ADH1B and ALDH2 polymorphisms and their associations with increased risk of squamous cell carcinoma of the head and neck in the Korean population

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.

Possible role of ALDH1 and CD44 in lip carcinogenesis

BACKGROUND

Lip squamous cell carcinoma (LSCC) accounts for 12% of all head and neck cancers. It is caused by chronic exposure to ultraviolet light solar radiation and related to previous actinic cheilitis (AC). This study aimed to investigate the immunostaining of the putative cancer stem cells (CSC) markers ALDH1 and CD44 in AC (n=30) and LSCC (n=20). ALDH1 positivity was found to be statistically higher in LSCC than in AC lesions (p=0.0045), whilst CD44 expression was statistically higher in AC than in LSCC lesions (p=0.0155). ALDH1+ cells in AC lesions were associated with specific clinical features: a younger age (<60 years old), the female gender, white skin, not smoking or consuming alcohol, and a fast evolution, and not associated with the chronic exposure to UV radiation (p<0.0001). CD44 positivity was associated with patients who were male, feoderm, smoked, consumed alcohol, underwent occupational exposure to UV-radiation, and demonstrated lesions with log-time evolution (p<0.0001). ALDH1 + cells were associated with mild dysplasia using a system from the World Health Organization (WHO), and with a low risk of malignant transformation, according to the binary system (p<0.0001). CD44+ cells were also associated with moderated dysplasia, according to the WHO system. In LSCC, ALDH1 + cells were positively associated with patients who were older (≥ 60 years old), smokers, and with those who consumed alcohol (p<0.0001). CD44 + cells in LSCC were associated with older (≥ 60 years old) patients as well, but also with female patients, white skin, non-smokers, and individuals who did not consume alcohol (p<0.0001), all of whom showed distinct patterns in pre- and malignant lesions of both markers. Additionally, in LSCC, both ALDH1 and CD44 staining were associated with smaller tumor sizes (T1/T2; p<0.0001). In summary, although both ALDH1 and CD44 were associated with the presence of dysplasia in AC lesions, the present findings suggest that ALDH1 and CD44 may be activated by different etiopathogenic pathways, predominantly in distinct steps of oral carcinogenesis. CD44 would thus be more significantly related to the potentially malignant lesion, while ALDH1 would be closely linked to malignancy.

Impact of Alcohol Dehydrogenase 7 Polymorphism and Alcohol Consumption on Risk of Head and Neck Squamous Cell Carcinoma: A Korean Case-Control Study

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is closely associated with alcohol consumption and individual genetic susceptibility, such as single nucleotide polymorphism (SNP) of alcohol dehydrogenase (ADH). This study aimed to investigate the association of ADH7 SNPs with the risk of HNSCC.

METHODS

We analyzed ADH7 rs1573496C>G, rs3737482T>C, rs1154460G>A, and rs284787T>C SNPs in 250 patients with HNSCC and 322 controls in the Korean populations. Genotyping was conducted using the TaqMan assay. Linkage disequilibrium and haplotypes were analyzed.

RESULTS

The odds ratios (OR) and 95% confidence intervals (CI) of the CT and CC genotypes of ADH7 rs3737482T>C were 0.48 (0.29-0.78) and 0.69 (0.49-0.96), indicating a significantly decreased risk. In SNP of rs1154460G>A, the OR and 95% CI of the AA genotype was 1.63 (1.11-2.40), showing a significant increase in the risk. Furthermore, SNPs of ADH7 rs3737482T>C and ADH7 rs1154460G>A exhibit synergistic interactions with alcohol composition on the risk of HNSCC. None of the haplotypes were associated with the risk of HNSCC.

CONCLUSIONS

ADH7 rs3737482T>C and rs1154460G>A SNPs are associated with the risk of development of HNSCC in Koreans. They could serve as molecular biological markers to screen high-risk groups for HNSCC.

