Polymorphism in ADH and MTHFR genes in oral squamous cell carcinoma of Indians

Association between alcohol dehydrogenase polymorphisms (rs1229984, rs1573496, rs1154460, and rs284787) and susceptibility to head and neck cancers: A systematic review and meta-analysis

OBJECTIVE

Head and neck cancer (HNC) is a prevalent and complex group of malignancies with increasing incidence globally. Alcohol dehydrogenases (ADHs) play a crucial role in alcohol metabolism, and their polymorphisms have been linked to HNC risk. This systematic review and meta-analysis aims to evaluate the association between ADH polymorphisms and susceptibility to HNCs, incorporating additional analyses and adding more studies to increase power and accuracy of the results.

DESIGN

Subgroup analysis, meta-regression analysis, and sensitivity analyses were conducted to explore potential differences within the data and assess the stability of pooled odds ratios (ORs). To mitigate the risk of false conclusions from meta-analyses, a trial sequential analysis was performed.

RESULTS

For ADH1B rs1229984, the pooled OR (95 % confidence interval (CI)) was 0.73 (0.65, 0.82), 0.42 (0.35, 0.50), 0.57 (0.44, 0.73), 0.56 (0.50, 0.62), and 0.80 (0.73, 0.88), as well as for ADH7 rs1573496, the pooled OR was 0.72 (0.62, 0.85), 0.36 (0.17, 0.74), 0.76 (0.64, 0.91), 0.80 (0.71, 0.91), and 0.38 (0.18, 0.78) with a p < 0.05 in all allelic, homozygous, heterozygous, recessive, and dominant models, respectively. However, no significant association was found between the ADH7 rs1154460 and rs284787 polymorphisms and the risk of HNC with pooled ORs of 1.11 (p = 0.19) and 1.09 (p = 0.24) for the recessive model, respectively. The ethnicities, tumor subsites, control sources, sample sizes, quality scores, and Hardy-Weinberg equilibrium statuses were confounding factors.

CONCLUSION

The ADH1B rs1229984 and ADH7 rs1573496 polymorphisms are significantly associated with a reduced risk of HNC.

Association of ADH1B Arg47His polymorphism with the risk of cancer: a meta-analysis

Alcohol consumption has been established to be a major factor in the development and progress of cancer. Genetic polymorphisms of alcohol-metabolism genes result in differences between individuals in exposure to acetaldehyde, leading to possible carcinogenic effects. Arg47His (rs1229984 G > A) in ADH1B have been frequently studied for its potential effect on carcinogenesis. However, the findings are as yet inconclusive. To gain a more precise estimate of this potential association, we conducted a meta-analysis including 66 studies from 64 articles with 31999 cases and 50964 controls. The pooled results indicated that ADH1B Arg47His polymorphism is significantly associated with the decreased risk of overall cancer (homozygous model, odds ratio (OR) = 0.62, 95% confidence interval (CI) = 0.49–0.77; heterozygous model, OR = 0.71, 95% CI = 0.60–0.84; recessive model, OR = 0.83, 95% CI = 0.76–0.91; dominant model, OR = 0.62, 95% CI = 0.53–0.72; and allele comparison, OR = 0.82, 95% CI = 0.75–0.89). Stratified analysis by cancer type and ethnicity showed that a decreased risk was associated with esophageal cancer and head and neck cancer amongst Asians. In conclusion, our meta-analysis suggested that ADH1B Arg47His polymorphism was significantly associated with decreased overall cancer risk. These findings need further validation in large multicenter investigations.

The association between MTHFR gene polymorphisms (C677T, A1298C) and oral squamous cell carcinoma: A systematic review and meta-analysis

A consensus has not been reached regarding the association of MTHFR gene polymorphism and susceptibility to oral squamous cell carcinoma (OSCC). We performed a meta-analysis to better evaluate the association between MTHFR C677T, A1298C polymorphism and OSCC risk. The studies regarding the association of MTHFR C677T, A1298C polymorphisms and OSCC were identified in PubMed and EMBASE and Google Scholar. The pooled odd rates (ORs) with 95%CIs were estimated using a fixed-effect or random-effect model. The associations between MTHFR polymorphisms and OSCC risk were assessed under the dominant, recessive and additive models. A collective total of 1539 OSCC patients and 2131 normal controls were included across 13 studies. The minor T allele of MTHFR C677T was significantly associated with the increased risk of OSCC development(OR = 1.35, 95%CI 1.04-1.76). Individuals carrying the ''T" allele (TT+CT) had a nearly 43% increased risk for OSCC development when compared with CC (OR = 1.43, 95%CI 1.02-1.99). Under additive model, the results also showed that individuals with CT or TT genotype were more susceptible to OSCC than CC (OR = 1.45, 95%CI 1.02-2.08; OR = 1.79, 95%CI 1.28-2.50; respectively). The subgroup analysis by ethnicity revealed that significant difference in C677T allele distribution could be observed in European (OR = 1.33, 95%CI 1.02-1.75) rather than Asian (OR = 1.59, 95%CI 0.91-2.78). No significant association of MTHFR A1298C polymorphism and OSCC risk could be observed. The present study revealed that T allele and TT genotype of MTHFR C677T polymorphism were significantly associated with the increased risk of OSCC development.

