Polymorphic methyl group metabolism genes in patients with transitional cell carcinoma of the urinary bladder

A meta-analysis on the susceptibility to the development of bladder cancer in the presence of DNMT3A, DNMT3B, and MTHFR gene polymorphisms

Background

The etiology of bladder cancer is not yet well known. In this study, we want to evaluate the effect of polymorphisms of genes that have an epigenetic effect (MTHFR, DNMT3A/B) on the susceptibility to develop bladder cancer (BC).

Methods

A systematic review was performed for MTHFR, DNMT3A, and DNMT3B, followed by a meta-analysis conducted for rs1801131, rs1801133, rs2274976, rs1550117, and rs1569686 SNPs. A sensitivity and a subgroup analysis were then used.

Results

20 studies were included, where no statistically significant association between any of the analyzed SNPs and the occurrence of BC was detected. Subgroup analysis revealed a statistically significant association in North African population with rs1801133: TT vs. TC + CC (P = 0.013; OR 95% CI = 0.52 [0.311–0.872]); TT vs.TC (P = 0.003; OR 95% CI = 0.448 [0.261–0.769]) and in North American population with rs1801131: CC vs. CA (P = 0.039; OR 95% CI = 0.71 [0.523–0.984]). A sensitivity analysis revealed that there is a statistically significant association between rs1801131 and the occurrence of BC (OR = 0.79, 95%CI [0.65–0.97]), (OR = 0.80, 95%CI [0.65–0.98]) and (OR = 0.78, 95%CI [0.63–0.96]) which correspond to CC vs. CA + AA; CC vs. CA; and CC vs. AA genetic models.

Conclusion

This is the first study to assess the effect of DNMTs on bladder cancer risk. No statistically significant association was found between polymorphisms of MTHFR, DNMT3A/B genes and bladder cancer development, except for the North African and the North American populations with rs1801133 and  rs1801131, respectively, with a protective effect of rs1801131 based on a sensitivity analysis.

Lack of association between MTHFR Ala222Val and Glu429Ala polymorphisms and bladder cancer risk: A meta-analysis of case-control studies

Bladder cancer is a commom malignancy in the urinary tract that is influenced by genetic and environmental factors. The role of functional polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene with bladder cancer risk remains to be determined. This meta-analysis was performed to derive a more precise estimation of MTHFR Ala222Val and Glu429Ala polymorphisms and bladder cancer risk. Data were collected with the last report up to September 2013. A total of 3,463 cases and 3,927 controls for Ala222Val, and 3,177 cases and 3,502 controls for Glu429Ala were analyzed. The pooled odds ratios (ORs) and 95% confidence interval (CI) were estimated for the association with bladder cancer risk. Overall, no significant associations of Ala222Val and Glu429Ala polymorphisms with bladder cancer risk were found (for Ala222Val: Val/Val vs. Ala/Ala: OR, 1.02; 95% CI: 0.80–1.29; Val/Ala vs. Ala/Ala: OR, 1.02; 95% CI: 0.92–1.12; dominant model: OR, 1.01; 95% CI: 0.87–1.17; recessive model: OR, 1.00; 95% CI: 0.87–1.15; and for Glu429Ala: Ala/Ala vs. Glu/Glu: OR, 1.11; 95% CI: 0.78–1.58; Ala/Glu vs. Glu/Glu: OR, 1.16; 95% CI: 0.95–1.40; dominant model: OR, 1.15; 95% CI: 0.94–1.41; recessive model: OR, 0.96; 95% CI: 0.79–1.15). In stratified analyses by ethnicity, significant associations were observed for Glu429Ala polymorphism in individuals of Middle Eastern descent (Ala/Glu vs. Glu/Glu: OR, 2.11; 95% CI: 1.26–3.53; dominant model: OR, 2.16; 95% CI: 1.16–4.01; recessive model: OR, 1.82; 95% CI: 1.11–3.01). This meta-analysis demonstrated that overall there was no association of MTHFR Ala222Val and Glu429Ala polymorphisms with bladder cancer risk. However, in the stratified analysis by ethnicity the MTHFR Glu429Ala polymorphism was significantly associated with increased bladder cancer risk in individuals of Middle Eastern descent.

Quantitative assessment of the association between MHTFR C677T (rs1801133, Ala222Val) polymorphism and susceptibility to bladder cancer

Background

The association between Methylenetetrahydrofolate reductase (MTHFR) Ala222Val (rs1801133) has been implicated to alter the risk of bladder cancer, but the results are controversial.

