Relationship between three polymorphisms of methylenetetrahydrofolate reductase (MTHFR C677T, A1298C, and G1793A) gene and risk of prostate cancer: a case-control study

The combined effect of MTHFR C677T and A1298C polymorphisms on the risk of digestive system cancer among a hypertensive population

BACKGROUND AND PURPOSE

The enzyme methylenetetrahydrofolate reductase (MTHFR) plays a crucial role in directing folate species towards nucleotide synthesis or DNA methylation. The MTHFR polymorphisms C677T and A1298C have been linked to cancer susceptibility, but the evidence supporting this association has been equivocal. To investigate the individual and joint associations between MTHFR C677T, A1298C, and digestive system cancer in a Chinese hypertensive population, we conducted a population-based case-control study involving 751 digestive system cancer cases and one-to-one matched controls from the China H-type Hypertension Registry Study (CHHRS).

METHODS

We utilized the conditional logistic regression model to evaluate multivariate odds ratios (ORs) and 95% confidence intervals (CIs) of digestive system cancer.

RESULTS

The analysis revealed a significantly lower risk of digestive system cancer in individuals with the CT genotype (adjusted OR: 0.71; 95% CI 0.52, 0.97; P = 0.034) and TT genotype (adjusted OR: 0.57; 95% CI 0.40, 0.82; P = 0.003; P for trend = 0.003) compared to those with the 677CC genotype. Although A1298C did not show a measurable association with digestive system cancer risk, further stratification of 677CT genotype carriers by A1298C homozygotes (AA) and heterozygotes (AC) revealed a distinct trend within these subgroups.

CONCLUSION

These findings indicate a potential protective effect against digestive system cancer associated with the T allele of MTHFR C677T. Moreover, we observed that the presence of different combinations of MTHFR polymorphisms may contribute to varying susceptibilities to digestive system cancer.

No association between MTHFR gene C677T/A1298C polymorphisms, serum folate, vitamin B12, homocysteine levels, and prostate cancer in an Algerian population

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate and homocysteine metabolism, which are necessary for DNA methylation and nucleotide synthesis. Genetic polymorphisms that reduce MTHFR activity have been linked to several diseases, including prostate cancer. In this study, we aimed to investigate whether MTHFR polymorphisms, along with serum levels of folate, vitamin B12, and homocysteine, are associated with prostate cancer risk in the Algerian population.

METHODS

A total of 106 Algerian men with newly diagnosed prostate cancer and 125 healthy controls were included in this case-control study. The MTHFR C677T and A1298C polymorphisms were analyzed using PCR/RFLP and Real-Time PCR TaqMan® assays, respectively. Serum levels of folate, total homocysteine, and vitamin B12 were measured using an automatic biochemistry analyzer.

RESULTS

We found no significant differences in the genotype frequency of A1298C and C677T between prostate cancer patients and controls. Moreover, serum levels of folate, total homocysteine, and vitamin B12 were not significantly associated with prostate cancer risk (p > 0.05). However, age and family history were identified as significant risk factors (OR = 1.178, p = 0.00 and OR = 10.03, p = 0.007, respectively).

CONCLUSION

Our study suggests that MTHFR C677T and A1298C, as well as serum levels of folate, total homocysteine, and vitamin B12, are not associated with prostate cancer risk in the Algerian population. However, age and family history are significant risk factors. Further studies with a larger sample size are required to confirm these findings.

Targeting Homocysteine and Hydrogen Sulfide Balance as Future Therapeutics in Cancer Treatment

A high level of homocysteine (Hcy) is associated with oxidative/ER stress, apoptosis, and impairment of angiogenesis, whereas hydrogen sulfide (H2S) has been found to reverse this condition. Recent studies have shown that cancer cells need to produce a high level of endogenous H2S to maintain cell proliferation, growth, viability, and migration. However, any novel mechanism that targets this balance of Hcy and H2S production has yet to be discovered or exploited. Cells require homocysteine metabolism via the methionine cycle for nucleotide synthesis, methylation, and reductive metabolism, and this pathway supports the high proliferative rate of cancer cells. Although the methionine cycle favors cancer cells for their survival and growth, this metabolism produces a massive amount of toxic Hcy that somehow cancer cells handle very well. Recently, research showed specific pathways important for balancing the antioxidative defense through H2S production in cancer cells. This review discusses the relationship between Hcy metabolism and the antiapoptotic, antioxidative, anti-inflammatory, and angiogenic effects of H2S in different cancer types. It also summarizes the historical understanding of targeting antioxidative defense systems, angiogenesis, and other protective mechanisms of cancer cells and the role of H2S production in the genesis, progression, and metastasis of cancer. This review defines a nexus of diet and precision medicine in targeting the delicate antioxidative system of cancer and explores possible future therapeutics that could exploit the Hcy and H2S balance.

