Application Of RASSF1A,P16 And DAPK Gene Hypermethylation Measurement In Detection Of Lung Cancer

Objective To investigate the methylation status of RASSF1A, P16 and DAPK promoter in sputum and tumor tissues obtained by bronchoscope of lung cancer and explore its clinical significance and diagnostic value.A valuable index for early detection of lung cancer wish to be found.Methods The methylation status of RASSF1A,P16 and DAPK promoter in 35 patients with lung caner and 15 patients with lung benign lesions were detected by methylation specific PCR(MSP).The relationship of its abnormal methylation and lung cancer clinical features were analysised and the difference between the sputum and tissues from lung cancer patients were compared.Results1 The methylation frequencies of the 3 genes examined in 35 lung cancer cases were 60.0% (21/35) for PASSF1A,42.9% (15/35) for P16,60.0 % (21/35) for DAPK of tumor tissues and were 44.1 % (16/35),28.6%(10/35),45.5% (17/35) of corresponding sputum specimens, respectively.The 15 patients with lung benign lesions are all un-methylated for RASSF1A,P16 or DAPK genes.There are no difference of the methylated sequence in sputum and tissue.2 The RASSF1A gene promoter methylation was found associated significantly with tumor differentiation degree and lymphatic metastasis. The P16 and DAPK gene promoter methylation frequency in these specimens did not differ according to the clinical features.3 The individual sensitivity was 44.1% for RASSF1A,28.6% for P16 and 45.5% for DAPK.Evaluating the combined effect of methylation of at least one of the three genes in sputum increased the sensitivity to 62.9%.Conclusion1 This study demonstrates that RASSF1A,P16 and DAPK promoter hyperaiethylation is a common event in lung cancer and it may play an important role in the progression of lung cancer.2 The RASSF1A gene promoter hypermethylation was found associated significantly with tumor differentiation degree and lymphatic metastasis and not significantly different to the patient's age,sex,smoking status,tumor histology or clinical stages.The P16 and DAPK gene promoter hypermethylation frequency in these tumors did not differ according to the clinical features.3 Methylation analysis of RASSFlA,P16andDAPK genes in sputum DNA may be a promising new approach to detect the lung cancer in early stage.