Study on the association of COX-2 genetic polymorphisms with risk of gastric cancer in high incidence Hexi area of Gansu province in China

Association of COX2 -765G>C promoter polymorphism and coronary artery disease in Korean population

BACKGROUND

Cyclooxygenase-2 (COX2) plays a role in the formation of prostaglandins, which contribute to the inflammation involved in atherosclerosis. However, the role of the COX2 -765G>C polymorphism in susceptibility to coronary artery disease (CAD) is controversial.

OBJECTIVE

To identify the association between COX2 -765G>C polymorphism with CAD risk in Korean patients. We recruited 622 patients who were diagnosed to have coronary artery disease and 202 controls who did not have history and vascular disease risk factors.

METHODS

Using polymerase chain reaction-restriction fragment length polymorphism, the COX2 -765G>C polymorphism was analyzed in 622 Korean patients who received percutaneous coronary intervention and in 202 healthy control subjects.

RESULTS

The GC+CC genotype frequencies of the -765G>C polymorphism were significantly different between the CAD and control groups. The COX2 -765G>C polymorphism showed peculiar associations with CAD according to the presence of hyperlipidemia and plasma folate levels. However, there were no associations between the -765G>C polymorphism and the rates of hypertension, diabetes mellitus, or homocysteine levels.

CONCLUSION

This study suggests that the COX2 -765G>C polymorphism is a possible genetic determinant for the risk of CAD, and an individual risk factor in Koreans. Thus, further association studies between the COX2 polymorphism and atherosclerotic-related diseases such as cerebrovascular or cardiovascular diseases in other races or ethnicities will be needed.

Role of gene polymorphisms in gastric cancer and its precursor lesions: Current knowledge and perspectives in Latin American countries

Latin America shows one of the highest incidence rates of gastric cancer in the world, with variations in mortality rates among nations or even within countries belonging to this region. Gastric cancer is the result of a multifactorial complex process, for which a multistep model of carcinogenesis is currently accepted. Additionally to the infection with Helicobacter pylori, that plays a major role, environmental factors as well as genetic susceptibility factors are significant players at different stages in the gastric cancer process. The differences in population origin, demographic structure, socio-economic development, and the impact of globalization lifestyles experienced in Latin America in the last decades, all together offer opportunities for studying in this context the influence of genetic polymorphisms in the susceptibility to gastric cancer. The aim of this article is to discuss current trends on gastric cancer in Latin American countries and to review the available published information about studies of association of gene polymorphisms involved in gastric cancer susceptibility from this region of the world. A total of 40 genes or genomic regions and 69 genetic variants, 58% representing markers involved in inflammatory response, have been used in a number of studies in which predominates a low number of individuals (cases and controls) included. Polymorphisms of IL-1B (-511 C/T, 14 studies; -31 T/C, 10 studies) and IL-1RN (variable number of tandem repeats, 17 studies) are the most represented ones in the reviewed studies. Other genetic variants recently evaluated in large meta-analyses and associated with gastric cancer risk were also analyzed in a few studies [e.g., prostate stem cell antigen (PSCA), CDH1, Survivin]. Further and better analysis centered in gene polymorphisms linked to other covariates, epidemiological studies and the information provided by meta-analyses and genome-wide association studies should help to improve our understanding of gastric cancer etiology in order to develop appropriate health programs in Latin America.

Association between Helicobacter pylori infection and host genetic background in a population in Hexi, Gansu Province

AIM: To investigate the association between Helicobacter pylori (H. pylori) infection and host genetic background in a population in Gansu Province, and to reveal genes associated with H. pylori susceptibility.

METHODS: H. pylori infection was detected by the urea breath test. The human leukocyte antigen DQ (HLA-DQ) gene polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The single nucleotide polymorphisms (SNP) of the interleukin 8 (IL-8), interleukin 4 (IL-4), interleukin 1β (IL-1β), cluster of differentiation 14 (CD14), tumor necrosis factor α (TNF-α), and protein-tyrosine phosphatase, non-receptor-type11 (PTPN11) genes were detected by polymerase chain reaction with confronting two-pair primers (PCR-CTPP) method. Experimental data were analyzed using SAS statistical software.

