Impact of one-carbon metabolism-related gene polymorphisms on risk of lung cancer in Japan: a case control study

Influence of MTHFR polymorphism, alone or in combination with smoking and alcohol consumption, on cancer susceptibility

5,10-methylenetetrahydrofolate reductase (MTHFR) mutations play a significant role in various types of cancers, serving as crucial regulators of folate levels in this process. Several studies have examined the effects of smoking and drinking on MTHFR-related cancers, yielding inconsistent results. Therefore, the objective of this study was to evaluate the magnitude of the effects of gene-smoking or gene-drinking interactions on cancer development. We conducted a comprehensive literature search in PubMed, Web of Science, CNKI, and Wan Fang databases up until May 10th, 2022, to identify relevant articles that met our inclusion criteria. The extracted data from these studies were used to calculate the overall odds ratio (OR) and corresponding 95% confidence interval (95% CI) using either a fixed-effect or random-effect model in Stata version 11.2. Stratified analyses were performed based on ethnicity, control group origin, and cancer classification to assess the risk of cancers associated with gene-smoking or gene-drinking interactions. Sensitivity analyses were conducted to investigate potential sources of heterogeneity, and publication bias was assessed using the Begg's test and Egger's test. Additionally, regression analysis was employed to explore the influence of relevant variables on heterogeneity. To evaluate the statistical correlations, analytical methods such as the false-positive report probability and the Bayesian false discovery probability were applied to assess the reliability of the findings. In our meta-analysis, a total of 47 articles were included, comprising 13,701 cases and 21,995 controls for the C677T polymorphism and 5,149 cases and 8,450 controls for the A1298C polymorphism. The results indicated a significant association between C677T polymorphism and cancer risks when combined with smoking (CT + TT vs CC, OR [95% CI] = 1.225 [1.009-1.487], p = 0.041). Stratified analysis further revealed a significant increase in liver cancer risk for individuals with the C677T when combined with smoking (liver cancer: CT + TT vs CC, OR [95% CI] = 1.564 [1.014-2.413], p = 0.043), particularly among Asian smokers (CT + TT vs CC, OR [95% CI] = 1.292 [1.007-1.658], p = 0.044). Regarding the A1298C polymorphism, an elevated risk of cancer was observed in mixed populations alone (CC + AC vs AA, OR [95% CI] = 1.609 [1.087-2.381], p = 0.018), as well as when combined with smoking (CC + AC vs AA, OR [95% CI] = 1.531 [1.127-2.080], p = 0.006). In non-drinkers, C677T polymorphism was found to be associated with esophageal cancer risk (C677T: CT + TT vs CC, OR [95% CI] = 1.544 [1.011-2.359], p = 0.044) and colon cancer risk (CC + AC vs AA, OR [95% CI] = 1.877 [1.166-3.054], p = 0.010), but there was no clear link between this polymorphism and cancer risk among drinkers. The association between the C677T polymorphism and cancer risk among smokers was found to be significant, suggesting that the combination of tobacco and the C677T polymorphism may enhance the carcinogenic process, particularly in liver cancer. However, no similar relationship was observed for the A1298C polymorphism. Interestingly, significantly increased cancer risk was observed in individuals with C677T genetic variants who were nondrinkers, but not among drinkers. These findings highlight the potential role of the C677T polymorphism in modifying cancer risk in specific contexts, such as smoking and alcohol consumption.

Reproducibility and validity of food group intake in a short food frequency questionnaire for the middle-aged Japanese population

Purpose

The purpose of this study was to evaluate the reproducibility and validity of a short food frequency questionnaire (FFQ) for food group intake in Japan, the reproducibility and partial validity of which were previously confirmed for nutrients.

Methods

A total of 288 middle-aged healthy volunteers from 11 different areas of Japan provided nonconsecutive 3-day weighed dietary records (DRs) at 3-month intervals over four seasons. We evaluated reproducibility based on the first (FFQ1) and second (FFQ2) questionnaires and their validity against the DRs by comparing the intake of 20 food groups. Spearman’s rank correlation coefficients (SRs) were calculated between energy-adjusted intake from the FFQs and that from the DRs.

Results

The intake of 20 food groups estimated from the two FFQs was mostly equivalent. The median energy-adjusted SRs between the FFQ1 and FFQ2 were 0.61 (range 0.38–0.86) for men and 0.66 (0.45–0.84) for women. For validity, the median de-attenuated SRs between DRs and the FFQ1 were 0.51 (0.17–0.76) for men and 0.47 (0.23–0.77) for women. Compared with the DRs, the proportion of cross-classification into exact plus adjacent quintiles with the FFQ1 ranged from 58 to 86% in men and from 57 to 86% in women. According to the robust Z scores and the Bland–Altman plot graphs, the underestimation errors in the FFQ1 tended to be greater in individuals with high mean levels of consumption for meat for men and for other vegetables for both men and women.

Conclusion

The FFQ demonstrated high reproducibility and reasonable validity for food group intake. This questionnaire is short and remains appropriate for identifying associations between diet and health/disease among adults in Japan.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12199-021-00951-3.

Folate pathways mediating the effects of ethanol in tumorigenesis

Folate and alcohol are dietary factors affecting the risk of cancer development in humans. The interaction between folate status and alcohol consumption in carcinogenesis involves multiple mechanisms. Alcoholism is typically associated with folate deficiency due to reduced dietary folate intake. Heavy alcohol consumption also decreases folate absorption, enhances urinary folate excretion and inhibits enzymes pivotal for one-carbon metabolism. While folate metabolism is involved in several key biochemical pathways, aberrant DNA methylation, due to the deficiency of methyl donors, is considered as a common downstream target of the folate-mediated effects of ethanol. The negative effects of low intakes of nutrients that provide dietary methyl groups, with high intakes of alcohol are additive in general. For example, low methionine, low-folate diets coupled with alcohol consumption could increase the risk for colorectal cancer in men. To counteract the negative effects of alcohol consumption, increased intake of nutrients, such as folate, providing dietary methyl groups is generally recommended. Here mechanisms involving dietary folate and folate metabolism in cancer disease, as well as links between these mechanisms and alcohol effects, are discussed. These mechanisms include direct effects on folate pathways and indirect mediation by oxidative stress, hypoxia, and microRNAs.

Methylenetetrahydrofolate Reductase (MTHFR) Gene rs1801133 C>T Polymorphisms and Lung Cancer Susceptibility: An Updated Meta-analysis

Objective: The aim of this study was to investigate the methylenetetrahydrofolate reductase (MTHFR) gene rs1801133 C>T polymorphisms and lung cancer susceptibility by pooling openly published data.

Methods: Electronic databases of Medline, Web of Science, Embase, Google scholar, CBM and CNKI were systematic searched to find the relevant studies related to MTHFR gene rs1801133 C>T polymorphisms and lung cancer susceptibility. The odds of TT, CT and CC alleles in lung cancer patients compared with healthy controls was pooled by the effect size of odds ratio (OR) and corresponding 95% confidence interval (95%CI) under random or fixed effect model. Publication bias was analyzed by Begg’s funnel plot and Egger’s line regression test.

Results: Overall, twenty-one studies relevant to MTHFR gene rs1801133 C>T polymorphisms and lung cancer susceptibility were included. The pooled data showed subject with T allele had significant increased risk of developing lung cancer in dominant (OR=1.14, 95%CI: 1.01-1.28, p<0.05), recessive (OR=1.26, 95%CI:1.08-1.48, p<0.01) and homologous (OR=1.36, 95%CI:1.12-1.65, p<0.01) genetic model. Begg’s funnel plot and Egger’s line regression test showed significant publication bias in all genetic models.

Conclusion: Based on present data, subjects with TT or CT alleles may have increased susceptibility to lung cancer. However, due to significant publication bias, the conclusion should be drawn with caution and should be proved by further well-designed case-control or cohort studies relevant to MTHFR gene rs1801133 C>T polymorphisms and lung cancer risk.

Folate/homocysteine metabolism and lung cancer risk among smokers

Background

Folate and homocysteine are involved in DNA synthesis and methylation processes, which are deregulated during carcinogenesis.

Objectives

The aim of this study was to assess the relationship between folate/homocysteine concentrations, the functional polymorphisms of folate/homocysteine genes and lung cancer risk among cigarette smokers.