Study protocol of brief intervention using gene polymorphism information for excessive drinking among Japanese college students and adults aged 20-30 years: a randomized controlled trial

Background

The alcohol-metabolizing enzyme aldehyde dehydrogenase 2 (ALDH2) is a carcinogenic acetaldehyde-degrading enzyme, and its low activity is a genetic constitution peculiar to East Asians. People with low alcohol dehydrogenase 1B activity (ADH1B*1/*1 genotype) have a high risk of developing head and neck cancer and alcoholism. The study aims to evaluate the effectiveness of brief interventions for excessive drinking among college students and adults in their 20s, including information on five constitutions that combine the ALDH2 and ADH1B genotypes.

Methods

Participants comprised university students and staff aged 20–30 years who had consumed ≥40 g (males) or ≥20 g (females) of pure alcohol; they were classified into intervention and control groups using a simple randomization method. Participants anonymously filled out questionnaires linked to identification numbers and recorded the drinking days and amounts on the drinking calendar. The intervention group will then be tested for genotype testing using saliva (5 types of combinations of ALDH2 and ADH1B enzyme activities); the result report will arrive approximately 1 month later. We will conduct a 30-min face-to-face or online intervention. The control group will be merely given the conventional materials, and genetic testing will be performed voluntarily after 6 months (end of study). The intervention group will undergo questionnaire surveys 1 month after the intervention and 3 and 6 months after baseline. Questionnaire surveys will be conducted 1, 3, and 6 months after baseline for the control group. The average amount of drinking before and after the intervention, attribute/baseline data between the two groups, and time-series data were compared using various analysis tools. For interventions, we engaged in dialog based on intervention materials that added genotyping content to the existing materials, result reports, baseline data, and drinking calendar records. Participants’ ingenuity is respected to support their drinking behavior and goal setting.

Discussion

Individual information on the genetic makeup of alcohol-metabolizing enzymes provided during the intervention is more personal and objective than general health information, especially in Japan, where the ALDH2 low activity rate is high. This information may be useful for health care and precautionary measures.

Trial registration

R000050379, UMIN000044148, Registered on June 1, 2021.

Scientific Title: Examination of simple intervention using genetic polymorphism information for excessive drinking.

Can gene therapy be used to prevent cancer? Gene therapy for aldehyde dehydrogenase 2 deficiency

Approximately 8% of the world population and 35-45% of East Asians are carriers of the hereditary disorder aldehyde dehydrogenase 2 (ALDH2) deficiency. ALDH2 plays a central role in the liver to metabolize ethanol. With the common E487K variant, there is a deficiency of ALDH2 function; when ethanol is consumed, there is a systemic accumulation of acetaldehyde, an intermediate product in ethanol metabolism. In ALDH2-deficient individuals, ethanol consumption acutely causes the "Alcohol Flushing Syndrome" with facial flushing, tachycardia, nausea, and headaches. With chronic alcohol consumption, ALDH2 deficiency is associated with a variety of disorders, including a remarkably high risk for aerodigestive tract cancers. Acetaldehyde is a known carcinogen. The epidemiologic data relating to the association of ALDH2 deficiency and cancer risk are striking: ALDH2 homozygotes who are moderate-to-heavy consumers of ethanol have a 7-12-fold increased risk for esophageal cancer, making ALDH2 deficiency the most common hereditary disorder associated with an increased cancer risk. In this review, we summarize the genetics and biochemistry of ALDH2, the epidemiology of cancer risk associated with ALDH2 deficiency, the metabolic consequences of ethanol consumption associated with ALDH2 deficiency, and gene therapy strategies to correct ALDH2 deficiency and its associated cancer risk. With the goal of reducing the risk of aerodigestive tract cancers, in the context that ALDH2 is a hereditary disorder and ALDH2 functions primarily in the liver, ALDH2 deficiency is an ideal target for the application of adeno-associated virus-mediated liver-directed gene therapy to prevent cancer.

