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

The effects of modest drinking on life expectancy and mortality risks: a population-based cohort study

Modest drinking has been repeatedly discussed in scientific papers as protective against certain diseases, such as cardiovascular diseases, but in most cases, alcohol worsens health conditions, especially when consumed at high risk levels. The complexity of the risk relationship between alcohol and health conditions has confused clinicians as to whether it should be recommended. The study aims to balance the risks and benefits of modest drinking. This retrospective cohort study of 430,016 adults recruited from a standard health-screening program since 1994, with 11,031 deaths identified as of 2008. Drinking distinguished “modest drinker” (no more than one drink a day) from “regular drinker”. Mortality risks including all-cause mortality and diseases-specific mortality with hazard ratio (HR) were calculated by adjusting for 15 confounders. Life table was used for life expectancy. Risk predictors were subjected to Cox proportional hazards regression analysis to identify significant predictors in multivariate models and life expectancy analysis. Nearly one out of 4 males (23%) was a modest drinker, who gained 0.94 year (95% CI 0.65–1.23 year) in life over non-drinker and had 8% reduction in adjusted all-cause mortality (HR 0.92, 95% CI 0.86–0.97). In contrast, regular drinkers had 43% increase in overall mortality (HR 1.43, CI 1.35–1.52) and shortened life by 6.9 years (95% CI 6.6–7.1 years). As most drinkers also smoked, 59% in modest and 75% in regular, the combined effect shortened life by 2.0 years (95% CI 1.6–2.4 years) in modest drinker and 10.3 years (95% CI 9.8–10.7 years) in regular drinker. Cancer were increased in modest drinkers for oral (HR 2.35, CI 1.38–4.01) and esophageal (HR 3.83, CI 1.90–7.73) cancer. The gain of one year by modest drinkers was erased by a two to fourfold increase in oral and esophageal cancer and that drinking beyond modest amount led to a large loss of life expectancy. Given that drinkers are prone to cross the line of drinking, clinicians should balance the risks and benefits of drinking, as well as the understanding of whether the patient is at risk for addiction.

Genotoxic aldehydes in the hematopoietic system

Reactive aldehydes are potent genotoxins that threaten the integrity of hematopoietic stem cells and blood production. To protect against aldehydes, mammals have evolved a family of enzymes to detoxify aldehydes, and the Fanconi anemia DNA repair pathway to process aldehyde-induced DNA damage. Loss of either protection mechanisms in humans results in defective hematopoiesis and predisposition to leukemia. This review will focus on the impact of genotoxic aldehydes on hematopoiesis, the sources of endogenous aldehydes, and potential novel protective pathways.

Computational Investigation of Structural Basis for Enhanced Binding of Isoflavone Analogues with Mitochondrial Aldehyde Dehydrogenase

Isoflavone compounds are potent inhibitors against mitochondrial aldehyde dehydrogenase (ALDH2) for the treatment of alcoholism and drug addiction, and an in-depth understanding of the underlying structural basis helps design new inhibitors for enhanced binding. Here, we investigated the binding poses and strengths of eight isoflavone analogues (including CVT-10216 and daidzin) with ALDH2 via computational methods of molecular docking, molecular dynamics (MD) simulation, molecular mechanics Poisson-Boltzmann surface area (MM-PBSA), steered MD, and umbrella sampling. Neither the Vina scoring of docked and MD-sampled complexes nor the nonbonded protein-inhibitor interaction energy from MD simulations is able to reproduce the relative binding strength of the inhibitors compared to experimental IC₅₀ values. Considering the solvation contribution, MM-PBSA and relatively expensive umbrella sampling yield good performance for the relative binding (free) energies. The isoflavone skeleton prefers to form π-π stacking, π-sulfur, and π-alkyl interactions with planar (Phe and Trp) or sulfur-containing (Cys and Met) residues. The enhanced inhibition of CVT-10216 originates from both end groups of the isoflavone skeleton offering strong van der Waals contacts and from the methylsulfonamide group at the 4' position by hydrogen bonding (HB) with neighboring receptor residues. These results indicate that the hydrophobic binding tunnel of ALDH2 is larger than the isoflavone skeleton in length and thus an extended hydrophobic core is likely a premise for potent inhibitors.

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.

Molecular Characterization and Clinical Relevance of ALDH2 in Human Cancers

Background: Aldehyde dehydrogenase 2 (ALDH2) is well-known to be a key enzyme in alcohol metabolism. However, a comprehensive understanding of ALDH2 across human cancers is lacking.

Methods: A systematic and comprehensive analysis of the molecular alterations and clinical relevance for ALDH2 in more than 10,000 samples from 33 cancer types was performed. qRT-PCR was performed on 60 cancer and 60 paired nontumor tissues.

Results: It was observed that ALDH2 was generally downregulated in most cancers, which was mainly driven by DNA hypermethylation rather than mutations or copy number variations. Besides, ALDH2 was closely related to the inhibition and activation of tumor pathways and a variety of potential targeted agents had been discovered in our research. Last but not least, ALDH2 had the best prediction efficacy in assessing immunotherapeutic response compared with PD-L1, PD-1, CTLA4, CD8, and tumor mutation burden (TMB) in cutaneous melanoma. According to the analysis of large-scale public data and 60 pairs of clinical cancer samples, we found the downregulation of ALDH2 expression tends to suggest the malignant phenotypes and adverse prognosis, which might enhance the precise diagnosis and timely intervention of cancer patients.

Conclusion: This study advanced the understanding of ALDH2 across cancers, and provided important insight into chemotherapy, immunotherapy and prognosis of patients with cancer.

microRNA-133b Regulates Cell Proliferation and Cell Cycle Progression via Targeting HuR in Colorectal Cancer

MicroRNAs (miRNAs/miRs) have been identified to serve a key role in the development of tumors. However, the role of miR-133b in colorectal cancer (CRC) remains largely unclear. This study will investigate the role and mechanism of miR-133b in CRC. Reverse transcription-quantitative polymerase chain reaction analysis was performed to detect the level of miR-133b in CRC cell lines. Bioinformatics software TargetScan predicted the potential target genes of miR-133b, and a dual luciferase reporter assay was used to confirm this. To investigate the role of miR-133b in CRC cells, miR-133b was upregulated or downregulated in CRC cell lines (SW620 and HT-29) by transfecting with a miR-133b mimic or inhibitor, respectively. Subsequently, cell viability was analyzed using MTT assay, whereas cell apoptosis and the cell cycle distribution were analyzed by flow cytometry. In addition, the associated protein levels were detected using western blot analysis. The results demonstrated that miR-133b was significantly downregulated in CRC cell lines when compared with the normal colonic epithelial NCM-460 cell line. Human antigen R (HuR; also termed ELAVL1) was demonstrated to be a direct target of miR-133b and was negatively regulated by miR-133b. HuR was also notably upregulated in the CRC cell lines when compared with the normal control. Transfection of SW620 and HT-29 cells with the miR-133b mimic significantly inhibited cell viability, and induced cell apoptosis and G1 phase arrest, while upregulation of HuR demonstrated the opposite effects. Furthermore, the present data demonstrated that the miR-133b mimic significantly enhanced the protein levels of p21 and p27, and downregulated cyclin D1 and cyclin A levels in SW620 and HT-29 cells; the opposite effects were observed following treatment with the miR-133b inhibitor. In conclusion, the data indicate that miR-133b suppressed CRC cell growth by targeting HuR.

Biliary Epithelial Senescence in Liver Disease: There Will Be SASP

Cellular senescence is a pathophysiological phenomenon in which proliferative cells enter cell cycle arrest following DNA damage and other stress signals. Natural, permanent DNA damage can occur after repetitive cell division; however, acute stress or other injuries can push cells into premature senescence and eventually a senescence-associated secretory phenotype (SASP). In recent years, there has been increased evidence for the role of premature senescence in disease progression including diabetes, cardiac diseases, and end-stage liver diseases including cholestasis. Liver size and function change with aging, and presumably with increasing cellular senescence, so it is important to understand the mechanisms by which cellular senescence affects the functional nature of the liver in health and disease. As well, cells in a SASP state secrete a multitude of inflammatory and pro-fibrogenic factors that modulate the microenvironment. Cellular SASP and the associated, secreted factors have been implicated in the progression of liver diseases, such as cholestatic injury that target the biliary epithelial cells (i.e., cholangiocytes) lining the bile ducts. Indeed, cholangiocyte senescence/SASP is proposed to be a driver of disease phenotypes in a variety of liver injuries. Within this review, we will discuss the impact of cholangiocyte senescence and SASP in the pathogenesis of cholestatic disorders.

