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

Association of ADH1B and ALDH2 genotypes with the risk of lung adenocarcinoma

OBJECTIVE

The incidence of lung adenocarcinoma (LAD) is increasing worldwide. Single-nucleotide polymorphisms in aldehyde dehydrogenase 2 family member gene ( ALDH2 ) rs671 and alcohol dehydrogenase 1B ( ADH1B ) rs1229984 are common and functionally important genetic variants to metabolize endogenous and exogenous aldehyde chemicals, related to cancer.

METHODS

This is a case-control study. A total of 150 newly diagnosed LAD patients were from Kaohsiung Medical University Hospital, Taiwan, between 2019 and 2022. Two control groups, TWB-1 ( n  = 600) and TWB-2 ( n  = 29 683), were selected from Taiwan Biobank (TWB), and the case patients were frequency-matched with TWB-1 based on age category (30-60 or >60 years old), sex, and education levels. Logistic regression models were employed to analyze the association between two genetic variants and LAD risk.

RESULTS

A significant association was noted between ALDH2 and LAD risk. Those with ALDH2 rs671 *2/*2 in TWB-1 and TWB-2 controls had a 2.68-fold (95% CI = 1.43-4.99) and a 1.83-fold (95% CI = 1.07-3.11) increased risk of LAD, respectively, compared with those with ALDH2 rs671 *1/*1 or *1/*2 , after adjusting for covariates. This association was particularly pronounced in females. No overall significant association between ADH1B rs1229984 and LAD risk was observed.

CONCLUSION

The findings indicate a strong and robust risk association between ALDH2 rs671*2/*2 and LAD in the Taiwan population, particularly in Taiwanese female adults.

Alcohol-Metabolizing Enzymes, Liver Diseases and Cancer

Alcohol is generally believed to be metabolized in the liver by alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), and to a much lesser extent cytochrome P450 2E1 (CYP2E1) and other enzymes. Recent studies suggest that gut also play important roles in the promotion of alcohol metabolism. ADH, ALDH, and CYP2E1 have several polymorphisms that markedly impact alcohol metabolism. These alcohol-metabolizing enzymes not only affect alcohol-associated liver disease (ALD), but may also modulate the pathogenesis of other liver diseases and cancer in the absence of alcohol consumption. In this review, we discuss alcohol metabolism and the roles of alcohol-metabolizing enzymes in the pathogenesis of ALD, metabolic dysfunction-associated steatotic liver disease, metabolic dysfunction and alcohol-associated liver disease, viral hepatitis, and liver cancer. We also discuss how alcohol-metabolizing enzymes may affect endogenous ethanol production, and how ethanol metabolism in the gut affects liver disease and cancer. Directions for future research on the roles of alcohol-metabolizing enzymes in liver disease and cancer are also elaborated.

Expression pattern and prognostic significance of aldehyde dehydrogenase 2 in lung adenocarcinoma as a potential predictor of immunotherapy efficacy

Background

The incidence of alcohol-associated cancers is higher within Asian populations having an increased prevalence of an inactivating mutation in aldehyde dehydrogenase 2 (ALDH2), a mitochondrial enzyme required for the clearance of acetaldehyde, a cytotoxic metabolite of ethanol. The role of alcohol consumption in promoting lung cancer is controversial, and little attention has been paid to the association between alcohol drinking and pulmonary ALDH2 expression.

Methods

We performed a comprehensive bioinformatic analysis of multi-omics data available in public databases to elucidate the role of ALDH2 in lung adenocarcinoma (LUAD).

Results

Transcriptional and proteomic data indicate a substantial pulmonary expression of ALDH2, which is functional for the metabolism of alcohol diffused from the bronchial circulation. ALDH2 expression is higher in healthy lung tissue than in LUAD and inhibits cell cycle, apoptosis, and epithelial-mesenchymal transition pathways. Moreover, low ALDH2 mRNA levels predict poor prognosis and low overall survival in LUAD patients. Interestingly, ALDH2 expression correlates with immune infiltration in LUAD.

Conclusions

A better understanding of the role of ALDH2 in lung tumor progression and immune infiltration might support its potential use as a prognostic marker and therapeutic target for improving immunotherapeutic response.

Integrated Analysis of Proteome and Transcriptome Profiling Reveals Pan-Cancer-Associated Pathways and Molecular Biomarkers

Understanding dysregulated genes and pathways in cancer is critical for precision oncology. Integrating mass spectrometry-based proteomic data with transcriptomic data presents unique opportunities for systematic analyses of dysregulated genes and pathways in pan-cancer. Here, we compiled a comprehensive set of datasets, encompassing proteomic data from 2404 samples and transcriptomic data from 7752 samples across 13 cancer types. Comparisons between normal or adjacent normal tissues and tumor tissues identified several dysregulated pathways including mRNA splicing, interferon pathway, fatty acid metabolism, and complement coagulation cascade in pan-cancer. Additionally, pan-cancer upregulated and downregulated genes (PCUGs and PCDGs) were also identified. Notably, RRM2 and ADH1B, two genes which belong to PCUGs and PCDGs, respectively, were identified as robust pan-cancer diagnostic biomarkers. TNM stage-based comparisons revealed dysregulated genes and biological pathways involved in cancer progression, among which the dysregulation of complement coagulation cascade and epithelial-mesenchymal transition are frequent in multiple types of cancers. A group of pan-cancer continuously upregulated and downregulated proteins in different tumor stages (PCCUPs and PCCDPs) were identified. We further constructed prognostic risk stratification models for corresponding cancer types based on dysregulated genes, which effectively predict the prognosis for patients with these cancers. Drug prediction based on PCUGs and PCDGs as well as PCCUPs and PCCDPs revealed that small molecule inhibitors targeting CDK, HDAC, MEK, JAK, PI3K, and others might be effective treatments for pan-cancer, thereby supporting drug repurposing. We also developed web tools for cancer diagnosis, pathologic stage assessment, and risk evaluation. Overall, this study highlights the power of combining proteomic and transcriptomic data to identify valuable diagnostic and prognostic markers as well as drug targets and treatments for cancer.