Alcohol Use Disorder: Neurobiology and Therapeutics

Alcohol use disorder (AUD) encompasses the dysregulation of multiple brain circuits involved in executive function leading to excessive consumption of alcohol, despite negative health and social consequences and feelings of withdrawal when access to alcohol is prevented. Ethanol exerts its toxicity through changes to multiple neurotransmitter systems, including serotonin, dopamine, gamma-aminobutyric acid, glutamate, acetylcholine, and opioid systems. These neurotransmitter imbalances result in dysregulation of brain circuits responsible for reward, motivation, decision making, affect, and the stress response. Despite serious health and psychosocial consequences, this disorder still remains one of the leading causes of death globally. Treatment options include both psychological and pharmacological interventions, which are aimed at reducing alcohol consumption and/or promoting abstinence while also addressing dysfunctional behaviours and impaired functioning. However, stigma and social barriers to accessing care continue to impact many individuals. AUD treatment should focus not only on restoring the physiological and neurological impairment directly caused by alcohol toxicity but also on addressing psychosocial factors associated with AUD that often prevent access to treatment. This review summarizes the impact of alcohol toxicity on brain neurocircuitry in the context of AUD and discusses pharmacological and non-pharmacological therapies currently available to treat this addiction disorder.

Association Between Alcohol Dehydrogenase Polymorphisms and the Recurrence of Laryngeal Carcinoma

OBJECTIVES

Alcohol consumption is closely associated with prognosis for laryngeal squamous cell carcinoma (LSCC) patients. As key enzymes in ethanol metabolism, proteins in the alcohol dehydrogenase (ADH) family make for valuable targets to establish a novel predictive nomogram model. This study attempts to do so by focusing on the single nucleotide polymorphisms (SNPs) of ADH1B and ADH1C in LSCC.

METHODS

Sixty eight LSCC patients that were followed up for more than 10 years were retrospectively analyzed. Endpoints of the current study included disease-free survival and overall survival. Survival analyses were performed using the Kaplan-Meier method and evaluated by log-rank test. The prognostic value of eight ADH1B SNPs and three ADH1C SNPs were evaluated using univariate and multivariate Cox regression analyses. A nomogram model for disease-free survival was established and evaluated using the receiver operating characteristic curve, the C-index, and a calibration plot.

RESULTS

Significant association was exhibited between rs17033 (p < 0.001) and rs1229984 (p = 0.002) with an increase in LSCC recurrence rate on Kaplan-Meier curves. Multivariate logistic regression analysis revealed that the rs17033 polymorphism of ADH1B was independently associated with an increased risk of LSCC recurrence (HR = 3.325, 95% CI = 1.684-6.566, p = 0.001). Based on these findings, a prognostic nomogram of LSCC patients involving ADH1B rs17033 was constructed.

CONCLUSION

This study has demonstrated an independent association between ADH1B gene variants and the recurrence of LSCC. A nomogram model based on rs17033 of ADH1B, age, T, and N stages were successfully developed for the first time to predict the probability of recurrence in LSCC patients.

LEVEL OF EVIDENCE

III Retrospective cohort study Laryngoscope, 2022.

Exploring ALDH2 expression and immune infiltration in HNSC and its correlation of prognosis with gender or alcohol intake

The aldehyde dehydrogenase 2 point mutation (ALDH2*2) is a common frequent human gene variant, especially in East Asians. However, the expression and mechanism of action of ALDH2 in HNSC remain unknown. The present study explored the clinical significance and immune characteristics of ALDH2 in HNSC. The receiver operating characteristic curve was analysed to assess the diagnostic value of ALDH2 expression. ALDH2 expression in normal tissues and HNSC tissues was evaluated by IHC, and we also analysed ALDH2 gene expression in 4 HNSC cell lines. ALDH2 expression was significantly reduced in HNSC tissues compared to normal tissues (p < 0.05). HNSC patients with high ALDH2 expression had a better prognosis compared to patients with low ALDH2 expression (p < 0.05). GSEA indicated that these gene sets were correlated with signalling pathways, including the JAK-STAT signalling pathway. Unexpectedly, we found a significant prognostic effect of ALDH2 for HNSC based on alcohol consumption and the male sex. The correlation between ALDH2 expression and immune inhibitors showed an effect for ALDH2 in modifying tumour immunology in HNSC, and there may be a possible mechanism by which ALDH2 regulates the functions of T cells in HNSC. In addition, we developed a prognostic nomogram for HNSC patients, which suggested that low ALDH2 expression indicated poor prognosis in HNSC patients who were males and alcoholics.