Distinct prognostic values of alcohol dehydrogenase mRNA expression in pancreatic adenocarcinoma

Background

Alcohol dehydrogenase (ADH) isoenzymes have been reported as a potential diagnostic marker for pancreatic cancer, but their prognostic value in pancreatic cancer remains unclear. The aim of this investigation was to identify the prognostic value of ADH genes in human patients with pancreatic adenocarcinoma (PAAD).

Materials and methods

An RNA sequencing dataset and corresponding survival profiles of PAAD were obtained from The Cancer Genome Atlas. Survival analysis and gene set enrichment analysis were used to investigate the prediction value and potential mechanism of ADH genes in PAAD prognosis.

Results

Survival analysis of ADH genes suggests that a high expression of ADH1A (adjusted P=0.037, adjusted hazard ratio [HR] =0.627, 95% CI =0.404–0.972) and ADH6 (adjusted P=0.018, adjusted HR =0.588, 95% CI =0.378–0.914) were associated with a significantly decreased risk of death, while a high expression of ADH5 was associated with a significantly increased risk of death (adjusted P=0.043, adjusted HR =1.564, 95% CI =1.013–2.414). Joint effects analysis of three ADH gene prognostic markers suggests that the prognosis difference for any marker combination was more significant than that for any individual marker. The potential mechanism of ADH1A and ADH6 in PAAD prognosis was that a high expression of ADH1A and ADH6 was involved in the P450 pathway and biological processes, while high ADH5 expression was involved in transforming growth factor β regulation-related pathways and biological processes, Wnt, the cell cycle, ErbB, and mitogen-activated protein kinase signaling pathways.

Conclusion

Our data suggest that ADH1A, ADH5, and ADH6 expression may be potential prognostic markers of PAAD and in combination have a strong interaction and better predictive value for PAAD prognosis.

Association of MTHFR C677T and A1298C polymorphisms with oral cancer susceptibility: evidence from a meta-analysis

Methylenetetrahydrofolate reductase (MTHFR) is a central enzyme involved in folate metabolism and plays an important role in DNA synthesis and methylation. Several studies have been conducted to illustrate the associations between MTHFR C677T and A1298C polymorphisms with oral cancer susceptibility; however, the results are inconsistent. Therefore, we conducted an updated meta-analysis to obtain a more reliable estimation of the associations. We retrieved eligible studies from PubMed, EMBASE, and CBM databases through September 2016. Ultimately, pooled analyses involved 10 studies with 1443 cases and 1640 controls for the C677T polymorphism, as well as five studies with 973 cases and 1024 controls for the A1298C polymorphism. Risk estimates were presented as odds ratios (ORs) and 95% confidence intervals (95% CIs). Pooled results indicated that neither C677T nor A1298C polymorphism was associated with oral cancer susceptibility. However, a borderline significant association was detected between MTHFR C677T polymorphism and a decreased oral cancer risk (homozygous model: OR=0.71, 95% CI=0.50–1.00) in hospital-based studies. Our results suggested that MTHFR C677T and A1298C polymorphisms might not be associated with oral cancer risk. However, more evidence is needed to further confirm these findings in the future.

Retrospective case-control study of correlation between MTHFR gene and OSCC risk in North India

BACKGROUND

Oral squamous cell carcinoma (OSCC) occurrence appears to be the number one among all cancers in India. Folate is a methyl donor during DNA methylation, as it provides substrate for methylenetetrahydrofolate reductase (MTHFR) to convert 5,10-MTHF to 5-MTHF and subsequently metabolizes it to methionine. The purpose of this study was to identify MTHFR C677T gene polymorphism in patients with OSCC.

MATERIALS AND METHODS

A total of 350 OSCC cases and 350 healthy controls participated in this study. MTHFR C677T single-nucleotide polymorphism was evaluated by PCR-RFLP.

RESULTS

In the present study, MTHFR gene 677CC, CT, and TT genotype frequencies of the total OSCC cases were 74.8; 19.4 and 5.71; and 88.5, 9.42, and 2.0 % in controls. The average frequency of the MTHFR 677T allele was 15.4 % in OSCC cases compared to 6.71 % in the controls. The CT genotype occurrence prevailed more in patients than controls in contrast to TT genotype, although both the genotypes were statistically significant for OSCC. Moreover, we found that T allele was significant in cases of smoking and tobacco chewing.

CONCLUSIONS

In this study, we found that the homozygous mutant T allele appeared to have significantly higher risk of OSCC especially in late stages and therefore supporting in OSCC susceptibility and its progression.

Association of vdr, cyp27b1, cyp24a1 and mthfr gene polymorphisms with oral lichen planus risk

OBJECTIVES

The current study investigated the association between VDR EcoRV (rs4516035), FokI (rs2228570), ApaI (rs7975232) and TaqI (rs731236), CYP27B1 (rs4646536), CYP24A1 (rs2296241), and MTHFR (rs1801133) gene polymorphisms and risk of oral lichen planus (OLP) occurrence.

MATERIALS AND METHODS

The study group consisted of 65 oral lichen planus patients and 100 healthy blood donors in the control group. Single nucleotide polymorphisms were genotyped by real time PCR or PCR-restriction fragment length polymorphism (RFLP) method.