Study design

The study included 132 lung cancer patients and 396 controls from northern Poland, matched by sex, age and smoking status. The median cigarette pack-years of smoking among both cases and controls was 30.0. Serum, red blood cell (RBC) folates and serum homocysteine concentrations were measured. The genotypes in selected polymorphic sites of the MTHFR, CBS, SHMT1, MTHFD1, MTRR, MTR, TYMS DHFR, TCN2, and SLC19A1 genes were determined. All study participants underwent scanning with low-dose computed tomography.

Results

Serum folate concentrations above the median (> 17.5 nmol/l among the healthy controls) were associated with an increased lung cancer risk (odds ratio [OR], 1.54, 95% confidence intervals [CI], 1.04–2.29, P = 0.031). An analogous trend was observed when the population was analysed after subdivision according to RBC folate concentrations, that is, above a value of 506.5 nmol/l (OR, 1.53; 95% CI, 0.95–2.47; P = 0.084). Additionally, in a subset of women, an increased risk of lung cancer development was associated with the SLC19A1 c.80AA genotype (c.80AA versus GG OR, 3.14; 95% CI, 1.32–7.46; P = P = 0.010).

Conclusion

These results suggest that, in the population consisting of heavy smokers, high folate levels add to the cancerogenic effect of smoking.

Aberrant Expression of Folate Metabolism Enzymes and Its Diagnosis and Survival Prediction in Ovarian Carcinoma

This study was to validate changes in the levels of folate receptor-α (FOLR1), dihydrofolate reductase (DHFR), and methionine synthase reductase (MTRR) in the tissue of OC patients. The expression of FOLR1, DHFR, and MTRR was evaluated in 80 cases of primary OC, 50 cases of benign ovarian tumors, and 30 normal ovarian tissues. Associations between protein expression and clinicopathological characters were assessed, and diagnostic and prognostic evaluation of FOLR1, DHFR, and MTRR was performed. Results showed that upregulated FOLR1 and MTRR and downregulated DHFR were detected in OC. Patients with abnormality of FOLR1, DHFR, and MTRR tend to have a higher percentage of platinum resistance. Moreover, the areas under receiver operating characteristic curves (AUCs-ROC) for FOLR1, DHFR, and MTRR were 0.723, 0.717, and 0.714, respectively. The combination of FOLR1, DHFR, and MTRR could produce an area of 0.864 under the receiver-operating characteristic curve in distinguishing platinum-resistant patients from platinum-sensitive patients (P < 0.0001). Correlations were present between the expression of FOLR1, DHFR, and MTRR. Furthermore, Kaplan-Meier curves indicated that the patients with overexpressed MTRR had a poorer overall survival time compared to those with low expression (P < 0.05). Thus, folate metabolic enzymes could provide a potential promising biomarker for diagnosis platinum-resistant in OC.

Progress of Individualized Chemotherapy for Gastric Carcinoma Under the Guidance of Genetic Testing

BACKGROUND

Gastric cancer is a major malignancy that has high incidence rates worldwide. Approximately 30% of patients with gastric cancer have progressed into advanced stages at the time of diagnosis. Chemotherapy is the standard-of-care for most advanced gastric cancer and elicits variable responses among patients. Personalized chemotherapy based on genetic information of individual patients with gastric cancer has gained increasing attention among oncologists for guiding chemotherapeutic regimens.

METHODS

This review summarizes recent progress of individualized chemotherapy in gastric cancer guided by pharmacogenomics. Variable medical research search engines, such as PubMed, Google Scholar, SpringerLink and ScienceDirect, were used to retrieve related literature. Only peerreviewed journal articles were selected for further analyses.

RESULTS AND CONCLUSION

The efficiency of chemotherapy in patients with gastric cancer is not only determined by chemotherapeutic drugs but is also directly and indirectly influenced by functionally correlative genes. Individual gene alteration or polymorphism remarkably affects patients' responses to particular chemotherapy. Most studies have focused on the influence of single-gene alteration on a selected drug, and only a few works explored the interaction between therapeutics and a panel of genes. Individualized chemotherapy regimens guided by a genetic survey of a multiple-gene panel are expected to remarkably improve the treatment efficacy in patients with advanced gastric cancer and may become the new standard for personalizing chemotherapy for gastric cancer in the near future.

Association of One-Carbon Metabolism-Related Vitamins (Folate, B6, B12), Homocysteine and Methionine With the Risk of Lung Cancer: Systematic Review and Meta-Analysis

Background: Studies on serum one-carbon metabolism factors (folate, B6, B12, homocysteine, and methionine) with lung cancer (LC) risk have produced inconsistent results. We aimed to systematically evaluate the association between them. Methods: This study was reported in accordance with the PRISMA Statement and was registered with PROSPERO (no. CRD42018086654). Relevant studies were searched in PubMed, Embase, MEDLINE, and CNKI up to February 2018. Random-effects models were used to estimate the pooled standardized mean differences (SMD) or odds ratios (OR), as well as their 95% confidence interval (CI). Sensitivity and subgroup analysis were performed to identify the source of heterogeneity. Publication bias was also assessed. Results: A total of 14 articles (8,097 patients) were included. The concentration of serum folate and vitamin B6 of LC patients were lower than the controls [SMD -0.53, 95% CI (-0.70, -0.35), p = 0.001 and SMD -0.28, 95%CI (-0.53, -0.02), p = 0.001, respectively]. While the concentration of homocysteine of the cases was higher than the controls [SMD 0.41, 95% CI (0.24, 0.59), p = 0.001]. However, there were no significant differences between LC patients and the controls in terms of vitamin B12 and methionine [SMD -0.09, 95% CI (-0.27, 0.09), p = 0.202 and SMD -0.13, 95% CI (-0.36, 0.10), p = 0.001]. Subgroup analysis showed that these results were more significant in Europe, Asia, former and current smokers, and the male population (p-value < 0.05). Conclusions: Serum folate and vitamin B6 might be protective factors against lung carcinogenesis and homocysteine could contribute to LC risk.

Long-Term, Supplemental, One-Carbon Metabolism-Related Vitamin B Use in Relation to Lung Cancer Risk in the Vitamins and Lifestyle (VITAL) Cohort

Purpose Inconsistent findings have been reported of a link between the use of one-carbon metabolism-related B vitamins and lung cancer risk. Because of the high prevalence of supplemental vitamin B use, any possible increased association warrants further investigation. We examined the association between long-term use of supplemental B vitamins on the one-carbon metabolism pathway and lung cancer risk in the Vitamins and Lifestyle (VITAL) cohort, which was designed specifically to look at supplement use relative to cancer risk. Methods A total of 77,118 participants of the VITAL cohort, 50 to 76 years of age, were recruited between October 2000 and December 2002 and included in this analysis. Incident, primary, invasive lung cancers (n = 808) were ascertained by prospectively linking the participants to a population-based cancer registry. The 10-year average daily dose from individual and multivitamin supplements were the exposures of primary interest. Results Use of supplemental vitamins B₆, folate, and B₁₂ was not associated with lung cancer risk among women. In contrast, use of vitamin B₆ and B₁₂ from individual supplement sources, but not from multivitamins, was associated with a 30% to 40% increase in lung cancer risk among men. When the 10-year average supplement dose was evaluated, there was an almost two-fold increase in lung cancer risk among men in the highest categories of vitamin B₆ (> 20 mg/d; hazard ratio, 1.82; 95% CI, 1.25 to 2.65) and B₁₂ (> 55µg/d; hazard ratio, 1.98; 95% CI, 1.32 to 2.97) compared with nonusers. For vitamin B₆ and B₁₂, the risk was even higher among men who were smoking at baseline. In addition, the B₆ and B₁₂ associations were apparent in all histologic types except adenocarcinoma, which is the type less related to smoking. Conclusion This sex- and source-specific association provides further evidence that vitamin B supplements are not chemopreventive for lung cancer and may be harmful.

Serum folate concentration and the incidence of lung cancer

Background

Lung cancer is a leading cause of cancer-related mortality globally. Folate helps to maintain DNA integrity and to regulate gene expression. Serum folate levels may affect the risk of several cancers, including lung cancer. In this study we evaluated the association between serum folate concentration and variations in genes involved in folate metabolism with lung cancer incidence in Poland.

Methods

The study included 366 lung cancer patients and 366 control subjects. We measured serum folate concentration and genotyped six variants in MTHFR, MTR and MTRR genes. The odds ratios of being diagnosed with lung cancer were calculated using conditional univariable and multivariable logistic regression with respect to folate level and genotypes.

