Comprehensive expression analysis of TNF-related apoptosis-inducing ligand and its receptors in colorectal cancer: Correlation with MAPK alterations and clinicopathological associations

TNF-related, apoptosis-inducing ligand (TRAIL) apoptotic pathway constitutes a promising therapeutic target due to high selectivity and low toxicity of TRAIL targeting agents when administered in combination therapies. 106 colorectal cancers were examined for: relative mRNA expression of TRAIL pathway genes, decoy receptors TRAIL-R3 and TRAIL-R4 promoter methylation and the presence of KRAS, NRAS, BRAF mutations. Elevated mRNA levels were observed in 26%, 15%, 13%, 12% and 10% of the cases for TRAIL-R4, TRAIL-R3, TRAIL-R2, TRAIL-R1 and TRAIL genes respectively. Reduced mRNA levels were detected in 77%, 65%, 64%, 60% and 37% of the cases for TRAIL, TRAIL-R2, TRAIL-R3, TRAIL-R1 and TRAIL-R4 genes respectively. TRAIL-R3 and TRAIL-R4 promoter methylation was detected in 55% and 16% of the analysed samples respectively. TRAIL-R1, TRAIL-R2 elevated relative mRNA levels inversely correlated with tumor stage (p =.036, p =.048). Strong linear correlations of TRAIL receptors’ mRNA levels were found: TRAIL-R1/TRAIL-R2 (R = 0.653, p