The MTHFR 677C→T polymorphism and risk of prostate cancer: results from the CAPS study

Genotyping the High Altitude Mestizo Ecuadorian Population Affected with Prostate Cancer

Prostate cancer (PC) is the second most commonly diagnosed type of cancer in males with 1,114,072 new cases in 2015. The MTHFR enzyme acts in the folate metabolism, which is essential in methylation and synthesis of nucleic acids. MTHFR C677T alters homocysteine levels and folate assimilation associated with DNA damage. Androgens play essential roles in prostate growth. The SRD5A2 enzyme metabolizes testosterone and the V89L polymorphism reduces in vivo SRD5A2 activity. The androgen receptor gene codes for a three-domain protein that contains two polymorphic trinucleotide repeats (CAG, GGC). Therefore, it is essential to know how PC risk is associated with clinical features and polymorphisms in high altitude Ecuadorian mestizo populations. We analyzed 480 healthy and 326 affected men from our three retrospective case-control studies. We found significant association between MTHFR C/T (odds ratio [OR] = 2.2; P = 0.009), MTHFR C/T+T/T (OR = 2.22; P = 0.009), and PC. The SRD5A2 A49T substitution was associated with higher pTNM stage (OR = 2.88; P = 0.039) and elevated Gleason grade (OR = 3.15; P = 0.004). Additionally, patients with ≤21 CAG repeats have an increased risk of developing PC (OR = 2.99; P < 0.001). In conclusion, genotype polymorphism studies are important to characterize genetic variations in high altitude mestizo populations.

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

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

Breast cancer risk associated with gene expression and genotype polymorphisms of the folate-metabolizing MTHFR gene: a case-control study in a high altitude Ecuadorian mestizo population

Breast cancer (BC) is the leading cause of cancer-related death among women in 2014. Methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and MTR reductase (MTRR) are enzymes that play an important role in folate metabolism. The single nucleotide polymorphisms, MTHFR C677T, A1298C, MTR A2756G, and MTRR A66G, alter plasmatic folate and homocysteine concentrations, causing problems during the repairment, synthesis, and methylation of the genetic material. Therefore, it is essential to know how BC risk is associated with histopathological and immunohistochemical characteristics, genotype polymorphisms, and gene expression in a high altitude Ecuadorian mestizo population. DNA was extracted from 195 healthy and 114 affected women. Genotypes were determined by restriction enzymes and genomic sequencing. mRNA was extracted from 26 glandular breast tissue samples, both from cancerous tissue and healthy tissue adjacent to the tumor. Relative gene expression was determined with the comparative Livak method (2(-ΔΔCT)). We found significant association between the rs1801133 (A222V) genotypes and an increased risk of BC development: C/T (odds ratio [OR] = 1.8; 95 % confidence interval [CI] = 1.1-3.2; P = 0.039), T/T (OR = 2.9; 95 % CI = 1.2-7.2; P = 0.025), and C/T + T/T (OR = 1.9; 95 % CI = 1.1-3.3; P = 0.019). Regarding relative gene expression, we found significant mRNA subexpression between the combined genotypes C/T + T/T (rs1801133) and triple negative breast cancer (TNBC) (P = 0.034). In brief, the MTHFR gene and its protein could act as potential predictive biomarkers of BC, especially TNBC among the high altitude Ecuadorian mestizo population.

Genetic polymorphisms in MTHFR (C677T, A1298C), MTR (A2756G) and MTRR (A66G) genes associated with pathological characteristics of prostate cancer in the Ecuadorian population

INTRODUCTION

The methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR) and MTR reductase (MTRR) enzymes act in the folate metabolism, which is essential in methylation and synthesis of nucleic acids. The single nucleotide polymorphisms, MTHFR C677T, A1298C, MTR A2756G and MTRR A66G, cause alteration in the homocysteine levels and reduced enzymatic activity that generates deficiency in the assimilation of folates associated with DNA damage; that is, why it is important to know if the single nucleotide polymorphisms are associated with the pathological characteristics and development of prostate cancer, through a case-control retrospective study.

METHODS

DNA was extracted from 110 healthy and 104 affected men. The genotypes were determined by means of the polymerase chain reaction-restriction fragment length polymorphism and confirmed with genomic sequencing.