RESULTS

Heterozygous as well as mutated genotype of vitamin D receptor (VDR) FokI (rs2228570) polymorphism was associated with increased oral lichen planus risk in comparison with wild type genotype (odds ratio (OR) = 3.877, p = 0.017, OR = 38.153, p = 0.001, respectively). A significantly decreased OLP risk was observed for heterozygous genotype of rs2296241 polymorphism in CYP24A1 gene compared with the wild type form (OR = 0.314, p = 0.012). VDR gene polymorphisms ApaI and TaqI were in linkage disequilibrium (D' = 0.71, r(2) = 0.22). Identified haplotype AT was associated with decreased OLP risk (OR = 0.592, p = 0.047).

CONCLUSION

Our results highlight the possible important role of VDR FokI (rs2228570) and CYP24A1 rs2296241 gene polymorphisms for oral lichen planus susceptibility.

CLINICAL RELEVANCE

Identification of new molecular biomarkers could potentially contribute to determination of individuals with OLP predisposition.

Methylenetetrahydrofolate reductase C677T and A1298C gene polymorphisms in oral squamous cell carcinoma in south-east Iran

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) gene encodes an essential enzyme involving in folate metabolism. Due to the role of folate in DNA integrity, polymorphisms of MTHFR are interesting targets for cancer risk studies. Our goal was to evaluate the prevalence of MTHFR C677T and A1298T single nucleotide polymorphisms in oral squamous cell carcinoma (OSCC).

METHODS

The study was conducted on 57 OSCC patients diagnosed within 2004-2013 along with 62 non-OSCC subjects. DNA was extracted by standard kit protocol. Subsequently, tetra-ARMS (amplification refractory mutation system)-PCR was applied to identify the selected polymorphisms.

RESULTS

Data showed that CT and TT genotypes of C677T polymorphisms significantly increased the risk of OSCC [odds ratio (OR) = 2.2, 95% CI: 1-5, P = 0.04]. Although allelic distribution was not significantly different between patients and controls, T allele of C677T polymorphism was closely associated with the risk of OSCC (OR = 2.5; 95% CI: 0.9-6.9; P = 0.07). Results indicated that C677T/A1298C: CC/AC and C677T/A1298C: CC/AA haplotypes were the most common combinations in OSCC patient and control groups, respectively. (OR = 1.5, 95% CI: 0.6-3.8, P > 0.05).

CONCLUSION

Our results highlight the possible impact of C677T polymorphism in increasing the risk of OSCC development.

MTHFR C677T polymorphism interaction with heavy alcohol consumption increases head and neck carcinoma risk

MTHFR C677T polymorphism has been indicated to be a risk factor for cancers, but its association with head and neck cancer (HNC) risk remains inconclusive. In the present study, we aimed to get a more precise estimation by performing a quantitative meta-analysis. Published papers up to Jun 2014 was searched and screened. Necessary information was rigorously extracted for data pooling and analyzing, and then, subgroup analyses on ethnicity, source of controls, sample size, tumor type, smoking and drinking status were also carried out. As a result, twenty-three case-control studies including 14298 subjects were included. The overall data failed to reveal a significant association between MTHFR C677T polymorphism and HNC risk (homozygote comparison model: OR = 1.16; 95%CI = 0.93-1.45; dominant model: OR = 1.05; 95%CI = 0.90-1.21; recessive model: OR = 1.14; 95%CI = 0.93-1.38). However, in the subgroup analysis about drinking status, increase risk was shown in the heavy drinking subgroup (TT vs CC: OR = 3.11; 95%CI = 1.52-3.02). In conclusion, the results of the present study suggest that Homozygous TT alleles of MTHFR C677T polymorphism might be a risk factor for HNC among individuals who have a heavy drinking history. Further studies are needed to get a more definitive conclusion.

MTHFR C677T gene polymorphism and head and neck cancer risk: a meta-analysis based on 23 publications

OBJECTIVE

Conflicting results on the association between MTHFR polymorphism and head and neck cancer (HNC) risk were reported. We therefore performed a meta-analysis to derive a more precise relationship between MTHFR C677T polymorphism and HNC risk.

METHODS

Three online databases of PubMed, Embase, and CNKI were researched on the associations between MTHFR C677T polymorphism and HNC risk. Twenty-three published case-control studies involving 4,955 cases and 8,805 controls were collected. Odds ratios (ORs) with 95% confidence interval (CI) were used to evaluate the relationship between MTHFR C677T polymorphism and HNC risk. Sensitivity analysis, cumulative analyses, and publication bias were conducted to validate the strength of the results.

RESULTS

Overall, no significant association between MTHFR C677T polymorphism and HNC risk was found in this meta-analysis (T versus C: OR = 1.04, 95% CI = 0.92-1.18; TT versus CC: OR = 1.15, 95% CI = 0.90-1.46; CT versus CC: OR = 1.00, 95% CI = 0.85-1.17; CT + TT versus CC: OR = 1.01, 95% CI = 0.87-1.18; TT versus CC + CT: OR = 1.11, 95% CI = 0.98-1.26). In the subgroup analysis by HWE, ethnicity, study design, cancer location, and negative significant associations were detected in almost all genetic models, except for few significant risks that were found in thyroid cancer.

CONCLUSION

This meta-analysis demonstrates that MTHFR C677T polymorphism may not be a risk factor for the developing of HNC.

