Gene Summary

Gene:ALDH2; aldehyde dehydrogenase 2 family (mitochondrial)
Summary:This protein belongs to the aldehyde dehydrogenase family of proteins. Aldehyde dehydrogenase is the second enzyme of the major oxidative pathway of alcohol metabolism. Two major liver isoforms of aldehyde dehydrogenase, cytosolic and mitochondrial, can be distinguished by their electrophoretic mobilities, kinetic properties, and subcellular localizations. Most Caucasians have two major isozymes, while approximately 50% of Orientals have the cytosolic isozyme but not the mitochondrial isozyme. A remarkably higher frequency of acute alcohol intoxication among Orientals than among Caucasians could be related to the absence of a catalytically active form of the mitochondrial isozyme. The increased exposure to acetaldehyde in individuals with the catalytically inactive form may also confer greater susceptibility to many types of cancer. This gene encodes a mitochondrial isoform, which has a low Km for acetaldehydes, and is localized in mitochondrial matrix. Alternative splicing results in multiple transcript variants encoding distinct isoforms.[provided by RefSeq, Mar 2011]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:aldehyde dehydrogenase, mitochondrial
Source:NCBIAccessed: 17 March, 2015


What does this gene/protein do?
Show (13)
Pathways:What pathways are this gene/protein implicaed in?
Show (15)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 17 March 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 17 March, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: ALDH2 (cancer-related)

Zhang CX, Qin YM, Guo LK
Correlations between polymorphisms of extracellular superoxide dismutase, aldehyde dehydrogenase-2 genes, as well as drinking behavior and pancreatic cancer.
Chin Med Sci J. 2014; 29(3):162-6 [PubMed] Related Publications
OBJECTIVE: To investigate the correlation between drinking behavior combined with polymorphisms of extracellular superoxide dismutase (EC-SOD) and aldehyde dehydrogenase-2 (ALDH2) genes and pancreatic cancer.
METHODS: The genetic polymorphisms of EC-SOD and ALDH2 were analyzed by polymerase chain reaction restriction fragment length polymorphism in the peripheral blood leukocytes obtained from 680 pancreatic cancer cases and 680 non-cancer controls. Subsequently the frequency of genotype was compared between the pancreatic cancer patients and the healthy controls.The relationship of drinking with pancreatic cancer was analyzed.
RESULTS: The frequencies of EC-SOD (C/G) and ALDH2 variant genotypes were 37.35% and 68.82% respectively in the pancreatic cancer cases, and were significantly higher than those in the healthy controls (21.03% and 44.56%, all P<0.01). People who carried EC-SOD (C/G) (OR=2.24, 95% CI= 1.81-4.03, P<0.01) or ALDH2 variant genotypes (OR=2.75, 95% CI=1.92-4.47, P<0.01) had a high risk to develop pancreatic cancer. Those who carried EC-SOD (C/G) genotype combined with ALDH2 variant genotype had a high risk for pancreatic cancer (29.56% vs. 6.76%, OR=7.69, 95% CI=3.58-10.51, P<0.01). The drinking rate of the pancreatic cancer group (64.12%) was significantly higher than that of the control group (40.15%; OR=2.66, 95% CI=1.30-4.42, P<0.01). An interaction between drinking and EC-SOD (C/G)/ALDH2 variant genotypes increased the risk of occurrence of pancreatic cancer (OR=25.00, 95% CI= 11.87-35.64, P<0.01).
CONCLUSION: EC-SOD (C/G), ALDH2 variant genotypes and drinking might be the risk factors of pancreatic cancer.

Tsai ST, Wong TY, Ou CY, et al.
The interplay between alcohol consumption, oral hygiene, ALDH2 and ADH1B in the risk of head and neck cancer.
Int J Cancer. 2014; 135(10):2424-36 [PubMed] Related Publications
Alcohol consumption is an established risk factor for head and neck cancer (HNC). The major carcinogen from alcohol is acetaldehyde, which may be produced by humans or by oral microorganisms through the metabolism of ethanol. To account for the different sources of acetaldehyde production, the current study examined the interplay between alcohol consumption, oral hygiene (as a proxy measure for the growth of oral microorganisms), and alcohol-metabolizing genes (ADH1B and ALDH2) in the risk of HNC. We found that both the fast (*2/*2) and the slow (*1/*1+ *1/*2) ADH1B genotypes increased the risk of HNC due to alcohol consumption, and this association differed according to the slow/non-functional ALDH2 genotypes (*1/*2+ *2/*2) or poor oral hygiene. In persons with the fast ADH1B genotype, the HNC risk associated with alcohol drinking was increased for those with the slow/non-functional ALDH2 genotypes. For those with the slow ADH1B genotypes, oral hygiene appeared to play an important role; the highest magnitude of an increased HNC risk in alcohol drinkers occurred among those with the worst oral hygiene. This is the first study to show that the association between alcohol drinking and HNC risk may be modified by the interplay between genetic polymorphisms of ADH1B and ALDH2 and oral hygiene. Although it is important to promote abstinence from or reduction of alcohol drinking to decrease the occurrence of HNC, improving oral hygiene practices may provide additional benefit.

