Methionine synthase reductase A66G polymorphism and leukemia risk: evidence from published 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.

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.

Targeting Amino Acid Metabolic Vulnerabilities in Myeloid Malignancies

Tumor cells require a higher supply of nutrients for growth and proliferation than normal cells. It is well established that metabolic reprograming in cancers for increased nutrient supply exposes a host of targetable vulnerabilities. In this article we review the documented changes in expression patterns of amino acid metabolic enzymes and transporters in myeloid malignancies and the growing list of small molecules and therapeutic strategies used to disrupt amino acid metabolic circuits within the cell. Pharmacological inhibition of amino acid metabolism is effective in inducing cell death in leukemic stem cells and primary blasts, as well as in reducing tumor burden in in vivo murine models of human disease. Thus targeting amino acid metabolism provides a host of potential translational opportunities for exploitation to improve the outcomes for patients with myeloid malignancies.

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.

Characterization of pharmacogenetic markers related to Acute Lymphoblastic Leukemia toxicity in Amazonian native Americans population

Acute Lymphoblastic Leukemia (ALL) is the most common cancer in children. Differences are found among ethnic groups in the results of the treatment of pediatric ALL. In general, children with a high level of native American ancestry tend to respond less positively to ALL treatments, which may be related to specific genomic variants found in native American groups. Despite the evidence, few data are available on the distribution of the pharmacogenomic variants relevant to the treatment of ALL in traditional Amerindian populations, such the those of the Amazon region. Given this, the present study investigated 27 molecular markers related to the treatment of ALL in Amerindians from Brazilian Amazonia and compared the frequencies with those recorded previously on five continents, that are available in the 1,000 Genomes database. The variation in the genotype frequencies among populations was evaluated using Fisher's exact test. The False Discovery Rate method was used to correct the results of the multiple analyses. Significant differences were found in the frequencies of the majority of markers between the Amerindian populations and those of other regions around the world. These findings highlight the unique genetic profile of the indigenous population of Brazilian Amazonia, which may reflect a distinct therapeutic profile for the treatment of ALL in these populations.

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.

Clinical Implications of Methotrexate Pharmacogenetics in Childhood Acute Lymphoblastic Leukaemia

Background:

In the past two decades, a great body of research has been published regarding the effects of genetic polymorphisms on methotrexate (MTX)-induced toxicity and efficacy. Of particular interest is the role of this compound in childhood acute lymphoblastic leukaemia (ALL), where it is a pivotal drug in the different treatment protocols, both at low and high doses. MTX acts on a variety of target enzymes in the folates cycle, as well as being transported out and into of the cell by several transmembrane proteins.

Methods:

We undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question.

Results:

This review has intended to summarize the current knowledge concerning the clinical impact of polymorphisms in enzymes and transporters involved in MTX disposition and mechanism of action on paediatric patients with ALL.

Conclusion:

In this work, we describe why, in spite of the significant research efforts, pharmacogenetics findings in this setting have not yet found their way into routine clinical practice.

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.

Association of Three Single Nucleotide Polymorphisms in MTR and MTRR Genes with Lung Cancer in a Turkish Population

AIMS

Folate metabolism plays a critical role in DNA methylation and synthesis. Polymorphisms in folate metabolism may affect enzyme activities and thereby affect the cancer risk. Methionine synthase (MTR) and methionine synthase reductase (MTRR) are critical enzymes for the folate cycle. In this study, possible associations between genetic variabilities in MTR and MTRR and susceptibility to lung cancer (LC) were investigated in a Turkish population.

METHODS

A case-control study with 193 LC cases and 199 noncancerous controls was conducted. DNA was extracted from leukocytes using the high pure polymerase chain reaction (PCR) template preparation kit. The MTR 2756 A>G (rs1805087), MTRR 524 C > T (rs1532268), and MTRR 66 A>G (rs1801394) genotypes were determined using PCR-restriction fragment length polymorphism (PCR-RFLP) assays. The genotype and haplotype analyses of these polymorphisms were performed using SPSS 21 and Haploview 4.2, respectively.