Methods

A comprehensive databases of Pubmed, Embase, Web of Science, and the Chinese Biomedical Database (CBM) were searched for case–control studies investigating the association between MTHFR Ala222Val polymorphism and bladder cancer susceptibility. Odds ratios (OR) and 95% confidence intervals (95%CI) were used to assess this possible association. A χ²-based Q-test was used to examine the heterogeneity assumption. Begg’s and Egger’s test were used to examine the potential publication bias. The leave-one-out sensitivity analysis was conducted to determine whether our assumptions or decisions have a major effect on the results of the review. Statistical analysis was performed with the software program Stata 12.0.

Results

A total of 15 independent studies were identified, including 3,570 cases and 3,926 controls. Our analysis suggested that Ala222Val was not associated with bladder cancer risk in overall population under additive model (OR=0.96, 95%CI=0.76-1.21, P=0.731), dominant model (OR=1.00, 95%CI=0.87-1.15, P=0.975), recessive model (OR=0.92, 95%CI=0.79-1.07, P=0.279), and Ala allele versus Val allele (OR=0.96, 95%CI=0.86-1.07, P=0.427). In the subgroup analysis stratified by ethnicity and sources of controls, there were also no significant associations detected among different descent populations, population-based studies and hospital-based studies.

Conclusion

This meta-analysis showed the evidence that MTHFR Ala222Val polymorphism was not contributed to the development of bladder cancer.

Virtual slide

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2117182849994994.

MTHFR C677T and A1298C polymorphisms were associated with bladder cancer risk and disease progression: a meta-analysis

Epidemiological studies have investigated that functional polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene may play an essential role in bladder carcinogenesis, but the association between these single-nucleotide polymorphisms in the MTHFR gene and the susceptibility of bladder cancer (BC) was inconsistent in previous studies. The objective of this current study was to conduct an update analysis investigating the association between three polymorphisms in the MTHFR gene and the risk of BC. We performed a meta-analysis of 13 publications involving an association between BC and MTHFR gene three polymorphisms (C677T, A1298C, and G1793A). We assessed the strength of the association, using odds ratios (ORs) with 95% confidence intervals (CIs). On one hand, we found that the C677T polymorphism was associated with increased BC risk among Asians, however, with decreased BC risk among a mixed population. Interestingly, BC patients who carried the T-allele (TT+TC) had a higher percentage than the individuals who carried the CC genotype (OR=1.38, 95% CI=1.13-1.69, p=0.002). On the other hand, the A1298C polymorphism may increase BC risk among Asians and Africans, but played a decreased association among Europeans. Results from the current update analysis suggested that the C677T and A1298C polymorphisms in the MTHFR gene were associated with BC risk and disease progression.

Imprinting of Genes and the Barker Hypothesis

Several common adult diseases appear to be related to impaired fetal growth and this may be caused either by nutritional inadequacies at particular stages of pregnancy or by variation in alleles at specific growth loci. Little is known about the genes involved in the underlying mechanism. This review proposes that at least some of the effects have their origins at imprinted loci, genes that are unusual because they are expressed from only one parental allele. Many imprinted genes are crucial for fetal growth and determine birthweight. They can be disrupted in the early embryo by environmental influences and these disruptions can be inherited through many cell cycles into adult tissues. Their disruption can affect specific organs during fetal development and disruption could affect adult disease in a variety of direct and indirect means. Imprinted genes may be particularly vulnerable to disruption as they are functionally haploid and their expression is regulated by different means from the rest of the genome. Thus many imprinted genes provide plausible candidates for programming adult disease and warrant further study in this context.