Results

The mean serum folate level was lower in lung cancer cases than in control group (20.07 nmol/l vs. 22.52 nmol/l, p = 0.002). The odds ratio for lung cancer declined with increasing serum content of the folate. The folate concentration of >25.71 nmol/l (IVth quartile) in comparison to <15.92 nmol/l (Ist quartile) was associated with an odds ratio of 0.61 (95%CI 0.40–0.95, p = 0.03). The analysis of variations in MTHFR, MTR and MTRR genes did not reveal any significant difference between lung cancer cases and controls in univariable and multivariable analyses.

Conclusion

In this case-control study, lower serum folate concentrations were associated with a higher risk of lung cancer diagnosis. Although previous findings have been somewhat mixed, our results add to the evidence that circulating folate levels may be an indicator of lung cancer risk.

Lack of association between the MTHFRC677T polymorphism and lung cancer in a Turkish population

BACKGROUND

In this case-control study, we aimed to investigate the relationship between the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and lung cancer.

MATERIALS AND METHODS

Total 200 individuals including 100 patients with lung cancer and 100 controls were analyzed. Genotyping of MTHFR C677T was performed using PCR and RFLP methods.

RESULTS

The majority of the patients were men and 90% were smokers. We found that the risk ratio for development of LC was 13-times higher in smokers compared with non-smokers between patient and control groups in our study (OR:13.5, 95%CI:6.27-29.04, p:0.0001). Besides, the risk ratio for development of LC was nine times higher in individuals with cancer history in their family than those without cancer history (OR:9.65, 95%CI: 2.79-33.36; p:0.0001). When genotype distributions and allele frequencies were analyzed in the study groups, no significant difference was apparent (χ2:0.53, p=0.76). In addition, no correlation between genotypes of MTHFRC677T polymorphism and histological type of LC was found (χ2:0.99, p=0.60).

CONCLUSIONS

These results suggest that there was no association between the MTHFR C677T polymorphism and lung cancer in the 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.

Thymidylate Synthase Polymorphisms and Risk of Lung Cancer among the Jordanian Population: a Case Control Study

BACKGROUND

Thymidylate synthase (TS) catalyzes the methylation of deoxyuridylate to deoxythymidylate and is involved in DNA methylation, synthesis and repair. Two common polymorphisms have been reported, tandem repeats in the promoter-enhancer region (TSER), and 6bp ins/del in the 5'UTR, that are implicated in a number of human diseases, including cancer. The association between the two polymorphisms in risk for lung cancer (LC) was here investigated in the Jordanian population.

MATERIALS AND METHODS

An age, gender, and smoking-matched case-control study involving 84 lung cancer cases and 71 controls was conducted. The polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP) technique was used to detect the polymorphism of interest.

RESULTS

Individuals bearing the ins/ins genotype were 2.5 times more likely to have lung cancer [(95%CI: 0.98-6.37), p=0.051]. Individuals who were less than or equal to 57 years and carrying ins/ins genotype were 4.6 times more susceptible to lung cancer [OR<57 vs >57years: 4.6 (95%CI: 0.93-22.5), p=0.059)]. Genotypes and alleles of TSER were distributed similarly between cases and controls. Weak linkage disequilibrium existed between the two loci of interest (Lewontin's coefficient [D']) (LC: D' =0.03, r2: 0. 001, p= 0.8;

CONTROLS

D' =0.29, r2: 0.08, p=0.02). Carriers of the "3 tandem repeats_insertion" haplotype (3R_ins) were 2 times more likely to have lung cancer [2 (95%CI: 1.13-3.48), p=0.061].

CONCLUSIONS

Genetic polymorphism of TS at 3` UTR and its haplotype analysis may modulate the risk of lung cancer in Jordanians. The 6bp ins/del polymorphism of TS at 3 `UTR is more informative than TSER polymorphism in predicting increased risk.

Folate pathway gene MTHFR C677T polymorphism and risk of lung cancer in Asian populations

BACKGROUND

Previous studies concerning the association between the 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism with lung cancer in Asian populations have provided inconclusive findings.

AIM

A meta-analysis was performed to investigate a more reliable association between MTHFR C677T polymorphism and lung cancer in Asians.

MATERIALS AND METHODS

A comprehensive search was conducted to identify all case-control studies of MTHFR polymorphisms and lung cancer in Asia, using odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of any association.

RESULTS

Meta-analysis results suggested that the MTHFR C677T polymorphism contributed to an increased lung cancer risk in Asian populations (for T vs C: OR=1.11, 95%CI=1.0-1.23; for CT vs CC: OR= 1.1, 95%CI= 0.95-1.2 ; for TT+CT vs CC: OR=1.13, 95%CI=1.0-1.30; for TT vs CC: OR=1.25, 95%CI=1.01-1.30; for TT vs CT+CC: OR=1.16, 95%CI=1.0-1.36).

CONCLUSIONS

MTHFR C677T polymorphism is significantly associated with lung cancer in Asians.

Polymorphisms of Genes Involved in the Folate Metabolic Pathway Impact the Occurrence of Unexplained Recurrent Pregnancy Loss

Low levels of folate combined with high levels of homocysteine may cause unexplained recurrent pregnancy loss (URPL). However, the relationships between polymorphisms in genes of the folate metabolic pathway and URPL remain controversial. We conducted a case-control study to explore polymorphisms of the major folate pathway genes, including methylenetetrahydrofolate reductase (MTHFR) 677C>T, MTHFR 1298A>C, methionine synthase (MTR) 2756A>G, methionine synthase reductase (MTRR) 66A>G and reduced folate carrier 1 (RFC-1) 80A>G, and their associations with URPL. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to determine the distributions of MTHFR, MTR and RFC-1 polymorphisms, and the results were validated using direct sequencing. The polymorphisms in MTRR were determined using direct sequencing. Haplotypes were analyzed using SHEsis, an online tool for biological analysis. We found that the MTHFR 677T allele and the 677T/1298A/2756A/66A/80G haplotype were risk factors for URPL, while the MTR 2756G allele and the 677C/1298A/2756A/66A/80A haplotype exhibited protective effects on susceptibility to URPL in a Chinese Han population from the Hangzhou area.

Single nucleotide polymorphisms of one-carbon metabolism and cancers of the esophagus, stomach, and liver in a Chinese population

One-carbon metabolism (folate metabolism) is considered important in carcinogenesis because of its involvement in DNA synthesis and biological methylation reactions. We investigated the associations of single nucleotide polymorphisms (SNPs) in folate metabolic pathway and the risk of three GI cancers in a population-based case-control study in Taixing City, China, with 218 esophageal cancer cases, 206 stomach cancer cases, 204 liver cancer cases, and 415 healthy population controls. Study participants were interviewed with a standardized questionnaire, and blood samples were collected after the interviews. We genotyped SNPs of the MTHFR, MTR, MTRR, DNMT1, and ALDH2 genes, using PCR-RFLP, SNPlex, or TaqMan assays. To account for multiple comparisons and reduce the chances of false reports, we employed semi-Bayes (SB) shrinkage analysis. After shrinkage and adjusting for potential confounding factors, we found positive associations between MTHFR rs1801133 and stomach cancer (any T versus C/C, SB odds-ratio [SBOR]: 1.79, 95% posterior limits: 1.18, 2.71) and liver cancer (SBOR: 1.51, 95% posterior limits: 0.98, 2.32). There was an inverse association between DNMT1 rs2228612 and esophageal cancer (any G versus A/A, SBOR: 0.60, 95% posterior limits: 0.39, 0.94). In addition, we detected potential heterogeneity across alcohol drinking status for ORs relating MTRR rs1801394 to esophageal (posterior homogeneity P = 0.005) and stomach cancer (posterior homogeneity P = 0.004), and ORs relating MTR rs1805087 to liver cancer (posterior homogeneity P = 0.021). Among non-alcohol drinkers, the variant allele (allele G) of these two SNPs was inversely associated with the risk of these cancers; while a positive association was observed among ever-alcohol drinkers. Our results suggest that genetic polymorphisms related to one-carbon metabolism may be associated with cancers of the esophagus, stomach, and liver. Heterogeneity across alcohol consumption status of the associations between MTR/MTRR polymorphisms and these cancers indicates potential interactions between alcohol drinking and one-carbon metabolic pathway.