Transformer-based deep learning model for the diagnosis of suspected lung cancer in primary care based on electronic health record data

BACKGROUND

Due to its late stage of diagnosis lung cancer is the commonest cause of death from cancer in the UK. Existing epidemiological risk models in clinical usage, which have Positive Predictive Values (PPV) of less than 10%, do not consider the temporal relations expressed in sequential electronic health record (EHR) data. We aimed to build a model for lung cancer early detection in primary care using machine learning with deep 'transformer' models on EHR data to learn from these complex sequential 'care pathways'.

METHODS

We split the Whole Systems Integrated Care (WSIC) dataset into 70% training and 30% validation. Within the training set we created a case-control study with lung cancer cases and control cases of 'other' cancers or respiratory conditions or 'other' non cancer conditions. Based on 3,303,992 patients from January 1981 to December 2020 there were 11,847 lung cancer cases. 5789 cases and 7240 controls were used for training and 50,000 randomly selected patients out of the whole validation population of 368,906 for validation. GP EHR data going back three years from the date of diagnosis less the most recent one months were semantically pre-processed by mapping from more than 30,000 terms to 450. Model building was performed using ALBERT with a Logistic Regression Classifier (LRC) head. Clustering was explored using k-means. An additional regression model alone was built on the pre-processed data as a comparator.

FINDINGS

Our model achieved an AUROC of 0.924 (95% CI 0.921-0.927) with a PPV of 3.6% (95% CI 3.5-3.7) and Sensitivity of 86.6% (95% CI 85.3-87.8) based on the three year's data prior to diagnosis less the immediate month before index diagnosis. The comparator regression model achieved a PPV of 3.1% (95% CI 3.0-3.1) and AUROC of 0.887 (95% CI 0.884-0.889). We interpreted our model using cluster analysis and have identified six groups of patients exhibiting similar lung cancer progression patterns and clinical investigation patterns.

INTERPRETATION

Capturing temporal sequencing between cancer and non-cancer pathways to diagnosis enables much more accurate models. Future work will focus on external dataset validation and integration into GP clinical systems for evaluation.

FUNDING

Cancer Research UK.

Molecular mechanisms underlying oesophageal cancer development triggered by chronic alcohol consumption

This review explores the mechanisms underlying alcohol‐induced oesophageal carcinogenesis, including DNA damage, oxidative stress, and nutritional deficiencies. Alcohol metabolism primarily involves alcohol dehydrogenase (ADH) converting ethanol to acetaldehyde, which can cause DNA damage, inhibit repair mechanisms, and form DNA adducts thus inhibiting DNA replication. Plus, it delves into the epidemiological evidence, genetic susceptibility, epigenetic modifications, biomarkers, and preventive strategies associated with alcohol‐related oesophageal cancers. Consumption of alcohol increases the risk of gastroesophageal reflux disease thus compromising mucosal integrity of the oesophagus as dysregulation of cytokines such as IL‐18, TNFA, GATA3, TLR4, and CD68 expands the intercellular spaces of epithelial cells. Genetic variants, such as ADH1B rs1229984 and ALDH2 rs671, significantly influence susceptibility to alcohol‐related oesophageal cancers, with these variations affecting acetaldehyde metabolism and cancer risk. Understanding these factors is crucial for early detection, effective treatment, and the development of targeted prevention strategies. Biomarkers, such as miRNA and metabolite markers, offer non‐invasive methods for early detection, while advanced endoscopic techniques provide better diagnostic accuracy. Pharmacological interventions, such as statins and proton pump inhibitors, also show potential for reducing cancer progression in high‐risk individuals. Despite advances, late‐stage oesophageal cancer diagnoses are still common, highlighting the need for better screening and prevention. Further research, including this study, should aim to improve early detection, personalise prevention, and explore new treatments to reduce cases and enhance outcomes in alcohol‐related oesophageal cancers.

Impairment of Intermediate Filament Expression Reveals Impact on Cell Functions Independent from Keratinocyte Transformation

Although cytoplasmic intermediate filaments (cIFs) are essential for cell physiology, the molecular and cell functional consequences of cIF disturbances are poorly understood. Identifying defaults in cell function-controlled tissue homeostasis and understanding the interrelationship between specific cIFs and distinct cell functions remain key challenges. Using an RNAi-based mechanistic approach, we connected the impairment of cell-inherent cIFs with molecular and cell functional consequences, such as proliferation and differentiation. To investigate cIF disruption consequences in the oral epithelium, different cell transformation stages, originating from alcohol-treated oral gingival keratinocytes, were used. We found that impairment of keratin (KRT) KRT5, KRT14 and vimentin (VIM) affects proliferation and differentiation, and modulates the chromatin status. Furthermore, cIF impairment reduces the expression of nuclear integrity participant lamin B1 and the terminal keratinocyte differentiation marker involucrin (IVL). Conversely, impairment of IVL reduces cIF expression levels, functionally suggesting a regulatory interaction between cIFs and IVL. The findings demonstrate that the impairment of cIFs leads to imbalances in proliferation and differentiation, both of which are essential for tissue homeostasis. Thus, targeted impairment of cIFs appears promising to investigate the functional role of cIFs on cell-dependent tissue physiology at the molecular level and identifies putative interactions of cIFs with epithelial differentiation.