Methionine synthase A2756G polymorphism and cancer risk: a meta-analysis

Polymorphisms in methionine synthase (MTR) gene may be involved in carcinogenesis by affecting DNA methylation. However, association studies on MTR A2756G polymorphism in cancers have reported conflicting results. Therefore we performed a meta-analysis to better assess the associations. A total of 24 896 cancer patients and 33 862 controls from 52 articles for MTR A2756G were investigated. Overall, individuals carrying MTR 2756GG genotype had a subtly reduced cancer risk under a recessive genetic model (odds ratio (OR), 0.92; P=0.053; 95% confidence interval (95% CI), 0.84-1.00; I(2)=0.0%; P(heterogeneity)=0.61). In the subgroup analyses by ethnicity, 2756GG was associated with a significantly reduced cancer risk in European populations (OR, 0.83; P=0.001; 95% CI, 0.74-0.93; I(2)=0.0%; P(heterogeneity)=0.99). However, in Asian populations, a significantly elevated association between 2756GG genotype and cancer risk was observed (OR, 1.33; P=0.012; 95% CI, 1.06-1.65; I(2)=0.0%; P(heterogeneity)=0.50). In studies stratified by tumor site, there was a significantly reduced risk of acute lymphoblastic leukemia (ALL) (OR, 0.54; P=0.049; 95% CI, 0.29-1.00; I(2)=10.7%; P(heterogeneity)=0.33) and colorectal cancer (OR, 0.63; P=0.004; 95% CI, 0.47-0.87; I(2)=0.0%; P(heterogeneity)=0.73) in European populations. Our study indicates that MTR A2756G polymorphism is a candidate gene polymorphism for cancer susceptibility regardless of environmental factors. Large-scale, well-designed, and population-based studies are required to further investigate gene-gene and gene-environment interactions on MTR A2756G polymorphism and tissue-specific cancer risk in an ethnicity-specific population.

Polymorphisms of methylenetetrahydrofolate reductase and methionine synthase genes and bladder cancer risk: a case-control study with meta-analysis

Folate deficiency due to the methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MS) variants leads to carcinogenesis by affecting DNA synthesis, repair, and methylation. We hypothesized that the MTHFR C677T, A1298C, and MS A2756G polymorphisms are associated with risk of bladder cancer. In a case-control study of 239 bladder cancer cases and 250 cancer-free controls, we found that the MTHFR 677TT genotype was statistically significantly associated with an increased risk of bladder cancer compared with the 677CC genotype (OR = 2.06, 95% CI = 1.16-3.64). Furthermore, the TA haplotype was associated with a significantly increased bladder cancer risk (OR = 1.38, 95% CI = 1.05-1.81) than was the most common haplotype, CA (e.g., CA denotes MTHFR 677C -1298A). We also found that the combined genotypes with 4-6 variant (risk) alleles (i.e., MTHFR 677T, 1298A, and MS 2756G alleles) were associated with an increased risk of bladder cancer (OR = 1.62, 95% CI = 1.03-2.53) compared with those with 0-3 variants, and this increased risk was more pronounced among subgroup of older people (OR = 1.71, 95% CI = 1.03-2.83). A meta-analysis of seven studies did not show a significant risk of bladder cancer in the MTHFR polymorphisms. The MTHFR polymorphisms and their haplotypes appear to jointly contribute to risk of bladder cancer.

No association of Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in susceptibility to gallbladder cancer

Gallbladder carcinoma (GBC) is a leading cause of cancer deaths in north India. Evidence has highlighted the role of abnormal DNA methylation patterns on inappropriate gene expression in development and progression of various cancers. 5,10-Methylenetetrahydrofolate reductase (MTHFR) plays a major role in provision of methyl groups for DNA methylation. A C/T substitution in MTHFR at nucleotide 677 results in replacement of ala222-to-val in the N-terminal catalytic domain of protein, and causes considerable decrease in enzymatic activity. Thus, MTHFR C677T polymorphism may influence genetic susceptibility to GBC. The present study aimed to examine the role of C677T MTHFR polymorphism in conferring genetic susceptibility to GBC. The present study included 146 proven GBC patients and 210 healthy controls. Genotyping was done by PCR-RFLP method. The MTHFR C677T genotypes in control population were in Hardy-Weinberg equilibrium (p = ns). No statistically significant difference was observed in frequency of variant TT genotype in GBC patients in comparison to healthy controls (4.1% and 2.9%). Stratification of GBC patients on the basis of presence or absence of gallstones showed no significant association with the disease. Further, gender and age of onset of the disease did not show any significant association. In conclusion, the present study indicates that the genetic risk for GBC is not modulated by MTHFR C677T polymorphism.

Genomic DNA hypomethylation as a biomarker for bladder cancer susceptibility in the Spanish Bladder Cancer Study: a case-control study

BACKGROUND

DNA hypomethylation has been suggested to cause genomic instability and increase cancer risk. We aimed to test the hypothesis that DNA hypomethylation is associated with increased risk of bladder cancer.