Polymorphism of cytosolic serine hydroxymethyltransferase and breast cancer risk: evidence from a meta-analysis

One-carbon metabolism has been presumed to influence cancer pathogenesis. Cytosolic serine hydroxymethyltransferase (cSHMT) is a critical enzyme in one-carbon metabolism pathway. Until now, many studies have investigated the association between cSHMT (also named SHMT1) C1420T polymorphism and breast cancer risk. However, the results remained conflicting rather than conclusive. Literature search was conducted using PubMed, Embase, and China National Knowledge Infrastructure (CNKI) databases until December 2013 to identify studies investigating the association of SHMT1 C1420T polymorphism with breast cancer risk. The strength of the association was assessed by the summary odd ratios (ORs) and their corresponding 95 % confidence interval (CI). Seven studies with a total of 5,534 cases and 6,581 controls were included. Overall, no association was detected between SHMT1 C1420T polymorphism and breast cancer risk (T vs. C, OR = 0.97, 95 % CI = 0.92-1.03). In the subgroup analysis based on ethnicity, SHMT1 C1420T polymorphism has shown a protective effect on breast cancer in Asians (T vs. C, OR = 0.78, 95 % CI = 0.66-0.93) but not in Caucasian (T/T vs. C/C, OR = 0.98, 95 % CI = 0.86-1.12). Significant heterogeneity across studies could be observed in some genetic comparison models in the overall estimation (C/T vs. C/C, P het = 0.004; T/T+C/T vs. C/C, P het = 0.006) but turned to be mild in all comparison models when stratified by ethnicity. Our meta-analysis failed to detect association between SHMT1 C1420T polymorphism and breast cancer risk. However, we found evidence for association of SHMT1 C1420T polymorphism with significantly reduced risk of breast cancer in Asians. Further well-designed studies with larger sample size and better selected controls are warranted.

The methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and tumor risk: evidence from 134 case-control studies

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate metabolism, which is essential for DNA synthesis and methylation. Genetic variations in the MTHFR gene seem to contribute to a decreased activity of MTHFR, ultimately confer increased susceptibility to cancer. As the most extensively studied polymorphism, MTHFR C677T polymorphism was shown to contribute to cancer susceptibility but the results were inconsistent. The authors performed a meta-analysis including 134 studies (46,207 cases and 69,160 controls) to address the issue. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to assess the association. Overall, a significant elevated risk of cancer was associated with the MTHFR C677T polymorphism in T-allele versus C-allele comparison (OR = 1.06, 95% CI 1.02-1.11, P(heterogeneity) < 0.001), homozygote model (OR = 1.08, 95% CI 1.01-1.17, P(heterogeneity) < 0.001) and dominant model (OR = 1.05, 95% CI 1.00-1.10, P(heterogeneity) < 0.001). In the stratified analyses, significantly increased cancer risks were indicated among Asians in all genetic models except for heterozygote model. Further analysis revealed that C677T was significantly associated with an increased risk of esophageal and stomach cancer. This meta-analysis supports an association between the MTHFR C677T polymorphism and increased risk of esophageal and stomach cancer, especially among Asians. Additionally, more high-quality studies and that the covariates responsible for heterogeneity should be controlled to obtain a more conclusive response about the function of MTHFR C677T in cancer.

Association between folate intake and the risk of lung cancer: a dose-response meta-analysis of prospective studies

Background

Studies have reported inconsistent results regarding the existence of an association between folate intake and the risk of lung cancer. The purpose of this study was to summarize the evidence from prospective cohort studies regarding this relationship by using a dose-response meta-analytic approach.

Methodology and Principal Findings

In September 2013, we performed electronic searches in PubMed, Embase, and the Cochrane Library to identify studies examining the effect of folate intake on the incidence of lung cancer. Only prospective cohort studies that reported the effect estimates about the incidence of lung cancer with 95% confidence intervals (CIs) for more than 2 categories of folate intake were included. Overall, we examined 9 cohort studies reporting the data of 566,921 individuals. High folate intake had little effect on the risk of lung cancer (risk ratio [RR], 0.92; 95% CI, 0.84–1.01; P = 0.076). Dose-response meta-analysis also suggested that a 100 µg/day increase in folate intake had no significant effect on the risk of lung cancer (RR, 0.99; 95% CI, 0.97–1.01; P = 0.318). Subgroup analysis suggested that the potential protective effect of low folate intake (100–299 µg/day) was more evident in women than men, while the opposite was true of high folate intake (>400 µg/day). Finally, subgroup analyses of a 100 µg/day increment in folate intake indicated that its potential protective effect was more evident in men than in women.

Conclusion/Significance

Our study revealed that folate intake had little or no effect on the risk of lung cancer. Subgroup analyses indicated that an increased folate intake was associated with a reduced risk of lung cancer in men. Furthermore, low folate intake may be a protective factor for women, and high folate intake for men.

Influence of methylenetetrahydrofolate reductase C677T polymorphism on the risk of lung cancer and the clinical response to platinum-based chemotherapy for advanced non-small cell lung cancer: an updated meta-analysis

PURPOSE

Methylenetetrahydrofolate reductase (MTHFR) has been implicated in lung cancer risk and response to platinum-based chemotherapy in advanced non-small cell lung cancer (NSCLC). However, the results are controversial. We performed meta-analysis to investigate the effect of MTHFR C677T polymorphism on lung cancer risk and response to platinum-based chemotherapy in advanced NSCLC.

MATERIALS AND METHODS

The databases of PubMed, Ovid, Wanfang and Chinese Biomedicine were searched for eligible studies. Nineteen studies on MTHFR C677T polymorphism and lung cancer risk and three articles on C677T polymorphism and response to platinum-based chemotherapy in advanced NSCLC, were identified.

RESULTS

The results indicated that the allelic contrast, homozygous contrast and recessive model of the MTHFR C677T polymorphism were associated significantly with increased lung cancer risk. In the subgroup analysis, the C677T polymorphism was significantly correlated with an increased risk of NSCLC, with the exception of the recessive model. The dominant model and the variant T allele showed a significant association with lung cancer susceptibility of ever smokers. Male TT homozygote carriers had a higher susceptibility, but the allelic contrast and homozygote model had a protective effect in females. No relationship was observed for SCLC in any comparison model. In addition, MTHFR 677TT homozygote carriers had a better response to platinum-based chemotherapy in advanced NSCLC in the recessive model.

CONCLUSION

The MTHFR C677T polymorphism might be a genetic marker for lung cancer risk or response to platinum- based chemotherapy in advanced NSCLC. However, our results require further verification.

Cancer-testis gene expression is associated with the methylenetetrahydrofolate reductase 677 C>T polymorphism in non-small cell lung carcinoma

Background

Tumor-specific, coordinate expression of cancer-testis (CT) genes, mapping to the X chromosome, is observed in more than 60% of non-small cell lung cancer (NSCLC) patients. Although CT gene expression has been unequivocally related to DNA demethylation of promoter regions, the underlying mechanism leading to loss of promoter methylation remains elusive. Polymorphisms of enzymes within the 1-carbon pathway have been shown to affect S-adenosyl methionine (SAM) production, which is the sole methyl donor in the cell. Allelic variants of several enzymes within this pathway have been associated with altered SAM levels either directly, or indirectly as reflected by altered levels of SAH and Homocysteine levels, and altered levels of DNA methylation. We, therefore, asked whether the five most commonly occurring polymorphisms in four of the enzymes in the 1-carbon pathway associated with CT gene expression status in patients with NSCLC.

Methods

Fifty patients among a cohort of 763 with NSCLC were selected based on CT gene expression status and typed for five polymorphisms in four genes known to affect SAM generation by allele specific q-PCR and RFLP.

Results

We identified a significant association between CT gene expression and the MTHFR 677 CC genotype, as well as the C allele of the SNP, in this cohort of patients. Multivariate analysis revealed that the genotype and allele strongly associate with CT gene expression, independent of potential confounders.

Conclusions

Although CT gene expression is associated with DNA demethylation, in NSCLC, our data suggests this is unlikely to be the result of decreased MTHFR function.

Serum vitamin B6, folate, and homocysteine concentrations and oxidative DNA damage in Japanese men and women

OBJECTIVE

Higher vitamin B status has been linked to a lower risk for cancer, but the underlying mechanism remains elusive. The aim of the present study was to examine the association of pyridoxal, folate, and homocysteine (Hcy) with urinary 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative DNA damage.

METHODS

The participants were 500 employees (293 men and 207 women), ages 21 to 66 y, of two municipal offices in Japan. Serum pyridoxal and Hcy concentrations were measured using high-performance liquid chromatography (HPLC) method, and serum folate concentrations were measured using chemiluminescent immunoassay. Urinary 8-OHdG concentrations were measured using HPLC method. Multiple regression was used to estimate means of 8-OHdG for each tertile of pyridoxal, folate, and Hcy with adjustment for potential confounders.

