Lack of association between methionine synthase A2756G polymorphism and digestive system cancer risk: evidence from 3,9327 subjects

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.

Gene-Gene Interaction Study Between Genetic Polymorphisms of Folate Metabolism and MTR SNPs on Prognostic Features Impact for Breast Cancer

Background

Breast Cancer (BC), the second leading cause of cancer mortality after lung cancer and varied across the world due to genetic and environmental factors. In this study, we evaluated the interaction between the polymorphisms in genes encoding enzymes of folate metabolism: methylenetetrahydrofolate reductase (MTHFR), methionine synthesis reductase (MTR) with the BC prognostic factors.

Methods

This study was conducted on 160 Egyptian subjects, 60 controls and 100 cases. Sequencing, RFLP analysis in addition to statistical analysis including Chi-squared test, haplotype analysis was used to evaluate associations with BC risk and its clinicopathological parameters. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using unconditional logistic regression.

Results

Strong significant association with breast cancer risk was observed for the haplotype (T-C-G) of MTHFR C677T/ MTHFR A1289C and MTRA2576G and hormonal receptor expression (ER-/PR-/HER2+), bigger and advanced tumor and metastatic lymph nodes. However, no significant difference was observed for age.

Conclusion

The combination of SNPs from MTHFR and MTR genes has a more synergistically genetic effect on BC disease progression. These SNPs could be used as tumor aggressiveness markers among Egyptian females with BC and could help in saving money and time.

Association of MTHFR 677C > T, 1298A > C and MTR 2756A > G Polymorphisms with Susceptibility to Childhood Retinoblastoma: A Systematic Review and Met-Analysis

BackgroundRecently, epidemiological studies investigating the association of MTHFR 677 C > T, 1298 A > C and MTR 2756 A > G polymorphism with retinoblastoma susceptibility reported controversial results. Methods: Data were collected from several electronic databases such as PubMed, EMBASE, and Google Scholar databases, with the last search up to December 05, 2019. Results: A total of eleven case-control studies including four studies with 324 cases and 490 controls on MTHFR 677 C > T, four studies with 324 cases and 490 controls on MTHFR 1298 A > C, and three studies with 283 cases and 485 controls on MTR 2756 A > G were selected. There was a significant association between MTHFR 677 C > T and MTR 2756 A > G polymorphisms and an increased risk of retinoblastoma. However, MTHFR 1298 A > C polymorphism was not significantly associated with risk of retinoblastoma. Conclusion: This meta-analysis demonstrated that MTHFR 677 C > T and MTR 2756 A > G polymorphisms might play important roles in the development of retinoblastoma. No association with MTHFR 1298 A > C polymorphism was observed.

Contribution of MTR A2756G polymorphism and MTRR A66G polymorphism to the risk of idiopathic male infertility

BACKGROUND

Methionine synthase reductase gene (MTRR A66G) polymorphism and methionine synthase gene (MTR A2756G) polymorphism have shown an association with idiopathic male infertility risk in several ethnic populations. However, their small sample sizes and inconsistent outcomes have prevented strong conclusions. We performed a meta-analysis with published studies to evaluate the associations of the 2 single nucleotide polymorphisms (SNPs) and idiopathic male infertility risk.

METHODS

A thorough literature search was performed up to Jun 21, 2019 with Medline, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), China Biology Medical literature (CBM), China Science and Technology Journal Database (VIP), and Chinese literature (Wan Fang) databases. Odds ratio (OR) and 95% confidence interval (95% CI) were used to assess the strength of associations.

RESULTS

Seventeen studies including 3269 cases and 3192 controls met the inclusion criteria. Our meta-analysis showed that the MTR A2756G mutation may contribute to genetic susceptibility to the risk of idiopathic male infertility in Non-Asians, but not to Asian population, whereas the MTRR A66G polymorphism may be unrelated to idiopathic male infertility in both Non-Asian and Asian populations. In the stratified analysis by infertility type, the MTR A2756G polymorphism was a risk factor for both non-obstructive azoospermia (NOA) and oligoasthenoteratozoospermia (OAT) patients. However, the MTRR A66G polymorphism is associated with risk for OAT in Asian, but not in Non-Asian population.

CONCLUSION

This meta-analysis suggested that the MTR A2756G and MTRR A66G polymorphisms were risk factors for idiopathic male infertility. Studies with larger sample sizes and representative population-based cases and well-matched controls are needed to validate our results.