Tyms double (2R) and triple repeat (3R) confers risk for human oral squamous cell carcinoma

The oral cancer is responsible for approximately 3 % of cases of cancer in Brazil. Epidemiological studies have associated low folate intake with an increased risk of epithelial cancers, including oral cancer. Folic acid has a key role in DNA synthesis, repair, methylation and this is the basis of explanations for a putative role for folic acid in cancer prevention. The role of folic acid in carcinogenesis may be modulated by polymorphism C677T in MTHFR and tandem repeats 2R/3R in the promoter site of TYMS gene that are related to decreased enzymatic activity and quantity and availability of the enzyme, respectively. These events cause a decrease in the synthesis, repair and DNA methylation, which can lead to a disruption in the expression of tumor suppressor genes as TP53. The objective of this study was investigate the distribution of polymorphisms C677T and tandem repeats 2R/3R associated with the development of oral squamous cell carcinoma (OSCC). 53 paraffin-embedded samples from patients who underwent surgery but are no longer at the institution and 43 samples collected by method of oral exfoliation by cytobrush were selected. 132 healthy subjects were selected by specialists at the dental clinics of the Faculdade de Odontologia de Pernambuco-FOP. The MTHFR genotyping was performed by PCR-RFLP, and the TYMS genotyping was performed by conventional PCR. Fisher's Exact test at significant level of 5 %. Odds ratios (ORs) and 95 % confidence intervals (CIs) were used to measure the strength of association between genotype frequency and OSCC development. The results were statistically significant for the tandem repeats of the TYMS gene (p = 0.015). The TYMS 2R3R genotype was significantly associated with the development of OSCC (OR = 3.582; 95 % CI 1.240-10.348; p = 0.0262) and also the genotype 3R3R (OR = 3.553; 95 % CI 1.293-9.760; p = 0.0345). When analyzed together, the TYMS 2R3R + 3R3R genotypes also showed association (OR = 3.518; 95 % CI 11.188-10.348; p = 0.0177). No differences for the MTHFR C677T polymorphisms distribution were found between the oral cancer patients and controls subjects in our study (p = 0.499). Therefore, these data suggest that determination of TYMS tandem repeats could provide information on the comprehension of the risk factors and prevention of the OSCC.

Alcohol dehydrogenase-1B Arg47His polymorphism is associated with head and neck cancer risk in Asian: a meta-analysis

Head and neck cancers (HNCs) include cancers which arise in oral cavity, pharynx, and larynx. Recent studies have demonstrated that alcohol drinking is an established risk factor for HNC. The alcohol dehydrogenase-1B (ADH1B) plays a major role in the oxidized process of alcohol. To investigate the association of ADH1B Arg47His with HNC in Asian populations, we combined all available studies into a meta-analysis. A total of 2186 cases and 4488 controls were analyzed for this meta-analysis. We used odds ratios (ORs) to assess the strength of the association and 95% confidence intervals (CIs) to give a sense of the precision of the estimate. The ADH1B*47Arg allele was found to be associated with increased risk of HNC in Asians, with the pooled odds ratios (ORs) (Arg/Arg vs. Arg/His + His/His: OR = 2.35, 95% CI = 1.56-3.55, P < 0.0001) in all eight studies. In the subgroup analysis by alcohol consumption, the Arg/Arg vs. Arg/His + His/His genotype was found to be interacted with alcohol consumption, with the OR = 2.44, 95% CI = 1.85-3.20 among ever drinkers. Besides, no significant association was found in non-drinkers. This meta-analysis revealed that ADH1B Arg47His (rs1229984) polymorphism could increase the risk of HNC in Asians significantly.

Genetic variants in nicotine addiction and alcohol metabolism genes, oral cancer risk and the propensity to smoke and drink alcohol: a replication study in India

BACKGROUND

Genetic variants in nicotinic acetylcholine receptor and alcohol metabolism genes have been associated with propensity to smoke tobacco and drink alcohol, respectively, and also implicated in genetic susceptibility to head and neck cancer. In addition to smoking and alcohol, tobacco chewing is an important oral cancer risk factor in India. It is not known if these genetic variants influence propensity or oral cancer susceptibility in the context of this distinct etiology.

METHODS

We examined 639 oral and pharyngeal cancer cases and 791 controls from two case-control studies conducted in India. We investigated six variants known to influence nicotine addiction or alcohol metabolism, including rs16969968 (CHRNA5), rs578776 (CHRNA3), rs1229984 (ADH1B), rs698 (ADH1C), rs1573496 (ADH7), and rs4767364 (ALDH2).

RESULTS

The CHRN variants were associated with the number of chewing events per day, including in those who chewed tobacco but never smoked (P =  0.003, P =  0.01 for rs16969968 and rs578776 respectively). Presence of the variant allele contributed to approximately 13% difference in chewing frequency compared to non-carriers. While no association was observed between rs16969968 and oral cancer risk (OR =  1.01, 95% CI =  0.83- 1.22), rs578776 was modestly associated with a 16% decreased risk of oral cancer (OR =  0.84, 95% CI =  0.72- 0.98). There was little evidence for association between polymorphisms in genes encoding alcohol metabolism and oral cancer in this population.

CONCLUSION

The association between rs16969968 and number of chewing events implies that the effect on smoking propensity conferred by this gene variant extends to the use of smokeless tobacco.

