Association of MTRR A66G polymorphism with cancer susceptibility: Evidence from 85 studies

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.

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 Roles of MTRR and MTHFR Gene Polymorphisms in Colorectal Cancer Survival

Background: Paradoxically epidemiological data illustrate a negative relationship between dietary folate intake and colorectal cancer (CRC) risk. The occurrence and progression of CRC may be influenced by variants in some key enzyme coding genes in the folate metabolic pathway. We investigated the correlation between genetic variants in methionine synthase reductase (MTRR) and methylenetetrahydrofolate reductase (MTHFR) and CRC survival. Methods: This study used data collected from the Newfoundland Familial Colorectal Cancer Study. A total of 532 patients diagnosed with CRC for the first time from 1999 to 2003 were enrolled, and their mortality were tracked until April 2010. DNA samples were genotyped by Illumina’s integrated quantum 1 million chip. Cox models were established to assess 33 tag single-nucleotide polymorphisms in MTRR and MTHFR in relation to overall survival (OS), disease-free survival (DFS) and CRC-specific survival. Results: The MTRR and MTHFR genes were associated with DFS and CRC-specific survival in CRC patients at the gene level. After multiple comparison adjustment, MTRR rs1801394 A (vs. G) allele was associated with increased DFS (p = 0.024), while MTHRT rs3737966 (G vs. A), rs4846049 (T vs. G), rs1476413 (A vs. G), rs1801131 (C vs. A), rs12121543 (A vs. C), rs1801133 (C vs. T), rs4846052 (T vs. C), rs2066471 (A vs. G) and rs7533315 (T vs. C) were related to worse CRC-specific survival. Additionally, significant interactions were seen among pre-diagnostic alcohol consumption with MTRR rs1801394, rs3776467, rs326124, rs162040, and rs3776455, with superior OS associated with those protective variant alleles limited to patients with alcohol consumption under the median. The MTHFR rs3737966 (G vs. A) allele seemed to be detrimental to CRC survival only among subjects with fruit intake below the median. Conclusions: Polymorphic variants in MTRR and MTHFR genes that code for key enzymes for folate metabolism may be associated with survival in patients with CRC. The gene-CRC outcome association seems modulated by alcohol drinking and fruit intake.

Impact of Methionine Synthase Reductase Polymorphisms in Chronic Myeloid Leukemia Patients

Introduction： Metabolism methionine and of folate play a vital function in cellular methylation reactions, DNA synthesis and epigenetic process.However, polymorphisms of methionine have received much attention in recent medical genetics research. Objectives: To ascertain whether the common polymorphisms of the MTRR (Methionine Synthase Reductase) A66G gene could play a role in affecting susceptibility to Chronic Myeloid Leukemia (CML) in Sudanese individuals. Methods: In a case-controlled study, we extracted and analyzed DNA from 200 CML patients and 100 healthy control subjects by the PCR-RFLP method. Results: We found no significant difference in age orgender between the patient group and controls. The MTRR A66G genotypes were distributed based on the Hardy-Weinberg equilibrium (p > 0.05). The variation of MTRR A66G was less significantly frequent in cases with CML (68.35%) than in controls (87%) (OR = 0.146, 95% CI = 0.162−0.662, p < 0.002). Additionally, AG and GG genotypes and G allele were reducing the CML risk (Odds ratio [OR] = 0.365; 95% CI [0.179−0.746]; p = 0.006; OR = 0.292; 95% CI [0.145−0.590]; p = 0.001 and OR = 0.146; 95% CI [0.162−0.662]; p = 0.002 and OR = 2.0; 95% CI [1.3853−2.817]; respectively, (p = 0.000)). Conclusions: Our data demonstrated that heterozygous and homozygous mutant genotypes of MTRR polymorphisms were associated with decreased risk of developing CML in the Sudanese population.

Investigation of the relationship between MTRR A66G, MTR A2756G gene variations and cell anomalies in early diagnosis and progression of bladder cancer

BACKGROUND

The aim of this study is to investigate the relationship between MTRR A66G, MTRA2756G gene variations and cell anomalies in the early diagnosis and progression of bladder cancer.