Ahrens W, Pohlabeln H, Foraita R, et al.
Oral health, dental care and mouthwash associated with upper aerodigestive tract cancer risk in Europe: the ARCAGE study.
Oral Oncol. 2014; 50(6):616-25 [PubMed] Related Publications
OBJECTIVE: We aimed to assess the association of oral health (OH), dental care (DC) and mouthwash with upper-aerodigestive tract (UADT) cancer risk, and to examine the extent that enzymes involved in the metabolism of alcohol modify the effect of mouthwash.
MATERIALS AND METHODS: The study included 1963 patients with incident cancer of the oral cavity, oropharynx, hypopharynx, larynx or esophagus and 1993 controls. Subjects were interviewed about their oral health and dental care behaviors (which were converted to scores of OH and DC respectively), as well as smoking, alcohol drinking, diet, occupations, medical conditions and socio-economic status. Blood samples were taken for genetic analyses. Mouthwash use was analyzed in relation to the presence of polymorphisms of alcohol-metabolizing genes known to be associated with UADT. Adjusted odds ratios (ORs) and 95%-confidence intervals [CI] were estimated with multiple logistic regression models adjusting for multiple confounders.
RESULTS: Fully adjusted ORs of low versus high scores of DC and OH were 2.36[CI=1.51-3.67] and 2.22[CI=1.45-3.41], respectively, for all UADT sites combined. The OR for frequent use of mouthwash use (3 or more times/day) was 3.23[CI=1.68-6.19]. The OR for the rare variant ADH7 (coding for fast ethanol metabolism) was lower in mouthwash-users (OR=0.53[CI=0.35-0.81]) as compared to never-users (OR=0.97[CI=0.73-1.29]) indicating effect modification (pheterogeneity=0.065) while no relevant differences were observed between users and non-users for the variant alleles of ADH1B, ADH1C or ALDH2.
CONCLUSIONS: Poor OH and DC seem to be independent risk factors for UADT because corresponding risk estimates remain substantially elevated after detailed adjustment for multiple confounders. Whether mouthwash use may entail some risk through the alcohol content in most formulations on the market remains to be fully clarified.

Parajuli B, Georgiadis TM, Fishel ML, Hurley TD
Development of selective inhibitors for human aldehyde dehydrogenase 3A1 (ALDH3A1) for the enhancement of cyclophosphamide cytotoxicity.
Chembiochem. 2014; 15(5):701-12 [PubMed] Article available free on PMC after 21/03/2015 Related Publications
Aldehyde dehydrogenase 3A1 (ALDH3A1) plays an important role in many cellular oxidative processes, including cancer chemoresistance, by metabolizing activated forms of oxazaphosphorine drugs such as cyclophosphamide (CP) and its analogues, such as mafosfamide (MF), ifosfamide (IFM), and 4-hydroperoxycyclophosphamide (4-HPCP). Compounds that can selectively target ALDH3A1 could permit delineation of its roles in these processes and could restore chemosensitivity in cancer cells that express this isoenzyme. Here we report the detailed kinetic and structural characterization of an ALDH3A1-selective inhibitor, CB29, previously identified in a high-throughput screen. Kinetic and crystallographic studies demonstrate that CB29 binds within the aldehyde substrate-binding site of ALDH3A1. Cellular proliferation of ALDH3A1-expressing lung adenocarcinoma (A549) and glioblastoma (SF767) cell lines, as well as ALDH3A1 non-expressing lung fibroblast (CCD-13Lu) cells, is unaffected by treatment with CB29 and its analogues alone. However, sensitivity toward the anti-proliferative effects of mafosfamide is enhanced by treatment with CB29 and its analogue in the tumor cells. In contrast, the sensitivity of CCD-13Lu cells toward mafosfamide was unaffected by the addition of these same compounds. CB29 is chemically distinct from the previously reported small-molecule inhibitors of ALDH isoenzymes and does not inhibit ALDH1A1, ALDH1A2, ALDH1A3, ALDH1B1, or ALDH2 isoenzymes at concentrations up to 250 μM. Thus, CB29 is a novel small molecule inhibitor of ALDH3A1, which might be useful as a chemical tool to delineate the role of ALDH3A1 in numerous metabolic pathways, including sensitizing ALDH3A1-positive cancer cells to oxazaphosphorines.