Lifestyle and Hepatocellular Carcinoma What Is the Evidence and Prevention Recommendations

Simple Summary

The increasing public health burden of Hepatocellular carcinoma (HCC) emphasizes the importance of defining important modifiable risk factors. In the following review, we will discuss the evidence for the relation of major lifestyle risk factors, mostly from large population-based studies. Generally, it is has been shown that healthy lifestyle habits, including minimizing obesity, eating a healthy diet, avoidance of smoking and alcohol, and increasing physical activity, have the potential to prevent HCC. Dietary composition is important beyond obesity. Consumption of n-3 polyunsaturated fatty acids, as well as fish and poultry, vegetables and fiber, are inversely associated with HCC, while red meat, saturated fat, cholesterol and sugar are related to increased risk. Data from multiple studies clearly show a beneficial effect for physical activity in reducing the risk of HCC. Smoking and alcohol can lead to liver fibrosis and liver cancer and jointly lead to an even greater risk.

Abstract

The increasing burden of hepatocellular carcinoma (HCC) emphasizes the unmet need for primary prevention. Lifestyle measures appear to be important modifiable risk factors for HCC regardless of its etiology. Lifestyle patterns, as a whole and each component separately, are related to HCC risk. Dietary composition is important beyond obesity. Consumption of n-3 polyunsaturated fatty acids, as well as fish and poultry, are inversely associated with HCC, while red meat, saturated fat, and cholesterol are related to increased risk. Sugar consumption is associated with HCC risk, while fiber and vegetable intake is protective. Data from multiple studies clearly show a beneficial effect for physical activity in reducing the risk of HCC. However, the duration, mode and intensity of physical activity needed are yet to be determined. There is evidence that smoking can lead to liver fibrosis and liver cancer and has a synergistic effect with alcohol drinking. On the other hand, an excessive amount of alcohol by itself has been associated with increased risk of HCC directly (carcinogenic effect) or indirectly (liver fibrosis and cirrhosis progression. Large-scale intervention studies testing the effect of comprehensive lifestyle interventions on HCC prevention among diverse cohorts of liver disease patients are greatly warranted.

Insight Into Nicotinamide Adenine Dinucleotide Homeostasis as a Targetable Metabolic Pathway in Colorectal Cancer

Tumour cells modify their cellular metabolism with the aim to sustain uncontrolled proliferation. Cancer cells necessitate adequate amounts of NAD and NADPH to support several enzymes that are usually overexpressed and/or overactivated. Nicotinamide adenine dinucleotide (NAD) is an essential cofactor and substrate of several NAD-consuming enzymes, such as PARPs and sirtuins, while NADPH is important in the regulation of the redox status in cells. The present review explores the rationale for targeting the key enzymes that maintain the cellular NAD/NADPH pool in colorectal cancer and the enzymes that consume or use NADP(H).

Intake of Lactobacillus rhamnosus GG (LGG) fermented milk before drinking alcohol reduces acetaldehyde levels and duration of flushing in drinkers with wild-type and heterozygous mutant ALDH2: a randomized, blinded crossover controlled trial

Alcohol consumption leads to acetaldehyde accumulation, especially in people with mutant aldehyde dehydrogenase 2 gene (ALDH2). Novel strategies to promote acetaldehyde detoxification are required to prevent alcohol-related toxicity. Probiotic bacteria such as Lactobacillus rhamnosus GG (LGG) were shown to have in vitro capacity to detoxify acetaldehyde. This randomized, blinded, placebo-controlled cross-over trial investigated the effect of LGG fermented milk in people with ALDH2 polymorphisms after moderate alcohol intake. Ten healthy wild-type and ten heterozygous mutant ALDH2 Thai men were block randomized into two groups. Each group consumed a different sequence of 150 mL fermented milk containing 10⁸ CFU mL^-1 LGG and lactic-acidified milk (placebo), followed by five glasses of beer (0.4 g ethanol per kg body weight), with a one-week wash-out. Consuming LGG fermented milk before alcohol reduced areas under the response curves of blood and salivary acetaldehyde in wild-type and heterozygous mutant ALDH2 individuals (p < 0.05 and p < 0.01, respectively). Interestingly, participants with mutant ALDH2 responded better than wild-type participants for salivary acetaldehyde (90% vs. 70%, p < 0.001). Their durations of flushing were reduced when consuming LGG milk. Regardless of ALDH2 status, 10⁵ CFU mL^-1 LGG was retained in saliva at least 3.5 h after milk consumption. In conclusion, intake of LGG fermented milk before drinking alcohol reduces blood and salivary acetaldehyde levels and duration of flushing in drinkers with wild-type and heterozygous mutant ALDH2. The addition of exogenous capacity to detoxify acetaldehyde using the probiotic product could be a potential strategy to promote the alleviation of exposure to reactive and carcinogenic acetaldehyde associated with alcohol drinking in individuals with defective ALDH2 enzyme.

Global colorectal cancer burden in 2020 and projections to 2040

As the third most common malignancy and the second most deadly cancer, colorectal cancer (CRC) induces estimated 1.9 million incidence cases and 0.9 million deaths worldwide in 2020. The incidence of CRC is higher in highly developed countries, and it is increasing in middle- and low-income countries due to westernization. Moreover, a rising incidence of early-onset CRC is also emerging. The large number of CRC cases poses a growing global public health challenge. Raising awareness of CRC is important to promote healthy lifestyle choices, novel strategies for CRC management, and implementation of global screening programs, which are critical to reducing CRC morbidity and mortality in the future. CRC is a heterogeneous disease, and its subtype affiliation influences prognosis and therapeutic response. An accurate CRC subtype classification system is of great significance for basic research and clinical outcome. Here, we present the global epidemiology of CRC in 2020 and projections for 2040, review the major CRC subtypes to better understand CRC molecular basis, and summarize current risk factors, prevention, and screening strategies for CRC.

The Aldehyde Dehydrogenase ALDH2*2 Allele, Associated with Alcohol Drinking Behavior, Dates Back to Prehistoric Times

Human alcohol-consumption behavior is partly genetically encoded. The alcohol consumption of 987 residents in Keelung, Taiwan, was evaluated by using the Alcohol Use Disorder Identification Test (AUDIT). We assessed ~750,000 genomic variants of 71 residents who drank hazardously (AUDIT score ≥ 8) and 126 residents who did not drink in their daily lives (AUDIT score = 0), using high-density single nucleotide polymorphism (SNP) arrays. The rs671 G > A manifests the highest significance of the association with drinking behavior (Fisher’s exact P = 8.75 × 10⁻⁹). It is a pleiotropic, non-synonymous variant in the aldehyde dehydrogenase 2 (ALDH2) gene. The minor allele “A”, commonly known as ALDH2*2, is associated with non-drinkers. Intriguingly, identity-by-descent haplotypes encompassing genomic regions with a median length of 1.6 (0.6–2.0) million nucleotide bases were found in all study participants with either heterozygous or homozygous ALDH2*2 (n = 81 and 13, respectively). We also analyzed a public-domain dataset with genome-wide genotypes of 2000 participants in Guangzhou, a coastal city in Southern China. Among them, 175 participants have homozygous ALDH2*2 genotype, and again, long ALDH2*2-carrying haplotypes were found in all 175 participants without exceptions. The median length of the ALDH2*2-carrying haplotype is 1.7 (0.5–2.8) million nucleotide bases. The haplotype lengths in the Keelung and Guangzhou cohorts combined indicate that the origin of the ALDH2*2 allele dates back to 7935 (7014–9381) years ago. In conclusion, the rs671 G > A is the leading genomic variant associated with the long-term drinking behavior among residents of Keelung, Taiwan. The ALDH2*2 allele has been in Asian populations since prehistoric times.