Interactions of SNPs in Folate Metabolism Related Genes on Prostate Cancer Aggressiveness in European Americans and African Americans

BACKGROUND

Studies showed that folate and related single nucleotide polymorphisms (SNPs) could predict prostate cancer (PCa) risk. However, little is known about the interactions of folate-related SNPs associated with PCa aggressiveness. The study's objective is to evaluate SNP-SNP interactions among the DHFR 19-bp polymorphism and 10 SNPs in folate metabolism and the one-carbon metabolism pathway associated with PCa aggressiveness.

METHODS

We evaluated 1294 PCa patients, including 690 European Americans (EAs) and 604 African Americans (AAs). Both individual SNP effects and pairwise SNP-SNP interactions were analyzed.

RESULTS

None of the 11 individual polymorphisms were significant for EAs and AAs. Three SNP-SNP interaction pairs can predict PCa aggressiveness with a medium to large effect size. For the EA PCa patients, the interaction between rs1801133 (MTHFR) and rs2236225 (MTHFD1), and rs1801131 (MTHFR) and rs7587117 (SLC4A5) were significantly associated with aggressive PCa. For the AA PCa patients, the interaction of DHFR-19bp polymorphism and rs4652 (LGALS3) was significantly associated with aggressive PCa.

CONCLUSIONS

These SNP-SNP interactions in the folate metabolism-related genes have a larger impact than SNP individual effects on tumor aggressiveness for EA and AA PCa patients. These findings can provide valuable information for potential biological mechanisms of PCa aggressiveness.

One-Carbon and Polyamine Metabolism as Cancer Therapy Targets

Cancer metabolic reprogramming is essential for maintaining cancer cell survival and rapid replication. A common target of this metabolic reprogramming is one-carbon metabolism which is notable for its function in DNA synthesis, protein and DNA methylation, and antioxidant production. Polyamines are a key output of one-carbon metabolism with widespread effects on gene expression and signaling. As a result of these functions, one-carbon and polyamine metabolism have recently drawn a lot of interest for their part in cancer malignancy. Therapeutic inhibitors that target one-carbon and polyamine metabolism have thus been trialed as anticancer medications. The significance and future possibilities of one-carbon and polyamine metabolism as a target in cancer therapy are discussed in this review.

The potential use of folate and its derivatives in treating psychiatric disorders: A systematic review

OBJECTIVES

To examine the strengths and limitations of existing data to provide guidance for the use of folate supplements as treatment, with or without other psychotropic medications, in various psychiatric disorders. To identify area for further research in terms of the biosynthesis of mechanism of folate and genetic variants in metabolic pathway in human.

METHODS

A systematic review of published literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, to assess whether folate supplements are beneficial in certain psychiatric disorders (depression, bipolar disorder, schizophrenia, autism spectrum disorder, and attention deficit hyperactivity disorder). Methodology of this review is registered with Prospero (Registration number CRD 42021266605).

DATA SOURCES

Eligible studies were identified using a systematic search of four electronic databases: Embase, Pubmed, PsycINFO, and Cochrane. The search strategy covered the time period from 1974 to August 16th, 2021. Therefore, this review examines randomized control trials or open-label trials completed during this period.

RESULTS

We identified 23 studies of folate supplements in various psychiatric disorders for critical review. Of these, 9 studies investigated the efficacy of folate supplements in major depressive disorders, 5 studies in schizophrenia, 6 studies in autism spectrum disorder, 2 studies in bipolar affective disorder and 1 study in attention deficit hyperactive disorder. The most consistent finding association of oral levomefolic acid or 5-methylfolate with improvement in clinical outcomes in mental health conditions as mentioned above, especially in major depressive disorder (including postpartum and post-menopausal depression), schizophrenia, autism spectrum disorder, attention deficit hyperactivity disorder and bipolar affective disorder. Folate supplements were well tolerated.

LIMITATION

Our results are not representative of all types of studies such as case reports or case series studies, nor are they representative of the studies conducted in languages that are not in English or not translated in English.

CONCLUSION

Increasing evidence from clinical trials consistently demonstrate folate supplements, especially levomefolic acid or 5-methylfolate, may improve clinical outcomes for certain psychiatric diseases, especially as an adjunct pharmacotherapy with minimal side effects.

Association between methylenetetrahydrofolate reductase gene rs1801131 A/C polymorphism and urinary tumors' susceptibility

Background

The methylenetetrahydrofolate reductase (MTHFR) rs1801131 A/C variant results in a decrease in MTHFR enzymatic activity, which may play an important role in folate metabolism and is also an important source of DNA methylation and DNA synthesis. Several case-control studies have been conducted to assess the association of MTHFR rs1801131 polymorphism with the risk of urinary cancers, yet with conflicting conclusions. To derive a more precise estimation of above relationship, the association between the MTHFR rs1801131 A/C polymorphism and the risk of urinary cancer was performed.