RESULTS

In multivariate analysis, 8-OHdG concentration was inversely associated with pyridoxal concentration in men (P for trend = 0.045) but not in women. The association in men was confined to non-smokers (P for trend = 0.033) or those who consumed no or < 20 g/d of ethanol (P for trend = 0.048). 8-OHdG concentrations were not appreciably associated with folate and Hcy concentrations.

CONCLUSION

The results suggest that vitamin B6, but not folate and homocysteine, plays a role against oxidative DNA damage in Japanese men.

Meta-analysis on MTHFR polymorphism and lung cancer susceptibility in East Asian populations

Lung cancer is the most frequently occurring type of cancer worldwide and the leading cause of cancer mortality. Environmental and genetic factors play important roles in lung carcinogenesis. The aim of this meta-analysis was to investigate the association between methylenetetrahydrofolate reductase (MTHFR) polymorphism and the risk of lung cancer in East Asian populations. Related articles were identified through searching literature databases, such as PubMed, EMBASE, Web of Science, Chinese Biomedicine and CNKI. The odds ratio (OR) values in those studies were incorporated by meta-analysis to assess lung cancer susceptibility associated with the MTHFR mutation genotype. The MTHFR C677TT genotype exhibited a significantly increased risk of lung cancer compared to the MTHFR 677CC/CT genotype (OR=1.24; 95% CI, 1.01-1.52). No relationship was identified between the other MTHFR C677T genetic models and the risk of lung cancer and there was no significantly increased risk of lung cancer in A1298C genetic models. In a subgroup of hospital-based controls, according to the source of controls, the C677TT genotype exhibited a significantly increased risk of lung cancer, compared to the C677CC genotype (OR=3.01; 95% CI, 1.07-8.46). In the stratified analysis, the study indicated that the MTHFR 677TT genotype was associated with a significant increase in the risk of lung squamous carcinoma (OR=1.53; 95% CI, 1.09-2.14), whereas no association was observed between the MTHFR C677TT genotype and the risk of lung adenocarcinoma. No association was observed between MTHFR C677TT polymorphism and the risk of lung cancer when smoking was considered. In conclusion, the meta-analysis results suggested that MTHFR C677T polymorphisms exhibit a significantly increased risk of lung cancer and that the MTHFR 677TT genotype is associated with a significantly increased risk of lung squamous carcinoma.

Investigating multiple candidate genes and nutrients in the folate metabolism pathway to detect genetic and nutritional risk factors for lung cancer

PURPOSE

Folate metabolism, with its importance to DNA repair, provides a promising region for genetic investigation of lung cancer risk. This project investigates genes (MTHFR, MTR, MTRR, CBS, SHMT1, TYMS), folate metabolism related nutrients (B vitamins, methionine, choline, and betaine) and their gene-nutrient interactions.

METHODS

We analyzed 115 tag single nucleotide polymorphisms (SNPs) and 15 nutrients from 1239 and 1692 non-Hispanic white, histologically-confirmed lung cancer cases and controls, respectively, using stochastic search variable selection (a Bayesian model averaging approach). Analyses were stratified by current, former, and never smoking status.

RESULTS

Rs6893114 in MTRR (odds ratio [OR] = 2.10; 95% credible interval [CI]: 1.20-3.48) and alcohol (drinkers vs. non-drinkers, OR = 0.48; 95% CI: 0.26-0.84) were associated with lung cancer risk in current smokers. Rs13170530 in MTRR (OR = 1.70; 95% CI: 1.10-2.87) and two SNP*nutrient interactions [betaine*rs2658161 (OR = 0.42; 95% CI: 0.19-0.88) and betaine*rs16948305 (OR = 0.54; 95% CI: 0.30-0.91)] were associated with lung cancer risk in former smokers. SNPs in MTRR (rs13162612; OR = 0.25; 95% CI: 0.11-0.58; rs10512948; OR = 0.61; 95% CI: 0.41-0.90; rs2924471; OR = 3.31; 95% CI: 1.66-6.59), and MTHFR (rs9651118; OR = 0.63; 95% CI: 0.43-0.95) and three SNP*nutrient interactions (choline*rs10475407; OR = 1.62; 95% CI: 1.11-2.42; choline*rs11134290; OR = 0.51; 95% CI: 0.27-0.92; and riboflavin*rs8767412; OR = 0.40; 95% CI: 0.15-0.95) were associated with lung cancer risk in never smokers.

CONCLUSIONS

This study identified possible nutrient and genetic factors related to folate metabolism associated with lung cancer risk, which could potentially lead to nutritional interventions tailored by smoking status to reduce lung cancer risk.

Methylenetetrahydrofolate reductase gene C677T polymorphism and lung cancer: an updated meta-analysis

OBJECTIVE

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the metabolism of folate and nucleotides needed for DNA synthesis and repair. Variations in MTHFR functions likely play roles in the etiology of lung cancer (LC). So far, several studies between MTHFR C677T polymorphism and LC provide controversial or inconclusive results.

METHODS

To better assess the purported relationship, we performed a meta-analysis of 14 publications. Eligible studies were identified by searching the Pubmed, Embase, Web of Science and Google Scholar databases. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the association.

RESULTS

Overall, no significant association was detected between the MTHFR C677T polymorphism and LC risk, the same as in race subgroup. However, in the stratified analysis by histological type, significantly increased non-small-cell lung cancer (NSCLC) risk was indicated (T-allele vs. C-allele: OR=1.11, 95%CI=1.03-1.19; TT vs. CC: OR=1.24, 95%CI=1.09-1.41; TC vs. CC: OR=1.11, 95%CI=1.03-1.20 and TT+TC vs. CC: OR=1.09, 95%CI=1.03-1.15). At the same time, ever-smokers who carried T-allele (TT+TC) had a 10% decreased LC risk compared with CC genotype carriers.

CONCLUSIONS

Our study provided evidence that the MTHFR 677T null genotype may increase NSCLC risk, however, it may protect ever-smokers against LC risk. Future studies with large sample sizes are warranted to further evaluate this association in more detail.

Methylenetetrahydrofolate reductase 677TT genotype might be associated with an increased lung cancer risk in Asians

BACKGROUND

The association between methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism and lung cancer risk has been studied in various populations with conflicting results. The aim of this study was to assess the association strength by a meta-analysis of published studies.

METHODS

We searched PubMed and Chinese Biomedical (CBM) databases for relevant literatures published by July 18, 2012. Pooled odds ratio (OR) with 95% confidence interval (CI) was calculated to assess the strength of the association.

RESULTS

A total of 20 studies comprising 11,653 cases and 12,032 controls were included in the final meta-analysis. Using the random effect model, we found that MTHFR 677TT variant genotype was associated with an increased lung cancer risk (OR=1.26, 95% CI=1.05-1.50, P=0.011 for TT vs. CC; OR=1.19, 95% CI=1.03-1.37, P<0.001 for TT vs. CC+CT; OR=1.11, 95% CI=1.02-1.22, P=0.017 for T allele vs. C allele). In the further stratified analyses, the increased lung cancer risk was found in Asian subjects (OR=1.31, 95% CI=1.01-1.71, P=0.045 for TT vs. CC; OR=1.17, 95% CI=1.00-1.38, P=0.048 for TT vs. CC+CT). There were no evidences for obvious publication bias in the overall meta-analysis and Asian subjects.

CONCLUSIONS

MTHFR 677TT genotype might increase the susceptibility of lung cancer, especially in Asians.

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.

Sex-specific association of sequence variants in CBS and MTRR with risk for promoter hypermethylation in the lung epithelium of smokers

Gene promoter hypermethylation is now regarded as a promising biomarker for the risk and progression of lung cancer. The one-carbon metabolism pathway is postulated to affect deoxyribonucleic acid (DNA) methylation because it is responsible for the generation of S-adenosylmethionine (SAM), the methyl donor for cellular methylation reactions. This study investigated the association of single nucleotide polymorphisms (SNPs) in six one-carbon metabolism-related genes with promoter hypermethylation in sputum DNA from non-Hispanic white smokers in the Lovelace Smokers Cohort (LSC) (n = 907). Logistic regression was used to assess the association of SNPs with hypermethylation using a high/low methylation cutoff. SNPs in the cystathionine beta synthase (CBS) and 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR) genes were significantly associated with high methylation in males [CBS rs2850146 (-8283G > C), OR = 4.9; 95% CI: 1.98, 12.2, P = 0.0006] and low methylation in females [MTRR rs3776467 (7068A > G), OR = 0.57, 95% CI: 0.42, 0.77, P = 0.0003]. The variant allele of rs2850146 was associated with reduced gene expression and increased plasma homocysteine (Hcy) concentrations. Three plasma metabolites, Hcy, methionine and dimethylglycine, were associated with increased risk for gene methylation. These studies suggest that SNPs in CBS and MTRR have sex-specific associations with aberrant methylation in the lung epithelium of smokers that could be mediated by the affected one-carbon metabolism and transsulfuration in the cells.

