The MTHFR C677T polymorphism and prostate cancer risk: new findings from a meta-analysis of 7306 cases and 8062 controls

MTHFR c.677C>T Inhibits Cell Proliferation and Decreases Prostate Cancer Susceptibility in the Han Chinese Population in Shanghai

Methylenetetrahydrofolate reductase (MTHFR) c.677C>T and c.1298A>C variants were known to be associated with prostate cancer (PCa) risk with conflicting results, because of MTHFR and nutrient status interaction in the prostate development. In this large-scale, hospital-based, case-control study of 1817 PCa cases and 2026 cancer-free controls, we aimed to clarify the association between these two MTHFR variants and PCa risk in Shanghai and to explore the underlying molecular mechanisms. We found that both the heterozygous CT (adjusted OR = 0.78, 95% CI: 0.67-0.92) and the homozygous TT genotypes (adjusted OR = 0.68, 95% CI: 0.55-0.83) of c.677C>T were associated with a significantly decreased risk of PCa compared with homozygous wild-type CC genotype, respectively, using multivariate logistic regression. Furthermore, we confirmed that MTHFR c.677T allele was related to an increased serum homocysteine level in the Han Chinese population in Shanghai. In the cultured PCa cell lines, we observed that MTHFR c.677T could elevate the cellular homocysteine level and cause DNA damage, thus increasing cell apoptosis and finally inhibiting cell proliferation. In conclusion, MTHFR c.677T was a protective factor of PCa risk in ethnic Han Chinese males by inducing DNA damage and cell apoptosis.

Methylenetetrahydrofolate reductase gene C677T polymorphism and breast cancer risk: Evidence for genetic susceptibility

There are several evidences supporting the role of 5–10 methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms in breast cancer (BC). Case control association studies on breast cancer have been repeatedly performed over the last two decades, but results are inconsistent. We performed a meta-analysis to confirm the association between MTHFR C677T polymorphism and BC risk.

The articles were retrieved by searching the PubMed, Google Scholar, and Springer Link databases. Crude odds ratios (OR) with 95% confidence intervals (CIs) was used to assess the strength of association between C677T polymorphism and BC. Publication bias was assessed by Egger's and Begg-Mazumdar tests. Meta-analysis was performed with Open Meta Analyst.

Total 75 studies with 31,315 cases and 35, 608 controls were found suitable for the inclusion in the present meta-analysis. The results of meta-analysis suggested that there were moderate significant association between C677T polymorphism and BC risk using overall comparisons in five genetic models (T vs. C: OR = 1.08, 95% CI = 1.03–1.13, p = < 0.001; TT + CT vs. CC: OR = 1.06, 95% CI = 1.02–1.09, p = < 0.001; TT vs. CC: OR = 1.17, 95% CI = 1.06–1.28, p = 0.001; CT vs. CC OR = 1.05, 95% CI = 1.01–1.08, p = 0.005; TT vs. CT + CC: OR = 1.12, 95% CI = 1.03–1.22, p = 0.005). In conclusion, results of present meta-analysis showed modest association between MTHFR C677T polymorphism with breast cancer in total studies. However, sub-group analysis results based on ethnicity showed strong significant association between TT genotype and breast cancer (TT vs. CC; OR°=°1.26; 95% CI: 1.06–1.51; p = 0.009) in Asian population but in Caucasian population such association was not observed (TT vs. CC; OR°=°1.08; 95% CI: 0.99–1.14; p = 0.05).

The methylenetetrahydrofolate reductase C677T polymorphism and breast cancer risk in Asian populations

BACKGROUND

Methylenetetrahydrofolate (MTHFR) is the key enzyme of the folate metabolic pathway and several studies have pointed to association between the MTHFR C677T polymorphism and breast cancer risk. Although significant association was observed in some studies, in others no clear link could be established.

OBJECTIVE

A meta-analysis of published Asian case control studies was therefor carried out to shed further light on any C677T breast cancer association.

MATERIALS AND METHODS

PubMed, Springer Link, Google Scholar and Elsevier databases were searched for case control studies of associations between MTHFR C677T polymorphism and breast cancer risk. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association. A total of 36 studies including 8,040 cases and 10,008 controls were included in the present meta-analysis.

