Methionine synthase A2756G polymorphism and risk of colorectal adenoma and cancer: evidence based on 27 studies

• Published in: PloS one 2013-04, Vol.8 (4), p.e60508-e60508
• Main Authors: Ding, Weixing, Zhou, Dong-Lei, Jiang, Xun, Lu, Lie-Sheng
• Format: Article
• Language: English
• Subjects: 5-Methyltetrahydrofolate-homocysteine S-methyltransferase; 5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase - genetics; Adenoma; Adenoma - genetics; Alcohol; Alcohol use; Alcoholic beverages; Amino acids; Biology; Biomarkers; Cancer; Cancer research; Carbon; Colorectal cancer; Colorectal carcinoma; Colorectal Neoplasms - genetics; Deoxyribonucleic acid; Development and progression; Disease susceptibility; DNA; DNA methylation; Drinking behavior; Ethnicity; Female; Folic acid; Gastroenterology; Gene expression; Gene polymorphism; Genes; Genetic aspects; Genetic polymorphisms; Genetic Predisposition to Disease; Genotype; Health risk assessment; Health risks; Homocysteine; Humans; Male; Medicine; Meta-analysis; Metabolism; Methionine; Methylation; Minority & ethnic groups; Odds Ratio; Polymorphism; Polymorphism, Genetic; Polymorphism, Single Nucleotide; Publication Bias; Risk; Smoking; Studies; Tumors; Vitamin B
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0060508

Methionine synthase (MTR), which plays a central role in maintaining adequate intracellular folate, methionine and normal homocysteine concentrations, was thought to be involved in the development of colorectal cancer (CRC) and colorectal adenoma (CRA) by affecting DNA methylation. However, studies on the association between MTR A2756G polymorphism and CRC/CRA remain conflicting. We conducted a meta-analysis of 27 studies, including 13465 cases and 20430 controls for CRC, and 4844 cases and 11743 controls for CRA. Potential sources of heterogeneity and publication bias were also systematically explored. Overall, the summary odds ratio of G variant for CRC was 1.03 (95% CI: 0.96-1.09) and 1.05 (95% CI: 0.99-1.12) for CRA. No significant results were observed in heterozygous and homozygous when compared with wild genotype for these polymorphisms. In the stratified analyses according to ethnicity, source of controls, sample size, sex, and tumor site, no evidence of any gene-disease association was obtained. Results from the meta-analysis of four studies on MTR stratified according to smoking and alcohol drinking status showed an increased CRC risk in heavy smokers (OR = 2.06, 95% CI: 1.32-3.20) and heavy drinkers (OR = 2.00, 95% CI: 1.28-3.09) for G allele carriers. This meta-analysis suggests that the MTR A2756G polymorphism is not associated with CRC/CRA susceptibility and that gene-environment interaction may exist.