RESULTS: The rate of H. pylori infection rate was 79.6% in men and 75.5% in women. The DQA1*0301 genotype was associated with a higher risk of H. pylori infection (OR = 5.75, 95%CI: 1.01-32.77). The CT genotype of the CD14C-159T allele showed a protective effect against H. pylori infection (OR = 0.18, 95%CI: 0.03-0.95).

CONCLUSION: The HLA-DQ and CD14 genes may play a key role in H. pylori infection and the occurrence and development of gastric cancer.

Cyclooxygenase-2 polymorphisms were associated with the risk of gastric cancer: evidence from a meta-analysis based on case-control studies

The associations between cyclooxygenase-2 (COX-2) polymorphisms (-765G>C, -1195G>A, and -587G>A) and risk of gastric cancer have been investigated, but the results were inconsistent. The aim of this study was to explore the associations between COX-2 polymorphisms and risk of gastric cancer using a meta-analytic method. We searched the databases of PubMed, Embase, and Wanfang (Chinese database) to identify the eligible studies. Odds ratio and 95 % confidence interval (OR and 95% CI) were used as effect size, and combined analyses were conducted using fixed- or random-effects model. Overall, ten studies for COX-2-765G>C, six studies for -1195G>A, and three studies for -587G>A were included in this study. The results for combined analysis for COX-2-765G>C indicated that C allele was significantly associated with increased risk of gastric cancer compared with G allele, especially for Asians (OR and 95 % CI: 1.58 (1.06-2.35), P(z-test) = 0.03, and P heterogeneity <0.01 for CC+GC vs. GG). In addition, the A allele of COX-2-1195G>A was also significantly associated with risk of gastric cancer compared with G allele (OR and 95 % CI: 1.20 (1.09-1.32), P(z-test) <0.001, and P(heterogeneity) = 0.82 for A carriers vs. G carriers). In contrast, the COX-2-587G>A polymorphism was not associated with risks of gastric cancer. In summary, this meta-analysis indicated that the COX-2-765G>C and -1195G>A polymorphisms were significantly associated with risk of gastric cancer development.

Socioeconomic and nutritional factors account for the association of gastric cancer with Amerindian ancestry in a Latin American admixed population

Gastric cancer is one of the most lethal types of cancer and its incidence varies worldwide, with the Andean region of South America showing high incidence rates. We evaluated the genetic structure of the population from Lima (Peru) and performed a case-control genetic association study to test the contribution of African, European, or Native American ancestry to risk for gastric cancer, controlling for the effect of non-genetic factors. A wide set of socioeconomic, dietary, and clinic information was collected for each participant in the study and ancestry was estimated based on 103 ancestry informative markers. Although the urban population from Lima is usually considered as mestizo (i.e., admixed from Africans, Europeans, and Native Americans), we observed a high fraction of Native American ancestry (78.4% for the cases and 74.6% for the controls) and a very low African ancestry (<5%). We determined that higher Native American individual ancestry is associated with gastric cancer, but socioeconomic factors associated both with gastric cancer and Native American ethnicity account for this association. Therefore, the high incidence of gastric cancer in Peru does not seem to be related to susceptibility alleles common in this population. Instead, our result suggests a predominant role for ethnic-associated socioeconomic factors and disparities in access to health services. Since Native Americans are a neglected group in genomic studies, we suggest that the population from Lima and other large cities from Western South America with high Native American ancestry background may be convenient targets for epidemiological studies focused on this ethnic group.