The mutagenic properties of formaldehyde and acetaldehyde: Reflections on half a century of progress

Formaldehyde and acetaldehyde are reactive, small compounds that humans are exposed to routinely, variously from endogenous and exogenous sources. Both small aldehydes are classified as human carcinogens. Investigation of the DNA damaging properties of these two compounds began some 50 years ago. In this review, we summarize progress in this field since its inception over half a century ago, distilling insights gained by the collective efforts of many research groups while highlighting areas for future directions. Over the decades, general consensus about aspects of the mutagenicity of formaldehyde and acetaldehyde has been reached. But other characteristics of formaldehyde and acetaldehyde remain incompletely understood and require additional investigation. These include crucial details about the mutational signature(s) induced and possible mechanistic role(s) during carcinogenesis.

Long-term Risks of Cirrhosis and Hepatocellular Carcinoma Across Steatotic Liver Disease Subtypes

INTRODUCTION

The prospective study aimed to investigate the long-term associated risks of cirrhosis and hepatocellular carcinoma (HCC) across various subtypes of steatotic liver disease (SLD).

METHODS

We enrolled 332,175 adults who participated in a health screening program between 1997 and 2013. Participants were categorized into various subtypes, including metabolic dysfunction-associated SLD (MASLD), MASLD with excessive alcohol consumption (MetALD), and alcohol-related liver disease (ALD), based on ultrasonography findings, alcohol consumption patterns, and cardiometabolic risk factors. We used computerized data linkage with nationwide registries from 1997 to 2019 to ascertain the incidence of cirrhosis and HCC.

RESULTS

After a median follow-up of 16 years, 4,458 cases of cirrhosis and 1,392 cases of HCC occurred in the entire cohort, resulting in an incidence rate of 86.1 and 26.8 per 100,000 person-years, respectively. The ALD group exhibited the highest incidence rate for cirrhosis and HCC, followed by MetALD, MASLD, and non-SLD groups. The multivariate adjusted hazard ratios for HCC were 1.92 (95% confidence interval [CI] 1.51-2.44), 2.91 (95% CI 2.11-4.03), and 2.59 (95% CI 1.93-3.48) for MASLD, MetALD, and ALD, respectively, when compared with non-SLD without cardiometabolic risk factors. The pattern of the associated risk of cirrhosis was similar to that of HCC (all P value <0.001). The associated risk of cirrhosis for ALD increased to 4.74 (95% CI 4.08-5.52) when using non-SLD without cardiometabolic risk factors as a reference.

DISCUSSION

This study highlights elevated risks of cirrhosis and HCC across various subtypes of SLD compared with non-SLD, emphasizing the importance of behavioral modifications for early prevention.

Addressing the credibility crisis in Mendelian randomization

BACKGROUND

Genome-wide association studies have enabled Mendelian randomization analyses to be performed at an industrial scale. Two-sample summary data Mendelian randomization analyses can be performed using publicly available data by anyone who has access to the internet. While this has led to many insightful papers, it has also fuelled an explosion of poor-quality Mendelian randomization publications, which threatens to undermine the credibility of the whole approach.

FINDINGS

We detail five pitfalls in conducting a reliable Mendelian randomization investigation: (1) inappropriate research question, (2) inappropriate choice of variants as instruments, (3) insufficient interrogation of findings, (4) inappropriate interpretation of findings, and (5) lack of engagement with previous work. We have provided a brief checklist of key points to consider when performing a Mendelian randomization investigation; this does not replace previous guidance, but highlights critical analysis choices. Journal editors should be able to identify many low-quality submissions and reject papers without requiring peer review. Peer reviewers should focus initially on key indicators of validity; if a paper does not satisfy these, then the paper may be meaningless even if it is technically flawless.

CONCLUSIONS

Performing an informative Mendelian randomization investigation requires critical thought and collaboration between different specialties and fields of research.

Escherichia coli alcohol dehydrogenase YahK is a protein that binds both iron and zinc

Background

Previous studies have highlighted the catalytic activity of Escherichia coli alcohol dehydrogenase YahK in the presence of coenzyme nicotinamide adenine dinucleotide (NAD) and metal zinc. Notably, competitive interaction between iron and zinc ligands has been shown to influence the catalytic efficiency of several key proteases. This study aims to unravel the intricate mechanisms underlying YahK's catalytic action, with a particular focus on the pivotal roles played by metal ions zinc and iron.

Methods

The purified YahK protein from E. coli cells cultivated in LB medium was utilized to investigate its metal-binding properties through UV-visible absorption measurements and determination of metal content. Subsequently, the effects of excess zinc and iron on the metal-binding ability and alcohol dehydrogenase activity of the YahK protein were explored using M9 minimal medium. Furthermore, site-directed mutagenesis technology was employed to determine the iron-binding site location within the YahK protein. Polyacrylamide gel electrophoresis was conducted to examine the relationship between iron and zinc with respect to the YahK protein.