MTHFR polymorphisms, folate intake and carcinogen DNA adducts in the lung

The methylenetetrahydrofolate reductase (MTHFR) genes and folate in one-carbon metabolism are essential for DNA methylation and synthesis. However, their role in carcinogen DNA damage in target lung tissue, a dosimeter for cancer risk, is not known. Our study aimed to investigate the association between genetic and nutritional one-carbon metabolism factors and DNA adducts in target lung. Data on 135 lung cancer cases from the Massachusetts General Hospital were studied. Genotyping was completed for MTHFR C677T (rs1801133) and A1298C (rs1801131). Information on dietary intake for one-carbon related micronutrients, folate and other B vitamin was derived from a validated food frequency questionnaire. DNA adducts in lung were measured by (32) P-postlabeling. After adjusting for potential confounders, DNA adduct levels in lung significantly increased by 69.2% [95% confidence interval (CI), 5.5% to 171.5%] for the MTHFR 1298AC+CC genotype. The high risk group, combining the A1298C (AC+CC) plus C677T (CT+TT) genotypes, had significantly enhanced levels of lung adducts by 210.7% (95% CI, 21.4% to 695.2%) in contrast to the A1298C (AA) plus C677T (CC) genotypes. Elevation of DNA adduct was pronounced-111.3% (95% CI, -3.0 to 360.5%) among 1298AC+CC patients, who consumed the lowest level of folate intake as compared to 1298AA individuals with highest tertile of intake. These results indicate that DNA adducts levels are influenced by MTHFR polymorphisms and low folate consumption, suggesting an important role of genetic and nutritional factors in protecting DNA damage from lung carcinogen in at-risk populations.

Folate and choline metabolism gene variants in relation to ovarian cancer risk in the Polish population

Data indicates that genetic factors alone do not account for ovarian tumorigenesis, suggesting that epigenetic status additionally affects this process. Therefore, we assessed the possible contribution of polymorphic variants of genes that may affect DNA methylation to the risk of ovarian cancer incidence in the Polish population. Using PCR-RFLP and HRM analyses, we studied the distribution of BHMT (rs3733890), MTHFD1 (rs2236225), MTHFR (rs1801133), MTR (rs1805087), MTRR (rs1801394) and TCN2 (rs1801198) genotypes and alleles in patients with ovarian cancer (n = 136) and controls (n = 160). Moreover, using DNA and methylation-specific PCR (MSP) we also determined the methylation of the Cadherin 13 (CDH13) promoter in cancerous tissue from these patients. We did not observe a significant association between all studied gene variants and the incidence of ovarian cancer. The lowest P (trend) = 0.1226 was observed for the MTHFR Ala222Val polymorphism. Moreover, the lowest P = 0.0772 was found in the comparison of MTHFR Ala/Ala versus Val/Val and Val/Ala genotypes in patients and control groups. The multifactor dimensionality reduction analysis also did not indicate a significant interactive genetic effect on ovarian cancer incidence for all analyzed SNPs. However, we observed frequent methylation of the CDH13 promoter in approximately 21% (29/136) patients with ovarian carcinomas. Our results might suggest that the selected polymorphic gene variants may not contribute to ovarian cancer incidence.

Methylenetetrahydrofolate reductase polymorphisms and interaction with smoking and alcohol consumption in lung cancer risk: a case-control study in a Japanese population

Background

Cigarette smoking is an established risk factor of lung cancer development while the current epidemiological evidence is suggestive of an increased lung cancer risk associated with alcohol consumption. Dietary folate, which is present in a wide range of fresh fruits and vegetables, may be a micronutrient that has a beneficial impact on lung carcinogenesis. Methylenetetrahydrofolate reductase (MTHFR) plays a crucial role in regulating folate metabolism, which affects both DNA synthesis/repair and methylation. We examined if smoking or alcohol consumption modify associations between MTHFR polymorphisms and lung cancer risk.

Methods

We evaluated the role of the MTHFR C677T (rs1801133) and A1298C (rs1801131) polymorphisms in a case-control study comprised of 462 lung cancer cases and 379 controls in a Japanese population. Logistic regression was used to assess the adjusted odds ratios (OR) and 95% confidence intervals (95% CI).

Results

The TT genotype of the C677T polymorphism was significantly associated with an increased risk of lung cancer (OR = 2.27, 95% CI = 1.42 - 3.62, P < 0.01) while the A1298C polymorphism was not associated with lung cancer risk. The minor alleles of both polymorphisms behaved in a recessive fashion. The highest risks were seen for 677TT-carriers with a history of smoking or excessive drinking (OR = 6.16, 95% CI = 3.48 - 10.9 for smoking; OR = 3.09, 95% CI = 1.64 - 5.81 for drinking) compared with C-carriers without a history of smoking or excessive drinking, but no interactions were seen. The 1298CC genotype was only associated with increased risk among non-smokers (P < 0.05), and smoking was only associated with increased risks among 1298A-carriers (P < 0.01), but no significant interaction was seen. There was a synergistic interaction between the A1298C polymorphism and drinking (P < 0.05). The highest risk was seen for the CC-carriers with excessive drinking (OR = 7.24, 95% CI = 1.89 - 27.7) compared with the A-carriers without excessive drinking).

Conclusions

The C677T polymorphism was significantly associated with lung cancer risk. Although the A1298C polymorphism was not associated with lung cancer risk, a significant interaction with drinking was observed. Future studies incorporating data on folate intake may undoubtedly lead to a more thorough understanding of the role of the MTHFR polymorphisms in lung cancer development.

Folate metabolism-related gene polymorphisms and susceptibility to primary liver cancer in North China

Genetic factors may contribute to individual differences in cancer susceptibility. This study was designed to investigate the effects of the polymorphisms of methylenetetrahydrofolate reductase 677 C → T (MTHFR 677 C → T), methylenetetrahydrofolate reductase 1298 A → C (MTHFR 1298A → C), thymidylate synthase (TYMS 3R → 2R), and methionine synthase 2756 A → G (MTR 2756 A → G) on the risk of primary liver cancer (PLC). We conducted a case-control study involving 356 PLC cases and 641 healthy controls in North China. Compared with the MTHFR 677CC genotype, the MTHFR 677TT genotype showed an increased risk for PLC (TT vs. CC: adjusted odds ratio (OR) = 1.56; 95% confidence interval (CI): 1.02-2.40; P = 0.043) after adjusting for gender and age, whereas the MTHFR 1298CC genotype showed a significantly decreased risk for PLC (CC vs. AA: adjusted OR = 0.23; 95% CI: 0.08-0.70; P = 0.010). However, no significant association was found between the TYMS 3R → 2R or the MTR 2756 A → G polymorphism and the risk of PLC. Our results suggest that the MTHFR 677 C → T and the MTHFR 1298A → C genetic polymorphisms might play important role in hepatic carcinogenesis. Further studies with larger sample sizes are required to validate this association.

An association study of polymorphisms in JAK3 gene with lung cancer in the Korean population

Purpose

The genetic alteration of the janus kinases (JAKs), non-receptor tyrosine kinase, is related to the development of human cancers. However, little is known about how the sequence variation of JAK3 contributes to the development of lung cancer. This study investigated whether polymorphisms at the promoter region of the JAK3 gene are associated with the risk of lung cancer in the Korean population.

Materials and Methods

A total of 819 subjects, including 409 lung cancer patients and 410 healthy controls were recruited. The SNaPshot assay and polymerase chain reaction-restriction fragment length polymorphism analysis were used, and logistic regression analyses were performed to characterize the association between polymorphisms of JAK3 and lung cancer risk.

Results

Three polymorphisms (-672 G>A, +64 A>G and +227 G>A) of JAK3 were analyzed for large-scale genotyping (n=819). Statistical analyses revealed that polymorphisms and haplotypes in the JAK3 gene were not significantly associated with lung cancer.

Conclusion

JAK3 gene was not significantly associated with the risk of lung cancer in the Korean population.