Alcohol and Cancer: Epidemiology and Biological Mechanisms

Approximately 4% of cancers worldwide are caused by alcohol consumption. Drinking alcohol increases the risk of several cancer types, including cancers of the upper aerodigestive tract, liver, colorectum, and breast. In this review, we summarise the epidemiological evidence on alcohol and cancer risk and the mechanistic evidence of alcohol-mediated carcinogenesis. There are several mechanistic pathways by which the consumption of alcohol, as ethanol, is known to cause cancer, though some are still not fully understood. Ethanol's metabolite acetaldehyde can cause DNA damage and block DNA synthesis and repair, whilst both ethanol and acetaldehyde can disrupt DNA methylation. Ethanol can also induce inflammation and oxidative stress leading to lipid peroxidation and further DNA damage. One-carbon metabolism and folate levels are also impaired by ethanol. Other known mechanisms are discussed. Further understanding of the carcinogenic properties of alcohol and its metabolites will inform future research, but there is already a need for comprehensive alcohol control and cancer prevention strategies to reduce the burden of cancer attributable to alcohol.

Molecular Mechanisms of Alcohol-Induced Colorectal Carcinogenesis

The etiology of colorectal cancer (CRC) is complex. Approximately, 10% of individuals with CRC have predisposing germline mutations that lead to familial cancer syndromes, whereas most CRC patients have sporadic cancer resulting from a combination of environmental and genetic risk factors. It has become increasingly clear that chronic alcohol consumption is associated with the development of sporadic CRC; however, the exact mechanisms by which alcohol contributes to colorectal carcinogenesis are largely unknown. Several proposed mechanisms from studies in CRC models suggest that alcohol metabolites and/or enzymes associated with alcohol metabolism alter cellular redox balance, cause DNA damage, and epigenetic dysregulation. In addition, alcohol metabolites can cause a dysbiotic colorectal microbiome and intestinal permeability, resulting in bacterial translocation, inflammation, and immunosuppression. All of these effects can increase the risk of developing CRC. This review aims to outline some of the most significant and recent findings on the mechanisms of alcohol in colorectal carcinogenesis. We examine the effect of alcohol on the generation of reactive oxygen species, the development of genotoxic stress, modulation of one-carbon metabolism, disruption of the microbiome, and immunosuppression.

Global, regional, and national burden of respiratory tract cancers and associated risk factors from 1990 to 2019: a systematic analysis for the Global Burden of Disease Study 2019

BACKGROUND

Prevention, control, and treatment of respiratory tract cancers are important steps towards achieving target 3.4 of the UN Sustainable Development Goals (SDGs)-a one-third reduction in premature mortality due to non-communicable diseases by 2030. We aimed to provide global, regional, and national estimates of the burden of tracheal, bronchus, and lung cancer and larynx cancer and their attributable risks from 1990 to 2019.

METHODS

Based on the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 methodology, we evaluated the incidence, mortality, years lived with disability, years of life lost, and disability-adjusted life-years (DALYs) of respiratory tract cancers (ie, tracheal, bronchus, and lung cancer and larynx cancer). Deaths from tracheal, bronchus, and lung cancer and larynx cancer attributable to each risk factor were estimated on the basis of risk exposure, relative risks, and the theoretical minimum risk exposure level input from 204 countries and territories, stratified by sex and Socio-demographic Index (SDI). Trends were estimated from 1990 to 2019, with an emphasis on the 2010-19 period.

FINDINGS

Globally, there were 2·26 million (95% uncertainty interval 2·07 to 2·45) new cases of tracheal, bronchus, and lung cancer, and 2·04 million (1·88 to 2·19) deaths and 45·9 million (42·3 to 49·3) DALYs due to tracheal, bronchus, and lung cancer in 2019. There were 209 000 (194 000 to 225 000) new cases of larynx cancer, and 123 000 (115 000 to 133 000) deaths and 3·26 million (3·03 to 3·51) DALYs due to larynx cancer globally in 2019. From 2010 to 2019, the number of new tracheal, bronchus, and lung cancer cases increased by 23·3% (12·9 to 33·6) globally and the number of larynx cancer cases increased by 24·7% (16·0 to 34·1) globally. Global age-standardised incidence rates of tracheal, bronchus, and lung cancer decreased by 7·4% (-16·8 to 1·6) and age-standardised incidence rates of larynx cancer decreased by 3·0% (-10·5 to 5·0) in males over the past decade; however, during the same period, age-standardised incidence rates in females increased by 0·9% (-8·2 to 10·2) for tracheal, bronchus, and lung cancer and decreased by 0·5% (-8·4 to 8·1) for larynx cancer. Furthermore, although age-standardised incidence and death rates declined in both sexes combined from 2010 to 2019 at the global level for tracheal, bronchus, lung and larynx cancers, some locations had rising rates, particularly those on the lower end of the SDI range. Smoking contributed to an estimated 64·2% (61·9-66·4) of all deaths from tracheal, bronchus, and lung cancer and 63·4% (56·3-69·3) of all deaths from larynx cancer in 2019. For males and for both sexes combined, smoking was the leading specific risk factor for age-standardised deaths from tracheal, bronchus, and lung cancer per 100 000 in all SDI quintiles and GBD regions in 2019. However, among females, household air pollution from solid fuels was the leading specific risk factor in the low SDI quintile and in three GBD regions (central, eastern, and western sub-Saharan Africa) in 2019.

INTERPRETATION

The numbers of incident cases and deaths from tracheal, bronchus, and lung cancer and larynx cancer increased globally during the past decade. Even more concerning, age-standardised incidence and death rates due to tracheal, bronchus, lung cancer and larynx cancer increased in some populations-namely, in the lower SDI quintiles and among females. Preventive measures such as smoking control interventions, air quality management programmes focused on major air pollution sources, and widespread access to clean energy should be prioritised in these settings.

FUNDING

Bill & Melinda Gates Foundation.

Global burden of cancer in 2020 attributable to alcohol consumption: a population-based study

BACKGROUND

Alcohol use is causally linked to multiple cancers. We present global, regional, and national estimates of alcohol-attributable cancer burden in 2020 to inform alcohol policy and cancer control across different settings globally.

METHODS

In this population-based study, population attributable fractions (PAFs) calculated using a theoretical minimum-risk exposure of lifetime abstention and 2010 alcohol consumption estimates from the Global Information System on Alcohol and Health (assuming a 10-year latency period between alcohol consumption and cancer diagnosis), combined with corresponding relative risk estimates from systematic literature reviews as part of the WCRF Continuous Update Project, were applied to cancer incidence data from GLOBOCAN 2020 to estimate new cancer cases attributable to alcohol. We also calculated the contribution of moderate (<20 g per day), risky (20-60 g per day), and heavy (>60 g per day) drinking to the total alcohol-attributable cancer burden, as well as the contribution by 10 g per day increment (up to a maximum of 150 g). 95% uncertainty intervals (UIs) were estimated using a Monte Carlo-like approach.

FINDINGS

Globally, an estimated 741 300 (95% UI 558 500-951 200), or 4·1% (3·1-5·3), of all new cases of cancer in 2020 were attributable to alcohol consumption. Males accounted for 568 700 (76·7%; 95% UI 422 500-731 100) of total alcohol-attributable cancer cases, and cancers of the oesophagus (189 700 cases [110 900-274 600]), liver (154 700 cases [43 700-281 500]), and breast (98 300 cases [68 200-130 500]) contributed the most cases. PAFs were lowest in northern Africa (0·3% [95% UI 0·1-3·3]) and western Asia (0·7% [0·5-1·2]), and highest in eastern Asia (5·7% [3·6-7·9]) and central and eastern Europe (5·6% [4·6-6·6]). The largest burden of alcohol-attributable cancers was represented by heavy drinking (346 400 [46·7%; 95% UI 227 900-489 400] cases) and risky drinking (291 800 [39·4%; 227 700-333 100] cases), whereas moderate drinking contributed 103 100 (13·9%; 82 600-207 200) cases, and drinking up to 10 g per day contributed 41 300 (35 400-145 800) cases.