Results

The study confirmed the presence of iron and zinc in the YahK protein, with the zinc-bound form exhibiting enhanced catalytic activity in alcohol dehydrogenation reactions. Conversely, the presence of iron appears to play a pivotal role in maintaining overall stability of the YahK protein. Furthermore, experimental findings indicate that excessive zinc within M9 minimal medium can competitively bind to iron-binding sites on YahK, thereby augmenting its alcohol dehydrogenase activity.

Conclusion

The dynamic binding of YahK to iron and zinc unveils its intricate regulatory mechanism as an alcohol dehydrogenase, thereby highlighting the possible physiological role of YahK in E. coli and its significance in governing cellular metabolic processes. This discovery provides a novel perspective for further investigating the specific impact of metal ion binding on YahK and E. coli cell metabolism.

Risk stratification of synchronous gastric cancers including alcohol-related genetic polymorphisms

BACKGROUND AND AIM

We previously identified that ever-smoking and severe gastric atrophy in pepsinogen are risk factors for synchronous gastric cancers (SGCs). This study aimed to determine the association of alcohol drinking status or alcohol-related genetic polymorphism with SGCs and also stratify their risk.

METHODS

This multi-center prospective cohort study included patients who underwent endoscopic submucosal dissection for the initial early gastric cancers at 22 institutions in Japan. We evaluated the association of alcohol drinking status or alcohol dehydrogenase 1B (ADH1B) and acetaldehyde dehydrogenase 2 (ALDH2) genotypes with SGCs. We then stratified the risk of SGCs by combining prespecified two factors and risk factors identified in this study.

RESULTS

Among 802 patients, 130 had SGCs. Both the ADH1B Arg and ALDH2 Lys alleles demonstrated a significant association with SGCs on multivariate analysis (odds ratio, 1.77), although alcohol drinking status showed no association. The rates of SGCs in 0-3 risk factors in the combined evaluation of three risk factors (ever-smoking, severe gastric atrophy in pepsinogen, and both the ADH1B Arg and ALDH2 Lys alleles) were 7.6%, 15.0%, 22.0%, and 32.1%, respectively. The risk significantly increased from 0 to 3 risk factors on multivariate analysis (P for trend <0.001).

CONCLUSIONS

Both the ADH1B Arg and ALDH2 Lys alleles were at high risk for SGCs. The risk stratification by these three factors may be a less invasive and promising tool for predicting their risk.

The Impact of Tobacco Smoking and Alcohol Consumption on the Development of Gastric Cancers

Chronic infection of Helicobacter pylori is considered the principal cause of gastric cancers, but evidence has accumulated regarding the impact of tobacco smoking and alcohol consumption on the development of gastric cancers. Several possible mechanisms, including the activation of nicotinic acetylcholine receptors, have been proposed for smoking-induced gastric carcinogenesis. On the other hand, local acetaldehyde exposure and ethanol-induced mucosal inflammation have been proposed as the mechanisms involved in the development of gastric cancers in heavy alcohol drinkers. In addition, genetic polymorphisms are also considered to play a pivotal role in smoking-related and alcohol-related gastric carcinogenesis. In this review, we will discuss the molecular mechanisms involved in the development of gastric cancers in relation to tobacco smoking and alcohol consumption.

A phenome-wide association and Mendelian randomisation study of alcohol use variants in a diverse cohort comprising over 3 million individuals

BACKGROUND

Alcohol consumption is associated with numerous negative social and health outcomes. These associations may be direct consequences of drinking, or they may reflect common genetic factors that influence both alcohol consumption and other outcomes.

METHODS

We performed exploratory phenome-wide association studies (PheWAS) of three of the best studied protective single nucleotide polymorphisms (SNPs) in genes encoding ethanol metabolising enzymes (ADH1B: rs1229984-T, rs2066702-A; ADH1C: rs698-T) using up to 1109 health outcomes across 28 phenotypic categories (e.g., substance-use, mental health, sleep, immune, cardiovascular, metabolic) from a diverse 23andMe cohort, including European (N ≤ 2,619,939), Latin American (N ≤ 446,646) and African American (N ≤ 146,776) populations to uncover new and perhaps unexpected associations. These SNPs have been consistently implicated by both candidate gene studies and genome-wide association studies of alcohol-related behaviours but have not been investigated in detail for other relevant phenotypes in a hypothesis-free approach in such a large cohort of multiple ancestries. To provide insight into potential causal effects of alcohol consumption on the outcomes significant in the PheWAS, we performed univariable two-sample and one-sample Mendelian randomisation (MR) analyses.

FINDINGS

The minor allele rs1229984-T, which is protective against alcohol behaviours, showed the highest number of PheWAS associations across the three cohorts (N = 232, European; N = 29, Latin American; N = 7, African American). rs1229984-T influenced multiple domains of health. We replicated associations with alcohol-related behaviours, mental and sleep conditions, and cardio-metabolic health. We also found associations with understudied traits related to neurological (migraines, epilepsy), immune (allergies), musculoskeletal (fibromyalgia), and reproductive health (preeclampsia). MR analyses identified evidence of causal effects of alcohol consumption on liability for 35 of these outcomes in the European cohort.