Influence of polymorphisms in MTHFR 677 C→T, TYMS 3R→2R and MTR 2756 A→G on NSCLC risk and response to platinum-based chemotherapy in advanced NSCLC

AIMS

Genetic factors may contribute to individual differences in cancer susceptibility, drug efficacy and toxicity. This study was designed to investigate the effects of the polymorphisms of methylenetetrahydrofolate reductase 677 C→T (MTHFR 677 C→T), thymidylate synthase (TYMS 3R→2R),and methionine synthase 2756 A→G (MTR 2756 A→G) on the risk of lung cancer and response to platinum-based chemotherapy in advanced non-small-cell lung cancer (NSCLC).

MATERIALS & METHODS

We conducted a case-control study involving 438 NSCLC cases (including 101 follow-up cases) and 641 healthy controls in North China.

RESULTS & CONCLUSION

Using a genetic model analysis, the polymorphism MTHFR 677 C→T showed a significantly increased risk for NSCLC in women but not in men, which was observed in the codominant model (CT vs CC adjusted odds ratio [OR] = 2.46; 95% confidence interval [CI]: 1.37-4.42; p = 0.003; TT vs CC adjusted OR: 2.04; 95% CI: 1.09-3.81; p = 0.03) and the dominant model (CT + TT vs CC adjusted OR: 2.30; 95% CI: 1.31-4.05; p = 0.004). In addition, we found that patients with the MTHFR 677 TT genotype showed a better response to platinum-based chemotherapy in the recessive model (TT vs CT + CC adjusted OR: 0.24; 95% CI: 0.09-0.68; p = 0.007), the generalized OR was 0.44 (0.22-0.88; p = 0.04). There were no significant associations of the polymorphisms of TYMS 3R→2R or MTR 2756 A→G with the risk of NSCLC or response to platinum-based chemotherapy in advanced NSCLC in any genetic model. Our results suggest that genetic polymorphisms of MTHFR 677 C→T may contribute to NSCLC development in Chinese women and could also influence treatment response for advanced NSCLC patients with platinum-based chemotherapy. Further studies with larger sample sizes are required to validate this association.

Methionine synthase reductase A66G polymorphism contributes to tumor susceptibility: evidence from 35 case-control studies

Methionine synthase reductase (MTRR) gene is involved in tumorigenesis by regulating DNA methylation through activation of methionine synthase (MTR). MTRR is polymorphic at nucleotide 66 (A-to-G) and the resulting variant enzyme has a lower affinity for MTR. The reported associations of MTRR A66G polymorphism with cancer risk are contradictory. Therefore, we performed a meta-analysis to better assess the associations, including 18,661 cases and 27,678 controls from 35 studies. Crude ORs with 95% CIs were used to assess the strength of association between the MTRR A66G polymorphism and cancer risk. The pooled ORs were performed for homozygote model (GG vs. AA), heterozygote model (GG vs. GA), recessive genetic model (GG vs. GA + AA), and dominant genetic model (GG + GA vs. AA), respectively. Overall, results indicated that the G allele and GG variant genotypes were associated with a significantly increased cancer risk (G vs. A: OR, 1.039; 95% CI, 1.009-1.078; homozygote model: OR, 1.094; 95% CI, 1.006-1.191). In subgroup analysis by ethnicity, significant increased risks were found among Asians with G allele (G vs. A: OR, 1.063; 95% CI, 1.011-1.119; homozygote model: OR, 1.189; 95% CI, 1.055-1.341; recessive model: OR, 1.197; 95% CI, 1.068-1.341). For stratification analysis, the cancer types with fewer than three studies were categorized into "other cancers", and the results indicated that there was a significant elevated cancer risk in "other cancers" in all genetic models, not in colorectal cancer, lymphoid leukemia or breast cancer. In summary, our study suggests that the MTRR A66G polymorphism is a potential biomarker for cancer risk.

Methylenetetrahydrofolate reductase C677T polymorphism in patients with lung cancer in a Korean population

Background

This study was designed to investigate an association between methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and the risk of lung cancer in a Korean population.

Methods

We conducted a large-scale, case-control study involving 3938 patients with newly diagnosed lung cancer and 1700 healthy controls. Genotyping was performed with peripheral blood DNA for MTHFR C677T polymorphisms. Statistical significance was estimated by logistic regression analysis.

Results

The MTHFR C677T frequencies of CC, CT, and TT genotypes were 34.5%, 48.5%, and 17% among lung cancer patients, and 31.8%, 50.7%, and 17.5% in the controls, respectively. The MTHFR 677CT and TT genotype showed a weak protection against lung cancer compared with the homozygous CC genotype, although the results did not reach statistical significance. The age- and gender-adjusted odds ratio (OR) of overall lung cancer was 0.90 (95% confidence interval (CI), 0.77-1.04) for MTHFR 677 CT and 0.88 (95% CI, 0.71-1.07) for MTHFR 677TT. However, after stratification analysis by histological type, the MTHFR 677CT genotype showed a significantly decreased risk for squamous cell carcinoma (age- and gender-adjusted OR, 0.78; 95% CI, 0.64-0.96). The combination of 677 TT homozygous with 677 CT heterozygous also appeared to have a protection effect on the risk of squamous cell carcinoma. We observed no significant interaction between the MTHFR C677T polymorphism and age and gender or smoking habit.

Conclusions

This is the first reported study focusing on the association between MTHFR C677T polymorphisms and the risk of lung cancer in a Korean population. The T allele was found to provide a weak protective association with lung squamous cell carcinoma.

The association between two polymorphisms in the TYMS gene and breast cancer risk: a meta-analysis

Thymidylate synthase (TYMS), which catalyzes the conversion of deoxyuridine monophosphate to deoxythymidine monophosphate, is a central enzyme in the folate metabolic pathway. Epidemiological studies have evaluated the association between TYMS gene polymorphisms and breast cancer susceptibility; however, the published data are still inconclusive. To derive a more precise assessment of this relationship, we performed a meta-analysis based on currently available data by searching PubMed, EMBASE databases, and the Cochrane Library. A total of 10 eligible studies were identified for the TYMS TSER polymorphism (six studies with 2,718 cases and 3,423 controls) and for the TYMS TS3'-UTR polymorphism (five studies with 1,969 cases and 2,290 controls). The overall odds ratio (OR) and the corresponding 95% confidence interval (CI) showed a statistical association between the TSER polymorphism and breast cancer risk under homozygote comparison (2R/2R vs. non-2R/non-2R; OR 1.25; 95% CI 1.04-1.50), allele contrast (2R vs. non-2R; OR 1.09; 95% CI 1.01-1.19) and the recessive model (OR 1.19; 95% CI 1.01-1.39). In the subgroup analysis by ethnicity, a statistically significant increase in cancer risk was found among Caucasians for homozygote comparison (OR 1.31; 95% CI 1.10-1.57), the allele contrast model (OR 1.12; 95% CI 1.02-1.23) and the dominant model (OR 1.40; 95% CI 1.00-1.95). For the TS3'-UTR polymorphism, significant effects were shown using the allele contrast model (OR 1.33; 95% CI 1.03-1.73). However, the TS3'-UTR polymorphism increased breast cancer risk among Asian women (del6 vs. ins6; OR 1.41; 95% CI 1.01-1.98) but not Caucasian women using the homozygote comparison. In conclusion, our meta-analysis suggests that the TSER polymorphism may increase susceptibility to breast cancer in the Caucasian population and the TS3'-UTR polymorphism may be a genetic determinant for developing breast cancer in the Asian population; therefore, ethnic background should be carefully considered in further studies.

Replication of lung cancer susceptibility loci at chromosomes 15q25, 5p15, and 6p21: a pooled analysis from the International Lung Cancer Consortium

BACKGROUND

Genome-wide association studies have identified three chromosomal regions at 15q25, 5p15, and 6p21 as being associated with the risk of lung cancer. To confirm these associations in independent studies and investigate heterogeneity of these associations within specific subgroups, we conducted a coordinated genotyping study within the International Lung Cancer Consortium based on independent studies that were not included in previous genome-wide association studies.

METHODS

Genotype data for single-nucleotide polymorphisms at chromosomes 15q25 (rs16969968, rs8034191), 5p15 (rs2736100, rs402710), and 6p21 (rs2256543, rs4324798) from 21 case-control studies for 11 645 lung cancer case patients and 14 954 control subjects, of whom 85% were white and 15% were Asian, were pooled. Associations between the variants and the risk of lung cancer were estimated by logistic regression models. All statistical tests were two-sided.