Methods

A total of 28 case-control studies was identified. The odds ratios (OR) with 95% confidence intervals (CI) was calculated to assess.

Results

On one hand, we found that the MTHFR rs1801131 A/C polymorphism was associated with increased whole urinary cancers’ risk (for example CA vs. AA: OR = 1.12. 95%CI = 1.01–1.24). On the other hand, we found that the MTHFR rs1801131 A/C polymorphism might increase bladder cancer risk both in Asian (C-allele vs. A-allele: OR = 1.35. 95%CI = 1.15–1.60) and African populations (CA vs. AA: OR = 1.63. 95%CI = 1.17–2.25).

Conclusions

Our current analysis suggested that MTHFR rs1801131 A/C is associated with urinary cancers, especially bladder cancer.

Genetic and molecular determinants of prostate cancer among Iranian patients: An update

Prostate cancer (PCa) is one of the most common age-related cancers among men. Various environmental and genetic factors are involved in the development and progression of PCa. In most cases, the primary symptoms of disease are not severe. Therefore, it is common for patients to be referred with severe clinical manifestations at advanced stages of disease. Since this malignancy is age related and Iran will face a significant increase in the number of seniors, it is expected that the prevalence of PCa among Iranian men will rise. PCa progression has been observed to be associated with genetic and ethnic factors. It may therefore be clinically useful to determine a panel of genetic markers, in addition to routine diagnostic methods, to detect tumors in the early stages. In the present review, we have summarized the reported genetic markers in PCa Iranian patients to pave the way for the determination of an ethnic specific genetic marker panel for the early detection of PCa. To understand the genetic and molecular biology of PCa among Iranians, we have categorized these genetic markers based on their cellular functions.

Disturbed homocysteine metabolism is associated with cancer

Hyperhomocysteinemia/Homocysteinuria is characterized by an increased level of toxic homocysteine in the plasma. The plasma concentration of homocysteine is 5–15 μmol/L in healthy individuals, while in hyperhomocysteinemic patients, it can be as high as 500 μmol/L. While increased homocysteine levels can cause symptoms such as osteoporosis and eye lens dislocation, high homocysteine levels are most closely associated with cardiovascular complications. Recent advances have shown that increased plasma Hcy is also a fundamental cause of neurodegenerative diseases (including Alzheimer’s disease, Parkinson’s disease, and dementia), diabetes, Down syndrome, and megaloblastic anemia, among others. In recent years, increased plasma homocysteine has also been shown to be closely related to cancer. In this review, we discuss the relation between elevated plasma Hcy levels and cancer, and we conclude that disturbed homocysteine metabolism is associated with cancer. Future clinical perspectives are also discussed.

Cancer can be added to the wide range of diseases known to be associated with elevated blood levels of the small amino acid homocysteine. Abnormally high levels of this compound are already known to contribute to conditions including cardiovascular problems, neurodegenerative diseases, neural tube defects, Down’s syndrome, diabetes and megaloblastic anemia. This review, by Laishram R. Singh and colleagues at the University of Delhi, India, concludes that disturbed homocysteine metabolism is associated with many forms of human cancer. The authors discuss a range of genetic, epigenetic and environmental factors that may be involved in the cause and effect relationships between homocysteine metabolism and cancer. It is particularly interesting that low folate (vitamin B9) levels result in high homocysteine levels, and vice versa. Further research may yield insights leading to new forms of cancer treatment and diagnosis.

Association of Bone Turnover Levels with MTHFR Gene Polymorphisms among Pregnant Women in Wuhan, China

Pregnancy is a critical stimulator of bone mineral resorption. We used to find the MTHFR gene polymorphisms are related with blood lead levels among pregnant women. Pregnancy-stimulated bone turnover may be associated with MTHFR gene polymorphisms too. In this article, we aimed to determine the relationship between MTHFR gene polymorphisms and bone turnover rates among the pregnant women. The participants including pregnant and non-pregnant women were selected and recruited during their routine prenatal or physical examination from July to October in 2012. A total of 1000 participants, including 250 pregnant women in the first, second, and third trimesters and 250 non-pregnant women, were enrolled in the study. Finally, after excluding 27 participants unable to provide blood samples, 973 eligible participants (i.e., 234,249, and 248 pregnant women in the first, second, and third trimesters, respectively, and 242 non-pregnant women) were included in the research. The MTHFR gene 1298CC homozygote carriers were more susceptible to yield higher plasma homocysteine levels than the 1298AA/AC carriers, with standardized coefficients of 0.086 (P<0.05) and 0.104 (P<0.01) of all the participants and the pregnant women, respectively. The MTHFR gene 1793AA homozygote carriers more likely showed higher plasma osteocalcin levels (standardized β=0.091,P<0.01) than the 1793GG/GA carriers among all the subjects. Plasma homocysteine levels were positively correlated with blood lead levels among the participants and the pregnant women with standardized coefficients of 0.320 (P<0.01) and 0.179 (P<0.01), respectively. Plasma osteocalcin levels were positively associated with blood lead levels among pregnant and non-pregnant women with standardized coefficients of 0.084 (P<0.05) and 0.125 (P<0.01), respectively. In conclusion, homocysteine and osteocalcin contents in plasma are associated with the MTHFR gene A1298C polymorphism and blood lead levels among pregnant women. The MTHFR gene A1298C polymorphism-related homocysteine is a possible risk factor for increased blood lead levels among Chinese women.