INTERPRETATION

Our work demonstrates that polymorphisms in genes encoding alcohol metabolising enzymes affect multiple domains of health beyond alcohol-related behaviours. Understanding the underlying mechanisms of these effects could have implications for treatments and preventative medicine.

FUNDING

MVJ, NCK, SBB, SSR and AAP were supported by T32IR5226 and 28IR-0070. SSR was also supported by NIDA DP1DA054394. NCK and RBC were also supported by R25MH081482. ASH was supported by funds from NIAAA K01AA030083. JLMO was supported by VA 1IK2CX002095. JLMO and JJMM were also supported by NIDA R21DA050160. JJMM was also supported by the Kavli Postdoctoral Award for Academic Diversity. EGA was supported by K01MH121659 from the NIMH/NIH, the Caroline Wiess Law Fund for Research in Molecular Medicine and the ARCO Foundation Young Teacher-Investigator Fund at Baylor College of Medicine. MSA was supported by the Instituto de Salud Carlos III and co-funded by the European Union Found: Fondo Social Europeo Plus (FSE+) (P19/01224, PI22/00464 and CP22/00128).

A glycolytic metabolite bypasses "two-hit" tumor suppression by BRCA2

Knudson's "two-hit" paradigm posits that carcinogenesis requires inactivation of both copies of an autosomal tumor suppressor gene. Here, we report that the glycolytic metabolite methylglyoxal (MGO) transiently bypasses Knudson's paradigm by inactivating the breast cancer suppressor protein BRCA2 to elicit a cancer-associated, mutational single-base substitution (SBS) signature in nonmalignant mammary cells or patient-derived organoids. Germline monoallelic BRCA2 mutations predispose to these changes. An analogous SBS signature, again without biallelic BRCA2 inactivation, accompanies MGO accumulation and DNA damage in Kras-driven, Brca2-mutant murine pancreatic cancers and human breast cancers. MGO triggers BRCA2 proteolysis, temporarily disabling BRCA2's tumor suppressive functions in DNA repair and replication, causing functional haploinsufficiency. Intermittent MGO exposure incites episodic SBS mutations without permanent BRCA2 inactivation. Thus, a metabolic mechanism wherein MGO-induced BRCA2 haploinsufficiency transiently bypasses Knudson's two-hit requirement could link glycolysis activation by oncogenes, metabolic disorders, or dietary challenges to mutational signatures implicated in cancer evolution.

Effects of Glutathione S-Transferases (GSTM1, GSTT1 and GSTP1) gene variants in combination with smoking or drinking on cancers: A meta-analysis

BACKGROUND

This meta-analysis aimed to systematically summarize the association between cancer risks and glutathione s-transferases (GSTs) among smokers and drinkers.

METHODS

Literature was searched through PubMed, Web of Science, CNKI, and WANFANG published from 2001 to 2022. Stata was used with fixed-effect model or random-effect model to calculate pooled odds ratios (ORs) and the 95% confidence interval (95% CI). Sensitivity and heterogeneity calculations were performed, and publication bias was analyzed by Begg and Egger's test. Regression analysis was performed on the correlated variables about heterogeneity, and the false-positive report probabilities (FPRP) and the Bayesian False Discovery Probability (BFDP) were calculated to assess the confidence of a statistically significant association.

RESULTS

A total of 85 studies were eligible for GSTs and cancer with smoking status (19,604 cases and 23,710 controls), including 14 articles referring to drinking status (4409 cases and 5645 controls). GSTM1-null had significant associations with cancer risks (for smokers: OR = 1.347, 95% CI: 1.196-1.516, P < .001; for nonsmokers: OR = 1.423, 95% CI: 1.270-1.594, P < .001; for drinkers: OR = 1.748, 95% CI: 1.093-2.797, P = .02). GSTT1-null had significant associations with cancer risks (for smokers: OR = 1.356, 95% CI: 1.114-1.651, P = .002; for nonsmokers: OR = 1.103, 95% CI: 1.011-1.204, P = .028; for drinkers: OR = 1.423, 95% CI: 1.042-1.942, P = .026; for nondrinkers: OR = 1.458, 95% CI: 1.014-2.098, P = .042). Negative associations were found between GSTP1rs1695(AG + GG/AA) and cancer risks among nondrinkers (OR = 0.840, 95% CI: 0.711-0.985, P = .032).

CONCLUSIONS

GSTM1-null and GSTT1-null might be related cancers in combination with smoking or drinking, and GSTP1rs1695 might be associated with cancers among drinkers.

The aldehyde dehydrogenase 2 rs671 variant enhances amyloid β pathology

In the ALDH2 rs671 variant, a guanine changes to an adenine, resulting in a dramatic decrease in the catalytic activity of the enzyme. Population-based data are contradictory about whether this variant increases the risk of Alzheimer's disease. In East Asian populations, the prevalence of the ALDH2 rs671 variant is 30-50%, making the National Human Brain Bank for Development and Function (the largest brain bank in East Asia) an important resource to explore the link between the ALDH2 rs671 polymorphism and Alzheimer's disease pathology. Here, using 469 postmortem brains, we find that while the ALDH2 rs671 variant is associated with increased plaque deposits and a higher Aβ40/42 ratio, it is not an independent risk factor for Alzheimer's disease. Mechanistically, we show that lower ALDH2 activity leads to 4-HNE accumulation in the brain. The (R)-4-HNE enantiomer adducts to residue Lys53 of C99, favoring Aβ40 generation in the Golgi apparatus. Decreased ALDH2 activity also lowers inflammatory factor secretion, as well as amyloid β phagocytosis and spread in brains of patients with Alzheimer's disease. We thus define the relationship between the ALDH2 rs671 polymorphism and amyloid β pathology, and find that ALDH2 rs671 is a key regulator of Aβ40 or Aβ42 generation.