INTERPRETATION

Our findings highlight the need for effective policy and interventions to increase awareness of cancer risks associated with alcohol use and decrease overall alcohol consumption to prevent the burden of alcohol-attributable cancers.

FUNDING

None.

Pancreatic cancer: A review of epidemiology, trend, and risk factors

Despite rapid advances in modern medical technology and significant improvements in survival rates of many cancers, pancreatic cancer is still a highly lethal gastrointestinal cancer with a low 5-year survival rate and difficulty in early detection. At present, the incidence and mortality of pancreatic cancer are increasing year by year worldwide, no matter in the United States, Europe, Japan, or China. Globally, the incidence of pancreatic cancer is projected to increase to 18.6 per 100000 in 2050, with the average annual growth of 1.1%, meaning that pancreatic cancer will pose a significant public health burden. Due to the special anatomical location of the pancreas, the development of pancreatic cancer is usually diagnosed at a late stage with obvious clinical symptoms. Therefore, a comprehensive understanding of the risk factors for pancreatic cancer is of great clinical significance for effective prevention of pancreatic cancer. In this paper, the epidemiological characteristics, developmental trends, and risk factors of pancreatic cancer are reviewed and analyzed in detail.

Generation of IBMS-iPSC-021, -022, -023 human induced pluripotent stem cells (IBMSi016-A, IBMSi017-A, and IBMSi018-A) derived from patients with the ALDH2 rs671 polymorphism

ALDH2 gene is coded for the aldehyde dehydrogenase (ALDH), which is an enzyme involved in alcohol metabolism. Compared to normal aldehyde dehydrogenases, a homozygous point mutation on exon 12 from G to A significantly reduces its efficiency. In this study, we have reported the generation of IBMS-iPSC-021-04, IBMS-iPSC-022-01, and IBMS-iPSC-023-03 as induced pluripotent stem cell (iPSC) lines carrying the homozygous form of ALDH2 with the rs671 genetic polymorphism (E487K mutation). These cell lines were characterized in terms of pluripotency and differentiation potential. They serve as useful platforms to study alcohol metabolism and other chronic diseases associated with alcohol consumption.

Insights into Aldehyde Dehydrogenase Enzymes: A Structural Perspective

Aldehyde dehydrogenases engage in many cellular functions, however their dysfunction resulting in accumulation of their substrates can be cytotoxic. ALDHs are responsible for the NAD(P)-dependent oxidation of aldehydes to carboxylic acids, participating in detoxification, biosynthesis, antioxidant and regulatory functions. Severe diseases, including alcohol intolerance, cancer, cardiovascular and neurological diseases, were linked to dysfunctional ALDH enzymes, relating back to key enzyme structure. An in-depth understanding of the ALDH structure-function relationship and mechanism of action is key to the understanding of associated diseases. Principal structural features 1) cofactor binding domain, 2) active site and 3) oligomerization mechanism proved critical in maintaining ALDH normal activity. Emerging research based on the combination of structural, functional and biophysical studies of bacterial and eukaryotic ALDHs contributed to the appreciation of diversity within the superfamily. Herewith, we discuss these studies and provide our interpretation for a global understanding of ALDH structure and its purpose–including correct function and role in disease. Our analysis provides a synopsis of a common structure-function relationship to bridge the gap between the highly studied human ALDHs and lesser so prokaryotic models.

The Role of Alcohol, LPS Toxicity, and ALDH2 in Dental Bony Defects

It is estimated that 560 million people carry an East Asian-specific ALDH2*2 dominant-negative mutation which leads to enzyme inactivation. This common ALDH2 polymorphism has a significant association with osteoporosis. We hypothesized that the ALDH2*2 mutation in conjunction with periodontal Porphyromonas gingivalis bacterial infection and alcohol drinking had an inhibitory effect on osteoblasts and bone regeneration. We examined the prospective association of ALDH2 activity with the proliferation and mineralization potential of human osteoblasts in vitro. The ALDH2 knockdown experiments showed that the ALDH2 knockdown osteoblasts lost their proliferation and mineralization capability. To mimic dental bacterial infection, we compared the dental bony defects in wild-type mice and ALDH2*2 knockin mice after injection with purified lipopolysaccharides (LPS), derived from P. gingivalis which is a bacterial species known to cause periodontitis. Micro-computed tomography (micro-CT) scan results indicated that bone regeneration was significantly affected in the ALDH2*2 knockin mice with about 20% more dental bony defects after LPS injection than the wild-type mice. Moreover, the ALDH2*2 knockin mutant mice had decreased osteoblast growth and more dental bone loss in the upper left jaw region after LPS injection. In conclusion, these results indicated that the ALDH2*2 mutation with alcohol drinking and chronic exposure to dental bacterial-derived toxin increased the risk of dental bone loss.

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.

Identification of New Markers of Alcohol-Derived DNA Damage in Humans

Alcohol consumption is a risk factor for the development of several cancers, including those of the head and neck and the esophagus. The underlying mechanisms of alcohol-induced carcinogenesis remain unclear; however, at these sites, alcohol-derived acetaldehyde seems to play a major role. By reacting with DNA, acetaldehyde generates covalent modifications (adducts) that can lead to mutations. Previous studies have shown a dose dependence between levels of a major acetaldehyde-derived DNA adduct and alcohol exposure in oral-cell DNA. The goal of this study was to optimize a mass spectrometry (MS)-based DNA adductomic approach to screen for all acetaldehyde-derived DNA adducts to more comprehensively characterize the genotoxic effects of acetaldehyde in humans. A high-resolution/-accurate-mass data-dependent constant-neutral-loss-MS³ methodology was developed to profile acetaldehyde-DNA adducts in purified DNA. This resulted in the identification of 22 DNA adducts. In addition to the expected N²-ethyldeoxyguanosine (after NaBH₃CN reduction), two previously unreported adducts showed prominent signals in the mass spectra. MSⁿ fragmentation spectra and accurate mass were used to hypothesize the structure of the two new adducts, which were then identified as N⁶-ethyldeoxyadenosine and N⁴-ethyldeoxycytidine by comparison with synthesized standards. These adducts were quantified in DNA isolated from oral cells collected from volunteers exposed to alcohol, revealing a significant increase after the exposure. In addition, 17 of the adducts identified in vitro were detected in these samples confirming our ability to more comprehensively characterize the DNA damage deriving from alcohol exposures.

Low-level alcohol consumption and cancer mortality

The effect of light-to-moderate alcohol consumption on cancer risk remains controversial. We examined the association between low-level alcohol consumption and cancer mortality. A cohort study included 331,984 Korean adults free of cancer at baseline who underwent a comprehensive health checkup examination. Participants were categorized into never drinkers, former drinkers, and current drinkers who were further divided into light, moderate, heavy, and very heavy drinkers. Vital status and cancer-related deaths were ascertained through links to national death records. During 1,633,906 person-years of follow-up (median 5.3 years interquartile range 3.8–6.2), 374 cancer-related deaths were identified (cancer-cause mortality rate of 23 per 10⁵ person-years). When former and never drinkers were classified as non-drinkers, the light drinkers had a lowest risk of cancer mortality compared with non-drinkers and other current drinkers (J-shaped); however, with consideration of lifetime abstinence history, current drinking was positively associated with cancer mortality in a dose-dependent manner. When changes in alcohol drinking status and confounders during follow-up were updated as time-varying covariates and never drinkers were used as the reference, the multivariable-adjusted hazard ratios (HRs) (95% confidence intervals, CIs) for cancer mortality among current light, moderate, heavy, and very heavy drinkers were 1.58 (1.03–2.43), 2.28 (1.41–3.70), 2.34 (1.42–3.85), and 2.97 (1.80–4.90), respectively, and the highest risk of cancer mortality was observed in former drinkers, who had an HR (95% CI) of 3.86 (2.38–6.28). Alcohol consumption was significantly and positively associated with an increased risk of cancer mortality in a dose-dependent manner, beginning with light drinkers.