Genetic variants at 4q21, 4q23 and 12q24 are associated with esophageal squamous cell carcinoma risk in a Chinese population

A recently published genome-wide association study (GWAS) in European populations identified several loci at 4q21, 4q23 and 12q24 that were associated with risk of upper aerodigestive tract (UADT) cancers, including esophageal squamous cell carcinoma (ESCC). In the current study, we conducted a case-control study in a Chinese population including 2,139 ESCC cases and 2,273 controls to evaluate the associations of six reported single nucleotide polymorphisms (SNPs) (rs1494961, rs1229984, rs1789924, rs971074, rs671 and rs4767364) with risk of ESCC. We found significant association with risk of ESCC for four SNPs, including rs1494961 in HEL308 at 4q21 [odds ratio (OR) = 1.15, 95 % confidence interval (CI) = 1.05-1.26], rs1229984 in ADH1B at 4q23 (OR = 1.24, 95 % CI = 1.13-1.36) and rs1789924 near ADH1C at 4q23 (OR = 1.20, 95 % CI = 1.03-1.39), and rs671 in ALDH2 at 12q24 (OR = 0.83, 95 % CI = 0.75-0.91). Combined analysis of these four SNPs showed a significant allele-dosage effect on ESCC risk for individuals with different number of risk alleles (P trend = 2.23 × 10(-11)). Compared with individuals with "0-2" risk allele, those carrying "3", "4" or "5 or more" risk alleles had 1.42-, 1.66-, or 1.76-fold risk of ESCC, respectively. Thus, our findings indicate that rs1494961 at 4q21, rs1229984 and rs1789924 at 4q23, and rs671 at 12q24 may be used as genetic biomarkers for ESCC susceptibility in Chinese population.

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.

Current aspects on oral squamous cell carcinoma

Oral squamous cell carcinoma is the most common malignant epithelial neoplasm affecting the oral cavity. This article overviews the essential points of oral squamous cell carcinoma, highlighting its risk and genomic factors, the potential malignant disorders and the therapeutic approaches. It also emphasizes the importance of the early diagnosis.

ADH1C Ile350Val polymorphism and cancer risk: evidence from 35 case-control studies

BACKGROUND

Alcohol dehydrogenase 1C (ADH1C) is the key enzyme catalyze oxidation of alcohol to acetaldehyde, which plays vital roles in the etiology of various cancer. To date, studies investigated the association between a functional polymorphism in ADH1C, Ile350Val (rs698), and risk of cancer have shown inclusive results.

METHODS

A meta-analysis based on 35 case-control studies was performed to address this issue. Odds ratios (OR) with 95% confidence intervals (CIs) were used to assess the association. The statistical heterogeneity across studies was examined with χ2-based Q-test.

RESULTS

Overall, no significant associations between ADH1C Ile350Val polymorphism and cancer risk were observed in any genetic models (P>0.05). In the stratified analyses, there was a significantly increased cancer risk among African (Val/Val vs. Ile/Ile OR  =  2.19, 95% CI  =  1.29-3.73, P(heterogeneity)  =  0.989; Ile/Val + Val/Val vs. Ile/Ile: OR  =  1.79, 95%CI  =  1.18-2.71, P(heterogeneity)  =  0.761; Val/Val vs. Ile/Val + Ile/Ile: OR  =  1.92, 95% CI  =  1.16-3.17, P(heterogeneity)  =  0.981) and Asian (Ile/Val vs. Ile/Ile: OR  =  1.58, 95% CI  =  1.32-1.90, P(heterogeneity)  =  0.375; Val/Val vs. Ile/Ile: OR  =  3.84, 95% CI  =  1.74-8.49, P(heterogeneity)  =  0.160; Ile/Val + Val/Val vs. Ile/Ile: OR  =  1.65, 95% CI  =  1.38-1.96, P(heterogeneity)  =  0.330; Val/Val vs. Ile/Val + Ile/Ile: OR  =  3.54, 95% CI  =  1.62-7.75, P(heterogeneity)  =  0.154) studies.

CONCLUSIONS

The results indicate that ADH1C Ile350Val polymorphism may contribute to cancer risk among Africans and Asians. Additional comprehensive system analyses are required to validate this association combined with other related polymorphisms.

Association between 11 genetic polymorphisms in folate-metabolising genes and head and neck cancer risk

Genetic polymorphisms in folate metabolism may affect the risk of head and neck cancer (HNSCC) due to its involvement in DNA methylation and synthesis. We conducted a case-control study (265 HNSCC cases and 466 non-cancer controls) to investigate associations of MTHFR C677T and A1298C, MTR A2756G, MTRR A66G, RFC1 A80G, MTHFD1 G1958A, CBS 844ins68, TC2 C776G and A67G, SHMT C1420T and BHMT G742A polymorphisms with HNSCC risk. Interactions between polymorphisms and survival time, tobacco and alcohol habits, age, gender and tumour staging (TNM classification) were evaluated by multiple logistic regression analysis. We found that age ≥ 49 years (P<0.001), male gender (P=0.03), tobacco habit (P<0.001), MTHFR 1298AC/CC (P=0.028), MTR 2756AG/GG (P=0.010) and RFC1 80AG/GG (P=0.015) genotypes were associated with an increased risk of HNSCC. There were interactions between lower survival and CBS 844ins68 (P=0.005); age ≥ 49 years and MTR 2756 AG/GG (P=0.004) and RFC1 80AG/GG (P=0.006) genotypes; male gender and MTHFR 1298 AC/CC (P=0.030), MTR 2756 AG/GG (P=0.006) and RFC1 80 AG/GG (P=0.009); tobacco non-habit and MTHFD1 1958GA/AA (P=0.040); tobacco and MTHFR 1298 AC/CC (P=0.054) and MTR 2756 AG/GG (P=0.010); alcohol non-consume and RFC1 80 AG/GG (P=0.008) with HNSCC increased risk. MTHFR C677CT/TT genotypes were less frequently in advanced tumours (P=0.04). In conclusion, our data provide evidence that folate metabolism genetic polymorphisms associated with variables as advanced age, male gender, tobacco and alcohol increase HNSCC development; CBS 844ins68 and MTHFR C677T polymorphisms are associated with less survival time and advanced stage tumours, respectively.