Alcohol Consumption and Cigarette Smoking among Young Adults: An Instrumental Variable Analysis Using Alcohol Flushing

Association between drinking and smoking has remained controversial since the association between two studies were influenced by various confounding. Thus, our study aimed to explore the causal effect of alcohol consumption and cigarette smoking using alcohol flushing as an instrument variable, which is free from confounders. We analyzed cross-sectional survey data from 2500 Korean young adults (1600 men and 900 women). Alcohol flushing was strongly associated with log transformed alcohol consumption (F = 272). In men, alcohol non-flushers were 1.41 times (95% CI 1.28-1.55) more likely to smoke 100 cigarettes in their lifetime in logistic regression analysis. Alcohol non-flushers were also 1.3 times (95% CI 1.21-1.40) more likely to become daily smokers and 1.39 times (95% CI 1.27-1.51) more likely to be current smokers than alcohol flushers. However, in an IV analysis, no causal relationships between alcohol consumption and smoking status were found. Alcohol consumption, on the other hand, was causally associated with lowering nicotine dependence and former smoking in men. Alcohol consumption determined by alcohol flushing status does not appear to be causally linked to the smoking behavior of young adults. The relationship between alcohol consumption and nicotine dependence and smoking cessation needs further study.

Association Between the Aldehyde Dehydrogenase-2 rs671 G>A Polymorphism and Head and Neck Cancer Susceptibility: A Meta-Analysis in East Asians

BACKGROUND

Aldehyde dehydrogenase-2 (ALDH2) plays an important role in the alcohol detoxification and acetaldehyde metabolism. Published studies have demonstrated some inconsistent associations between ALDH2 rs671 G>A polymorphism and head and neck cancer (HNC) risk.

METHODS

A meta-analysis was performed to provide pooled data on the association between the ALDH2 rs671 G>A polymorphism and HNC risk. Electronic databases were searched to identify relevant studies. Odds ratios and 95% confidence intervals (CIs) were used to examine the pooled effect size of each genetic model. In addition, heterogeneity test, accumulative analysis, sensitivity analysis, and publication bias were conducted to test the statistical power.

RESULTS

Thirteen publications (14 independent case-control studies) involving 10,939 subjects were selected. The stratified analysis indicated that both light/moderated drinking (e.g., GA vs. GG: OR = 1.47, 95% CI = 1.16 to 1.86, p < 0.01, I²  = 81.1%) and heavy drinking would increase HNC risk with rs671 G>A mutation (e.g., GA vs. GG: OR = 2.30, 95% CI = 1.11 to 4.77, p = 0.03, I²  = 81.9%).

CONCLUSIONS

In summary, this meta-analysis suggested that the ALDH2 rs671 G>A polymorphism may play an important synergistic effect in the pathogenesis of HNC development in East Asians.

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.

Effect of ALDH2 polymorphism on cancer risk in Asians: A meta-analysis

Numerous studies have investigated the association between ALDH2 gene rs671G>A polymorphism and various cancer type in Asians. However, the results remain inconclusive.We conducted a comprehensive meta-analysis including 63 articles with 66 studies containing 25,682 cases and 47,455 controls retrieved by searching PubMed and Embase electronic databases up to March 5, 2018.Pooled results indicated that ALDH2 gene rs671 polymorphism was significantly associated with the overall cancer risk in Asians (homozygous model: odds ratio [OR] = 0.85, 95% confidence interval [CI] = 0.72-0.99, P = .042; heterozygous model: OR = 1.32, 95% CI = 1.14-1.52, P  < .001; recessive model: OR = 0.73, 95% CI = 0.60-0.88, P = .001; dominant model: OR = 1.32, 95% CI = 1.16-1.51, P < .001; and allele comparison model: OR = 1.11, 95% CI = 1.03-1.19, P = .004), especially in esophageal cancer and among the Chinese and the Japanese.Our results suggest that ALDH2 rs671 polymorphism is associated with the overall cancer risk in Asians. Well-designed prospective studies with more information about gene-environment interaction, such as drinking, should be conducted to validate our findings.

