Although an association between candidate SNPs and gastric cancer was not found in Peruvians, trend in our data is consistent with meta-analyses results that suggest PTGS2-rs689466-A is associated with H. pylori-associated gastric cancer in East Asia.
Previously we have found that early-onset gastric cancer has a unique COX-2 low-expressing phenotype that differs significantly from that of the frequent overexpression seen in conventional gastric cancers.
We conclude that the pCOX2-0.8 minimal promoter contains a novel functional T-cell factor/lymphoid enhancer factor (TCF/LEF)-response element (TBE Site II; -689/-684) that responds directly to enhanced Wnt/β-catenin signaling and which may be important for the onset/progression of GC.
The meta-analysis results showed that the COX-2 -1195G>A gene polymorphism significantly correlated with an increased risk of gastrointestinal cancers, particularly gastric cancer (A <i>vs</i> G: OR = 1.35; AA/AG <i>vs</i> GG: OR = 1.54; AA <i>vs</i> GG/AG: OR = 1.43; AA <i>vs</i> GG: OR = 1.80; AG <i>vs</i> GG: OR = 1.35).
In our analysis, PTGS2 5939C allele carriers were at increased risk of gastric cancer (odds ratio [OR] 1.742; 95% confidence interval [CI] 1.009, 3.005; p = 0.045).
The COX2 -1195G > A polymorphism showed significant correlation with gastric cancer susceptibility in total analysis, and stratification analysis by ethnicity also revealed a similar association in both Asian and Caucasian groups under the same contrast.
Our results suggested that the COX-2 promoter polymorphisms were associated with increased risk of GC, especially interacting with H. pylori infection.
In this study, we examined two single nucleotide polymorphism (SNP) sites of COX-2 gene in gastric cancer patients and explored the effect of the SNPs on the morbidity of gastric cancer.
In the Chinese subgroup, nominally significant associations were shown between (i) EBBR2+1963G (rs1801200) and H. pylori infection (per-allele OR: 0.48, 95% CI 0.23, 0.98, P = 0.04), (ii) PTGS2-1195G (rs689466) and an increased risk of GC on adjusting for H. pylori status (OR: 1.53, 95% CI 0.99, 2.37, P = 0.05), and (iii) IL1B-1473C (rs1143623) and a decreased risk of GC (OR: 0.64, 95% CI 0.41, 0.99, P = 0.05).
This meta-analysis of 15 case-control studies provides strong evidence that the COX-2rs20417 polymorphism increases the risk of GC susceptibility in general populations, especially in Asians.
Five different classes of methylation behaviors were found: (a). genes methylated in GC only (GSTP1 and RASSF1A), (b). genes showing low methylation frequency (<12%) in CG, IM, and gastric adenoma (GA) but significantly higher methylation frequency in GC (COX-2, hMLH1, p16), (c). a gene with low and similar methylation frequency (8.8-21.3%) in four-step lesions (MGMT), (d). genes with high and similar methylation frequency (53-85%) in four-step lesions (APC and E-cadherin), and (e). genes showing an increasing tendency with or without fluctuation of the methylation frequency along the progression (DAP-kinase, p14, THBS1, and TIMP-3).
The -765C, -1195A, -1290G, *2430T alleles and *429TT genotype of COX-2 polymorphisms were determined a significant association with susceptibility to GC.
Cell proliferation and migration experiments were conducted on the RhoA-silenced A6-B9 cells and COX-2-silenced D7-B8 cells so as to discuss their role in the development of gastric cancer.
In 180 cases of GC, the clinicopathologic features were correlated with the results obtained after paired immunohistochemical stains (tumor/normal mucosa) with 15 antibodies: E-cadherin, HER-2, VEGF, CD31, CD105, COX-2, maspin, bax, bcl-2, p53, Ki67, MLH-1, MSH-2, Mena protein, and vimentin.