RESULTS

An association between the MTRR A66G polymorphism and LC (p = 0.042) was found. In addition, this allele was observed more frequently in smokers compared to nonsmokers (p = 0.030). In contrast, the distribution of the MTR 2756 A>G and the MTRR 524 C > T allele frequencies were similar in the subject cases and controls.

CONCLUSIONS

In conclusion, the present study suggests an association between the MTRR 66 A>G gene polymorphisms and LC risk in a Turkish population.

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

Methionine synthase reductase (MTRR) is a key regulatory enzyme involved in the folate metabolic pathway. Previous studies investigating the association of MTRR A66G polymorphism with cancer susceptibility reported inconclusive results. We performed the current meta-analysis to obtain a more precise estimation of the possible association. Published literatures were identified from PubMed, Embase and CBM databases up to October 2016. The strength of the association between the MTRR A66G polymorphism and cancer susceptibility was assessed using odds ratios (ORs) and the corresponding 95% confidence intervals (CIs). Eighty five published studies with 32,272 cases and 37,427 controls were included in this meta-analysis. Pooled results indicated that the MTRR A66G polymorphism was associated with an increased overall cancer risk (homozygous model: OR = 1.08, 95% CI = 1.02-1.15, P = 0.009; recessive model: OR = 1.06, 95% CI = 1.00-1.12, P < 0.001 and allele comparison: OR = 1.03, 95% CI = 1.00-1.06, P < 0.001). Stratification analysis further indicated significant associations in head and neck cancer, Caucasians, Africans, and high quality studies. However, to avoid the "false-positive report", the significant findings were assessed by the false-positive report probability (FPRP) test. Interestingly, the results of FPRP test revealed that the increased risk for MTRR A66G polymorphism among Africans need further validation due to the high probabilities of false-positive results. This meta-analysis suggests that the MTRR A66G polymorphism is associated with significantly increased cancer risk, a finding that needs to be confirmed in single large studies.

Simultaneous Analysis of SEPT9 Promoter Methylation Status, Micronuclei Frequency, and Folate-Related Gene Polymorphisms: The Potential for a Novel Blood-Based Colorectal Cancer Biomarker

One challenge in colorectal cancer (CRC) is identifying novel biomarkers to be introduced in screening programs. The present study investigated the promoter methylation status of the SEPT9 gene in peripheral blood samples of subjects' positive fecal occult blood test (FOBT). In order to add new insights, we investigated the association between SEPT9 promoter methylation and micronuclei frequency, and polymorphisms in the folate-related pathway genes. SEPT9 promoter methylation, micronuclei frequency, and genotypes were evaluated on 74 individuals' FOBT positive. Individuals were subjected to a colonoscopy that provided written informed consent for study participation. SEPT9 promoter methylation status was significantly lower in the CRC group than controls (p = 0.0006). In contrast, the CaCo2 cell-line, analyzed as a tissue specific model of colon adenocarcinoma, showed a significantly higher percentage of SEPT9 promoter methylation compared to the CRC group (p < 0.0001). Linear regression analysis showed an inverse correlation between micronuclei frequency and the decrease in the methylation levels of SEPT9 promoter region among CRC patients (β = -0.926, p = 0.0001). With regard to genotype analysis, we showed the involvement of the DHFR polymorphism (rs70991108) in SEPT9 promoter methylation level in CRC patients only. In particular, the presence of at least one 19 bp del allele significantly correlates with decreased SEPT9 promoter methylation, compared to the 19 bp ins/ins genotype (p = 0.007). While remaining aware of the strengths and limitations of the study, this represents the first evidence of a novel approach for the early detection of CRC, using SEPT9 promoter methylation, micronuclei frequency and genotypes, with the potential to improve CRC risk assessment.