Risk assessment of metachronous squamous cell carcinoma after endoscopic resection for esophageal carcinoma based on the genetic polymorphisms of alcoholdehydrogense-1B aldehyde dehydrogenase-2: temperance reduces the risk

BACKGROUND

Metachronous multiple squamous cell carcinoma (SCC) of the esophagus and the head and neck is commonly observed in patients who have previously undergone endoscopic resection (ER) for SCC of the esophagus (ESCC). We evaluated the risk for developing metachronous SCC following ER for ESCC based on the genetic polymorphisms for alcohol dehydrogenase-1B (ADH1B) and aldehyde dehydrogenase-2 (ALDH2) as well as the alcohol consumption and smoking habits.

METHODS

We studied 158 patients who underwent ER for ESCC (median follow-up 80 months). Genotyping of ADH1B/ALDH2 was performed using saliva sampling. The alcohol consumption and smoking histories of the patients before and after the ER were documented.

RESULTS

Multivariate analyses revealed that inactive heterozygous ALDH2 [hazard ratio (HR) 2.25] and alcohol consumption after ER (HR 1.94) were independently associated with the risk of developing secondary SCC. Moreover, inactive heterozygous ALDH2 (HR 4.39) and alcohol consumption after the ER (HR 2.82) were independently associated with the risk of a third SCC. We analyzed 110 patients who had a history of moderate or heavy alcohol consumption before the ER. The 3-year cumulative incidence rates of secondary SCC in the temperance (n = 65) and non-temperance groups (n = 45) were 14.0 and 42.1% (p = 0.0002). Further, the 5-year cumulative incidence rates of a third SCC in the temperance and non-temperance groups were 0 and 15.6% (p = 0.0011), respectively. In addition, the 7-year cumulative incidence rates of a fourth SCC in the temperance and non-temperance groups were 0 and 15.3% (p = 0.0015), respectively.

CONCLUSIONS

Continued alcohol consumption is an important risk factor for the onset of metachronous SCC and is a risk factor for the third and subsequent SCCs. Strict advice in favor of temperance is crucial.

Prognostic value of ALDH2 polymorphism for patients with oropharyngeal cancer in a Japanese population

Background

Half of Japanese possess a polymorphism of aldehyde dehydrogenase 2(ALDH2), while few white individuals possess this mutation. The purpose of this study was to investigate the possibility of ALDH2 polymorphism as a prognostic factor for oropharyngeal cancer (OPC) among Japanese population.

Methods

We analyzed 82 Japanese patients with OPC treated between 2006 and 2011. The median observation period was 50 months. P16-staining and ALDH2 polymorphisms were investigated. To examine the frequencies of second primary pharyngeal and esophageal cancers (SPPEC),37 Japanese patients with OPC treated at Tokyo University Hospital were included for statistical analysis.

Results

Statistically significant differences were noted in OS among sex, age, N classification, and p16 (p = 0.045, 0.024, 0.020, 0.007, respectively). In addition, OS and DSS rates of the patients with heterozygous ALDH2 tended to be worse than those of the patients with homozygous ALDH2 (p = 0.21, 0.086, respectively). Of note, OS and DSS of the patients with p16-negative OPC and heterozygous ALDH2 was significant poorer than those of the patients with p16-positive OPC (p = 0.002, 0.006, respectively), while there was no significant difference in OS and DSS between patients with p16-positive OPC and patients with p16-negative OPC and homozygous ALDH2.

Conclusions

ALDH2 polymorphism might be a promising prognostic factor for Japanese patients with p16-negative OPC.

