Functional Genetic Variations In The Promoter Region Of Death Receptor 4 Are Associated With Susceptibility To Lung Cancer

Background & Aims TNF-related apoptosis-inducing ligand (TRAIL) is a member of TNF superfamily and is highly homologous to FasL and TNF-α. It attracts a great research interest after the observation that TRAIL selectively kills malignant cells but normal cells. TRAIL tends to bind 4 receptors, i.e., death receptor (DR) 4, DR5, decoy receptors (DcR) 1 and DcR2. This study investigated the association between single nucleotide polymorphisms (SNPs) in TRAIL and its receptor genes and susceptibility to lung cancer. The functional significance of SNPs associated with lung cancer were also examined.Methods This study employed a candidate SNP approach by selecting 13 SNPs in TRAIL and its 4 receptor genes that have potential function from NCBI and HapMap SNP databases. We used two stages of case-control analysis to examine the association of the SNPs with lung cancer risk. A pilot analysis consisted of 323 cases and 331 controls, and a final confirmation analysis consisted of 1304 patients and 1491 controls. The association was estimated by odds ratios (ORs) and their 95% confidence intervals (CIs) computed by unconditional logistic regression. All statistical tests were two-sided tests, and a P < 0.05 was used as the criterion of statistical significance. Dual luciferase reporter gene assay and electrophoretic mobility shift assay were used to examine the function of the SNPs located in the gene promoter.Results The pilot analysis showed that among the 13 SNPs investigated, only the -972A→G and -397C→A SNPs in DR4 promoter were associated with lung cancer and the rest of SNPs were not associated with lung cancer. In the confirmation analysis with larger sample size, we found that the frequency of the -397AA genotype in patients was significantly higher than that in controls (16.1% vs 8.9%, P < 0.001). Multivariate logistic regression analysis showed that subjects carrying the -397AA genotype had 1.94-fold increased risk of lung cancer (95% CI = 1.51-2.51, P < 0.001) compared with the -397CC genotype, whereas the -397CA genotype was not associated with increased risk (OR = 1.06, 95% CI = 0.90-1.25, P = 0.495). Stratification analysis revealed an interaction between this genetic polymorphism and smoking in intensifying lung cancer risk in a supermultiplicative manner. However, although the -972 SNP had no effect on susceptibility to the cancer in confirmation analysis, it interacted with the -397 SNP to increase susceptibility to lung cancer in the context of haplotype. Five SNPs with the minor allelic frequencies being >5% were identified in the promoter of DR4. Among them, the -1501G→A is a newly identified SNP because it is not recorded in the NCBI SNP database, although it was not associated with lung cancer in our study population. Reporter gene assays showed that the -397A-containing haplotype drove a significant lower promoter activity than the -397C-containing haplotype, suggesting that this SNP is a functional SNP. The -397A allele displayed a lower affinity to bind a nuclear protein than the -397C allele, but the identity of this protein remains to be clarified.Conclusions The DR4 -397C→A polymorphism confers host susceptibility to lung cancer, which might result from decreased DR4 transcription with the -397A allele.