The role of alcohol dehydrogenase genes in head and neck cancers: a systematic review and meta-analysis of ADH1B and ADH1C

Alcohol drinking is a major risk factor for head and neck cancer (HNC). This risk may be modified by alcohol dehydrogenase (ADH) genes, particularly ADH1B and ADH1C, that oxidise ethanol to its carcinogenic metabolite, acetaldehyde. A meta-analysis was conducted to assess the association between ADH1B and ADH1C and HNC risk. Twenty-nine studies from 28 articles identified from a literature search were included. Summary odds ratios (meta-ORs) were generated using random effect models. A reduced risk for HNC was associated with carrying the ADH1B*2 and ADH1C*1 alleles that confer faster metabolism of ethanol to acetaldehyde [meta-OR ADH1B, 0.50; 95% confidence interval (CI): 0.37-0.68, 13 studies; meta-OR ADH1C, 0.87; 95% CI: 0.76-0.99, 22 studies]. ADH1B*2 and ADH1C*1 alleles appear to be protective for HNC, possibly due to: (i) decreasing the opportunity for oral microflora to produce acetaldehyde locally from a prolonged systemic circulation of ethanol, (ii) preventing ethanol from acting as a solvent for other carcinogens, and (iii) decreasing the amount of ethanol a person consumes since a consequent peak in systemic acetaldehyde could cause discomfort. These results underscore the importance of ADH1B and ADH1C in the association between alcohol consumption and the risk for HNC.

Alcohol dehydrogenase-1B Arg47His polymorphism and upper aerodigestive tract cancer risk: a meta-analysis including 24,252 subjects

BACKGROUND

Cancers of the upper aerodigestive tract (UADT) include malignant tumors of the oral cavity, pharynx, larynx, and esophagus, account for approximately 4% of all new cancers in world. Alcohol drinking is an established risk factor for UADT cancers, and the rate of alcohol metabolism could significantly been influenced by genetic polymorphisms of alcohol dehydrogenase-1B (ADH1B) His47Arg (rs1229984). To evaluate whether combined evidence shows ADH1B His47Arg as a common genetic variant that influenced the risk of UADT cancers, we considered all available studies in a meta-analysis.

METHODS

Eighteen studies were combined representing data of 8,539 cases and 15,713 controls for meta-analysis. Stratified analyses were carried out to determine the gene-environment interaction between ADH1B His47Arg and alcohol drinking and gene-gene interaction between ADH1B His47Arg and aldehyde dehydrogenase-2 (ALDH2) Glu/Lys related to UADT cancer risk. Potential sources of heterogeneity between studies were explored; sensitivity analysis and publication bias was also evaluated.

RESULTS

The ADH1B 47Arg allele was found to be associated with increased risk of UADT cancers, the pooled odds ratios (ORs) being 1.66 (95% CI: 1.54 to 1.79) and 3.47 (95% CI: 2.76 to 4.36) for the His/Arg and Arg/Arg genotypes compared with the His/His genotype, respectively. An 18.48-fold increase in OR (95% CI: 12.95 to 26.40) for UADT cancers among alcohol drinkers with Arg/Arg genotype was found, when compared among nondrinkers with the His/His genotype. Significant interaction between carriers with ADH1B 47Arg and ALDH2 487Lys allele related to risk for UADT cancers was more evident, compared with noncarriers (OR = 10.31, 95% CI: 5.45 to 18.85).

CONCLUSIONS

ADH1B 47Arg allele is a common genetic variant that increased the risk of UADT cancers; furthermore, it modulates the susceptibility to UADT cancers coupled with alcohol drinking and interaction with the ALDH2 487Lys allele.

Genetic polymorphisms of ADH1C and CYP2E1 and risk of oral squamous cell carcinoma

OBJECTIVE

Several studies have suggested that the metabolism of alcohol is modulated by the polymorphisms in genes encoding ethanol-metabolizing enzymes, including alcohol dehydrogenase 1C, ADH1C, and cytochrome P450-dependent monooxygenase, CYP2E1. Genetic polymorphisms of ethanol-metabolizing enzymes may affect individual susceptibility to oral cancer. The purpose of this study was to investigate the associations between ADH1C and CYP2E1 gene polymorphisms with oral squamous cell carcinoma in an ethnically homogeneous Caucasian population.

DESIGN

Case-control study.

SETTING

Serbian national general hospital.

SUBJECTS AND METHODS

The study was conducted on 123 oral cancer patients and a control group of 177 individuals of the Caucasian race and the same ethnicity, matched in age and gender, without previous cancer history. The control group consisted of 120 population-based and 57 hospital-based controls of heavy-drinking individuals. Genetic polymorphisms of ADH1C SspI, ADH1C HaeIII, CYP2E1 RsaI, and CYP2E1 Ins were determined by the polymerase chain reaction and restriction fragment length polymorphisms.