RESULTS

We found significant association between the genotypes of the MTHFR C677T polymorphism: C/T (odds ratio [OR] = 2.2; 95% confidence interval [CI] = 1.3-3.9; P = 0.008) and C/T + T/T (OR = 2.2; 95% CI = 1.3-3.9; P = 0.009) with the risk of prostate cancer development, and a slight association with MTRR A66G. Regarding pathological characteristics, we found significant risk between the C/T + T/T genotypes and the Gleason score (7-10) of poorly differentiated carcinoma (OR = 5.2; 95% CI = 1.7-16.2; P = 0.007). On the other hand, a significant association between A1298C, A66G, and A2756G with the pathological characteristics was not found (P > 0.05).

CONCLUSIONS

The MTHFR C677T polymorphism has significant effects on susceptibility to prostate cancer in Ecuadorian population, especially with the Gleason grade.

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.

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.

Complex interaction between serum folate levels and genetic polymorphisms in folate pathway genes: biomarkers of prostate cancer aggressiveness

Little is known about the role of folate and polymorphisms associated with folate metabolism on prostate cancer risk in populations of African origin. We examined the relationship between serum folate and prostate cancer and whether any association was modified by genetic polymorphisms for folate metabolism. The study was case-control in design and consisted of 218 men 40-80 years old with newly diagnosed, histologically confirmed prostate cancer and 236 cancer-free men attending the same urology clinics in Jamaica, March 2005-July 2007. Serum folate was measured by an immunoassay method and genomic DNA evaluated for MTHR (C677T and A1298C), MTRR A66G, and MTR A2756G polymorphisms. Mean serum folate concentration was higher among cases (12.3 ± 4.1 nmol/L) than controls (9.7 ± 4.2 nmol/L). Serum folate concentration showed a positive association with prostate cancer (OR, 4.41; CI, 2.52-7.72 per 10 nmol/L) regardless of grade. No interactions were observed between genotype and folate concentration, but a weak gene effect was observed for MTHFR A1298C and low-grade prostate cancer. Larger studies to investigate the role of gene-gene/gene-diet interactions in Black men are needed.

Deficiency of DNA repair nuclease ERCC1-XPF promotes prostate cancer progression in a tissue recombination model

BACKGROUND

The excision repair cross complementing (ERCC1) gene product plays a vital role in the nucleotide excision repair (NER) and DNA interstrand crosslink repair pathways, which protect the genome from mutations and chromosomal aberrations, respectively. Genetic deletion of Ercc1 in the mouse causes dramatically accelerated aging. We examined the effect of Ercc1 deletion in the development of prostate cancer in a prostate recapitulation model as Ercc1 deficient mice die within four weeks of birth.

METHODS

Prostate tissues from Ercc1(-/-) mice or wild-type littermates were combined with embryonic rat urogenital mesenchyme and grown as renal grafts for a total of 8, 16, and 24 weeks before histological, expression and proliferative evaluation.

RESULTS

Invasive adenocarcinoma was observed in Ercc1(-/-) tissue recombinants but not wild-type as early as 8 weeks post-grafting. PIN-like lesions in Ercc1(-/-) tissue recombinants had more cytologic and architectural atypia than wild-type (P = 0.02, P = 0.0065, and P = 0.0003 at the 8, 16, and 24 weeks, respectively), as well as more proliferative cells (P = 0.022 and P = 0.033 at 8 and 16 weeks, respectively). With serial grafting, Ercc1(-/-) tissue recombinants progressed to a more severe histopathological phenotype more rapidly than wild-type (P = 0.011).

CONCLUSIONS

Results show that ERCC1 and by implication the NER and/or interstrand crosslink repair mechanisms protect against prostate carcinogenesis and mutations or polymorphisms affecting these DNA repair pathways may predispose prostate epithelial cells to transformation.

An increased risk of differentiated thyroid carcinoma in Iran with the 677C→T homozygous polymorphism in the MTHFR Gene

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) involves in folic acid metabolism which influences DNA methylation. A single nucleotide polymorphism (SNP) called 677C→T in MTHFR gene causes producing a thermolabile enzyme with reducing function and eventually defects DNA methylation. To determine association between germ-line polymorphism in MTHFR gene with differentiated thyroid carcinoma (DTC), this preliminary study was designed.

METHODS

This was a case-control study of 154 DTC patients and 198 cancer free individuals. Genotyping was performed by a multiplex PCR method and the frequencies of the 677C→T SNP in cases and controls were compared. The risk estimation was done by multivariate logistic regression analysis.