RESULTS

Associations between 15q25 and the risk of lung cancer were replicated in white ever-smokers (rs16969968: odds ratio [OR] = 1.26, 95% confidence interval [CI] = 1.21 to 1.32, P(trend) = 2 x 10(-26)), and this association was stronger for those diagnosed at younger ages. There was no association in never-smokers or in Asians between either of the 15q25 variants and the risk of lung cancer. For the chromosome 5p15 region, we confirmed statistically significant associations in whites for both rs2736100 (OR = 1.15, 95% CI = 1.10 to 1.20, P(trend) = 1 x 10(-10)) and rs402710 (OR = 1.14, 95% CI = 1.09 to 1.19, P(trend) = 5 x 10(-8)) and identified similar associations in Asians (rs2736100: OR = 1.23, 95% CI = 1.12 to 1.35, P(trend) = 2 x 10(-5); rs402710: OR = 1.15, 95% CI = 1.04 to 1.27, P(trend) = .007). The associations between the 5p15 variants and lung cancer differed by histology; odds ratios for rs2736100 were highest in adenocarcinoma and for rs402710 were highest in adenocarcinoma and squamous cell carcinomas. This pattern was observed in both ethnic groups. Neither of the two variants on chromosome 6p21 was associated with the risk of lung cancer.

CONCLUSIONS

In this international genetic association study of lung cancer, previous associations found in white populations were replicated and new associations were identified in Asian populations. Future genetic studies of lung cancer should include detailed stratification by histology.

The association between methylene-tetrahydrofolate reductase gene polymorphism and lung cancer risk

This study aimed to determine the relation between methylene-tetrahydrofolate reductase (MTHFR) gene polymorphism and lung cancer risk and the frequency of this polymorphism. The study involved 64 lung cancer patients (the study group) with definitive diagnosis and 61 noncancerous subjects (the control group). MTHFR C677T and A1298C mutation analysis was made using DNA isolated from peripheric blood and multiplex PCR and reverse hybridization strip test. Eighty-four percent of the patients were male. The age, gender, and history of alcohol use of the patients and control group were statistically similar. While MTHFR 677T and 677C allele frequency was 0.33 and 0.67 in the patients respectively, it was 0.29 and 0.71 in the control group. The frequencies of MTHFR 1298C and 1298A were 0.33 and 0.67 in the patients, and it was 0.31 and 0.69 in the control group respectively. When MTHFR 677TT and 677CT genotypes were compared with 677CC genotype, lung cancer risk was 2.4 times higher in the 677TT genotype. When MTHFR 1298AC and 1298CC genotypes were compared with 1298AA genotype, lung cancer risk was 1.5 times higher in 1298CC genotype. According to the results, allele frequency of homozygote T and C was high in lung cancer patients. It was 3.05 and 1.29 times higher in smokers than in non-smokers, and 3.05 and 1.64 times higher in males than in females; 3.0 and 2.44 times higher in those with non-small cell lung cancer than in those with small-cell lung cancer.

Methylenetetrahydrofolate reductase C677T polymorphism in patients with gastric and colorectal cancer in a Korean population

Background

This study was designed to investigate an association between the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and the risk of gastric and colorectal cancer in the Korean population.

Methods

We conducted a population-based large-scale case-control study involving 2,213 patients with newly diagnosed gastric cancer, 1,829 patients with newly diagnosed colorectal cancer, and 1,700 healthy controls. Genotyping was performed with peripheral blood DNA for MTHFR C677T polymorphisms. The statistical significance was estimated by logistic regression analysis.

Results

The MTHFR C677T frequencies of CC, CT, and TT genotypes were 35.2%, 47.5%, and 17.3% among stomach cancer, 34%, 50.5%, and 15.5% in colorectal cancer, and 31.8%, 50.7%, and 17.5% in the controls, respectively. The MTHFR 677TT genotype showed a weak opposite association with colorectal cancer compared to the homozygous CC genotype [adjusted age and sex odds ratio (OR) = 0.792, 95% confidence interval (CI) = 0.638-0.984, P = 0.035]. Subjects with the MTHFR 677CT showed a significantly reduced risk of gastric cancer compared whose with the 677CC genotype (age- and sex-adjusted OR = 0.810; 95% CI = 0.696-0.942, P = 0.006). We also observed no significant interactions between the MTHFR C677T polymorphism and smoking or drinking in the risk of gastric and colorectal cancer.

Conclusions

The T allele was found to provide a weak protective association with gastric cancer and colorectal cancer.

5-Methyltetrahydrofolate-homocysteine methyltransferase gene polymorphism (MTR) and risk of head and neck cancer

The functional effect of the A>G transition at position 2756 on the MTR gene (5-methyltetrahydrofolate-homocysteine methyltransferase), involved in folate metabolism, may be a risk factor for head and neck squamous cell carcinoma (HNSCC). The frequency of MTR A2756G (rs1805087) polymorphism was compared between HNSCC patients and individuals without history of neoplasias. The association of this polymorphism with clinical histopathological parameters was evaluated. A total of 705 individuals were included in the study. The polymerase chain reaction-restriction fragment length polymorphism technique was used to genotype the polymorphism. For statistical analysis, the chi-square test (univariate analysis) was used for comparisons between groups and multiple logistic regression (multivariate analysis) was used for interactions between the polymorphism and risk factors and clinical histopathological parameters. Using univariate analysis, the results did not show significant differences in allelic or genotypic distributions. Multivariable analysis showed that tobacco and alcohol consumption (P < 0.05), AG genotype (P = 0.019) and G allele (P = 0.028) may be predictors of the disease and a higher frequency of the G polymorphic allele was detected in men with HNSCC compared to male controls (P = 0.008). The analysis of polymorphism regarding clinical histopathological parameters did not show any association with the primary site, aggressiveness, lymph node involvement or extension of the tumor. In conclusion, our data provide evidence that supports an association between the polymorphism and the risk of HNSCC.

Chromosome 5p Region SNPs Are Associated with Risk of NSCLC among Women

In a population-based case-control study, we explored the associations between 42 polymorphisms in seven genes in this region and non-small cell lung cancer (NSCLC) risk among Caucasian (364 cases; 380 controls) and African American (95 cases; 103 controls) women. Two TERT region SNPs, rs2075786 and rs2853677, conferred an increased risk of developing NSCLC, especially among African American women, and TERT-rs2735940 was associated with a decreased risk of lung cancer among African Americans. Five of the 20 GHR polymorphisms and SEPP1-rs6413428 were associated with a marginally increased risk of NSCLC among Caucasians. Random forest analysis reinforced the importance of GHR among Caucasians and identified AMACR, TERT, and GHR among African Americans, which were also significant using gene-based risk scores. Smoking-SNP interactions were explored, and haplotypes in TERT and GHR associated with NSCLC risk were identified. The roles of TERT, GHR, AMACR and SEPP1 genes in lung carcinogenesis warrant further exploration.

International Lung Cancer Consortium: coordinated association study of 10 potential lung cancer susceptibility variants

BACKGROUND

Analysis of candidate genes in individual studies has had only limited success in identifying particular gene variants that are conclusively associated with lung cancer risk. In the International Lung Cancer Consortium (ILCCO), we conducted a coordinated genotyping study of 10 common variants selected because of their prior evidence of an association with lung cancer. These variants belonged to candidate genes from different cancer-related pathways including inflammation (IL1B), folate metabolism (MTHFR), regulatory function (AKAP9 and CAMKK1), cell adhesion (SEZL6) and apoptosis (FAS, FASL, TP53, TP53BP1 and BAT3).

METHODS

Genotype data from 15 ILCCO case-control studies were available for a total of 8431 lung cancer cases and 11 072 controls of European descent and Asian ethnic groups. Unconditional logistic regression was used to model the association between each variant and lung cancer risk.

RESULTS

Only the association between a non-synonymous variant of TP53BP1 (rs560191) and lung cancer risk was significant (OR = 0.91, P = 0.002). This association was more striking for squamous cell carcinoma (OR = 0.86, P = 6 x 10(-4)). No heterogeneity by center, ethnicity, smoking status, age group or sex was observed. In order to confirm this association, we included results for this variant from a set of independent studies (9966 cases/11,722 controls) and we reported similar results. When combining all these studies together, we reported an overall OR = 0.93 (0.89-0.97) (P = 0.001). This association was significant only for squamous cell carcinoma [OR = 0.89 (0.85-0.95), P = 1 x 10(-4)].

CONCLUSION

This study suggests that rs560191 is associated to lung cancer risk and further highlights the value of consortia in replicating or refuting published genetic associations.