Gastric cancer: basic aspects

Gastric cancer (GC) is a world health burden, ranging as the second cause of cancer death worldwide. Etiologically, GC arises not only from the combined effects of environmental factors and susceptible genetic variants but also from the accumulation of genetic and epigenetic alterations. In the last years, molecular oncobiology studies brought to light a number of genes that are implicated in gastric carcinogenesis. This review is intended to focus on the recently described basic aspects that play key roles in the process of gastric carcinogenesis. Genetic variants of the genes IL-10, IL-17, MUC1, MUC6, DNMT3B, SMAD4, and SERPINE1 have been reported to modify the risk of developing GC. Several genes have been newly associated with gastric carcinogenesis, both through oncogenic activation (GSK3β, CD133, DSC2, P-Cadherin, CDH17, CD168, CD44, metalloproteinases MMP7 and MMP11, and a subset of miRNAs) and through tumor suppressor gene inactivation mechanisms (TFF1, PDX1, BCL2L10, XRCC, psiTPTE-HERV, HAI-2, GRIK2, and RUNX3). It also addressed the role of the inflammatory mediator cyclooxygenase-2 (COX-2) in the process of gastric carcinogenesis and its importance as a potential molecular target for therapy.

Functional polymorphism of cyclooxygenase-2 gene (G-765C) in chronic obstructive pulmonary disease patients

Cyclooxygenase two (COX-2) is an important enzyme metabolizing arachidonic acid. In contrast to constitutive cyclooxygenase one (COX-1), COX-2 is induced by proinflammatory factors. Polymorphism -765 G/C in COX-2-encoding gene promoter is associated with development of Alzheimer's disease, depression, carcinoma of the pancreas in smokers, breast cancer and rheumatoid arthritis. It is interesting whether the -765 G/C polymorphism in COX-2-encoding gene promoter can be associated with COPD, a disease which is inflammatory in character. It is highly probable as the breast and pancreas cancers, whose associations with the analyzed polymorphism have been studied, are smoking-dependent tumors. Additionally, tobacco smoke has been demonstrated to induce COX-2 in the lungs. The study group consisted of 122 COPD patients (48 females, 74 males). The control group consisted of 149 healthy nonsmoking subjects (83 females, 66 males). Polymerase chain reaction/restriction fragment length polymorphism was used for genotyping. A statistically significant difference in genotype distribution was observed as a result of the comparison between healthy subjects and patients with COPD. The distribution of alleles in both groups conformed with Hardy-Weinberg equilibrium. In the group of COPD patients, GG allele was found in 79 subjects, GC in 36, and CC in 7 subjects (F = 0.094, P = 0.296927); in the control group, 73 subjects had GG allele, 68--GC and 8--CC (F = 0.12728, P = 0.120265). The allele frequency revealed differences between those groups, attaining the level of statistical significance (χ(2) = 29.043, df = 2, P = 0.0000. The carriers of -765 G allele are at 1.53-fold higher risk of developing COPD. The presence of GG genotype does not increase significantly the risk of the disease. It is also noteworthy that the carriers of CC or GC genotypes are at significantly lower risk of developing COPD than the group of subjects with GG genotype.

A new cyclo-oxygenase-2 gene variant in the Han Chinese population is associated with an increased risk of gastric carcinoma

BACKGROUND AND OBJECTIVE

Cyclo-oxygenase-2 (COX-2, also known as prostaglandin synthase 2) influences carcinogenesis through regulation of angiogenesis, apoptosis, and cytokine expression. COX-2 is encoded by the gene PTGS2. Several studies have suggested that PTGS2 single-nucleotide polymorphisms (SNPs) are involved in gastrointestinal carcinogenesis. In this study, we observed the PTGS2 Val511Ala (5939T/C) polymorphism in the Chinese population for the first time, and investigated whether this polymorphism might contribute to gastric cancer in a case-control study conducted in the Gansu province of China, a high-risk area for gastric cancer.

METHODS

We determined the genotypes of 110 gastric cancer patients and 138 controls using polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) analysis. Data were statistically analyzed using a chi-squared test and a logistic regression model.

RESULTS AND CONCLUSION

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). We also found an interaction between Helicobacter pylori infection, a family history of gastric cancer, and presence of the 5939C allele. This study further indicated that H. pylori-positive status and family history jointly contribute to a higher risk of gastric cancer.