Genetic Variants Involved in One-Carbon Metabolism: Polymorphism Frequencies and Differences in Homocysteine Concentrations in the Folic Acid Fortification Era

Folate and other B vitamins are essential co-factors of one-carbon metabolism, and genetic variants, such as polymorphisms, can alter the metabolism. Furthermore, the adoption of food fortification with folic acid showed a decrease of homocysteine concentration. The aim of this study was to investigate the frequencies of the polymorphisms of enzymes and carrier proteins involved in one-carbon metabolism, and to evaluate homocysteine concentrations in the presence of these genetic variants in a population exposed to mandatory food fortification with folic acid. Using data from a population-based cross-sectional study in São Paulo, Brazil, the study population comprised 750 participants above 12 years of age of both genders. A linear regression model was used to evaluate the homocysteine concentrations according to genetic variants and folate level. The results showed that the minor allelic frequencies were 0.33 for MTHFR (rs1801133), 0.24 for MTHFR (rs1801131), 0.19 for MTR (rs1805087), 0.42 for MTRR (rs1801394), 0.46 for RFC1 (rs1051266), and 0.47 for DHFR (19-bp deletion). The genetic variants of MTHFR 677C>T, MTRR 66A>G and RFC-1 80G>A were different according to race. The homocysteine concentrations increased in the CT and TT compared to CC genotypes of polymorphism MTHFR 677C>T in all populations, and differences between the homocysteine concentrations according to the genotypes of MTHFR 677C>T were observed regardless of folate level.

Combined genotype and haplotype distributions of MTHFR C677T and A1298C polymorphisms: A cross-sectional descriptive study of 13,473 Chinese adult women

Methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms are, independently and/or in combination, associated with many disorders. However, data on the combined genotype and haplotype distributions of the 2 polymorphisms in Chinese population were limited.We recruited 13,473 adult women from 9 Chinese provinces, collected buccal cell samples, and determined genotypes, to estimate the combined genotype and haplotype distributions of the MTHFR C677T and A1298C polymorphisms.In the total sample, the 6 common combined genotypes were CT/AA (29.5%), TT/AA (21.9%), CC/AA (15.4%), CC/AC (14.9%), CT/AC (13.7%), and CC/CC (3.4%); the 3 frequent haplotypes were 677T-1298A (43.6%), 677C-1298A (37.9%), and 677C-1298C (17.6%). Importantly, we observed that there were 51 (0.4%) individuals with the CT/CC genotype, 92 (0.7%) with the TT/AC genotype, 17 (0.1%) with the TT/CC genotype, and that the frequency of the 677T-1298C haplotype was 0.9%. In addition, the prevalence of some combined genotypes and haplotypes varied among populations residing in different areas and even showed apparent geographical gradients. Further linkage disequilibrium analysis showed that the D' and r values were 0.883 and 0.143, respectively.In summary, the findings of our study provide further strong evidence that the MTHFR C677T and A1298C polymorphisms are usually in trans and occasionally in cis configurations. The frequencies of mutant genotype combinations were relatively higher in Chinese population than other populations, and showed geographical variations. These baseline data would be useful for future related studies and for developing health management programs.

Elevated homocysteine level and folate deficiency associated with increased overall risk of carcinogenesis: meta-analysis of 83 case-control studies involving 35,758 individuals

BACKGROUND

Results of the association of folate metabolism and carcinogenesis are conflicting. We performed a meta-analysis to examine the effect of the interaction of serum concentration of homocysteine (Hcy), folate, and vitamin B12 and 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphism on risk of cancer overall.

METHOD

Two reviewers independently searched for all published studies of Hcy and cancer in PubMed, EMBASE-MEDLINE and Chinese databases. Pooled results were reported as odds ratios (ORs) and mean differences and presented with 95% confidence intervals (95% CIs) and 2-sided probability values.