METHODS

We measured cytosine methylation (5-mC) content in genomic DNA from blood cells from patients with bladder cancer enrolled in a large case-control study in Spain between Jan 1, 1998, and Dec 31, 2001. Cases were men and women with newly diagnosed and histologically confirmed urothelial carcinoma of the bladder. Controls were selected from patients admitted to the same hospital for diseases or conditions unrelated to smoking or other known risk factors for bladder cancer. Controls were individually matched to cases on age (within 5 years), sex, race, and area of hospital referral. 5-mC content was measured in leucocyte DNA by use of a combination of high-performance capillary electrophoresis, Hpa II digestion, and densitometry. Data on demographics, 34 polymorphisms in nine folate metabolism genes, and nutritional intake of six B vitamins (including folate), alcohol, and smoking were assessed as potential confounders. Relative 5-mC content was expressed as a percentage (%5-mC) with respect to the total cytosine content (the sum of methylated and non-methylated cytosines). The primary endpoint was median %5-mC DNA content.

FINDINGS

%5-mC was measured in leucocyte DNA from 775 cases and 397 controls. Median %5-mC DNA was significantly lower in cases (3.03% [IQR 2.17-3.56]) than in controls (3.19% [2.46-3.68], p=0.0002). All participants were subsequently categorised into quartiles by %5-mC content in controls. When the highest quartile of %5-mC content was used as the reference category (Q4), the following adjusted odds ratios (OR) and 95% CI were recorded for decreasing methylation quartiles: OR(Q3) 2.05 (95% CI 1.37-3.06); OR(Q2) 1.62 (1.07-2.44); and OR(Q1) 2.67 (1.77-4.03), p for trend <0.0001. The lowest cancer risk was noted in never smokers in the highest methylation quartile (never smokers in Q4). By comparison with never smokers in the highest quartile, current smokers in the lowest methylation quartile had the highest risk of bladder cancer (Q1: OR 25.51 [9.61-67.76], p for interaction 0.06). In analyses stratified by smoking, hypomethylation was a strong risk factor in never smokers (OR 6.39 [2.37-17.22]). Amount of methylation in controls were not associated with baseline characteristics, micronutrients, or selected genotypes in folate metabolism pathways.

INTERPRETATION

For the first time, to our knowledge, we have shown in a large case-control study that leucocyte DNA hypomethylation is associated with increased risk of developing bladder cancer, and this association is independent of smoking and the other assessed risk factors. Amount of global methylation in genomic DNA could provide a useful biomarker of susceptibility to certain cancer types and further research is warranted.

Polymorphisms in one-carbon metabolism and trans-sulfuration pathway genes and susceptibility to bladder cancer

We have previously reported significant inverse associations between bladder cancer risk and dietary intake of vitamins B2, B6, B12, folate and protein in a hospital-based bladder cancer case-control study conducted in Spain (1,150 cases;1,149 controls). Because these dietary factors are involved in the one-carbon metabolism pathway, we evaluated associations between bladder cancer risk and 33 single nucleotide polymorphisms (SNPs) in 8 genes (CBS, CTH, MTHFR, MTR, MTRR, SHMT1, SLC19A1 and TYMS) and interactions with dietary variables involved in this pathway. Two SNPs in the CTH gene were significantly associated with bladder cancer risk. OR (95% CI) for heterozygous and the homozygous variants compared to homozygous wild-type individuals were: 1.37 (1.04-1.80) IVS3-66 A > C and 1.22 (1.02-1.45) IVS10-430 C > T. Because the CTH gene is important for glutathione synthesis, we examined interactions with the GSTM1 gene, which codes for glutathione S-transferase muu. Increased risk for individuals with the IVS10-430 CT or TT genotype was limited to those with the GSTM1 null genotype (p-interaction = 0.02). No other SNPs were associated with risk of bladder cancer. These findings suggest that common genetic variants in the one-carbon pathway may not play an important role in the etiology of bladder cancer. However, our results provide some evidence that variation in glutathione synthesis may contribute to risk, particularly among individuals who carry a deletion in GSTM1. Additional work is needed to comprehensively evaluate genomic variation in CTH and related genes in the trans-sulfuration pathway and bladder cancer risk.

Polymorphisms of methionine synthase and methionine synthase reductase and risk of squamous cell carcinoma of the head and neck: a case-control analysis