Risk Factors and Genetic Biomarkers of Multiple Primary Cancers in Esophageal Cancer Patients

Esophageal cancer (EC) is a deadly cancer that frequently develops multiple primary cancers (MPCs). However, the risk biomarkers of MPC in EC have hardly been investigated. We retrospectively enrolled 920 subjects with primary EC and analyzed the possible risk factors as well as MPC single-nucleotide polymorphisms (SNPs) from blood DNA. A total of 184 subjects (20.0%) were confirmed to have MPC, 59 (32.8%) had synchronous MPC, and 128 (69.6%) had head and neck cancer. Elderly EC patients have an increased risk of having gastrointestinal cancer (Odds ratio, OR[95% CI]=6.70 [1.49-30.19], p=0.013) and a reduced risk of developing HNC (OR[95% CI]=0.44 [0.24-0.81], p=0.008). MPC risk was also associated with betel nut chewing (OR[95% CI]=1.63, 1.14-2.32], p=0.008), the A allele of ALDH2:rs671 (p=0.074 and 0.030 for GA and AA, respectively), the CC genotype in CISH:rs2239751 (OR[95% CI]=1.99 [1.2-3.32], p=0.008), and the G allele of ERCC5:rs17655 (p=0.001 and 0.090 for GC and CC, respectively). ADH1B:rs1229984 also correlated with MPC risk (p=0.117). Patients carrying four risk SNPs had a 40-fold risk of MPC (OR[95% CI]=40.25 [6.77-239.50], p<0.001) and a 12.57-fold risk of developing second primary cancer after EC (OR[95% CI]=12.57 [1.14-138.8], p=0.039) compared to those without any risk SNPs. In conclusion, hereditary variations in ALDH2, CISH, ERCC5, and ADH1B have great potential in predicting the incidence of MPC in EC patients. An extensive cancer screening program during clinical follow-up would be beneficial for patients with high MPC susceptibility.

Sources of Interindividual Variability

The efficacy, safety, and tolerability of drugs are dependent on numerous factors that influence their disposition. A dose that is efficacious and safe for one individual may result in sub-therapeutic or toxic blood concentrations in others. A significant source of this variability in drug response is drug metabolism, where differences in presystemic and systemic biotransformation efficiency result in variable degrees of systemic exposure (e.g., AUC, C_max, and/or C_min) following administration of a fixed dose.Interindividual differences in drug biotransformation have been studied extensively. It is recognized that both intrinsic factors (e.g., genetics, age, sex, and disease states) and extrinsic factors (e.g., diet , chemical exposures from the environment, and the microbiome) play a significant role. For drug-metabolizing enzymes, genetic variation can result in the complete absence or enhanced expression of a functional enzyme. In addition, upregulation and downregulation of gene expression, in response to an altered cellular environment, can achieve the same range of metabolic function (phenotype), but often in a less predictable and time-dependent manner. Understanding the mechanistic basis for variability in drug disposition and response is essential if we are to move beyond the era of empirical, trial-and-error dose selection and into an age of personalized medicine that will improve outcomes in maintaining health and treating disease.

The Impact of Acute or Chronic Alcohol Intake on the NF-κB Signaling Pathway in Alcohol-Related Liver Disease

Ethanol misuse is frequently associated with a multitude of profound medical conditions, contributing to health-, individual- and social-related damage. A particularly dangerous threat from this classification is coined as alcoholic liver disease (ALD), a liver condition caused by prolonged alcohol overconsumption, involving several pathological stages induced by alcohol metabolic byproducts and sustained cellular intoxication. Molecular, pathological mechanisms of ALD principally root in the innate immunity system and are especially associated with enhanced functionality of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway. NF-κB is an interesting and convoluted DNA transcription regulator, promoting both anti-inflammatory and pro-inflammatory gene expression. Thus, the abundancy of studies in recent years underlines the importance of NF-κB in inflammatory responses and the mechanistic stimulation of inner molecular motifs within the factor components. Hereby, in the following review, we would like to put emphasis on the correlation between the NF-κB inflammation signaling pathway and ALD progression. We will provide the reader with the current knowledge regarding the chronic and acute alcohol consumption patterns, the molecular mechanisms of ALD development, the involvement of the NF-κB pathway and its enzymatic regulators. Therefore, we review various experimental in vitro and in vivo studies regarding the research on ALD, including the recent active compound treatments and the genetic modification approach. Furthermore, our investigation covers a few human studies.

The applications of B. coagulans TCI711 in alcohol elimination

This study demonstrates the applications of Bacillus coagulans in alcohol elimination. Bacillus coagulans has recently drawn tremendous interest in the food industry and medicine considering its great environmental tolerance and beneficial effects on improving gastrointestinal diseases. However, few scientific reports connect its utilities with alcohol elimination. In this study, we introduced the unique strain B. coagulans TCI711 for such exploration. TCI711 contained alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) by mass spectrum and resisted gastric acid and bile acid. Also, taking TCI711 capsules for a week can significantly improve alcohol metabolism in humans (breath alcohol level indicated 0 mg/kg in 2 h after drinking 75 mL of whisky). In brief, this exploratory research unveiled the potent applications of B. coagulans in alcohol elimination in humans.

A glycolysis-related gene expression signature in predicting recurrence of breast cancer

Metabolic change is the hallmark of cancer. In the present study, we aimed to develop a glycolysis-related gene signature to predict the prognosis of breast cancer patients. Gene expression profiles and clinical data of breast cancer patients were obtained from the GEO database. A four-gene based signature (ALDH2, PRKACB, STMN1 and ZNF292) was developed to separate patients into high-risk and low-risk groups. Patients in the low-risk group had significantly better prognosis than those in the high-risk group. Time-dependent ROC analysis demonstrated that the glycolysis-related gene signature had excellent prognostic accuracy. We further confirmed the expression of the four prognostic genes in breast cancer and paracancerous tissue samples using qRT-PCR analysis. Expression level of PRKACB was higher in paracancerous tissues, while STMN1 and ZNF292 were overexpressed in tumor samples, no significant difference was observed in ALDH2 expression level. Global proteome data of 105 TCGA breast cancer samples obtained from the Clinical Proteomic Tumor Analysis Consortium (CPTAC) were used to evaluate the prognostic value in protein levels. Consistently, high expression level of PRKACB protein was associated with favorable prognosis, while high ZNF292 and STMN1 protein expression levels indicated poor prognosis. The glycolysis-related gene signature might provide an effective prognostic predictor and a new insight for individualize management of breast cancer patients.

Transformed ALDH2-/- hepatocytes by ethanol could serve as a useful tool for studying alcoholic hepatocarcinogenesis

Alcohol is a well-recognized hepatic carcinogen. Alcohol is metabolized into genotoxic acetaldehyde in hepatocytes, which is catalyzed by aldehyde dehydrogenase 2 (ALDH2). The detailed underlying mechanisms of alcohol-related hepatocellular carcinoma (HCC) remains unclear, at least partially, due to the absence of appropriate experimental models. Current studies suggest that rodents are not good models of the most common liver diseases that trigger HCC including alcoholic liver injury. We hypothesize that ethanol could induce transformation of immortalized normal liver cells, which may serve as a versatile tool for studying alcoholic HCC. Besides, we believe that knockout of ALDH2 will help to shorten the time course of transformation, as ALDH2 deficiency will significantly increase the accumulation of acetaldehyde in hepatocytes. Using this model, the dynamic changes of carcinogenesis-related molecular events could be easily examined. Furthermore, the transformed cells isolated from soft agar could be inoculated to mice for studying invasion, metastasis, and also for screening prophylactics.