RESULTS

After adjustment by potential confounders, the significant increase of oral cancer risk, independent of alcohol drinking, was observed in individuals with the variant ADH1C SspI*2/*2 genotype (odds ratio, 3.029; P = .014) and in combined ADH1C SspI*1/*2 and ADH1C SspI*2/*2 genotypes (odds ratio, 2.605; P = .002), compared to the ADH1C*1/1* wild type. The association of other polymorphisms under study was not observed.

CONCLUSION

This study suggested that the ADH1C SspI polymorphism could play a significant role in the etiology of oral cancer, whereas ADH1C HaeIII, CYP2E1 RsaI, and CYP2E1 Ins could have minor influence.

Polymorphisms and haplotypes in methylenetetrahydrofolate reductase gene and head and neck squamous cell carcinoma risk

Functional polymorphisms in genes encoding enzymes involved in folate metabolism might modulate head and neck carcinoma risk because folate participates in DNA methylation and synthesis. We therefore conducted a case-control study of 853 individuals (322 head and neck cancer cases and 531 non-cancer controls) to investigate associations among MTHFR C677T and MTHFR A1298C polymorphisms and head and neck squamous cell carcinoma risk. Interactions between these two polymorphisms and risk factors and clinical histopathological parameters were also evaluated. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to genotype the polymorphisms and Chi-square test and multiple logistic regression were used for statistical analyses. The variables age≥49 years, male gender, tobacco habits and alcohol consumption, MTHFR 1298 AC or CC genotypes, combined genotypes with two or more polymorphic alleles and 677T and 1298C polymorphic alleles were associated with increased risk for this disease (P<0.05). Furthermore, we found that 1298 AC or CC genotypes were associated with age≥49 years, tobacco and alcohol habits (P<0.05). Regarding clinical histopathological parameters, the A1298C polymorphism was more frequent in patients with oral cavity as primary site (P<0.05). MTHFR polymorphisms may contribute for increase risk for head and neck carcinoma and the variables age≥49 years, male gender, tobacco and alcohol habits were associated with MTHFR 1298AC or CC genotypes, confirming that individuals with these variables and MTHFR A1298C polymorphism has higher risk for this disease.

Hyperhomocysteinemia, methylenetetrahydrofolate reductase c.677C>T polymorphism and risk of cancer: cross-sectional and prospective studies and meta-analyses of 75,000 cases and 93,000 controls

Global DNA hypomethylation associates with development of cancer. DNA hypomethylation also associates with hyperhomocysteinemia and MTHFR c.677C>T homozygosity, both of which may associate with increased risk of cancer. We tested the putative association of hyperhomocysteinemia with cancer and the association of the MTHFR c.677TC>T variant with hyperhomocysteinemia and with cancer. We performed a cross-sectional study of 5,949 Danish general population adults, a prospective study of 9,235 Danish general population adults with up to 60 years of registry surveillance, and meta-analyses of 231 studies including 74,671 cases and 93,344 controls. Cross-sectionally, plasma homocysteine levels were 12.9 and 11.6 μmol/L in those with and without cancer (p < 0.0001). However, homocysteine levels increased with age and age-adjusted odds ratio for any cancer in those with homocysteine levels >12.4 versus < 9.4 μmol/L did not differ from 1.0. In cancer-free participants, plasma homocysteine levels were 14.7 and 11.7 μmol/L in MTHFR c.677C>T homozygtes and noncarriers (p < 0.0001). Prospectively, hazard ratios for any cancer and for cancer subtypes in MTHFR c.677C>T homozygotes versus noncarriers did not differ from 1.0. However, in meta-analyses odds ratio for MTHFR c.677C>T homozygotes versus noncarriers were 1.07 (95% CI: 1.01-1.12) for any cancer, 1.77 (1.17-2.68) for esophagus cancer, 1.40 (1.19-1.66) for gastric cancer and 0.85 (0.77-0.94) for colorectal cancer. Increased plasma homocysteine levels are not associated with an increased age-adjusted risk of any cancer. However, MTHFR c.677C>T homozygosity with lifelong hyperhomocysteinemia and hence hypomethylation associate with increased risk of esophagus and gastric cancer, and with decreased risk of colorectal cancer.

Interaction between the MTHFR C677T Polymorphism and Alcohol—Impact on Oral Cancer Risk and Multiple DNA Methylation of Tumor-related Genes

Several studies have reported Oral Squamous Cell Carcinoma ( OSCC) association with etiological factors, such as smoking and alcohol. The aim of the present study was to establish whether the methylenetetrahydrofolate reductase ( MTHFR) C677T genotype and a high alcohol intake, solely or in interaction, have an impact on the oral cancer risk, DNA methylation, or multiple methylation of tumor-related genes. MTHFR C677T genetic polymorphism was determined by the PCR/RFLP method, and DNA methylation was assessed by nested methylation-specific PCR. The risk for multiple methylation was significantly increased in heavy-drinking patients with the TT genotype, compared with CC and CT patients (OR = 10.873; 95% CI, 1.134-104.24). Multiple methylation was significantly associated with tumor stage ( p = 0.018), and showed a trend of association with the presence of nodal metastases ( p = 0.058). A significant association was found between TT genotype and methylation status of the RASSF1A gene in OSCC patients ( p = 0.012). Heavy-drinking individuals with the TT genotype showed increased oral cancer risk compared with the CC genotype (OR = 3.601; 95% CI, 1.036-12.513), and compared with the CC and CT genotypes (OR = 4.288; 95% CI, 1.325-13.877). Our study suggested gene-environment interactions between high alcohol intake and the MTHFR 677TT genotype for elevated oral cancer risk, with a significant impact on multiple methylation of cancer-related genes.