Asian flush is a potential protective factor against COVID-19: a web-based retrospective survey in Japan

BACKGROUND

Coronavirus disease 2019 (COVID-19), first reported in December 2019, spread worldwide in a short period, resulting in numerous cases and associated deaths; however, the toll was relatively low in East Asia. A genetic polymorphism unique to East Asians, Aldehyde dehydrogenase 2 rs671, has been reported to confer protection against infections.

METHOD

We retrospectively investigated the association between the surrogate marker of the rs671 variant, the skin flushing phenomenon after alcohol consumption, and the timing of COVID-19 incidence using a web-based survey tool to test any protective effects of rs671 against COVID-19.

RESULTS

A total of 807 valid responses were received from 362 non-flushers and 445 flushers. During the 42 months, from 12/1/2019 to 5/31/2023, 40.6% of non-flushers and 35.7% of flushers experienced COVID-19. Flushers tended to have a later onset (Spearman's partial rank correlation test, p = 0.057, adjusted for sex and age). Similarly, 2.5% of non-flushers and 0.5% of flushers were hospitalized because of COVID-19. Survival analysis estimated lower risks of COVID-19 and associated hospitalization among flushers (p = 0.03 and <0.01, respectively; generalized Wilcoxon test). With the Cox proportional hazards model covering 21 months till 8/31/2021, when approximately half of the Japanese population had received two doses of COVID-19 vaccine, the hazard ratio (95% confidence interval) of COVID-19 incidence was estimated to be 0.21 (0.10-0.46) for flusher versus non-flusher, with adjustment for sex, age, steroid use, and area of residence.

CONCLUSIONS

Our study suggests an association between the flushing phenomenon after drinking and a decreased risk of COVID-19 morbidity and hospitalization, suggesting that the rs671 variant is a protective factor. This study provides valuable information for infection control and helps understand the unique constitutional diversity of East Asians.

Alcohol intake and cause-specific mortality: conventional and genetic evidence in a prospective cohort study of 512 000 adults in China

BACKGROUND

Genetic variants that affect alcohol use in East Asian populations could help assess the causal effects of alcohol consumption on cause-specific mortality. We aimed to investigate the associations between alcohol intake and cause-specific mortality using conventional and genetic epidemiological methods among more than 512 000 adults in China.

METHODS

The prospective China Kadoorie Biobank cohort study enrolled 512 724 adults (210 205 men and 302 519 women) aged 30-79 years, during 2004-08. Residents with no major disabilities from ten diverse urban and rural areas of China were invited to participate, and alcohol use was self-reported. During 12 years of follow-up, 56 550 deaths were recorded through linkage to death registries, including 23 457 deaths among 168 050 participants genotyped for ALDH2-rs671 and ADH1B-rs1229984. Adjusted hazard ratios (HRs) for cause-specific mortality by self-reported and genotype-predicted alcohol intake were estimated using Cox regression.

FINDINGS

33% of men drank alcohol most weeks. In conventional observational analyses, ex-drinkers, non-drinkers, and heavy drinkers had higher risks of death from most major causes than moderate drinkers. Among current drinkers, each 100 g/week higher alcohol intake was associated with higher mortality risks from cancers (HR 1·18 [95% CI 1·14-1·22]), cardiovascular disease (CVD; HR 1·19 [1·15-1·24]), liver diseases (HR 1·51 [1·27-1·78]), non-medical causes (HR 1·15 [1·08-1·23]), and all causes (HR 1·18 [1·15-1·20]). In men, ALDH2-rs671 and ADH1B-rs1229984 genotypes predicted 60-fold differences in mean alcohol intake (4 g/week in the lowest group vs 255 g/week in the highest). Genotype-predicted alcohol intake was uniformly and positively associated with risks of death from all causes (n=12 939; HR 1·07 [95% CI 1·05-1·10]) and from pre-defined alcohol-related cancers (n=1274; 1·12 [1·04-1·21]), liver diseases (n=110; 1·31 [1·02-1·69]), and CVD (n=6109; 1·15 [1·10-1·19]), chiefly due to stroke (n=3285; 1·18 [1·12-1·24]) rather than ischaemic heart disease (n=2363; 1·06 [0·99-1·14]). Results were largely consistent using a polygenic score to predict alcohol intake, with higher intakes associated with higher risks of death from alcohol-related cancers, CVD, and all causes. Approximately 2% of women were current drinkers, and although power was low to assess observational associations of alcohol with mortality, the genetic evidence suggested that the excess risks in men were due to alcohol, not pleiotropy.

INTERPRETATION

Higher alcohol intake increased the risks of death overall and from major diseases for men in China. There was no genetic evidence of protection from moderate drinking for all-cause and cause-specific mortality, including CVD.