RESULTS

Overall, a significantly elevated breast cancer risk was associated with the T allele and TT genotype in homozygote comparison and dominant genetic models when all studies were pooled into the meta-analysis (T vs C (allele contrast model): OR=1,23, 95%CI=1.13-1.37, p=0.000 ; TT vs CC(homozygote model): OR=1.38, 95%CI=1.16-1.63, p=0.0003; TT+CT vs CC (dominant model): OR=1.12, 95%CI=1.01-1.23, p=0.02).

CONCLUSIONS

The present meta-analysis strongly suggested a significant association between the MTHFR C677T polymorphism and risk of breast cancer in Asian populations.

The protective effect of methylenetetrahydrofolate reductase C677T polymorphism against prostate cancer risk: Evidence from 23 case-control studies

Genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) were considered to have some influence on both folate metabolism and cancer risk. Previous studies on the relation between MTHFR C677T polymorphism and prostate cancer (PCa) risk remained controversial. To derive a more precise estimation of the relationship, we carried out an update comprehensive meta-analysis to assess the associations of the MTHFR C677T polymorphism with the susceptibility of PCa. Twenty-three trials with a total of 24,024 participants on the MTHFR C677T polymorphism that met inclusion criteria were analyzed in the current study. Overall, no statistical relationship was found with any MTHFR C677T genetic model associated with susceptibility to PCa (TT versus CC, OR=0.83, 95% CI 0.68-1.02, P=0.07; CT versus CC, OR=0.95, 95% CI 0.85-1.07, P=0.43; Dominant, OR=0.93, 95% CI 0.83-1.03, P=0.17; Recessive, OR=0.84, 95% CI 0.70-1.02, P=0.09.). Nevertheless, subgroup analysis found a reduced PCa risk associated with polymorphism in Asian population (TT versus CC, CT versus CC, dominant and recessive model). Moreover, the protective effect of polymorphism against PCa risk was also shown upon hospital-based studies (TT versus CC, and recessive model). When benign prostate hyperplasia was chosen as controls, both TT versus CC and recessive model showed significant difference. In addition, the protective effect of homozygote TT against high aggressive PCa was proved to have significant difference. Taken together, the existing evidence indicates the homozygote TT of MTHFR C677T should be viewed as a protective factor against PCa risk for clinical practice with the consideration of different gene background, study design as well as specific controls.

Methylenetetrahydrofolate Reductase A1298C Polymorphism and Breast Cancer Risk: A Meta-analysis of 33 Studies

Methylenetetrahydrofolate reductase (MTHFR) enzyme is essential for DNA synthesis and DNA methylation, and its gene polymorphisms have been implicated as risk factors for birth defects, neurological disorders, and different types of cancers. Several studies have investigated the association between the MTHFR A1298C polymorphism and breast cancer (BC) risk, but the results were inconclusive. To assess the risk associated with MTHFR A1298C polymorphism, a comprehensive meta-analysis was performed. PubMed, Google Scholar, Elsevier and Springer Link databases were searched for case-control studies relating the association between MTHFR A1298C polymorphism and BC risk and estimated summary odds ratios (ORs) with confidence intervals (CIs) for assessment. Up to January 2014, 33 case-control studies involving 15,919 BC patients and 19,700 controls were included in the present meta-analysis. The results showed that the A1298C polymorphism was not associated with BC risk in all the five genetic models (C vs. A allele (allele contrast): OR = 0.99, 95% confidence interval (CI): 0.93–1.05; AC versus AA (heterozygote/codominant): OR = 0.97, 95% CI: 0.89–1.04; CC versus AA (homozygote): OR = 0.99, 95% CI: 0.91–1.06; CC + AC versus AA (dominant model): OR = 0.97, 95% CI: 0.90–1.05; and CC versus AC + AA (recessive model): OR = 0.99, 95% CI: 0.91–1.07). The present meta-analysis did not support any association between the MTHFR A1298C polymorphism and BC risk.