The association between CBS 844ins68 polymorphism and head and neck squamous cell carcinoma risk - a case-control analysis

INTRODUCTION

Susceptibility to head and neck squamous cell carcinoma may be modified by functional polymorphisms in genes involved in the folate pathway, such as cystathionine beta-synthase (CBS). The CBS 844ins68 polymorphism is associated with DNA methylation changes and cancer development.

MATERIAL AND METHODS

A case-control retrospective study was conducted in 322 patients with head and neck squamous cell carcinoma and in 531 control subjects without cancer. The polymerase chain reaction-restriction fragment length polymorphism technique was used to genotype the polymorphism. For statistical analysis, χ(2) test was conducted to examine whether the genotypic frequency of CBS 844ins68 was in Hardy-Weinberg equilibrium and multiple logistic regression was used for comparisons between groups, and for interactions between the polymorphism and risk factors and clinical histopathological parameters.

RESULTS

No significant difference in CBS 844ins68 genotypic distribution was observed between the groups. Age > 50 years, male gender and tobacco consumption were predictors of the disease with increased risk of 7.89 (95% CI: 5.56-11.21), 2.49 (95% CI: 1.72-3.62), 6.44 (95% CI: 4.63-8.96) and 2.29 times (95% CI: 1.71-3.06) respectively. There was no association between the distribution of the CBS 844ins68 genotype and risk factors for this disease. According to clinical histopathological parameters, CBS 884ins68 polymorphism presented high frequency in oral cavity (p < 0.05) and patients with the polymorphism presented less survival time (p < 0.05).

CONCLUSIONS

We concluded that the CBS 844ins68 polymorphism is not associated with HNSCC risk and there is increased risk of this disease in male gender individuals smokers aged over 50 years. In adittion, the polymorphism is more frequent in patients with oral cavity as primary site and in patients with less survival time.

CYP2A13, ADH1B, and ADH1C gene polymorphisms and pancreatic cancer risk

OBJECTIVES

Pancreatic carcinoma etiology and molecular pathogenesis are weakly understood. Based on the assumption that genetic variation in carcinogen metabolism further modifies the risk of exposure-related cancers, we studied the association of polymorphisms in the tobacco carcinogen-metabolizing gene CYP2A13 (Arg101Stop) and the alcohol-metabolizing genes ADH1B (Arg48His) and ADH1C (Ile350Val) with pancreatic cancer risk.

METHODS

Polymorphisms were studied by allelic discrimination.

RESULTS

In a hospital-based case-control study, CYP2A13 variant alleles coding an inactive enzyme were found in 7 of 265 cancer-free controls and in none of 235 pancreatic carcinoma patients. Neither ADH1B or ADH1C polymorphisms alone nor their combinations showed a significant effect on pancreatic cancer risk.

CONCLUSIONS

The first study of the roles of CYP2A13, ADH1B, and ADH1C in pancreatic cancer etiology suggested that the controls may have a lower ability to bioactivate tobacco-derived procarcinogens than the cases.

Impact of multiple alcohol dehydrogenase gene polymorphisms on risk of upper aerodigestive tract cancers in a Japanese population

Alcohol intake is positively associated with the risk of upper aerodigestive tract (UAT) cancer. The genes that encode alcohol-metabolizing enzymes, primarily alcohol dehydrogenases (ADH) and aldehyde dehydrogenases (ALDH), are polymorphic. In Caucasians, significant associations between polymorphisms in ADH1B (rs1229984) and ADH1C (rs698 and rs1693482), and UAT cancer have been observed, despite strong linkage disequilibrium among them. Moreover, UAT cancer was significantly associated with rs1573496 in ADH7, and not with rs1984362 in ADH4. However, little evidence is available concerning ADH4 or ADH7 polymorphisms in Asian populations. We conducted a matched case-control study to clarify the role of ADH polymorphisms in a Japanese population. Cases and controls were 585 patients with UAT cancer and 1,170 noncancer outpatients. Genotyping for ADHs and ALDH2 was done using TaqMan assays. Associations between polymorphisms and UAT cancer were assessed by odds ratios and 95% confidence intervals using conditional logistic regression models that adjusted for age, sex, smoking, drinking, and ALDH2. Adjusted odds ratios were significant for rs4148887 and rs3805322 in ADH4, rs1229984 in ADH1B, rs698 and rs1693482 in ADH1C, and rs284787, rs1154460, and rs3737482 in ADH7. We also observed that ADH7 rs3737482 and ADH4 rs4148887 had independently and statistically significant effects on UAT cancer. The magnitude of effect of these ADH polymorphisms was greater in subjects who were heavy drinkers, heavy smokers, and had esophageal cancer. These findings show that multiple ADH gene polymorphisms were associated with UAT cancer in this Japanese population. Further studies in various ethnicities are required.