Association of low-activity ALDH2 and alcohol consumption with risk of esophageal cancer in Chinese adults: A population-based cohort study

Aldehyde dehydrogenase 2 gene rs671 G>A polymorphism is associated with an increased risk of digestive tract cancer

OBJECTIVE

Acetaldehyde can accumulate in cells and form acetaldehyde-DNA adducts that result in digestive tract cancer development. Acetaldehyde dehydrogenase 2 (ALDH2) enzymatic activity is involved in this process. Here, we aimed to analyze the relationship between an ALDH2 gene polymorphism and the digestive tract cancer risk in the Hakka population in China.

METHODS

This was a retrospective study, with the ALDH2 rs671 genotype and medical record information collected from all subjects. The relationships between these factors, including various blood cell parameters, and digestive tract cancer susceptibility were analyzed.

RESULTS

Overall, 307 cancer patients and 317 controls were included. The cancer patients had significantly higher percentages with a history of smoking and drinking alcohol, as well as an increased platelet to lymphocyte ratio and lower lymphocyte to monocyte ratio, compared with the controls. The ALDH2 rs671 genotype and allele distributions were significantly different between the cancer patients and controls. Logistic regression analysis showed that the ALDH2 G/A genotype (G/A vs. G/G) and A/A genotype (A/A vs. G/G) in the co-dominant mode were risk factors for digestive tract cancer susceptibility.

CONCLUSIONS

ALDH2 rs671 G/A or A/A genotype carriers may have an increased risk of developing digestive tract cancers among the Hakka people.

ALDH2 gene rs671 G > a polymorphism and the risk of colorectal cancer: A hospital-based study

BACKGROUND

The susceptibility to some cancers is linked to genetic factors, such as aldehyde dehydrogenase 2 (ALDH2) polymorphisms. The relationship between ALDH2 rs671 and colorectal cancer (CRC) is not clear in Hakka population.

METHODS

Between October 2015 and December 2020, a total of 178 CRC patients and 261 controls were recruited. ALDH2 rs671 was genotyped in these subjects, medical records (smoking history, drinking history and blood cell parameters) were collected, and the relationship between these information and CRC was analyzed.

RESULTS

The proportion of the ALDH2 rs671 G/G, G/A, and A/A genotype was 48.3%, 44.4%, and 7.3% in patients; 62.1%, 34.1%, and 3.8% in controls, respectively. The difference of ALDH2 genotypes distribution between cases and controls was statistically significant (p = 0.011). The higher percentage of smokers and alcoholics, higher level of neutrophil to lymphocyte ratio (NLR), platelet count, and platelet to lymphocyte ratio (PLR), and lower level of lymphocyte count, lymphocyte to monocyte ratio (LMR), and mean hemoglobin concentration were observed in patients. Logistic regression analysis indicated that ALDH2 rs671 G/A genotype (G/A vs. G/G) (adjusted OR 1.801, 95% CI 1.160-2.794, p = 0.009) and A/A genotype (A/A vs. G/G) (adjusted OR 2.630, 95% CI 1.041-6.645, p = 0.041) in the co-dominant model, while G/A + A/A genotypes (G/A + A/A vs. G/G) (adjusted OR 1.883, 95% CI 1.230-2.881, p = 0.004) in the dominant model were risk factors for CRC.

CONCLUSIONS

Individuals carrying ALDH2 rs671 A allele (G/A, A/A genotypes) may be at increased risk of colorectal cancer.

Alcohol metabolism genes and risks of site-specific cancers in Chinese adults: An 11-year prospective study