METHODS

PCR and RFLP methods were used to determine the genotype distributions of MTRR A66G and MTR A2756G gene variations. Peripheral smear preparations prepared from blood samples were fixed with methanol fixative and stained histochemically. Cellular morphological evaluations were made under the light microscope.

RESULTS

In our study, AA-GG haplotype was observed significantly more in the patient group than control group (OR: 3.304, 95% CI: 1.023-10.665, p = 0.046). The significant increase was determined in terms of histological damage parameters in the patient group compared to the control group (p < 0.05). For multiple vacuoles damage parameter (mild score), AA genotype of MTR A2756G gene variation was significantly different compared to AA genotype of MTRR A66G gene variation (OR: 0.211, 0.049-0.912, p = 0.037). AA genotype of MTR A2756G gene variation was observed more than AA homozygous genotype of MTR A66G gene variation for giant platelets with different sizes damage parameter (mild score) (OR: 0.062, 0.017-0.228, p < 0.001).

CONCLUSIONS

In conclusion, in Thrace population, AA genotype of the MTR A2756G gene variation was significantly higher than the AA homozygous genotype of the MTR A66G gene variation as a genetic risk factor for the multiple vacuoles damage parameter. In addition, AA genotype of MTR A2756G gene variation was determined as a genetic risk factor for giant platelets with different sizes damage parameter.

Levels of Folate and Vitamin B12, and Genetic Polymorphisms Involved in One-Carbon Metabolism May Increase the Risk of Cervical Cytological Abnormalities

To analyze the association of cervical cytological abnormalities with genetic polymorphisms of enzymes involved in folate metabolism, and the effect of micronutrients on association of polymorphisms with cervical carcinogenesis. Our samples were divided in Control (120 women with normal cytology), and Cases: 37 women with Atypical Squamous Cells of Undetermined Significance(ASC-US), 33 participants presenting Low-Grade Squamous Intraepithelial Lesion(LSIL), and 24 women presenting High-Grade cervical lesions(HSIL/ASC-H). We obtained cervical samples for cytological analysis, HPV detection, and analysis of polymorphisms and cervical cell folate. Blood samples were obtained for serum folate and vitamin B12 evaluation. To analyze all polymorphisms simultaneously, we calculated Genetic Risk Score(GRS). Median concentrations were used as cutoff for determination of micronutrient levels. We observed no differences of genotype or allelic frequencies of polymorphisms according to cervical lesions. However, high levels of cervical cell folate and high number of genetic alterations increased risk of High-Grade lesions [OR(IC95%):1.85(0.42-8.11)]. Instead, women with vitamin B12 ≤ 274 pg/ml and GRS ≥ 3 presented even greater risk of HSIL/ASC-H [OR(IC95%):2.91(0.46-18.62)]. High frequency of genetic polymorphisms involved in one-carbon metabolism associated with high levels of cell folate or low levels of serum vitamin B12, increased the risk of High-Grade lesion in uterine cervix.

B Vitamins and One-Carbon Metabolism: Implications in Human Health and Disease

Vitamins B9 (folate) and B12 are essential water-soluble vitamins that play a crucial role in the maintenance of one-carbon metabolism: a set of interconnected biochemical pathways driven by folate and methionine to generate methyl groups for use in DNA synthesis, amino acid homeostasis, antioxidant generation, and epigenetic regulation. Dietary deficiencies in B9 and B12, or genetic polymorphisms that influence the activity of enzymes involved in the folate or methionine cycles, are known to cause developmental defects, impair cognitive function, or block normal blood production. Nutritional deficiencies have historically been treated with dietary supplementation or high-dose parenteral administration that can reverse symptoms in the majority of cases. Elevated levels of these vitamins have more recently been shown to correlate with immune dysfunction, cancer, and increased mortality. Therapies that specifically target one-carbon metabolism are therefore currently being explored for the treatment of immune disorders and cancer. In this review, we will highlight recent studies aimed at elucidating the role of folate, B12, and methionine in one-carbon metabolism during normal cellular processes and in the context of disease progression.