ALDH2 polymorphism and alcohol-related cancers in Asians: a public health perspective

The occurrence of more than 200 diseases, including cancer, can be attributed to alcohol drinking. The global cancer deaths attributed to alcohol-consumption rose from 243,000 in 1990 to 337,400 in 2010. In 2010, cancer deaths due to alcohol consumption accounted for 4.2% of all cancer deaths. Strong epidemiological evidence has established the causal role of alcohol in the development of various cancers, including esophageal cancer, head and neck cancer, liver cancer, breast cancer, and colorectal cancer. The evidence for the association between alcohol and other cancers is inconclusive. Because of the high prevalence of ALDH2*2 allele among East Asian populations, East Asians may be more susceptible to the carcinogenic effect of alcohol, with most evidence coming from studies of esophageal cancer and head and neck cancer, while data for other cancers are more limited. The high prevalence of ALDH2*2 allele in East Asian populations may have important public health implications and may be utilized to reduce the occurrence of alcohol-related cancers among East Asians, including: 1) Identification of individuals at high risk of developing alcohol-related cancers by screening for ALDH2 polymorphism; 2) Incorporation of ALDH2 polymorphism screening into behavioral intervention program for promoting alcohol abstinence or reducing alcohol consumption; 3) Using ALDH2 polymorphism as a prognostic indicator for alcohol-related cancers; 4) Targeting ALDH2 for chemoprevention; and 5) Setting guidelines for alcohol consumption among ALDH2 deficient individuals. Future studies should evaluate whether these strategies are effective for preventing the occurrence of alcohol-related cancers.

Association between alcohol dehydrogenase-2 gene polymorphism and esophageal cancer risk: a meta-analysis

BACKGROUND

It has been shown that gene polymorphisms may play an important role in the carcinogenesis of esophageal cancer. This study is to investigate the role of alcohol dehydrogenase 1B (ADH1B) gene Arg47His polymorphism in esophageal cancer susceptibility.

METHODS

Case-control studies published between January 2000 and June 2015 were searched to retrieve relevant articles. The pooled odds ratio (OR) and 95 % confidence interval (CI) were employed to calculate the strength of association.

RESULTS

A total of 23 relevant articles were finally selected for the analysis, including 9338 esophageal cancer patients and 14,896 matched controls. Overall, we found that the 47His allele was significant associated with the decreased risk of esophageal cancer when compared with the 47Arg allele in total populations (A vs. G: OR = 0.67, 95 % CI = 0.59-0.76, P < 0.00001). This protective relationship was observed under other genetic models as well (P < 0.00001). Subgroup analysis by ethnicity showed that ADH1B Arg47His variant was associated with the decreased esophageal cancer risk under all the genetic models (P < 0.00001) among Asians, especially in Chinese and Japanese; while in non-Asians, no significant correlation was detected in any genetic models (P > 0.05). Furthermore, Arg/Arg genotype of ADH1B Arg47His variant combined with drinking, smoking and males appeared to show a high risk in patients with esophageal cancer.

CONCLUSIONS

Our results suggested that ADH1B gene Arg47His variant was associated with the decreased esophageal cancer risk. Genetic-environmental interaction should be further considered in the future researches.

Association between Glu504Lys polymorphism of ALDH2 gene and cancer risk: a meta-analysis

Background

The association of the aldehyde dehydrogenases-2 (ALDH2) Glu504Lys polymorphism (also named Glu487Lys, or rs671) and cancers has been investigated. This meta-analysis aims to comprehensively assess the influence of this polymorphism on the overall cancer risk.

Methods

Eligible publications were retrieved according to inclusion/exclusion criteria and the data were analyzed using the Review Manager software (V5.2).

Results

A meta-analysis based on 51 case-control studies consisting of 16774 cases and 32060 controls was performed to evaluate the association between the ALDH2 Glu504Lys polymorphism and cancer risk. The comparison of genotypes Lys+ (Lys/Lys and Lys/Glu) with Glu/Glu yielded a significant 20% increased cancer risk (OR = 1.20, 95%CI: 1.03–1.39, P = 0.02, I² = 92%). Subgroup analysis by cancer type indicated a significantly increased UADT cancer risk (OR = 1.39, 95%CI: 1.11–1.73, P = 0.004, I² = 94%) in individuals with the Lys+ genotypes. Subgroup analysis by country indicated that individuals from Japan with the Lys+ genotypes had a significant 38% increased cancer risk (OR = 1.38, 95%CI: 1.12–1.71, P = 0.003, I² = 93%).