Two genetic variants that alter alcohol metabolism, ALDH2-rs671 and ADH1B-rs1229984, can modify oesophageal cancer risk associated with alcohol consumption in East Asians, but their associations with other cancers remain uncertain. ALDH2-rs671 G>A and ADH1B-rs1229984 G>A were genotyped in 150 722 adults, enrolled from 10 areas in China during 2004 to 2008. After 11 years' follow-up, 9339 individuals developed cancer. Cox regression was used to estimate hazard ratios (HRs) for site-specific cancers associated with these genotypes, and their potential interactions with alcohol consumption. Overall, the A-allele frequency was 0.21 for ALDH2-rs671 and 0.69 for ADH1B-rs1229984, with A-alleles strongly associated with lower alcohol consumption. Among men, ALDH2-rs671 AA genotype was associated with HR of 0.69 (95% confidence interval: 0.53-0.90) for IARC alcohol-related cancers (n = 1900), compared to GG genotype. For ADH1B-rs1229984, the HRs of AG and AA vs GG genotype were 0.80 (0.69-0.93) and 0.75 (0.64-0.87) for IARC alcohol-related cancers, 0.61 (0.39-0.96) and 0.61 (0.39-0.94) for head and neck cancer (n = 196) and 0.68 (0.53-0.88) and 0.60 (0.46-0.78) for oesophageal cancer (n = 546). There were no significant associations of these genotypes with risks of liver (n = 651), colorectal (n = 556), stomach (n = 725) or lung (n = 1135) cancers. Among male drinkers, the risks associated with higher alcohol consumption were greater among ALDH2-rs671 AG than GG carriers for head and neck, oesophageal and lung cancers (Pinteraction  < .02). Among women, only 2% drank alcohol regularly, with no comparable associations observed between genotype and cancer. These findings support the causal effects of alcohol consumption on upper aerodigestive tract cancers, with ALDH2-rs671 AG genotype further exacerbating the risks.

ALDH2 Polymorphism rs671 *1/*2 Genotype is a Risk Factor for the Development of Alcoholic Liver Cirrhosis in Hakka Alcoholics

Background

Alcoholics are prone to alcoholic cirrhosis (ALC). Aldehyde dehydrogenase 2 (ALDH2) is involved in alcohol metabolism. Herein, the relationship between ALDH2 genotypes and ALC was analyzed among Hakka alcoholics in southern China.

Methods

A total of 213 alcoholics and 214 non-alcoholics were included in the study. The ALDH2 gene rs671 polymorphism was analyzed, life history, disease history, and auxiliary examination results of these participants were collected.

Results

The alcoholics had higher level of total serum protein, and serum globulin, lower level of serum albumin, serum albumin/globulin ratio, serum prealbumin, neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), and platelet-to-lymphocyte ratio (PLR) than non-alcoholics. In the 213 alcoholics, 180 developed ALC. There were 206 non-ALC persons in the 214 non-alcoholics. The proportion of the ALDH2 rs671 G/G homozygous (*1/*1) was significantly lower in ALC patients (83.3%) than that of other groups (100.0% in non-ALC in alcoholics, 95.6% in non-ALC in non-alcoholics), while the proportion of the G/A heterozygous (*1/*2) was significantly higher in ALC patients (16.7%) than that of other groups (0% in non-ALC in alcoholics, 4.4% in non-ALC in non-alcoholics). Logistic regression analysis indicated that participants with low level of NLR (adjusted OR 5.543, 95% CI 2.964–10.368, P<0.001), LMR (adjusted OR 9.256, 95% CI 4.740–18.076, P<0.001), and PLR (adjusted OR 6.047, 95% CI 3.372–10.845, P<0.001), and ALDH2 G/A genotype (adjusted OR 6.323, 95% CI 2.477–16.140, P<0.001) had a significantly higher risk of ALC.

Conclusion

ALDH2 polymorphism rs671 *1/*2 genotype is a potential risk factor for the development of ALC among Hakka alcoholics.

The role of ALDH2 in tumorigenesis and tumor progression: Targeting ALDH2 as a potential cancer treatment

A major mitochondrial enzyme for protecting cells from acetaldehyde toxicity is aldehyde dehydrogenase 2 (ALDH2). The correlation between ALDH2 dysfunction and tumorigenesis/growth/metastasis has been widely reported. Either low or high ALDH2 expression contributes to tumor progression and varies among different tumor types. Furthermore, the ALDH2∗2 polymorphism (rs671) is the most common single nucleotide polymorphism (SNP) in Asia. Epidemiological studies associate ALDH2∗2 with tumorigenesis and progression. This study summarizes the essential functions and potential ALDH2 mechanisms in the occurrence, progression, and treatment of tumors in various types of cancer. Our study indicates that ALDH2 is a potential therapeutic target for cancer therapy.

Association between ALDH2 polymorphism and esophageal cancer risk in South Koreans: a case-control study

Background

Alcohol consumption is a major risk factor for esophageal cancer; however, a high incidence of esophageal cancer is observed particularly among Eastern Asians, although they consume relatively less alcohol, presumably due to the high frequency of aldehyde dehydrogenase 2 (ALDH2) rs671 polymorphisms. Nevertheless, the association between ALDH2 polymorphisms and esophageal cancer remains under debate. In the present study, we evaluated the association between ALDH2 rs671 polymorphisms and the risk of esophageal cancer in the South Korean population.