3'UTR polymorphism of Thymidylate Synthase gene increased the risk of persistence of pre-neoplastic cervical lesions

BACKGROUND

Cervical cancer is caused by high-risk Human Papillomavirus (hr-HPV) infection associated with cofactors that has been analyzed as predictors of the remission or persistence of cytological abnormalities remission or persistence. These cofactors can be either environmental, epigenetic, or genetic. Polymorphism in genes of enzymes that act on one-carbon metabolism alter their activity and also may be associated with cervical carcinogenesis because they affect DNA synthesis and repair, and gene expression. Therefore, this study aimed to analyze the risk of persistence of pre-neoplastic cervical lesions according to genetic polymorphisms involved in one-carbon metabolism.

METHODS

Our sample consisted of 106 women, divided into two groups - Remission (n = 60), i.e., with the presence of pre-neoplastic lesions at first meeting (T₁) and normal cytology after 6 months of follow-up (T₂), and Persistence (n = 46), i.e., with the presence of pre-neoplastic lesions at T₁ and T₂. We obtained cervical samples for cytological analysis (T₁ and T₂), HPV detection (T₁), and evaluation of polymorphism C667T of Methylenetetrahydrofolate Reductase (MTHFR C677T), A2756G of Methionine Synthase (MS A2756G), A66G of Methionine Synthase Reductase (MTRR A66G), double or triple 28 bp tandem repeat in 5'-untranslated enhanced region of Thymidylate Synthase (TSER), and 6 bp deletion at nucleotide 1494 in TS 3'-untranslated region (TS3'UTR). To analyze all genetic polymorphisms simultaneously, we calculated the Genetic Risk Score (GRS).

RESULTS

We observed no differences between the Remission and Persistence groups regarding the GRS. Also, there were no differences in the genotypic and allelic distribution of MTHFR C677T and MS A2756G polymorphisms. However, the risk of persistence was higher among women with the heterozygote genotype - ins/del [OR (IC95%): 3.22 (1.19-8.69), p = 0.021], or the polymorphic genotype - del/del [OR (IC95%): 6.50 (1.71-24.70), p = 0.006] of TS3'UTR.

CONCLUSIONS

The presence of the TS3'UTR polymorphism increased the risk of persistence of cervical abnormalities. This genetic variant could be a potential marker of cervical carcinogenesis and therefore assist the follow-up of women with persistent pre-neoplastic cervical lesions.

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.

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.

Donor one‑carbon metabolism gene single nucleotide polymorphisms predict the susceptibility of cancer recurrence after liver transplantation

BACKGROUND

Many enzymes involved in one‑carbon metabolism (OCM) are considered to have important roles in carcinogenesis, especially in hepatocellular carcinoma (HCC). However, the influence of polymorphisms in OCM genes on recurrence in HCC patients with liver transplantation has yet not been reported. The aim of this study was to explore the impact of donor liver graft OCM gene polymorphism on the prognosis of liver transplant recipients with HCC.

METHODS

This study enrolled 100 liver transplantation patients from a Chinese Han population to detect the association between donor OCM genes polymorphisms and post-transplant HCC recurrence. Nine SNPs from seven OCM genes (MTHFD1, MTR, MTRR, DHFR, ALDH1L1, SHMT1, and CBS) were evaluated by Chi-square test and Kaplan-Meier survival analysis.

RESULT

None of the nine SNPs were significantly associated with cancer recurrence after liver transplantation. However, tumor-free survival for recipients with the AA genotype of rs1801394 polymorphism was significantly shorter than patients with AG/GG genotype (1097 ± 155 vs. 1657 ± 173 days, P < 0.05) among patients with alpha-fetoprotein < 400 ng/ml. Kaplan-Meier survival curves showed that recipients with donor rs1127717 homozygous TT had a significantly longer tumor-free survival and overall survival than heterozygous CT/CC recipients (tumor-free survival 1395 ± 128 vs. 671 ± 233 days, P < 0.05; overall survival 1540 ± 114 vs. 925 ± 242 days, P < 0.05) in the patient subgroup with well or moderately differentiated HCC.

CONCLUSION

This is the first genetic study to examine the relation between donor liver graft OCM gene polymorphisms and the risk of HCC recurrence after liver transplantation. Our findings support the hypothesis that polymorphisms of donor genes related to OCM play important roles in post-transplant HCC recurrence. Furthermore, donor rs1801394 and rs1127717 polymorphism may serve as promising prognostic biomarkers for HCC recurrence in liver transplant recipients.