Conclusions

Our results indicated that the ALDH2 Glu504Lys polymorphism is a susceptible loci associated with overall cancers, especially esophageal cancer and among Japanese population.

Association between ADH1B and ADH1C polymorphisms and the risk of head and neck squamous cell carcinoma

Alcohol consumption is one of the major risk factors for head and neck squamous cell carcinoma (HNSCC), and the alcohol dehydrogenase (ADH) family proteins are key enzymes in ethanol metabolism. We examined the associations between single nucleotide polymorphisms (SNPs) of ADH1B and ADH1C and the risk of HNSCC. We analyzed six SNPS of ADH1B, namely -992C > G, -957C > A, +3170A>G, +3377G>T, +3491G>A, and +13543A>G, and five SNPs of ADH1C, namely -1064C>T, -325G>C, +5702A>G, +7462T>C, and +13044A>G, in 260 Korean HNSCC patients and 330 controls, using single base extension and the TaqMan assay. The odds ratios (ORs) and 95 % confidence intervals (95 % CIs) of the CG and GG genotypes of ADH1B -992C>G, the AA genotype of -957C>A, the GG genotype of +3170A>G, the GA genotype of +3491G>A, and +13543A>G were 0.51 (0.32-0.82), 0.63 (0.42-0.94), 1.84 (1.13-2.99), 1.77 (1.15-2.73), 2.34 (1.44-3.79), and 2.21 (1.23-3.95), respectively. The ORs of ADH1C +13044A>G were 1.94 (1.01-3.71) and 1.97 (1.05-3.71) in the dominant and co-dominant models, respectively. The ORs of the GC genotype of ADH1C -325G>C and the AG genotype of +5702A>G were 2.52 (1.51-4.21) and 2.43 (1.36-4.32), respectively. ADH1B +3170A>G and ADH1C +13044A>G were in strong linkage disequilibrium with the other SNPs of ADH1B and ADH1C, respectively. There were gene-environment interactions between ADH1B +3170A>G and ADH1C +13044A>G and alcohol consumption and smoking. ADH1B +3170A>G and ADH1C +13044A>G SNPs are associated with an increased risk of HNSCC, and they could be used as biomarkers for the high-risk group of HNSCC in Koreans.

Tamoxifen, an anticancer drug, is an activator of human aldehyde dehydrogenase 1A1

The modulation of aldehyde dehydrogenase (ALDH) activity has been suggested as a promising option for the prevention or treatment of many diseases. To date, only few activating compounds of ALDHs have been described. In this regard, N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide has been used to protect the heart against ischemia/reperfusion damage. In the search for new modulating ALDH molecules, the binding capability of different compounds to the active site of human aldehyde dehydrogenase class 1A1 (ALDH1A1) was analyzed by molecular docking, and their ability to modulate the activity of the enzyme was tested. Surprisingly, tamoxifen, an estrogen receptor antagonist used for breast cancer treatment, increased the activity and decreased the Km for NAD(+) by about twofold in ALDH1A1. No drug effect on human ALDH2 or ALDH3A1 was attained, showing that tamoxifen was specific for ALDH1A1. Protection against thermal denaturation and competition with daidzin suggested that tamoxifen binds to the aldehyde site of ALDH1A1, resembling the interaction of N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide with ALDH2. Further kinetic analysis indicated that tamoxifen activation may be related to an increase in the Kd for NADH, favoring a more rapid release of the coenzyme, which is the rate-limiting step of the reaction for this isozyme. Therefore, tamoxifen might improve the antioxidant response, which is compromised in some diseases.

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.