Association study between genetic polymorphisms in folate metabolism and gastric cancer susceptibility in Chinese Han population: A case-control study

Background

Gastric cancer (GC), the second leading cause of cancer mortality behind lung cancer worldwide, is caused by both genetic and environmental factors. In this study, we evaluated the association between the genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR), methionine synthesis reductase (MTR), and methyltransferase reductase (MTRR) genes and ischemic stroke risk in Chinese population.

Methods

A case–control study was conducted including 681 patients with GC and 756 healthy controls. Chi‐squared test/Fisher's exact test and genetic model were used to evaluate associations. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using unconditional logistic regression.

Results

In the allele model, using the chi‐square test, we found that the rs1532268 in MTRR with a minor allele T was significantly associated with increased risk of GC (OR = 1.24, 95% CI, 1.00–1.53; p = 0.048). In the genetic model analysis, we identified that the single‐nucleotide polymorphism of the rs1801133 in MTHFR could increase the GC risk in the recessive model (OR = 1.31, 95% CI, 1.01–1.70; p = 0.042) and log‐additive model (OR = 1.19, 95% CI, 1.02–1.38; p = 0.025). In MTHFR, a strong linkage of rs2274976 and rs1801133 was detected. The haplotype “GC” in the MTHFR gene was found to prominently increase the risk of GC (OR = 1.26, 95% CI: 1.07–1.47; p = 0.005). Other haplotypes did not display the correlativity.

Conclusion

This study suggested that MTR and MTHFR polymorphisms may contribute to increase the risk of GC.

Polymorphisms in MTHFR, MTR, RFC1 and CßS genes involved in folate metabolism and thyroid cancer: a case-control study

INTRODUCTION

Polymorphisms in genes coding enzymes involved in folate metabolism may cause alterations in this metabolic pathway and contribute to carcinogenesis, because folate is essential for DNA synthesis, methylation and repair. The objective of this study was to investigate the association of MTHFR 677C>T (rs1801133), MTR 2756A>G (rs1805087), RFC1 80A>G (rs1051266) and CßS 844ins(68) (no rs#) polymorphisms and thyroid cancer development. The association of these polymorphisms with demographic risk factors and clinical histopathological parameters was also evaluated.

MATERIAL AND METHODS

The study is a case-control analysis with a total of 462 individuals (151 patients and 311 controls). Polymerase chain reaction-restriction fragment length polymorphism technique was used for genotyping. The χ² and multiple logistic regression were utilized for statistical analysis.

RESULTS

The polymorphisms analysis revealed an association between the MTHFR 677C>T polymorphism (OR = 2.87, 95% CI: 1.50-5.48, p < 0.01, codominant model), (OR = 1.76, 95% CI: 1.18-2.64, p < 0.01, dominant model), (OR = 2.37, 95% CI: 1.28-4.39, p < 0.01, recessive model) and thyroid cancer. RFC1 80A>G polymorphism also was associated with thyroid cancer under recessive mode of inheritance (OR = 1.55; 95% CI: 1.02-2.38; p = 0.04); however, this polymorphism showed Hardy-Weinberg disequilibrium in the control group (χ² = 24.71, p < 0.001). Furthermore, alcohol (OR = 1.56, 95% CI: 1.36-1.89, p < 0.01) and tobacco consumption (OR = 1.97, 95% CI: 1.28-3.04, p < 0.01) were associated with increased risk for thyroid cancer. The MTR 2756A>G polymorphism showed an association with tumor extent (OR = 2.69, 95% CI: 1.27-5.71, p < 0.01) and aggressiveness (OR = 4.51, 95% CI: 1.67-12.1, p < 0.01).

CONCLUSIONS

MTHFR 677C>T is significantly associated with increased risk for thyroid cancer and MTR 2756A>G is associated with tumor extent and aggressiveness. In addition, alcohol and tobacco consumption were associated with increased risk of thyroid cancer. These results may contribute to a better prognosis for thyroid cancer.

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.