RESULTS

Compared to CC genotype, an increased risk of DTC for the 677C→T homozygous genotype was demonstrated (odds ratio [OR]: 2.08, 95% confidence interval [CI]: 0.82-5.25). Also, multivariate analysis demonstrated an increased risk of DTC in recessive fashion (TT vs. CC or CT) (OR: 2.38, 95% CI: 0.97-5.82).

CONCLUSION

The MTHFR 677C→T homozygous variant allele may be associated with increased risk of DTC.

Association of folate-pathway gene polymorphisms with the risk of prostate cancer: a population-based nested case-control study, systematic review, and meta-analysis

Folate-pathway gene polymorphisms have been implicated in several cancers and investigated inconclusively in relation to prostate cancer. We conducted a systematic review, which identified nine case-control studies (eight included, one excluded). We also included data from four genome-wide association studies and from a case-control study nested within the UK population-based Prostate Testing for Cancer and Treatment study. We investigated by meta-analysis the effects of eight polymorphisms: MTHFR C677T (rs1801133; 12 studies; 10,745 cases; 40,158 controls), MTHFR A1298C (rs1801131; 5 studies; 3,176 cases; 4,829 controls), MTR A2756G (rs1805087; 8 studies; 7,810 cases; 37,543 controls), MTRR A66G (rs1801394; 4 studies; 3,032 cases; 4,515 controls), MTHFD1 G1958A (rs2236225; 6 studies; 7,493 cases; 36,941 controls), SLC19A1/RFC1 G80A (rs1051266; 4 studies; 6,222 cases; 35,821 controls), SHMT1 C1420T (rs1979277; 2 studies; 2,689 cases; 4,110 controls), and FOLH1 T1561C (rs202676; 5 studies; 6,314 cases; 35,190 controls). The majority (10 of 13) of eligible studies had 100% Caucasian subjects; only one study had <90% Caucasian subjects. We found weak evidence of dominant effects of two alleles: MTR 2756A>G [random effects pooled odds ratio, 1.06 (1.00-1.12); P = 0.06 (P = 0.59 for heterogeneity across studies)] and SHMT1 1420C>T [random effects pooled odds ratio, 1.11 (1.00-1.22); P = 0.05 (P = 0.38 for heterogeneity across studies)]. We found no effect of MTHFR 677C>T or any of the other alleles in dominant, recessive or additive models, or in comparing a/a versus A/A homozygous. Neither did we find any difference in effects on advanced or localized cancers. Our meta-analysis suggests that known common folate-pathway single nucleotide polymorphisms do not have significant effects on susceptibility to prostate cancer.

MTHFR C677T polymorphism contributes to prostate cancer risk among Caucasians: A meta-analysis of 3511 cases and 2762 controls

Published data regarding the association between 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphisms and prostate cancer risk have been conflicting. To derive a more precise estimation of the relationship, a meta-analysis was performed. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association between MTHFR C677T and A1298C polymorphisms and prostate cancer risk. Six studies including 3511 cases and 2762 controls described C677T genotypes, among which four articles totalling 838 cases and 1121 controls described A1298C genotypes, were involved in this meta-analysis. Overall meta-analysis indicated that the 677T allele was more likely to exert a protective effect on prostate cancer risk (OR=0.81, 95% CI: 0.68-0.98) with a recessive genetic model. No association was found for the 677CT genotype and the 677TT mutant homozygote with prostate cancer risk compared with 677CC, with OR=1.13 (95% CI: 0.88-1.45) and OR=0.85 (95% CI: 0.71-1.03), respectively. No evidence of an association of MTHFR A1298C polymorphism with prostate cancer was found. This meta-analysis supports that the C677T of the MTHFR gene is a low-penetrance susceptibility gene for prostate cancer, and might provide protective effects against prostate cancer risk.

No association of single nucleotide polymorphisms in one-carbon metabolism genes with prostate cancer risk

One-carbon metabolism mediates the interconversion of folates for the synthesis of precursors used in DNA synthesis, repair, and methylation. Inadequate folate nutrition or compromised metabolism can disrupt these processes and facilitate carcinogenesis. In this study, we investigated associations of 39 candidate single nucleotide polymorphisms (SNP) in 9 one-carbon metabolism genes with risk of prostate cancer using 1,144 cases and 1,144 controls from the Cancer Prevention Study-II Nutrition Cohort. None of these SNPs were significantly associated with prostate cancer risk, either overall or in cases with advanced prostate cancer. Thus, our findings do not support the hypothesis that common genetic variation in one-carbon metabolism genes influences prostate cancer risk.