Methods

This study included 783 hospital based-cases and 8732 population-based controls. Information on smoking history and alcohol consumption was obtained from the medical records or interview questionnaires. Age-adjusted logistic regression analysis was performed to assess the association between ALDH2 rs671 polymorphisms and esophageal cancer.

Results

Odds ratios (ORs) for esophageal cancer in men with GA and AA genotypes were 2.75 (95% confidence interval [CI]: 2.34–3.23) and 0.08 (95% CI: 0.00–0.35), respectively; whereas, in women, these ratios were 2.99 (95% CI: 1.43–6.34) and 6.18 (95% CI: 1.40–19.62), respectively, taking subjects with the ALDH2 GG genotype as a reference. In men, the association between ALDH2 polymorphisms and esophageal cancer was modified by alcohol consumption.

Conclusion

In Eastern Asians, ALDH2 rs671 polymorphisms are associated with esophageal cancer, which may be linked to acetaldehyde accumulation.

Alcohol drinking and risks of total and site-specific cancers in China: A 10-year prospective study of 0.5 million adults

Alcohol drinking is associated with increased risks of several site‐specific cancers, but its role in many other cancers remains inconclusive. Evidence is more limited from China, where cancer rates, drinking patterns and alcohol tolerability differ importantly from Western populations. The prospective China Kadoorie Biobank recruited >512 000 adults aged 30 to 79 years from 10 diverse areas during 2004 to 2008, recording alcohol consumption patterns by a standardised questionnaire. Self‐reported alcohol consumption was estimated as grams of pure alcohol per week based on beverage type, amount consumed per occasion and drinking frequency. After 10 years of follow‐up, 26 961 individuals developed cancer. Cox regression was used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) relating alcohol consumption to incidence of site‐specific cancers. Overall, 33% (n = 69 734) of men drank alcohol regularly (ie, ≥weekly) at baseline. Among male current regular drinkers, alcohol intake showed positive dose‐response associations with risks of cancers in the oesophagus (655 events; HR = 1.98 [95%CI 1.79‐2.18], per 280 g/wk), mouth and throat (236; 1.74 [1.48‐2.05]), liver (573; 1.52 [1.31‐1.76]), colon‐rectum (575; 1.19 [1.00‐1.43]), gallbladder (107; 1.60 [1.16‐2.22]) and lung (1017; 1.25 [1.10‐1.42]), similarly among never‐ and ever‐regular smokers. After adjustment for total alcohol intake, there were greater risks of oesophageal cancer in daily drinkers than nondaily drinkers and of liver cancer when drinking without meals. The risks of oesophageal cancer and lung cancer were greater in men reporting flushing after drinking than not. In this male population, alcohol drinking accounted for 7% of cancer cases. Among women, only 2% drank regularly, with no clear associations between alcohol consumption and cancer risk. Among Chinese men, alcohol drinking is associated with increased risks of cancer at multiple sites, with certain drinking patterns (eg, daily, drinking without meals) and low alcohol tolerance further exacerbating the risks.

What's new?

A comprehensive assessment of the role of alcohol in cancer aetiology is needed in China, where cancer rates, drinking patterns, and alcohol tolerability differ from those in the West. In this large prospective study, regular alcohol drinkers had increased risks of cancers in several sites previously considered to be alcohol‐related (i.e., oesophagus, mouth and throat, liver and colon‐rectum) as well as in the lung and gallbladder. Certain drinking patterns (e.g., drinking daily or without meals) and low alcohol tolerance further exacerbated the risks. The findings suggest that lowering population‐levels of alcohol consumption is an important strategy for cancer prevention.

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.

Inclusion of a gene-environment interaction between alcohol consumption and the aldehyde dehydrogenase 2 genotype in a risk prediction model for upper aerodigestive tract cancer in Japanese men

The well-known gene-environment interaction between alcohol consumption and aldehyde dehydrogenase 2 (ALDH2) genotype in upper aerodigestive tract cancer risk may improve our ability to identify high-risk subjects. Here, we developed and validated risk prediction models for this cancer in Japanese men and evaluated whether adding the gene-environment interaction to the model improved the predictive performance. We developed two case-cohort datasets in the Japan Public Health Center-based Prospective Study: one from subjects in the baseline survey for model development (108 cases and 4049 subcohort subjects) and the second from subjects in the 5-year follow-up survey for model validation (31 cases and 1527 subcohort subjects). We developed an environmental model including age, smoking status, and alcohol consumption, and a gene-environment interaction model including age, smoking status, and the combination of alcohol consumption and the ALDH2 genotype. We found a statistically significant gene-environment interaction for alcohol consumption and the ALDH2 genotype. The c-index for the gene-environment interaction model (0.71) was slightly higher than that for the environmental model (0.67). The values of integrated discrimination improvement and net reclassification improvement for the gene-environment interaction model were also slightly higher than those for the environmental model. Goodness-of-fit tests suggested that the models were well calibrated. Results from external model validation by the 5-year follow-up survey were consistent with those from the model development by the baseline survey. The addition of a gene-environment interaction to a lifestyle-based model might improve the performance to estimate the probability of developing upper aerodigestive tract cancer for Japanese men.