RESULTS

We identified 83 eligible studies of 15,046 cases and 20,712 controls. High level of Hcy but low level of folate was associated with risk of cancer overall, with little effect by type of cancer or ethnicity. Vitamin B12 level was inversely associated with only urinary-system and gastrointestinal carcinomas and for Asian and Middle Eastern patients. As well, MTHFR C677T, A1298C and G1793A polymorphisms were related to elevated serum level of Hcy, and folate and vitamin B12 deficiency. However, only MTHFR C677T homogeneity/wild-type (TT/CC) polymorphism was positively associated with overall risk of cancer.

CONCLUSION

Elevated serum Hcy level and folate deficiency are associated with increased overall risk of cancer.

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 (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 MTHFR C677T and A1298C gene polymorphisms: association with the risk of hepatocellular carcinoma

OBJECTIVE

Several studies have indicated an association between methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms and the risk of hepatocellular carcinoma (HCC). However, the conclusions are inconsistent. Therefore, a meta-analysis was performed.

METHODS

Databases like Pubmed, EMBASE, and EBSCO (up to September 2012) were searched to retrieve case-control trials about MTHFR (C677T or A1298C) polymorphisms and HCC. Literatures were independently screened by two researchers according to the inclusion and exclusion criteria. Data were extracted and analyzed by software STATA 11.0.

RESULTS

Nine studies were included with 10 datasets and 5132 cases. C677T polymorphism was associated with HCC risk in a heterozygous model (TT vs. CT: OR=1.20, 95% CI: 1.02-1.40). For the A1298C polymorphism, a significantly decreased HCC risk was found in the dominant, heterozygous and homozygous models (CC vs. AA+AC: OR=0.52, 95% CI: 0.33-0.80; CC vs. AC: OR=0.50, 95% CI: 0.32-0.79; CC vs. AA: OR=0.52, 95% CI: 0.33-0.81). Subgroup analysis stratified by ethnicity and type of control further indicated decreased HCC risks in Asians (CC vs. AA+AC: OR=0.47, 95% CI: 0.26-0.84; CC vs. AC: OR=0.41, 95% CI: 0.24-0.71; CC vs. AA: OR=0.46, 95% CI: 0.27-0.78), studies with controls of healthy people (CC vs. AA: OR=0.54, 95% CI: 0.31-0.93; CC vs. AC: OR=0.54, 95% CI: 0.31-0.94; CC vs. AA+AC: OR=0.55, 95% CI: 0.32-0.94), and controls of non-HCC patients (CC vs. AC: OR=0.43, 95% CI: 0.19-0.96).

CONCLUSIONS

Homozygous carriers of MTHFR C677T mutation are more susceptible to HCC, but homozygous mutations of MTHFR A1298C may play a protective role for developing HCC.

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

Methylenetetrahydrofolate reductase (MTHFR) is an essential enzyme involved in folate metabolism; a single nucleotide polymorphism (SNP) C677T has been reported to be linked with altered incidences of several diseases. We here conducted a meta-analysis of 15 published epidemiological studies with a total of 7306 cases and 8062 controls to evaluate its association with prostate cancer risk with overall and subgroup analyses. No statistical relationship was found overall with any genetic model (TT vs. CC: OR = 0.80, 95%CI = [0.62, 1.04], P = 0.094; CT vs. CC: OR = 0.97, 95%CI = [0.84; 1.12], P = 0.667; Dominant: OR = 0.94, 95%CI = [0.82; 1.07], P = 0.343; Recessive: OR = 0.81, 95%CI = [0.64; 1.04], P = 0.104), but after the exclusion of several studies, we could observe the homozygote TT to confer less susceptibility to prostate cancer in carriers; moreover, different effects of the polymorphism on prostate cancer risk was detected from subgroup analysis stratified by participants' residential region: significant reduced prostate cancer risk was found to be associated with the polymorphism from Asian studies (TT vs. CC: OR = 0.47, 95%CI = [0.33; 0.67], P< 0.001; CT vs. CC: OR = 0.73, 95%CI = [0.60; 0.90], P = 0.002; Dominant: OR = 0.67, 95%CI = [0.56; 0.82], P< 0.001; Recessive: OR = 0.55, 95%CI = [0.40; 0.76], P< 0.001) while studies from Europe indicated a slight increased risk under dominant model with marginal significance (OR = 1.14, 95%CI = [0.99; 1.30], P = 0.064). Moreover, the protective effect of the polymorphism against prostate cancer was also shown by studies performed in yellow Asians (TT vs. CC: OR = 0.48, 95%CI = [0.31; 0.75], P = 0.001; CT vs. CC: OR = 0.68, 95%CI = [0.51; 0.90], P = 0.006; Dominant: OR = 0.63, 95%CI = [0.48; 0.82], P < 0.001; Recessive: OR = 0.57, 95%CI = [0.39; 0.84], P = 0.004). We propose that these phenomena should be viewed with the consideration of folate metabolism profile and different gene background as well as living habits of different populations, and more relevant studies should be conducted to confirm our hypothesis and provide a comprehensive and clear picture concerning this topic.

