Hypermethylation of tumor necrosis factor decoy receptor gene in non-small cell lung cancer.

Abnormal methylation of theTNFRSF10CandTNFRSF10Dgenes has been observed in numerous types of cancer; however, no studies have investigated the methylation of these genes in non-small cell lung cancer (NSCLC). The aim of the present study was to investigate the association betweenTNFRSF10CandTNFRSF10Dmethylation and NSCLC. Methylation levels of 44 pairs of NSCLC tumor tissues and distant non-tumor tissues were analyzed using quantitative methylation specific PCR and methylation reference percentage values (PMR). The methylation levels of theTNFRSF10Cgene in NSCLC tumor tissue samples were significantly higher compared with those in the distant non-tumor tissues (median PMR, 2.73% vs. 0.75%; P=0.013). Subgroup analysis demonstrated that the methylation levels ofTNFRSF10Cin tumor tissues from male patients were significantly higher compared with those in distant non-tumor tissues (median PMR, 2.73% vs. 0.75%; P=0.041). The levels ofTNFRSF10Cmethylation were also higher in the tumor tissues of patients who were non-smokers compared with their distant non-tumor tissues (median PMR, 2.50% vs. 0.63%; P=0.013).TNFRSF10Cmethylation levels were higher in the tumor tissues from male patients compared with those from female patients (median PMR, 2.50% vs. 0.63%; P=0.031). However, no significant differences in the methylation levels of theTNFRSF10Dgene were observed between the sexes. Using the cBioPortal and The Cancer Genome Atlas lung cancer data, it was demonstrated thatTNFRSF10Cmethylation levels were inversely correlated withTNFRSF10CmRNA expression levels (r=-0.379; P=0.008). In addition, demethylation of lung cancer cell lines A549 and NCI-H1299 using 5 '-aza-deoxycytidine further confirmed thatTNFRSF10Chypomethylation was associated with significant upregulation ofTNFRSF10CmRNA expression levels [A549 fold-change (FC)=8; P=1.0x10(-4); NCI-H1299 FC=3.163; P=1.143x10(-5)]. A dual luciferase reporter gene assay was also performed with the insert ofTNFRSF10Cpromoter region, and the results revealed that theTNFRSF10Cgene fragment significantly enhanced the transcriptional activity of the reporter gene compared with that in the control group (FC=1.570; P=0.032). Overall, the results of the present study demonstrated that hypermethylation ofTNFRSF10Cwas associated with NSCLC.