Effects of interleukin-18 promoter (C607A and G137C) gene polymorphisms and their association with oral squamous cell carcinoma (OSCC) in northern India.

Interleukin-18 (IL-18) is one of the immunomodulatory cytokines that plays an important role in cellular functions against tumor development and progression. IL-18 (-607) C/A and (-0137) G/C gene promoter polymorphisms and their haplotypes variants are associated with risk of various cancers. We evaluated a possible association of IL-18 (-607) C/A and (-137) G/C gene promoter polymorphisms in the susceptibility to oral squamous cell carcinoma (OSCC). A total number of 272 patients with OSCC and 185 healthy volunteers were genotyped for the IL-18 (-607) C/A and (-137) G/C polymorphism. Polymorphism variants were examined by using tetra-primer amplification refractory mutation system (T-ARMS). Genotype frequencies were evaluated by chi-square test and odds ratio (OR) relative risk. IL-18 (-137) G/C gene polymorphism was significantly associated with the risk of OSCC as compared to healthy volunteers (genotype GG vs GC: OR 2.238; 95 % CI 1.455-3.441; p = 0.0003 and allele G vs C: OR 1.984; 95 % CI 1.335-2.947; p = 0.0007). The genotype and allele frequencies of the IL-18 promoter -607 C/A polymorphism in OSCC patients were not significantly different than that in healthy controls (p > 0.05). Our results suggest that IL-18 -137 G/C polymorphism is significantly associated with the progression of oral cancer but -607 C/A polymorphism is not associated with this.