Effects of EPA, γ-linolenic acid or coenzyme Q10 on serum prostate-specific antigen levels: a randomised, double-blind trial

The main objective of the present study was to determine the potential of n-3 and n-6 fatty acids or coenzyme Q10 (CoQ10) to alter serum prostate-specific antigen (PSA) levels in normal healthy men. A total of 504 healthy men with serum PSA level ≤ 2·5 ng/ml were recruited into the study. Serum PSA values were not segregated by decade of age. Participants were randomly assigned to a daily dietary supplement containing n-3 fatty acids (1·12 g of EPA and 0·72 g of DHA per capsule) (group 1, n 126), n-6 fatty acid (600 mg γ-linolenic acid (GLA) each capsule) (group 2, n 126), CoQ10 (100 mg per capsule) (group 3, n 126) or a similar regimen of placebo (group 4, n 126) for 12 weeks. Study medication was administered as two capsules to be taken twice daily. Serum levels of PSA, EPA, DHA, GLA, lipid profile and reproductive hormones were also measured. EPA treatment significantly reduced serum PSA level by 30·0 (95 % CI 25, 36) % (P= 0·004) from baseline. In contrast, GLA therapy significantly increased serum PSA concentration by 15·0 (95 % CI 11, 20) % (P= 0·02). CoQ10 therapy also significantly reduced serum PSA level by 33·0 (95 % CI 27, 40) % (P= 0·002). In multivariable analysis, serum values of PSA were strongly correlated with duration of EPA (r - 0·62; 95 % CI - 0·42, - 0·77; P= 0·003), n-6 (r 0·42; 95 % CI 0·31, 0·58; P= 0·02) and CoQ10 use (r - 0·77; 95 % CI - 0·56, - 0·87; P= 0·001). There were also significant correlations between serum values of DHA, EPA, GLA and CoQ10 and serum PSA levels. The present study demonstrates that dietary supplements containing EPA, GLA or CoQ10 may significantly affect serum PSA levels.

A literature review of MTHFR (C677T and A1298C polymorphisms) and cancer risk

5,10-Methlenetetrahydrofolate reductase (MTHFR) is one of the most important enzymes for folate metabolism. This enzyme is mapped on chromosome 1, which is located at the end of the short arm (1p36.3). The C677T and A1298C are MTHFR polymorphisms that decrease in vitro MTHFR enzyme activity. Folate metabolism plays a key role in cell metabolism. These reactions are associated with purine-pyrimidine synthesis: DNA, RNA, and protein methylation. Polymorphism is also a factor in biodiversity, and be affected by ethnic heritage and geographic locale. In the case of unknown outcomes, not only should all geographical regions be investigated to ascertain biodiversity, but all populations as well to fully understand the variations in the effect. PUBMED was searched from January 2006 to December 2011 to develop an investigatory pursuit strategy. MTHFR, cancer, C677T, A1298C, and polymorphisms were key words used to focus the search. The literature review included all published relevant cancer types and MTHFR polymorphisms for that 5 years period. All selected polymorphisms data for cancer types was listed in tables for easy access and retrieval.

No association of the MTHFR gene A1298C polymorphism with the risk of prostate cancer: A meta-analysis

Various studies have demonstrated that the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism contributes to the risk of prostate cancer, while other studies have provided conflicting findings. In the present study, we carried out a comprehensive meta-analysis with the aim of determining whether there is a significant association of the MTHFR gene A1298C polymorphism with the susceptibility of prostate cancer. Studies on the MTHFR gene A1298C polymorphism and prostate cancer were retrieved using the electronic PubMed database without any restriction on language through Aug 21, 2011. Data were abstracted by a standardized protocol. Crude odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to estimate the strength of association. The analyses were conducted with Review Manager software version 4.2. Nine case-control studies were identified, including 2,723 prostate cancer patients and 3,442 controls. Overall, no significant associations were found between the MTHFR gene A1298C polymorphism and prostate cancer (codominant models: CC vs. AA, OR=1.03, 95% CI 0.79-1.34, P=0.84; AC vs. AA, OR=1.04, 95% CI 0.93-1.16, P=0.46; dominant model: AC + CC vs. AA, OR=1.04, 95% CI 0.94-1.15, P=0.48; recessive model: CC vs. AC + AA, OR=1.02, 95% CI 0.76-1.35, P=0.91; allele model: C vs. A, OR=1.04, 95% CI 0.90-1.19, P=0.61). Similarly, in the subgroup analyses by DNA source, ethnicity, control source, pathological stage and Hardy-Weinberg equilibrium, no significant associations were observed. Our meta-analysis suggests that the MTHFR gene A1298C polymorphism is not associated with the risk of prostate cancer.

