A Polymorphism (rs2295080) in mTOR Promoter Region and Its Association with Gastric Cancer in a Chinese Population

Abstract

Background: As an imperative part of PI3K/Akt/mTOR pathway, mammalian target of rapamycin (mTOR) has been demonstrated to increase in gastric cancer cells and tumors. Our research explored the relationship between single nucleotide polymorphism (SNP) rs2295080 in mTOR promoter region and the risk of gastric cancer (GC). Methods: Seven hundred and fifty-three (753) gastric adenocarcinoma patients and 854 matched healthy subjects were recruited in the cancer association study and 60 tissues were used to test the expression of mTOR. Unconditional logistic regression was selected to evaluate the association between the rs2295080 T>G polymorphism and GC risk. We then examined the functionality of this promoter genetic variant by luciferase assay and EMSA. Results: Individuals with G allele had a 23% decreased risk of GC, comparing with those carrying T allele (adjusted OR = 0.77, 95% CI = 0.65-0.92). This protective effect of G allele stood out better in male group. Meanwhile, GC patients carrying TG/GG genotype also displayed a decreased mRNA level of mTOR (P = 0.004). In luciferase assay, T allele tended to enhance the transcriptional activity of mTOR with an approximate 0.5-fold over G allele. Furthermore, EMSA tests explained that different alleles of rs2295080 displayed different affinities to some transcriptional factor. Conclusion: The mTOR promoter polymorphism rs2295080 was significantly associated with GC risk. This SNP, which effectively influenced the expression of mTOR, may be a new biomarker of early diagnosis of gastric cancer and a suitable indicator of utilizing mTOR inhibitor for treatment of GC. © 2013 Xu et al.