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism: epidemiology, metabolism and the associated diseases

The Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism is associated with various diseases (vascular, cancers, neurology, diabetes, psoriasis, etc) with the epidemiology of the polymorphism of the C677T that varies dependent on the geography and ethnicity. The 5,10-Methylenetetrahydrofolate reductase (MTHFR) locus is mapped on chromosome 1 at the end of the short arm (1p36.6). This enzyme is important for the folate metabolism which is an integral process for cell metabolism in the DNA, RNA and protein methylation. The mutation of the MTHFR gene which causes the C677T polymorphism is located at exon 4 which results in the conversion of valine to alanine at codon 222, a common polymorphism that reduces the activity of this enzyme. The homozygous mutated subjects have higher homocysteine levels while the heterozygous mutated subjects have mildly raised homocysteine levels compared with the normal, non-mutated controls. Hyperhomocysteinemia is an emerging risk factor for various cardiovascular diseases and with the increasing significance of this polymorphism in view of the morbidity and mortality impact on the patients, further prevention strategies and nutritional recommendations with the supplementation of vitamin B12 and folic acid which reduces plasma homocysteine level would be necessary as part of future health education. This literature review therefore focuses on the recent evidence-based reports on the associations of the MTHFR C677T polymorphism and the various diseases globally.

Meta-analysis of the relation between the VDR gene TaqIpolymorphism and genetic susceptibility to prostate cancer in Asian populations

BACKGROUND

Polymorphisms of the Taq I gene have been associated with prostate cancer risk.

METHODS

We applied a fixed-effects model to combine odds ratios (ORs) and 95% confidence intervals (95% CI). The Egger's test was carried out to evaluate potential publication bias.

RESULTS

A total of 10 case-control studies enrolling 1,141 prostate cancer patients and 1,685 controls were included in this meta-analysis. Compared with the T allele, the OR for the C allele was 0.81 (0.70-0.94). The ORs for CT and CC+CT genotypes were 0.86 (0.74-1.01) and 0.84 (0.73-0.97) compared to wide type genotype (homozygote TT).

CONCLUSIONS

The present meta-analysis suggests that the TF gene Taq I polymorphism may reduce the prostate cancer risk in Asian populations.

CYP1A1 MspI polymorphism is associated with prostate cancer susceptibility: evidence from a meta-analysis

Cytochrome P450 1A1 (CYP1A1), an important phase I xenobiotic metabolizing enzyme, is responsible for metabolizing numerous carcinogens, particularly polycyclic aromatic hydrocarbons. The genetic polymorphism of CYP1A1 at the site of MspI (CYP1A1 MspI) has been implicated in prostate cancer risk, but the results of individual studies remain conflicting and inconclusive. The aim of this meta-analysis was to investigate the association of CYP1A1 MspI polymorphism with prostate cancer risk more precisely. We performed a comprehensive search of the PubMed, Embase, Web of Science, and China National Knowledge Infrastructure databases from their inception up to September 20, 2012 for relevant publications. The pooled odds ratios with the corresponding 95% confidence intervals (95% CIs) were calculated to assess the association of CYP1A1 MspI polymorphism with prostate cancer risk. In addition, stratified analyses by ethnicity and sensitivity analyses were conducted for further estimation. Sixteen eligible publications with 6,411 subjects were finally included into the meta-analysis after checking the retrieved papers. Overall, meta-analysis of total studies suggested that individuals carrying the TC genotype and a combined C genotype (CC + TC) were more susceptible to prostate cancer (OR(TC vs. TT) = 1.33, 95% CI 1.10-1.61, P(OR) = 0.004; OR(CC+TC vs. TT) = 1.27, 95% CI 1.05-1.55, P(OR) = 0.016). Stratified analysis of high quality studies also confirmed the significant association (OR(TC vs. TT) = 1.32, 95% CI 1.04-1.67, P(OR) = 0.024; OR(CC+TC vs. TT) = 1.30, 95% CI 1.02-1.66, P(OR) = 0.035). In subgroup analyses by ethnicity, a significant association between the CYP1A1 MspI polymorphism and risk of prostate cancer was found among Asians (OR(TC vs. TT) = 1.44, 95% CI 1.20-1.72, P(OR) < 0.001; OR(CC+TC vs. TT) = 1.33, 95% CI 1.12-1.58, P(OR) = 0.001), but not in Caucasians or mixed populations. The meta-analysis suggests an important role of the CYP1A1 MspI polymorphism in the risk of developing prostate cancer, especially in Asians.