Design, synthesis and the structure-activity relationship of agonists targeting on the ALDH2 catalytic tunnel

ALDH2, a key enzyme in the alcohol metabolism process, detoxifies several kinds of toxic small molecular aldehydes, which induce severe organ damages. The development of novel Alda-1 type ALDH2 activators was mostly relied on HTS but not rational design so far. To clarify the structure-activity relationship (SAR) of the skeleton of Alda-1 analogs by synthesis of the least number of analogs, we prepared 31 Alda-1 analogs and 3 isoflavone derivatives and evaluated for their ALDH2-activating activity. Among these, the ALDH2-activating activity of mono-halogen-substituted (Cl and Br) N-piperonylbenzamides 3b and 3 k, and non-aromatic amides 8a-8c, were 1.5-2.1 folds higher than that of Alda-1 at 20 μM. The relationship between binding affinity in computer aided molecular docking model and the ALDH2-activating activity assays were clarified as follows: for Alda-1 analogs, with the formation of halogen bonds, the enzyme-activating activity was found to follow a specific regression curve within the range between -5 kcal/mol and -4 kcal/mol. For isoflavone derivatives, the basic moiety on the B ring enhance the activating activity. These results provide a new direction of utilizing computer-aided modeling to design novel ALDH2 agonists in the future.

Establishment of the Prognostic Index Reflecting Tumor Immune Microenvironment of Lung Adenocarcinoma Based on Metabolism-Related Genes

Background: The incidence of lung adenocarcinoma (LUAD) increased substantially in recent years. A systematic investigation of the metabolic genomics pattern is critical to improve the treatment and prognosis of LUAD. This study aimed to analyze the relationship between tumor microenvironment (TME) and metabolism-related genes of LUAD.

Methods: The data was extracted from TCGA and GEO datasets. The metabolism-related gene expression profile and the corresponding clinical data of LUAD patients were then integrated. The survival-related genes were screened out using univariate COX regression and lasso regression analysis. The latent properties and molecular mechanisms of these LUAD-specific metabolism-related genes were investigated by computational biology.

Results: A novel prognostic model was established based on 8 metabolism-related genes, including TYMS, ALDH2, PKM, GNPNAT1, LDHA, ENTPD2, NT5E, and MAOB. The immune infiltration of LUAD was also analyzed using CIBERSORT algorithms and TIMER database. In addition, the high- and low-risk groups exhibited distinct layout modes in the principal component analysis.

Conclusions: In summary, our studies identified clinically significant metabolism-related genes, which were potential signature for LUAD diagnosis, monitoring, and prognosis.

Alcohol consumption is associated with glaucoma severity regardless of ALDH2 polymorphism

The present study investigated the effect of aldehyde dehydrogenase2 (ALDH2) rs671 polymorphism and alcohol consumption on the severity of primary open-angle glaucoma (POAG). The questionnaire for alcohol consumption pattern and targeted genotyping for ALDH2 rs671 polymorphism was performed from 445 Korean POAG patients. Retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL) thicknesses were measured and compared according to alcohol consumption and ALDH2 rs671 genotype. Heavy drinking group eyes had thinner RNFL thickness than did abstinence group eyes (65.0 ± 10.9 vs. 70.9 ± 11.5 µm, P = 0.023). Both mild (65.8 ± 9.6 µm) and heavy (63.8 ± 8.4 µm) drinking group eyes had significantly thinner macular GCIPL thickness than did abstinence group eyes (68.1 ± 8.2 µm, P = 0.003). However, ALDH2 rs671 polymorphism did not show any significant association with RNFL or GCIPL thickness. Alcohol consumption was significantly associated with GCIPL thinning (β = –0.446, P = 0.035) after adjustment for multiple confounding factors. As excessive alcohol consumption was significantly associated with thinner GCIPL thickness while ALDH2 polymorphism had no significant effect on RNFL or GCIPL thickness, glaucoma patients should avoid excessive alcohol consumption regardless of ALDH2 polymorphism.

Low Levels of Alcohol Consumption and Risk of Intestinal Metaplasia: A Cohort Study

BACKGROUND

The impact of alcohol drinking on gastric precancerous lesions remains unclear. We investigated the relationship of alcohol intake with risk of atrophic gastritis (AG) and intestinal metaplasia (IM).

METHODS

This study included 202,675 Korean adults free from AG and IM on their initial endoscopy who were followed with repeated endoscopic examinations. A parametric proportional hazards model was used to estimate the adjusted HR (aHR) with 95% confidence interval (CI) for incident AG and IM based on endoscopic diagnosis.

RESULTS

During a mean follow-up of 4.7 years, 64,853 incident AG cases and 4,536 IM cases were identified. Alcohol consumption including drinking frequency, quantity, and binge drinking were consistently associated with increased risk of both AG and IM in a dose-response manner. After adjustment for confounders, the multivariable aHRs (95% CIs) for incident IM comparing average alcohol intake of <10, 10-<20, 20-<40, and ≥40 g/day with lifetime abstainers were 1.27 (1.02-1.56), 1.34 (1.07-1.66), 1.50 (1.20-1.86), and 1.54 (1.23-1.93), respectively. Former drinkers were also at a higher risk for AG and IM compared with lifetime abstainers. These associations were consistently observed in never smokers and in time-dependent analyses.

CONCLUSIONS

In a large cohort of Korean individuals, alcohol intake even at low levels was independently associated with increased risk of developing endoscopic AG and IM, supporting a role of alcohol consumption in the pathogenesis of AG and IM, the precursor lesions of stomach cancer.

IMPACT

Alcohol consumption from low-level drinking may contribute to gastric carcinogenesis.

Aldehyde Dehydrogenase 2 Ameliorates Chronic Alcohol Consumption-Induced Atrial Fibrillation through Detoxification of 4-HNE

Aldehyde dehydrogenase 2 (ALDH2) is an enzyme that detoxifies reactive oxygen species (ROS)-generated aldehyde adducts such as 4-hydroxy-trans-2-nonenal (4-HNE). Previous meta-analyses have shown an increase in the risk of atrial fibrillation (AF) in patients with chronic alcohol consumption. ALDH2*2, a common dysfunctional polymorphism in the ALDH2 gene, has been linked to an increased risk of cancer and heart disease. We tested the effect of ALDH2 deficiency on alcohol-induced AF in a murine model of chronic-binge ethanol feeding, with ALDH2*2 knock-in (KI) mice generated by a CRISPR/CAS9 system. In addition, right atrial appendages were obtained from eight patients with AF undergoing open heart surgery. The results showed that burst atrial pacing induced a greater susceptibility to AF in ALDH2*2 KI mice exposed to chronic ethanol intoxication than in wild-type mice, resulting from a higher degree of 4-HNE accumulation and collagen deposition in their atria. Alda-1 attenuated transforming growth factor beta 1 (TGF-β1) expression and collagen deposition in the atria and reduced AF inducibility. Patients with AF and the ALDH2*2 allele exhibited greater oxidative stress and substrate remodeling in their atria than non-carriers. In conclusion, ALDH2 deficiency may increase the risk of chronic alcohol and tachypacing-induced AF through the accumulation of 4-HNE and increased ROS production.

Blood Orange Juice Consumption Increases Flow-Mediated Dilation in Adults with Overweight and Obesity: A Randomized Controlled Trial

BACKGROUND

Epidemiological studies have indicated an inverse association between citrus fruit consumption and cardiovascular disease (CVD) risk. There is, however, a paucity of data concerning effects of blood orange juice (BOJ) intake on endothelial function and cardiovascular risk biomarkers.

OBJECTIVES

We examined short-term effects of BOJ on endothelial function, blood pressure, lipid profile, and inflammatory markers in healthy participants of European origin who were overweight or obese.

METHODS

In a randomized, controlled, single-blind, crossover trial, 15 men and women (age: 28.7 ± 6.5 y; BMI: 28.3 ± 3.1 kg/m2) consumed BOJ or a sugar-matched control drink (CD) (200 mL twice daily) for 2 wk with a washout period of 1 wk. Endothelial function, measured as flow-mediated dilation (FMD) (primary outcome), and the secondary outcomes blood pressure, anthropometric measures, lipid profile, inflammatory markers, markers of vasodilation and vasoconstriction, and urinary flavanone metabolites were evaluated prior to and at the end of each treatment period following an overnight fast. Changes between treatments over time were assessed using repeated-measures ANOVA.

RESULTS

The results demonstrate a significant increase in FMD following BOJ consumption (pre: 8.15% ± 2.92%; post: 10.2% ± 3.31%; P = 0.002) compared with CD (pre: 8.11% ± 2.52%; post: 7.77% ± 2.43%; time × treatment interaction: P = 0.001). Concurrent significant increases in urinary hesperetin-3'-glucuronide and hesperetin-7-glucuronide were observed following BOJ supplementation only (time × treatment interaction: P ≤ 0.01). Baseline blood pressure, lipid profile, high-sensitivity C-reactive protein, and endothelin-1 were generally within healthy ranges and unaffected by the intervention.