Methionine synthase A2756G variation is associated with the risk of retinoblastoma in Iranian children

Association of epigenetic modifications with cancer has been widely studied. Gene-specific hypermethylation and global DNA hypomethylation are the most frequently observed patterns in great number of tumors. The methionine synthase (MTR) gene plays key role in maintaining adequate intracellular folate, methionine and normal homocysteine concentrations and, its polymorphism have been associated with the risk of retinoblastoma and other neoplasms. We evaluated the association of MTR A2756G polymorphism with the risk of retinoblastoma in an Iranian population. Totally, 150 retinoblastoma patients and 300 individuals with no family history of cancer as control were included in this study. Genotyping of the A2756G polymorphism was performed by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) using the restriction enzymes HaeIII. Our results showed that the "G" was the minor allele with a frequency of 31.7% and 20.3% in both retinoblastoma and control groups, respectively. The frequency of the 2756GG genotype (P=0.023) and 2756G allele (P=0.0001) were significantly higher in the patients than control group, respectively. Individual with the 2756GG genotype had a 2.99 fold increased risk for retinoblastoma. According to our results, the MTR A2756G polymorphism was associated with the risk of retinoblastoma in Iranian patients.

Association between Genetic Polymorphisms in DEFB1 and Susceptibility to Digestive Diseases

Background

Aberrant expression of defensins is implicated in the pathogenesis of digestive diseases. However, the contribution of specific defensins and the influence of their genetic polymorphisms on the progression of digestive diseases remain controversial. In the present meta-analysis, we investigated the association between DEFB1 SNPs and the susceptibility to digestive diseases.

Material/Methods

Case-control studies that reported the correlation between DEFB1 SNPs and the susceptibility to digestive diseases were identified through electronic databases searches, and high-quality studies that satisfied our inclusion criteria were selected for this meta-analysis. Statistical analyses were performed utilizing STATA software version 12.0.

Results

The present meta-analysis revealed that patients with digestive diseases exhibited higher frequencies of the DEFB1 genetic variants rs11362G>A, rs1800972C>G, and rs1799946G>A compared to healthy controls under the allele model. Subgroup analysis based on country showed that the rs1800972C>G variant under allele model and rs1799946G>A are associated with the susceptibility to digestive diseases in Hungarian and Italian populations, respectively. Subgroup analysis based on disease type showed that: (1) rs11362G>A variant was strongly associated with severe acute pancreatitis (SAP) and chronic gastritis, (2) frequency of rs1800972C>G variant was higher in SAP subgroup, and (3) frequency of rs1799946G>A variant was positively associated with the susceptibility to Crohn’s disease (CD) under the allele model and with SAP.

Conclusions

Our meta-analysis provides evidence that DEFB1 genetic polymorphisms rs11362G>A, rs1800972C>G and rs1799946G>A are important contributing factors to the development of digestive diseases.

Associations of MTHFR gene polymorphisms with hypertension and hypertension in pregnancy: a meta-analysis from 114 studies with 15411 cases and 21970 controls

BACKGROUND

Several epidemiological studies have investigated the associations of methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms with hypertension (H) or hypertension in pregnancy (HIP). However, the results were controversial. We therefore performed a comprehensive meta-analysis to provide empirical evidences on the associations.

METHODOLOGIES

The English and Chinese databases were systematically searched to identify relevant studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the associations. Meta-regression, subgroup analysis, sensitivity analysis, cumulative meta-analysis and assessment of publication bias were performed in our study.

PRINCIPAL FINDINGS

A total of 114 studies with 15411 cases and 21970 controls were included, 111 studies with 15094 cases and 21633 controls for the C677T polymorphism and 21 with 2533 cases and 2976 controls for the A1298C polymorphism. Overall, the C677T polymorphism was significantly associated with H and HIP (H & HIP: OR = 1.26, 95% CI = 1.17-1.34; H: OR = 1.36, 95% CI = 1.20-1.53; HIP: OR = 1.21, 95% CI = 1.08-1.32). Stratified analysis by ethnicity revealed a significant association among East Asians and Caucasians, but not among Latinos, Black Africans, and Indians and Sri Lankans. In the stratified analyses according to source of controls, genotyping method, sample size and study quality, significant associations were observed in all the subgroups, with the exception of population based subgroup in H studies and large sample size and "others" genotyping method subgroups in HIP studies. For the A1298C polymorphism, no significant association was observed either in overall or subgroup analysis under all genetic models.

CONCLUSIONS

This meta-analysis suggests that the MTHFR C677T rather than A1298C polymorphism may be associated with H & HIP, especially among East Asians and Caucasians.