Abstract: Objective This study was performed to elucidate whether the polymorphisms within the tumor immunity-regulated gene TIM-3 promoter region were associated with the risk of gastric cancer in the Han ethnic group of China. Methods The association was analyzed in a hospital-based case-control study of 190 gastric cancer cases and 216 cancerfree controls. DNA was obtained from blood samples and the polymorphisms of -574G/T, -882C/T, and -1 516G/T within TIM-3 gene promoter region were genotyped by the method of PCR-RFLP. The correlation between the risk of gastric cancer with the genotype of the polymorphisms was assessed by the odds ratio(OR) values and their 95% confidence intervals(CI). Unconditional Logistic regression model adjusted by the confounding factors was used to analyze the statistical association of the genotypes in two groups by using the SPSS 11.5 software. Results The results of PCR-RFLP showed that the three polymorphisms in TIM-3 gene promoter region were present in our study population. But the homozygous form of the polymorphisms almost did not appear. Statistical analysis revealed that the allele frequency of the three polymorphisms displayed significant difference between the gastric cancer patients and healthy controls(P<0.05). Logistic regression analysis adjusted for confounding factors exhibited that all the three loci genotypes possessed statistically significant difference(P<0.05): loci -574G/T(OR=3.92, 95% CI: 1.40-10.94), loci -882C/T(OR=3.20, 95% CI:1.22-8.41), and loci -1 516G/T(OR=2.32, 95% CI: 1.23-4.40), respectively. Conclusion Although the three polymorphic homozygous genotypes were very rare, the results still revealed that the polymorphisms within TIM-3 gene promoter region were significantly contributed to the genetic susceptibility of gastric cancer in the Han ethnic group of China.

Key words: TIM-3(T cell immunoglobulin domain and mucin domain-3), gastric cancer, single nucleotide polymorphism, susceptibility