FUNDING

Kadoorie Charitable Foundation, National Natural Science Foundation of China, British Heart Foundation, Cancer Research UK, GlaxoSmithKline, Wellcome Trust, Medical Research Council, and Chinese Ministry of Science and Technology.

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.

Relationship between esophageal squamous cell carcinoma risk and alcohol-related ALDH2 and ADH1B polymorphisms: Evidence from a meta-analysis and Mendelian randomization analysis

BACKGROUND

Previous studies have shown that ALDH2 and ADH1B genes may be associated with alcohol metabolism and the risk of esophageal squamous cell carcinoma (ESCC), with inconsistent results. This meta-analysis aimed at comprehensively assessing the associations between ALDH2 and ADH1B polymorphisms and the risk of ESCC to synthesize and clarify the evidence.

METHODS

We calculated summary estimates of the associations between four genetic variants (rs671 and rs674 in ALDH2, and rs1229984 and rs1042026 in ADH1B) and the ESCC risk across 23 publications in the additive model and allelic model. Venice criteria, Bayesian false discovery probability (BFDP), and false-positive reporting probability (FPRP) were used to assess the strength of epidemiological evidence. Heterogeneity among studies was evaluated by using the Higgin's I2 statistic, and publication bias was assessed by using funnel plots and Begg's test. A Mendelian randomization (MR) analysis was performed to determine the causal association between alcohol intake and esophageal cancer risk. Data from the HaploReg v4.1 and PolyPhen-2 were analyzed for functional annotations.

RESULTS

Of the four genetic variants, rs671 of ALDH2 was associated with a significantly reduced risk of ESCC (OR: 0.60, 95% CI: 0.50-0.73), whereas rs1229984 of ADH1B was associated with a significantly increased risk (2.50, 95% CI: 1.70-3.69) in the additive model. In the allelic model, the variant rs1229984 of ADH1B also increased the risk of ESCC (OR: 1.50; 95% CI: 1.21-1.87). The result for the variant rs671 was considered as strong epidemiological evidence. Functional annotations identified that the four variants were related to the enhancer histone marks and motif changes. The other two variants were not associated with the ESCC risk (rs674 of ALDH2 OR: 1.22, 95% CI: 0.71-2.12; rs1042026 of ADH1B OR: 1.28, 95% CI: 0.52-3.14) in the additive model. The MR analysis did not find a causal effect of alcohol on the esophageal cancer risk.

CONCLUSIONS

The results showed that ADH1B rs1229984 was significantly associated with an increased the risk of ESCC.

Alcohol consumption and risks of more than 200 diseases in Chinese men

Alcohol consumption accounts for ~3 million annual deaths worldwide, but uncertainty persists about its relationships with many diseases. We investigated the associations of alcohol consumption with 207 diseases in the 12-year China Kadoorie Biobank of >512,000 adults (41% men), including 168,050 genotyped for ALDH2- rs671 and ADH1B- rs1229984 , with >1.1 million ICD-10 coded hospitalized events. At baseline, 33% of men drank alcohol regularly. Among men, alcohol intake was positively associated with 61 diseases, including 33 not defined by the World Health Organization as alcohol-related, such as cataract (n = 2,028; hazard ratio 1.21; 95% confidence interval 1.09-1.33, per 280 g per week) and gout (n = 402; 1.57, 1.33-1.86). Genotype-predicted mean alcohol intake was positively associated with established (n = 28,564; 1.14, 1.09-1.20) and new alcohol-associated (n = 16,138; 1.06, 1.01-1.12) diseases, and with specific diseases such as liver cirrhosis (n = 499; 2.30, 1.58-3.35), stroke (n = 12,176; 1.38, 1.27-1.49) and gout (n = 338; 2.33, 1.49-3.62), but not ischemic heart disease (n = 8,408; 1.04, 0.94-1.14). Among women, 2% drank alcohol resulting in low power to assess associations of self-reported alcohol intake with disease risks, but genetic findings in women suggested the excess male risks were not due to pleiotropic genotypic effects. Among Chinese men, alcohol consumption increased multiple disease risks, highlighting the need to strengthen preventive measures to reduce alcohol intake.

High ALDH2 expression is associated with better prognosis in patients with gastric cancer

The relationship among alcohol, acetaldehyde, and gastric cancer (GC) is a very interesting research direction. Although many studies have focused on the correlation between ALDH2 polymorphism and GC, ALDH2 expression in GC and its relationship with the prognosis of GC patients remain to be fully understood. To explore these, 455 GC cases were included in this study. The relationships of ALDH2 expression with patients' survival and clinicopathological characteristics were assessed. The immune infiltration characteristics of ALDH2 in GC were also analyzed. Furthermore, the gene regulatory network and functional pathways of ALDH2 in GC were investigated. We found that high expression of ALDH2 was associated with better prognosis in GC patients. GC patients with high ALDH2 expression had a lower degree of pathological malignancy, consistent with our hypothesis that ALDH2 may play as a tumor suppressor role in GC. Mechanistically, ALDH2 may cooperate with genes such as C5orf32, TSPAN8 and RILP to inhibit GC progression via regulating multiple signaling pathways and chemical carcinogenesis. Therefore, our study suggested that ALDH2, an important variant gene in Asians, might serve as a prognostic marker and a potential therapeutic target for patients with GC.

