Lung Cancer Early Diagnosis By Using DNA Methylation Status

OBJECTIVE:The aim of this research was to find the candidate genes for lung cancer early diagnosis by using DNA specific PCR (MSP).METHODS:We selected 15 patients with lung cancer in the pulmonary surgery department of the Tianjin medical university general hospital from October 2008 to October 2009 and getted the tumor tissue the tumor remote lung tissue and BALF of the same patients. We extracted DNA from the samples and applied MSP which based on sodium bisulfite modification to detect the methylation status between the three different group samples. We detected RARβ,DAPK,MGMT,APClA,ECAD gene methylation status to find the difference between the three-group samples. 2.69 patients with lung cancer and 30 non-tumor patients was selected in the pulmonary surgery and respiratory department of general hospital from October 2008 to October 2009 the lung cancer patients was defined as cases and the non-tumor patients as control. We detected RARβ,DAPK,MGMT,APClA.ECAD gene methylation statu difference by using MSP in the two groups in the BALF and analyzed the relationship between the two groups in associated with the 5 genes methylation status.RESULTS:(1)In the lung cancer tissue,the methylation positive rate of the RARβ,DAPK,MGMT,APClA,ECAD and multiple genes was 53.3%(8/15),0%(0/15),26.7%(4/15),73.3%(11/15),0%(0/15) and 93.3%(14/15) respectively;(2)In the remote lung tumor tissue,the methylation positive rate of the RARβ,DAPK,MGMT,APClA,ECAD and multiple genes was 53.3%(8/15),0%(0/15),26.7%(4/15),73.3%(11/15),0%(0/15)and 93.3%(14/15);(3)In the BALF,the methylation positive rate of the RARβ,DAPK,MGMT,APCIA,ECAD and multiple genes was 73.3%(11/15),46.7%(7/15),80%(12/15),40%(6/15),20%(3/15)and100%(15/15);(4)The methylation status of the RARβand APClA reached statistical difference (P=0.00, P=0.041) between lung cancer group and non-malignant tumor group;(5)The sensitivity and specificity of DNA methylation to predict lung cancer:The sensitivity of the 5 genes were 60.0%,56.5%,50.7%,42%,10.1%; and the specificity were 80%,53%,56.7%,80%,83% respectivelly;(6)DNA methylation and lung cancer risk.By using logistic regression,we found advanced age and RARβgene promoter hypermethylation were risk factor of lung cancer with an odds ratio of 7.565 (1.687～33.922) and 6.833 (1.937～24.108) respectively.CONCLUSIONS:(1)Hypermetylation of the RARβ,DAPK,MGMT,APClA,ECAD five genes was observed in lung cancer tissue remote lung tumor tissue and BALF of the lung cancer patients.(2)The hypermethylation status of the tumor inhibite genes was similar between lung cancer tissue and BALF.(3)It was usefull for lung cancer early diagnosis by detecting multiple gene methylation status.(4)Sensitivity and specificity was not acceptable by using single gene methylation status.(5)The sensitivity and specificity was improved by detecting multiple tumor inhibitor genes.