Impact of methylenetetrahydrofolate reductase C677T polymorphism on the risk of gastric cancer and its interaction with Helicobacter pylori infection

BACKGROUND

Attempts for early detection of gastric cancer have recently focused on host's genetic susceptibility factors and gene-environment interactions. We have, herein, studied the association of MTHFR C677T single nucleotide polymorphism (SNP) and its interaction with Helicobacter pylori infection, smoking, age and gender on the risk of gastric cancer among an Iranian population.

METHODS

Gastric cancer patients (n = 450) and cancer-free controls (n = 780) were studied for serum H. pylori-specific IgG antibodies by ELISA and MTHFR C677T polymorphism (SNP) by PCR-RFLP. Demographic and life style data were collected through patient interviews. Unconditional logistic regression model estimated odds ratio (OR) and the corresponding 95% confidence intervals (CI).

RESULTS

The interactions of MTHFR genotype with H. pylori infection (P = 0.03), age (P = 0.049) and gender (P = 0.007) were statistically significant. Accordingly, MTHFR C677T carriers who were also positive for H. pylori infection exhibited 80% (OR = 1.8, 95% CI = 1.0-2.9) significant excess risk of non-cardia gastric cancer. Furthermore, subjects over the age of 50 or female subjects carrying MTHFR C677T SNP showed 40 (OR = 1.4, 95% CI = 1.0-2.0) and 100 (OR = 2.0, 95% CI = 1.2-3.2) percent increased risk of gastric cancer, respectively.

CONCLUSION

MTHFR C677T SNP seems to increase the risk of gastric cancer and the effect is significantly inflated by interactions with H. pylori infection, age and gender.

Polymorphisms of folate pathway enzymes (methylenetetrahydrofolate reductase and thymidylate synthase) and their relationship with thymidylate synthase expression in human astrocytic tumors

Two important polymorphisms of folate cycle enzymes, methylenetetrahydrofolate reductase (MTHFR) C677T and thymidylate synthase (TS) enhancer region (TSER) 28-bp tandem repeat, are related to risk of various types of cancer, including brain tumors, although there are few studies on this subject. A case-control study of these two polymorphisms in astrocytomas of different grades was carried out using polymerase chain reaction-restriction fragment length polymorphism, also determining the immunohistochemical expression of TS. The MTHFR 677 TT genotype was less associated with astrocytic tumors (odds ratio [OR]=0.00; p=0.0238), but the TSER polymorphism did not show any significant association. Combined genotype TT-double repeats/triple repeats (2R/3R) had a protective effect against astrocytomas (OR=0.00; p=0.0388). Expression of TS protein was observed in the majority of cases, with grade IV tumors being the exception. Moreover, the median H-score for the pilocytic astrocytomas was significantly higher when compared with that for diffuse tumors. There was an inverse correlation between the 2R/2R genotype and the highest TS-expressing tumors, and 3R/3R was relatively more frequent among the tumors grouped in the third and fourth quartiles. Our results provide support for the role of MTHFR and TS polymorphism in gliomagenesis, possibly because of the alteration of DNA methylation and repair status. Moreover, high levels of TS expression were detected in these tumors.

Methylenetetrahydrofolate reductase (MTHFR) gene C677T, A1298C and G1793A polymorphisms: association with risk for clear cell renal cell carcinoma and tumour behaviour in men

AIMS

Methylenetetrahydrofolate reductase (MTHFR) plays a crucial role in regulating folate metabolism, which affects DNA synthesis and methylation. This study investigated whether MTHFR C677T, A1298C and G1793A polymorphisms modified clear cell renal cell carcinoma (CCRCC) risk independently as well as in combination with serum total homocysteine (Hcy) and folate levels.

MATERIALS AND METHODS

A case-control study of 152 cases (men) and 304 age-matched healthy controls was conducted in one geographical area of Iran. Genotyping of MTHFR gene polymorphisms was carried out using a polymerase chain reaction restriction fragment length polymorphism technique. Serum levels of total Hcy, folate and vitamin B12 were also determined.