Although tobacco and alcohol use are the major risk factors, folate deficiency has been implicated in the risk of squamous cell carcinoma of the head and neck (SCCHN). We hypothesized that polymorphisms of methionine synthase (MTR) and methionine synthase reductase (MTRR) in the folate metabolic pathway are associated with SCCHN risk. In a hospital-based case-control study of 721 SCCHN cases and 1,234 controls of non-Hispanic Whites, frequency matched by age, sex, and smoking status, we genotyped the MTR A2756G and MTRR G66A polymorphisms. We found that the MTR variant AG and AG/GG genotypes were associated with a significantly increased SCCHN risk [adjusted odd ratio (OR), 1.31; 95% confidence interval (95% CI), 1.07-1.60 for AG and OR, 1.28; 95% CI, 1.05-1.56 for AG/GG] compared with the AA genotype. In contrast, the MTRR variant AA genotype was associated with a significantly decreased SCCHN risk (OR, 0.68; 95% CI, 0.52-0.90) compared with the 66GG genotype. When the two polymorphisms were evaluated together by the number of risk alleles, the SCCHN risk was significantly increased in a dose-dependent manner (P(trend) = 0.002). The risk of SCCHN was 1.47 (95% CI, 1.08-1.99) for one risk allele, 1.67 (95% CI, 1.23-2.27) for two risk alleles, and 1.74 (95% CI, 1.18-2.54) for three or four risk alleles compared with the wild-type (0 risk allele) genotype. In conclusion, our data provide evidence that support the association between the MTR A2756G and MTRR G66A polymorphisms and SCCHN risk and that these two polymorphisms may have a joint effect on risk of SCCHN.

Colorectal Cancer and the Methylenetetrahydrofolate Reductase 677C → T and Methionine Synthase 2756A → G Polymorphisms: A Study of 2,168 Case-Control Pairs from the JANUS Cohort

Polymorphisms in genes involved in the metabolism of folate and methyl groups have been implicated with risk of colorectal cancer. We evaluated the relation between the polymorphisms 677C → T of the methylenetetrahydrofolate reductase (MTHFR) and 2756A → G of the methionine synthase (MTR) genes and risk of colorectal cancer. From the Norwegian JANUS cohort of 309,000 subjects, 2,179 cases were identified and a similar number of controls were selected. The controls were matched for age, gender, time, and place of serum donation. Genotypes were obtained from 2,168 case-control pairs by real-time PCR of serum samples. Risk of colorectal cancer was estimated with conditional and unconditional logistic regression. Median age at diagnosis was 60 years and mean follow-up 13 years. The odds ratio for MTHFR TT versus CC was 0.73 [95% confidence interval (95% CI), 0.58-0.92] and for MTR GG versus AA was 0.65 (95% CI, 0.47-0.90). No interaction between the polymorphisms was found. Relative risk estimates were similar for men and women, and for young and old age at diagnosis. For the MTR GG genotype, risk reduction was observed at the two most distal sites (sigmoideum and rectum) only (P = 0.003). The folate marker, serum total homocysteine (tHcy), was measured in 1,837 subjects. Odds ratio for the upper versus the lower tertile of tHcy was 1.32 (95% CI, 1.04-1.68). No significant effect modification by tHcy levels was detected for either polymorphism. In summary, we found significantly reduced risk of colorectal cancer in subjects with the MTHFR 677 TT and MTR 2756 GG genotypes. No interaction between the polymorphisms, or of either polymorphism with tHcy, was detected.

Relationship between Methylenetetrahydrofolate Reductase C677T and A1298C Genotypes and Haplotypes and Prostate Cancer Risk and Aggressiveness

Previous reports indicate that polymorphisms in the MTHFR gene play a role in cancer development, but their potential impact on prostate cancer has not been well studied. Here, we evaluate the association between two MTHFR polymorphisms, C677T and A1298C, and prostate cancer risk and aggressiveness in a moderately large family-based case-control study (439 cases and 479 sibling controls). Among all study subjects, we observed no association between the C677T variant and prostate cancer but a slight positive association between the A1298C variant and risk of this disease [odds ratio (OR) 1.41, 95% confidence interval (CI) 0.96-2.06; P = 0.08]. When stratifying the study population by disease aggressiveness at diagnosis, the C677T variant was positively associated with risk among men with less advanced disease (OR 1.86, 95% CI 1.00-3.46; P = 0.05). In contrast, when looking at men with more advanced disease, the C677T variant was inversely associated with risk (OR 0.51, 95% CI 0.32-0.82; P = 0.01), whereas the A1298C variant was positively associated with risk (OR 1.79, 95% CI 1.06-3.02; P = 0.03). Furthermore, the 677T-1298A haplotype was positively associated with prostate cancer among men with less advanced disease (OR 1.84, 95% CI 1.07-3.16; P = 0.03) and inversely associated with risk of more advanced disease (OR 0.47, 95% CI 0.29-0.76; P = 0.002). Our findings suggest that 677T and 1298A, or another variant on their haplotype, may be associated with a reduced risk of progression to more advanced prostate cancer.