Background and aims: A number of theories have been put forward to clarify the etiology of colorectal cancer (CRC), such as genetic alterations and cytokine production. A combination of inflammatory cytokines has an important role in cancer development. The aim of our study was to screen for alterations located in promoter and exons of IL-16 gene sequence, to determine the distribution of genotypes in individuals with CRC and healthy controls in a sample of Iranian population.
Methods: The case group consisted of 260 individuals with colorectal cancer and the control group included 405 healthy individuals. Three IL-16 gene polymorphisms (rs4072111, rs11556218, rs4778889) were genotyped using PCR-RFLP method. RFLP results were confirmed by direct sequencing.
Results: A significant association between rs11556218 SNP in the IL-16 gene and the risk of CRC was found. The TG genotype of rs11556218 T/G polymorphism showed significant association with a 1.75 fold increased risk of CRC (P=0.005; adjusted OR: 1.759; 95% CI: 1.191-2.598). In addition a significant association between CC genotype of rs4778889 T/C polymorphism and decreased risk of CRC in male subjects (P=0.045; adjusted OR: 0.192; 95% CI: 0.038-0.967) was determined.
Conclusion: This study is the first report of IL-16 gene polymorphisms among CRC patients from Iran. Our results suggest an influence of rs11556218 T > G and rs4778889 T/C polymorphisms on the altered risk of CRC.