An analytic framework for exploring sampling and observation process biases in genome and phenome-wide association studies using electronic health records

Large-scale association analyses based on observational health care databases such as electronic health records have been a topic of increasing interest in the scientific community. However, challenges due to nonprobability sampling and phenotype misclassification associated with the use of these data sources are often ignored in standard analyses. The extent of the bias introduced by ignoring these factors is not well-characterized. In this paper, we develop an analytic framework for characterizing the bias expected in disease-gene association studies based on electronic health records when disease status misclassification and the sampling mechanism are ignored. Through a sensitivity analysis approach, this framework can be used to obtain plausible values for parameters of interest given summary results from standard analysis. We develop an online tool for performing this sensitivity analysis. Simulations demonstrate promising properties of the proposed method. We apply our approach to study bias in disease-gene association studies using electronic health record data from the Michigan Genomics Initiative, a longitudinal biorepository effort within The University Michigan health system.

Alcohol and gastrointestinal cancers

PURPOSE OF REVIEW

Alcohol is a type I carcinogen and the WHO stated that it caused 5% of all deaths in 2016, of which 13% because of cancers. Among digestive tract cancers, this association is clear for esophageal, liver and colorectal cancer, and more debated for gastric and pancreatic cancer. The present review will revise recent evidence on epidemiologic association and mechanisms linking alcohol with the risk of esophageal, gastric, colorectal and pancreatic cancers.

RECENT FINDINGS

Moderate alcohol intake increases the risk of esophageal squamous cell carcinoma and colorectal cancer. Heavy alcohol intake is associated with an increased risk of gastric and pancreatic cancers. These risks also depend on genetic variants and the interaction with smoking is inconsistent. The carcinogenic mechanisms are multiple with a key role of acetaldehyde because of its ability to cause DNA damage, alter telomere length and induce ROS. Data on the role of the gut microbiome as possible mediator of alcohol-induced carcinogenesis are limited.

SUMMARY

There is sufficient evidence for the association between alcohol consumption and cancers of the esophagus, stomach, colon-rectum and pancreas. Public health policies to prevent these cancer types should include modification of alcohol intake habits, especially among individuals at increased risk.

An integrated framework for the identification of potential miRNA-disease association based on novel negative samples extraction strategy

MicroRNAs (miRNAs) play an important role in prevention, diagnosis and treatment of human complex diseases. Predicting potential miRNA-disease associations could provide important prior information for medical researchers. Therefore, reliable computational models are expected to be an effective supplement for inferring associations between miRNAs and diseases. In this study, we developed a novel calculative model named Negative Samples Extraction based MiRNA-Disease Association prediction (NSEMDA). NSEMDA filtered reliable negative samples by two positive-unlabeled learning models, namely, the Spy and Rocchio techniques and calculated similarity weights for ambiguous samples. The positive samples, reliable negative samples and ambiguous samples with similarity weights were used to construct a Support Vector Machine-Similarity Weight model to predict miRNA-disease associations. NSEMDA improved the credibility of negative samples and reduced the impact of noise samples by introducing ambiguous samples with similarity weights to train prediction model. As a result, NSEMDA achieved the AUC of 0.8899 in global leave-one-out cross validation (LOOCV) and AUC of 0.8353 under local LOOCV. In 100 times 5-fold cross validation, NSEMDA obtained an average AUC of 0.8878 and standard deviation of 0.0014. These AUCs are higher than many classical models. Besides, we also carried out three kinds of case studies to evaluate the performance of NSEMDA. Among the top 50 potential related miRNAs of esophageal neoplasms, lung neoplasms and carcinoma hepatocellular predicted by NSEMDA, 46, 50 and 45 miRNAs were verified to be associated with the investigated disease by experimental evidences, respectively. Therefore, NSEMDA would be a reliable calculative model for inferring miRNA-disease associations.