CONCLUSIONS

A 2-wk consumption of BOJ exerted favorable effects on endothelial function in healthy women and men who were overweight or obese, which is likely mediated by the combined actions of anthocyanin and flavanone metabolites on mechanisms that contribute to enhancing NO bioavailability. This trial was registered at clinicaltrials.gov as NCT03611114.

Linking Environmental Exposures to Molecular Pathogenesis in Non-Hodgkin Lymphoma Subtypes

Non-Hodgkin lymphoma comprises a heterogeneous group of hematologic malignancies, with about 60 subtypes that arise via various pathogenetic mechanisms. Although establishing etiology for specific NHL subtypes has been historically difficult given their relative rarity, environmental exposures have been repeatedly implicated as risk factors across many subtypes. Large-scale epidemiologic investigations have pinpointed chemical exposures in particular, but causality has not been established, and the exact biologic mechanisms underpinning these associations are unclear. Here we review chemical exposures that have been associated with development of NHL subtypes and discuss their biologic plausibility based on current research.

Investigating the health disparities in the association between lifestyle behaviors and the risk of head and neck cancer

Many studies have reported a positive association between lower socioeconomic status (SES) and higher head and neck cancer (HNC) risk. Fewer studies have examined the impact of SES on the association between alcohol or cigarette use and HNC risk. The current case‐control study (1104 HNC cases and 1363 controls) investigated the influence of education, a SES indicator, on the association between HNC and the use of alcohol, cigarettes, or betel quids in Taiwan, a country with universal health care. Our results showed a larger increase in HNC risk associated with alcohol among those with lower educational level (odds ratio [OR] = 2.07; 95% confidence interval [CI], 1.53‐2.80) than those with higher educational level (OR = 1.38; 95% CI, 1.04‐1.85) (heterogeneity‐P = .03). Educational level had an influence on the association between alcohol use and HNC risk among those with genetic susceptibility (ALDH2‐deficient) to the carcinogenic effect of alcohol. The association between cigarette or betel quid use and HNC risk was similar between the high and low educational groups. National policies and social interventions have led to the decline in the prevalence of cigarette and betel quid users in Taiwan. In contrast, due to the lack of adequate alcohol control policies, alcohol consumption in Taiwan has continued to rise. A higher impact of alcohol on HNC risk among lower SES individuals even with universal health care could be the result of insufficient alcohol control policies in Taiwan.

Proteomic landscape of liver tissue in old male mice that are long-term treated with polysaccharides from Sargassum fusiforme

Sargassum fusiforme is a type of brown algae and well known as a longevity promoting vegetable in Northeastern Asia. The polysaccharides derived from Sargassum fusiforme (SFPs) have been suggested as an antioxidant component for anti-aging function. However, global molecular changes in vivo by SFPs have not been fully elucidated. Here, we present a proteomics study using liver tissues of aged male mice that were fed with SFPs. Of forty-nine protein spots, thirty-eight were up-regulated and eleven were down-regulated, showing significant changes in abundance by two-dimensional gel electrophoresis. These differentially expressed proteins were mainly involved in oxidation-reduction, amino acid metabolism, and energy metabolism. Forty-six proteins were integrated into a unified network, with catalase (Cat) at the center. Intriguingly, most of the proteins were speculated as mitochondrial-located proteins. Our findings suggested that SFPs modulated antioxidant enzymes to scavenge redundant free radicals, thus preventing oxidative damage. In conclusion, our study provides a proteomic view on how SFPs have beneficial effects on the aspects of antioxidant and energy metabolism during the aging process. This study facilitates the understanding of anti-aging molecular mechanisms in polysaccharides derived from Sargassum fusiforme.

Role of aldehyde dehydrogenases, alcohol dehydrogenase 1B genotype, alcohol consumption, and their combination in breast cancer in East-Asian women

The associations between genetic polymorphisms in ADH1B (rs1229984) and ALDH2 (rs671), alcohol consumption, the effect of a combination of the two polymorphisms, and breast cancer risk were studied in a population of East-Asian women. In this study, 623 breast cancer cases and 1845 controls, aged 40 or above, were included. The association between ALDH2 polymorphism and breast cancer risk was validated in 2143 breast cancer cases and 3977 controls. Alcohol consumption increased the risk of breast cancer regardless of ADH1B and ALDH2 genotypes. The rs671 polymorphism of ALDH2 was independently associated with increased breast cancer risk (OR = 1.27, 95% CI = 1.02–1.58 per increment of A). The ADH1B rs1229984 polymorphism, and combined effects of the rs671 and rs1229984 polymorphisms, did not reveal any significant association with breast cancer. Stratification by menopausal status revealed that rs671 gene polymorphisms were significantly associated with breast cancer only in postmenopausal women (OR = 1.45, 95% CI = 1.03–2.05 per increment of A). This is the first study to demonstrate an independent association between ALDH2 gene variants and breast cancer in Asian women. Further studies are warranted to further elucidate the etiology of breast cancer as it relates to alcohol consumption in Asian women.

Low Levels of Alcohol Consumption, Obesity, and Development of Fatty Liver With and Without Evidence of Advanced Fibrosis

BACKGROUND AND AIMS

The effects of low-level alcohol consumption on fatty liver disease and the potential for effect modification by obesity is uncertain. We investigated associations among low-level alcohol consumption, obesity status, and the development of incident hepatic steatosis (HS), either with or without an increase in noninvasive liver fibrosis score category (from low to intermediate or high category).

APPROACH AND RESULTS

A total of 190,048 adults without HS and a low probability of fibrosis with alcohol consumption less than 30 g/day (men) and less than 20 g/day (women) were followed for up to 15.7 years. Alcohol categories of no, light, and moderate consumption were defined as 0, 1-9.9, and 10-29.9 g/day (10-19.9 g/day for women), respectively. HS was diagnosed by ultrasonography, and the probability of fibrosis was estimated using the fibrosis-4 index (FIB-4). Parametric proportional hazards models were used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). A total of 43,466 participants developed HS, 2,983 of whom developed HS with an increase in FIB-4 index (to intermediate or high scores). Comparing light drinkers and moderate drinkers with nondrinkers, multivariable-adjusted HRs (95% CI) for incident HS were 0.93 (0.90-0.95) and 0.90 (0.87-0.92), respectively. In contrast, comparing light drinkers and moderate drinkers with nondrinkers, multivariable-adjusted HRs (95% CI) for developing HS plus intermediate/high FIB-4 were 1.15 (1.04-1.27) and 1.49 (1.33-1.66), respectively. The association between alcohol consumption categories and incident HS plus intermediate/high FIB-4 was observed in both nonobese and obese individuals, although the association was stronger in nonobese individuals (P for interaction by obesity = 0.017).

CONCLUSIONS

Light/moderate alcohol consumption has differential effects on the development of different stages of fatty liver disease, which is modified by the presence of obesity.

Across-Site Differences in the Mechanism of Alcohol-Induced Digestive Tract Carcinogenesis: An Evaluation by Mediation Analysis

A genetic variant on aldehyde dehydrogenase 2 (ALDH2 rs671, Glu504Lys) contributes to carcinogenesis after alcohol consumption. Somewhat conversely, the ALDH2 Lys allele also confers a protective effect against alcohol-induced carcinogenesis by decreasing alcohol consumption due to acetaldehyde-related adverse effects. Here, we applied a mediation analysis to five case-control studies for head and neck, esophageal, stomach, small intestine, and colorectal cancers, with 4,099 cases and 6,065 controls, and explored the potentially heterogeneous impact of alcohol drinking on digestive tract carcinogenesis by decomposing the total effect of the ALDH2 Lys allele on digestive tract cancer risk into the two opposing effects of the carcinogenic effect (direct effect) and the protective effect (indirect effect mediated by drinking behavior). Alcohol was associated with an increased risk of most digestive tract cancers, but significant direct effects were observed only for upper gastrointestinal tract cancer risk, and varied substantially by site, with ORs (95% confidence interval) of 1.83 (1.43-2.36) for head and neck cancer, 21.15 (9.11-49.12) for esophageal cancer, and 1.65 (1.38-1.96) for stomach cancer. In contrast, a significant protective indirect effect was observed on risk for all cancers, except small intestine cancer. These findings suggest that alcohol is a major risk factor for digestive tract cancers, but its impact as a surrogate for acetaldehyde exposure appears heterogeneous by site. Meanwhile, the behavior-related effect of the ALDH2 Lys allele results in a decreased risk of most digestive tract cancers. SIGNIFICANCE: These findings support that genetic alcohol avoidance is a factor against alcohol-induced cancers.