The interplay between alcohol consumption, oral hygiene, ALDH2 and ADH1B in the risk of head and neck cancer

Alcohol consumption is an established risk factor for head and neck cancer (HNC). The major carcinogen from alcohol is acetaldehyde, which may be produced by humans or by oral microorganisms through the metabolism of ethanol. To account for the different sources of acetaldehyde production, the current study examined the interplay between alcohol consumption, oral hygiene (as a proxy measure for the growth of oral microorganisms), and alcohol-metabolizing genes (ADH1B and ALDH2) in the risk of HNC. We found that both the fast (*2/*2) and the slow (*1/*1+ *1/*2) ADH1B genotypes increased the risk of HNC due to alcohol consumption, and this association differed according to the slow/non-functional ALDH2 genotypes (*1/*2+ *2/*2) or poor oral hygiene. In persons with the fast ADH1B genotype, the HNC risk associated with alcohol drinking was increased for those with the slow/non-functional ALDH2 genotypes. For those with the slow ADH1B genotypes, oral hygiene appeared to play an important role; the highest magnitude of an increased HNC risk in alcohol drinkers occurred among those with the worst oral hygiene. This is the first study to show that the association between alcohol drinking and HNC risk may be modified by the interplay between genetic polymorphisms of ADH1B and ALDH2 and oral hygiene. Although it is important to promote abstinence from or reduction of alcohol drinking to decrease the occurrence of HNC, improving oral hygiene practices may provide additional benefit.

Extended genetic effects of ADH cluster genes on the risk of alcohol dependence: from GWAS to replication

Alcohol dependence (AD) is a multifactorial and polygenic disorder involving complex gene-to-gene and gene-to-environment interactions. Several genome-wide association studies have reported numerous risk factors for AD, but replication results following these studies have been controversial. To identify new candidate genes, the present study used GWAS and replication studies in a Korean cohort with AD. Genome-wide association analysis revealed that two chromosome regions on Chr. 4q22-q23 (ADH gene cluster, including ADH5, ADH4, ADH6, ADH1A, ADH1B, and ADH7) and Chr. 12q24 (ALDH2) showed multiple association signals for the risk of AD. To investigate detailed genetic effects of these ADH genes on AD, a follow-up study of the ADH gene cluster on 4q22-q23 was performed. A total of 90 SNPs, including ADH1B rs1229984 (H47R), were genotyped in an additional 975 Korean subjects. In case-control analysis, ADH1B rs1229984 (H47R) showed the most significant association with the risk of AD (p = 2.63 × 10(-21), OR = 2.35). Moreover, subsequent conditional analyses revealed that all positive associations of other ADH genes in the cluster disappeared, which suggested that ADH1B rs1229984 (H47R) might be the sole functional genetic marker across the ADH gene cluster. Our findings could provide additional information on the ADH gene cluster regarding the risk of AD, as well as a new and important insight into the genetic factors associated with AD.

Genetic variants at 4q23 and 12q24 are associated with head and neck cancer risk in China

A recent genome-wide association study (GWAS) reported significant associations of several novel genetic variants with risk of upper aerodigestive tract (UADT) cancers including head and neck cancer (HNC) in Europeans. However, these findings have not been confirmed in other populations including Chinese. According to the findings from the GWAS and other publications, we genotyped six genetic variants (rs1494961, rs1229984, rs1789924, rs971074, rs4767364, and rs671) in a case-control study with 397 HNC cases and 900 controls in China, by using the TaqMan allelic discrimination assay. We found that rs1229984 at 4q23 significantly increased the risk of HNC [dominant model: adjusted odds ratio (OR) = 1.34, 95% confidence interval (CI) = 1.05-1.71; additive model: adjusted OR = 1.24, 95% CI = 1.04-1.50], while rs671 at 12q24 significantly decreased the risk of HNC (recessive model: adjusted OR = 0.46, 95% CI = 0.25-0.85). Furthermore, when these two loci were evaluated together by the number (0-4) of putative risk alleles (rs1229984 G and rs671 G), a significant locus-dosage effect was found between the groups and risk of HNC (Ptrend  = 0.016). Compared with the "0-1" group, groups with "2" risk alleles and "3-4" risk alleles significantly increased the risk of HNC with adjusted ORs of 1.17 (95% CI = 0.84-1.64) and 1.51 (95% CI = 1.06-2.15), respectively. However, no significant association was detected between other four variants (rs1494961, rs1789924, rs971074, and rs4767364) and HNC risk. These findings suggest that rs1229984 at 4q23 and rs671 at 12q24 may serve as candidate markers for susceptibility to HNC in Chinese population.