Association between Dietary Behaviors and BMI Stratified by Sex and the ALDH2 rs671 Polymorphism in Japanese Adults

The rs671 polymorphism, unique to East Asians, is well known to change the sensitivity to alcohol. Moreover, this polymorphism is associated not only with alcohol intake but also with several dietary behaviors (DBs), chronic diseases, and BMI, but the triadic association among the rs671 genotype, DBs, and BMI is unclear. This study included 12,271 Japanese subjects and aimed to observe this three-way association using the rs671 polymorphism, data of 56 DBs, and BMI. All analyses were stratified by participant sex. First, linear regression analyses resulted in significant associations between 18 and 21 DBs and BMI in males and females, respectively. Next, genetic heterogeneity was observed in all sub-groups via interaction analysis of the rs671 genotype stratified by drinking habits. Finally, we observed the characteristics of BMI-related DBs based on the rs671 genotype via stepwise regression analyses stratified by the rs671 genotype and drinking habits. Notably, positive associations were observed between lactobacillus beverage intake and BMI among participants with the rs671 polymorphism AA genotype in both sexes. This study suggests that the rs671 polymorphism modifies the association between DBs and BMI independently of drinking habits, providing evidence for the potential use of rs671 polymorphism information for precision nutrition with East Asians.

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.

ALDH2 knockout protects against aortic dissection

Background

The incidence and mortality of aortic dissection (AD) are increasing. In pathological studies, macrophages, T lymphocytes and dendritic cells were found in the tunica media of the aorta. Acetaldehyde dehydrogenase 2 (ALDH₂) gene polymorphisms are associated with a high incidence of hypertension in Asian populations. However, there is no clear evidence of the relationship between ALDH₂ and aortic dissection in Asians. The aim of this study was to investigate the incidence of aortic dissection in different ALDH₂ genotypes and explore changes in the vasculature.

Materials and methods

Three-week-old male mice were administered freshly prepared β-aminopropionitrile solution dissolved in drinking water (1 g/kg/d) for 28 days to induce TAD. An animal ultrasound imaging system was used to observe the formation of arterial dissection and changes in cardiac function. Subsequently, mice were euthanized by cervical dislocation. The aortas were fixed for HE staining and EVG staining to observe aortic elastic fiber tears and pseudoluma formation under a microscope.

Results

Knockout of ALDH₂ mitigated β-aminopropionitrile-induced TAD formation in animal studies. Ultrasound results showed that ALDH₂ knockout reduced the degree of ascending aortic widening and the incidence of aortic dissection rupture. Pathological sections of multiple aortic segments showed that the protective effect of ALDH₂ knockout was observed in not only the ascending aorta but also the aortic arch and descending aorta. The expression levels of genes related to NK CD56bright cells, Th17 cells, T cells and T helper cells were decreased in ALDH₂ knockout mice treated with β-aminopropionitrile for 28 days.

Conclusion

ALDH₂ knockout protects against aortic dissection by altering the inflammatory response and immune response and protecting elastic fibers.

ALDH2 variance in disease and populations

The ALDH2*2 missense variant that commonly causes alcohol flushing reactions is the single genetic polymorphism associated with the largest number of traits in humans. The dysfunctional ALDH2 variant affects nearly 8% of the world population and is highly concentrated among East Asians. Carriers of the ALDH2*2 variant commonly present alterations in a number of blood biomarkers, clinical measurements, biometrics, drug prescriptions, dietary habits and lifestyle behaviors, and they are also more susceptible to aldehyde-associated diseases, such as cancer and cardiovascular disease. However, the interaction between alcohol and ALDH2-related pathology is not clearly delineated. Furthermore, genetic evidence indicates that the ALDH2*2 variant has been favorably selected for in the past 2000-3000 years. It is therefore necessary to consider the disease risk and mechanism associated with ALDH2 deficiency, and to understand the possible beneficial or protective effect conferred by ALDH2 deficiency and whether the pleiotropic effects of ALDH2 variance are all mediated by alcohol use.

Alcohol Consumption, ALDH2 Polymorphism as Risk Factors for Upper Aerodigestive Tract Cancer Progression and Prognosis

The upper aerodigestive tract (UADT) is highly susceptible to multiple primary cancers originated from squamous epithelia and constitutes a field of cancerization. Patients with head and neck cancer (head and neck squamous cell carcinoma, HNSCC) are at high risk of developing multiple cancers in the esophagus (esophageal squamous cell carcinoma, ESCC). Conversely, esophageal cancer patients are prone to develop multiple primary tumors in the head and neck region. The East Asian-specific dysfunctional ALDH2*2 missense mutation is a genetic risk factor for UADT cancer. It is not only associated with increased incidences of UADT cancer, but is also implicated in faster cancer progression and poorer prognosis. Alcohol use is a major lifestyle risk factor which causes UADT cancer among ALDH2*2 carriers. The accumulation of the immediate metabolite of alcohol, acetaldehyde, is likely the genotoxic agents that is involved in the process of tumorigenesis. This review summarizes recent publications on the risk and association of ALDH2*2 mutation, alcohol consumption in synchronous, metachronous UADT cancer. Possible molecular mechanisms involved in cancer initiation, progress and prognosis are discussed. The review also highlights a need for precision medicine-based preventive and therapeutic strategies by integrating lifestyle and genetic risk factors, such as alcohol consumption, genotypes of the alcohol metabolizing genes, ADH1B and ALDH2, into a risk assessment model for better screening, surveillance and treatment outcome.