Systemic Adeno-Associated Virus-Mediated Gene Therapy Prevents the Multiorgan Disorders Associated with Aldehyde Dehydrogenase 2 Deficiency and Chronic Ethanol Ingestion

Aldehyde dehydrogenase type 2 (ALDH2), a key enzyme in ethanol metabolism, processes toxic acetaldehyde to nontoxic acetate. ALDH2 deficiency affects 8% of the world population and 35-45% of East Asians. The ALDH2*2 allele common genetic variant has a glutamic acid-to-lysine substitution at position 487 (E487K) that reduces the oxidizing ability of the enzyme resulting in systemic accumulation of acetaldehyde with ethanol ingestion. With chronic ethanol ingestion, mutations in ALDH2 are associated with a variety of hematological, neurological, and dermatological abnormalities, and an increased risk for esophageal cancer and osteoporosis. Based on our prior studies demonstrating that a one-time administration of an adeno-associated virus (AAV) serotype rh.10 gene transfer vector expressing the human ALDH2 cDNA (AAVrh.10hALDH2) prevents the acute effects of ethanol administration (the "Asian flush syndrome"), we hypothesized that AAVrh.10hALDH2 would also prevent the chronic disorders associated with ALDH2 deficiency and chronic ethanol ingestion. To assess this hypothesis, AAVrh.10hALDH2 (10¹¹ genome copies) was administered intravenously to two models of ALDH2 deficiency, Aldh2 knockout homozygous (Aldh2^-/-) and knockin homozygous (Aldh2^E487K+/+) mice (n = 10 per group). Four weeks after vector administration, mice were given drinking water with 10-15% ethanol for 12 weeks. Strikingly, compared with nonethanol drinking littermates, AAVrh.10hALDH2 administration prevented chronic ethanol-induced serum acetaldehyde accumulation and elevated liver malondialdehyde levels, loss of body weight, reduced hemoglobin levels, reduced performance in locomotor activity tests, accumulation of esophageal DNA damage and DNA adducts, and development of osteopenia. AAVrh.10hALDH2 should be considered as a preventative therapy for the increased risk of chronic disorders associated with ALDH2 deficiency and chronic alcohol exposure.

Mitochondrially-targeted treatment strategies

Disruption of mitochondrial function is a common feature of inherited mitochondrial diseases (mitochondriopathies) and many other infectious and non-infectious diseases including viral, bacterial and protozoan infections, inflammatory and chronic pain, neurodegeneration, diabetes, obesity and cardiovascular diseases. Mitochondria therefore become an attractive target for developing new therapies. In this review we describe critical mechanisms involved in the maintenance of mitochondrial functionality and discuss strategies used to identify and validate mitochondrial targets in different diseases. We also highlight the most recent preclinical and clinical findings using molecules targeting mitochondrial bioenergetics, morphology, number, content and detoxification systems in common pathologies.

Effect of ALDH2 on Sleep Disturbances in Patients with Parkinson's Disease

Monoamine neurotransmitters play essential roles in the regulation of arousal and sleep. Impaired metabolism of monoamine neurotransmitters could result in the accumulation of neurotoxic aldehyde metabolites and, hence, neuronal degeneration. Aldehyde dehydrogenases play an important role in the metabolism of the neurotoxic aldehyde metabolites, including the aldehyde metabolites of dopamine, serotonin, and noradrenaline. Deficient aldehyde dehydrogenase 2 (ALDH2) has been suggested to result in the accumulation of these biogenic aldehydes. An ALDH2 single nucleotide polymorphism (SNP), rs671 (A), results in significantly reduced ALDH2 enzyme activity. A total of 83 Parkinson’s disease (PD) patients were recruited in this study. In addition to the genotypes of rs671, the patients were assessed with the PD sleep scale-2nd version (PDSS-2) and the Epworth sleepiness scale (ESS) for symptoms of daytime and nocturnal sleep disturbances. The patients carrying rs671 (A) had more frequent dozing while lying down to rest in the afternoon (ESS item5) (F = 7.308, p = 0.008) than the rs671 (GG) patients. The patients with rs671 (A) reported a trend toward more frequent difficulty staying asleep than the patients with rs671 (GG). (F = 3.278, p = 0.074). The results indicate that patients carrying allele rs671 (A) are more likely to experience impairment in the regulation of arousal and sleep. The results also support the hypothesis that the accumulation of neurotoxic monoamine neurotransmitter aldehyde metabolites secondary to reduced ALDH2 enzyme activity may cause more severe monoaminergic neuronal loss and, hence, more severe symptoms in the regulation of wakefulness and sleep.

Light to moderate amount of lifetime alcohol consumption and risk of cancer in Japan

BACKGROUND

Even light to moderate alcohol consumption has been shown to increase cancer incidence. However, this association has not been well characterized in Japan.

METHODS

Based on a nationwide, hospital-based data set (2005-2016), a multicenter case-control study was conducted (63,232 cancer cases and 63,232 controls matched for sex, age, admission date, and admitting hospital). The total amount of lifetime alcohol consumption (drink-years) was recalled for each patient by multiplication of the daily amount of standardized alcohol use (drinks per day) and the duration of drinking (years). Odds ratios (ORs) were estimated for overall and specific cancer sites via conditional logistic regression with restricted cubic splines, with adjustments made for smoking, occupational class, and comorbidities. Lifetime abstainers served as the reference group.

RESULTS

Spline curves showed a dose-response association with overall cancer risk: the minimum risk was at 0 drink-years, and the OR at 10 drink-years was 1.05 (95% confidence interval [CI], 1.04-1.06). In comparison with lifetime abstainers, the OR for >0 to 20 drink-years was 1.06 (95% CI, 1.01-1.11). Those who drank 2 drinks or fewer per day had elevated odds for overall cancer risk across all duration-of-drinking categories. The same patterns were observed at light to moderate levels of drinking for most gastrointestinal/aerodigestive cancers as well as breast and prostate cancers. Analyses stratified by sex, different drinking/smoking behaviors, and occupational class mostly showed the same patterns for overall cancer incidence associated with light to moderate levels of drinking.

CONCLUSIONS

In Japan, even light to moderate alcohol consumption appears to be associated with elevated cancer risks.

Global burden of colorectal cancer: emerging trends, risk factors and prevention strategies

Globally, colorectal cancer (CRC) is the third most commonly diagnosed malignancy and the second leading cause of cancer death. Arising through three major pathways, including adenoma-carcinoma sequence, serrated pathway and inflammatory pathway, CRC represents an aetiologically heterogeneous disease according to subtyping by tumour anatomical location or global molecular alterations. Genetic factors such as germline MLH1 and APC mutations have an aetiologic role, predisposing individuals to CRC. Yet, the majority of CRC is sporadic and largely attributable to the constellation of modifiable environmental risk factors characterizing westernization (for example, obesity, physical inactivity, poor diets, alcohol drinking and smoking). As such, the burden of CRC is shifting towards low-income and middle-income countries as they become westernized. Furthermore, the rising incidence of CRC at younger ages (before age 50 years) is an emerging trend. This Review provides a comprehensive summary of CRC epidemiology, with emphasis on modifiable lifestyle and nutritional factors, chemoprevention and screening. Overall, the optimal reduction of CRC incidence and mortality will require concerted efforts to reduce modifiable risk factors, to leverage chemoprevention research and to promote population-wide and targeted screening.