RESULTS

The MTHFR 677T and 1298C allele frequencies were 42.8 and 47.4% in cases, compared with 33.7 and 33.1% in controls. After controlling for confounding factors, a significant increase in CCRCC risk was found among carriers of the 677CT genotype compared with those with the 677CC genotype (odds ratio 2.21, 95% confidence interval 1.31-3.76), with a significant trend (P=0.014). Statistically significant odds ratios were also found in patients homozygous for MTHFR C677T, who have a 1.58-fold higher risk of developing CCRCC (95% confidence interval=1.21-2.44; P=0.024). Compared with the MTHFR 677CC genotype, the odds ratio (95% confidence interval) for the MTHFR 677TT genotype was 6.18 (95% confidence interval=4.75-8.34) for stage IV cancer and 4.68 (95% confidence interval=2.72-6.54) for grade 3 CCRCC (both P=0.0001). After adjustment for selected variants, the MTHFR 1298AC genotype showed a significantly increased risk of CCRCC compared with the wild-type (odds ratio=3.71, 95% confidence interval=2.22-5.33; P=0.001), and the 1298C allele carrier showed a positive association with the risk of CCRCC compared with the wild-type (odds ratio=3.9, 95% confidence interval=2.55-6.02; P=0.001). Furthermore, subjects carrying at least one copy of the variant allele showed a 4.4 times increased risk of developing CCRCC than their control counterparts (odds ratio=4.40, 95% confidence interval=2.41-6.72; P=0.0001). There was not a significant interaction between MTHFR polymorphisms and serum levels of total Hcy and folate in increasing the risk of CCRCC.

CONCLUSIONS

Our results provide evidence that the MTHFR polymorphisms might contribute to increased CCRCC risk in men.

Role of methylenetetrahydrofolate reductase gene polymorphisms (C677T, A1298C, and G1793A) in the development of early onset vasculogenic erectile dysfunction

BACKGROUND AND AIMS

The methylenetetrahydrofolate reductase (MTHFR) gene plays a key role in the metabolism of folate and homocysteine (Hcy) and its mutations have been associated with high serum Hcy level. Elevated serum Hcy has been linked to impaired endothelial function and occlusive vascular disease. We studied the association among the different genotypes of all three MTHFR polymorphisms (C677T, A1298C, and G1793A) and the risk of early-onset vasculogenic erectile dysfunction (VED).

METHODS

We performed a case-control study of 114 men with early-onset VED and 228 age-matched controls. Genotyping of MTHFR gene polymorphisms was performed using polymerase chain reaction restriction fragment length polymorphism (PCR-RLFP) technique. We also measured plasma lipids, Hcy, folate, and vitamin B12 levels.

RESULTS

Patients with early-onset VED had higher serum Hcy levels (12.29 ± 2.32 vs. 9.82 ± 2.35 μmol/L, p = 0.001) and higher prevalence of 677TT homozygocity compared to controls (15.8% vs. 11.4%, p = 0.01). Serum Hcy concentration was significantly higher in individuals with 677TT, 1298CC, and 1793GG genotypes. Subgroup analysis according to severity of ED (mild, moderate, and severe) showed that patients with severe VED had higher serum Hcy levels compared to patients with mild VED (13.48 ± 2.51 vs. 11.21 ± 2.32 μmol/L, p = 0.001).

CONCLUSIONS

Odds ratio seems to demonstrate that individuals with the MTHFR 677TT genotype and the 677TT + 1298AC combined genotype had a 3.16- and 3.89-fold increased risk for developing VED, suggesting a possible association of MTHFR polymorphisms with the risk of early-onset VED.

Relationship between genetic polymorphisms of methylenetetrahydrofolate reductase (C677T, A1298C, and G1793A) as risk factors for idiopathic male infertility

OBJECTIVE

The human methylenetetrahydrofolate reductase (MTHFR) gene plays a crucial role in folate metabolism. Data regarding the influence of MTHFR gene polymorphisms on male fertility status are scarce and conflicting. We determined associations between 3 MTHFR gene polymorphisms (C677T, A1298C, and G1793A), serum folate, and total homocysteine (tHcy) levels, with male fertility status and semen parameters.

METHODS

MTHFR genotypes were determined using polymerase chain reaction restriction fragment length polymorphism (PCR-RLFP) technique and serum tHcy, folate, and vitamin B12 concentrations were measured in 164 men with idiopathic infertility and 328 healthy participants.

RESULTS

There was a significant difference in genotype frequency distribution of MTHFR C677T polymorphism between infertile patients and controls (P = .004). The 677T allele carriers (TC or TT) had a significantly increased risk of infertility compared with the CC homozygotes (odds ratio [OR] 1.60, 95% confidence interval [CI] 1.21-2.75, and OR = 2.68, 95% CI = 1.84-3.44, respectively), in a logistic regression model after adjustment for confounding factors. Men with the 677T, 1298C, and 1793G alleles showed significantly higher serum tHcy and lower folate levels (all Ps < .01). We found a positive correlation between serum folate concentrations and sperm density (r = .74, P = .001), percentage of sperm with progressive motility (r = .68, P = .001), as well as percentage of sperm with normal morphology (r = .72, P = .001).

CONCLUSION

MTHFR C677T polymorphism is associated with an increased risk of idiopathic male infertility. Further study on the biologic role that this polymorphism plays in the development of infertility may lead to better understanding of the etiology of impaired spermatogenesis.