查与痰脱落细胞p16和RASSF1a基因甲基化检测结合起来可有效提高诊断的灵敏度(P<0.05)。结论:烟草可能具有潜在的诱导抑癌基因p16和RASSF1A发生甲基化的作用;p16和RASSF1A基因甲基化可能参与肺癌的生长过程。痰脱落细胞p16和RASSF1a基因甲基化检测结合液基痰细胞病理学诊断,可提高非小细胞肺癌诊断的灵敏度。

Objective： To investigate the relativity between p16 and RASSF1A gene methylation and development of peripheral non-small cell lung cancer,and investigate the value of detection of p16 and RASSF1A gene methylation in sputum cells as diagnosis method of non-small cell lung cancer.Methods： Methylation-specific PCR（MSP） was performed to detect the methylation status of p16 and RASSF1A genes in tissue and sputum cells of 120 cases of peripheral non-small cell lung cancer,and in sputum cells of 120 cases of cancer-free.The relationship between the methylation status and the clinic factors was analyzed.Results：（1） The frequencies of methyla-tion of the p16 and RASSF1a genes in tissue of peripheral non-small cell lung cancer were： 46.7%（56 of 120） and 53.3%（64 of 120）.There was a significant higher ratio of p16 and RASSF1A gene methylation in the degree of smoking,size of tumor and advanced clinical stage（P〈0.05）.（2） The frequencies of methylation of the genes in sputum of non-small cell lung cancer,heavy-smoking and normal samples were： 23.3%（28 of 120）,6%（4 of 66） and 3.7%（2 of 54） for p16,and 16.7%（20 of 120）,6%（4 of 66） and 0（0 of 54） for RASSF1A,respectively.（3） Combination of Liquid-based cytological analysis and detection of p16 and RASSF1a genes methylation in sputum could increase the sensitivity of diagnostic approach for non-small cell lung cancer（P〈0.05）.Conclusion： These results indicate that the tobacco may have the potential capability to induce methylation of p16 and RASSF1A genes.In addition,the Methylation of p16 and RASSF1A maybe play important roles in growth process of non-small cell lung cancer.Combination of Liquid-based cytological analysis and detection of p16 and RASSF1a genes methylation in sputum could be a more sensitive method for the diagnosis of this ma-lignancy.