Association of specific haplotype of tumor necrosis factor-α and interleukin-1β polymorphisms with infection and gastric carcinogenesis.

Introduction: The infection and cytokine-mediated inflammatory responses play significant roles in the pathogenesis of gastric cancer (GC). This study was performed to determine the association between the risk of GC and genetic polymorphisms in interleukin (IL)-1β and tumor necrosis factor-alpha (TNF-α).

Methods: The polymorphisms of IL-1β and TNF-α genes were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 290 patients who underwent endoscopy. Infection with was diagnosed by histological analysis, rapid urease test, and PCR of gastric biopsy samples. Quantitative real-time PCR was performed to determine the relative mRNA expression levels.

Results: No significant difference was detected in allele frequency and genotype of all studied polymorphisms between chronic gastritis (CG), GC and healthy individuals. IL-1β mRNA was down-regulated in both gastritis (relative quantification (RQ)=0.447) and the GC groups (RQ=0.151). In contrast, the expression of TNF-α was up-regulated in the GC group (RQ=2.817) compared to the gastritis group (RQ=0.861).

Conclusions: The studied single-nucleotide polymorphisms are not risk factors for development of CG and GC. However, infection causes a huge increase in the TNF-α expression in GC patients.