Wang HL, Zhou PY, Liu P, Zhang Y
ALDH2 and ADH1 genetic polymorphisms may contribute to the risk of gastric cancer: a meta-analysis.
PLoS One. 2014; 9(3):e88779 [PubMed] Article available free on PMC after 21/03/2015 Related Publications
AIM: We conducted a meta-analysis of case-control studies to determine whether ALDH2, ADH1 and ADH2 genetic polymorphisms contribute to the pathogenesis of gastric cancer.
METHODS: The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched for relevant articles published before November 1st, 2013 without any language restrictions. Meta-analysis was conducted using the STATA 12.0 software. We calculated crude odds ratios (ORs) with their 95% confidence intervals (95%CI) to evaluate their relationships under five genetic models. Seven case-control studies with a total of 2,563 gastric cancer patients and 4,192 healthy controls met the inclusion criteria. Nine common polymorphisms were evaluated, including rs671, rs16941667 and rs886205 in the ALDH2 gene, rs1230025, rs13123099, rs698 and rs1693482 in the ADH1 gene, and rs1229984 and rs17033 in the ADH2 gene.
RESULTS: The results of our meta-analysis suggested that ALDH2 genetic polymorphisms might be strongly correlated with an increased risk of gastric cancer (allele model: OR = 1.21, 95%CI: 1.11 ∼ 1.32, P<0.001; dominant model: OR = 1.23, 95%CI: 1.09 ∼ 1.39, P = 0.001; respectively), especially for rs671 polymorphism. Furthermore, we observed significant associations between ADH1 genetic polymorphisms and an increased risk of gastric cancer (allele model: OR = 1.21, 95%CI: 1.08 ∼ 1.36, P = 0.001; dominant model: OR = 10.52, 95%CI: 3.04 ∼ 36.41, P<0.001; respectively), especially for rs1230025 polymorphism. Nevertheless, no positive relationships were found between ADH2 genetic polymorphisms and gastric cancer risk (all P>0.05).
CONCLUSION: The current meta-analysis suggests that ALDH2 and ADH1 genetic polymorphisms may play crucial roles in the pathogenesis of gastric cancer. However, ADH2 genetic polymorphisms may not be important dominants of susceptibility to gastric cancer.

Anantharaman D, Chabrier A, Gaborieau V, et al.
Genetic variants in nicotine addiction and alcohol metabolism genes, oral cancer risk and the propensity to smoke and drink alcohol: a replication study in India.
PLoS One. 2014; 9(2):e88240 [PubMed] Article available free on PMC after 21/03/2015 Related Publications
BACKGROUND: Genetic variants in nicotinic acetylcholine receptor and alcohol metabolism genes have been associated with propensity to smoke tobacco and drink alcohol, respectively, and also implicated in genetic susceptibility to head and neck cancer. In addition to smoking and alcohol, tobacco chewing is an important oral cancer risk factor in India. It is not known if these genetic variants influence propensity or oral cancer susceptibility in the context of this distinct etiology.
METHODS: We examined 639 oral and pharyngeal cancer cases and 791 controls from two case-control studies conducted in India. We investigated six variants known to influence nicotine addiction or alcohol metabolism, including rs16969968 (CHRNA5), rs578776 (CHRNA3), rs1229984 (ADH1B), rs698 (ADH1C), rs1573496 (ADH7), and rs4767364 (ALDH2).
RESULTS: The CHRN variants were associated with the number of chewing events per day, including in those who chewed tobacco but never smoked (P =  0.003, P =  0.01 for rs16969968 and rs578776 respectively). Presence of the variant allele contributed to approximately 13% difference in chewing frequency compared to non-carriers. While no association was observed between rs16969968 and oral cancer risk (OR =  1.01, 95% CI =  0.83- 1.22), rs578776 was modestly associated with a 16% decreased risk of oral cancer (OR =  0.84, 95% CI =  0.72- 0.98). There was little evidence for association between polymorphisms in genes encoding alcohol metabolism and oral cancer in this population.
CONCLUSION: The association between rs16969968 and number of chewing events implies that the effect on smoking propensity conferred by this gene variant extends to the use of smokeless tobacco.

Chen CH, Ferreira JC, Gross ER, Mochly-Rosen D
Targeting aldehyde dehydrogenase 2: new therapeutic opportunities.
Physiol Rev. 2014; 94(1):1-34 [PubMed] Article available free on PMC after 21/03/2015 Related Publications
A family of detoxifying enzymes called aldehyde dehydrogenases (ALDHs) has been a subject of recent interest, as its role in detoxifying aldehydes that accumulate through metabolism and to which we are exposed from the environment has been elucidated. Although the human genome has 19 ALDH genes, one ALDH emerges as a particularly important enzyme in a variety of human pathologies. This ALDH, ALDH2, is located in the mitochondrial matrix with much known about its role in ethanol metabolism. Less known is a new body of research to be discussed in this review, suggesting that ALDH2 dysfunction may contribute to a variety of human diseases including cardiovascular diseases, diabetes, neurodegenerative diseases, stroke, and cancer. Recent studies suggest that ALDH2 dysfunction is also associated with Fanconi anemia, pain, osteoporosis, and the process of aging. Furthermore, an ALDH2 inactivating mutation (termed ALDH2*2) is the most common single point mutation in humans, and epidemiological studies suggest a correlation between this inactivating mutation and increased propensity for common human pathologies. These data together with studies in animal models and the use of new pharmacological tools that activate ALDH2 depict a new picture related to ALDH2 as a critical health-promoting enzyme.

Guo XF, Wang J, Yu SJ, et al.
Meta-analysis of the ADH1B and ALDH2 polymorphisms and the risk of colorectal cancer in East Asians.
Intern Med. 2013; 52(24):2693-9 [PubMed] Related Publications
OBJECTIVE: The aldehyde dehydrogenase 2 (ALDH2) and alcohol dehydrogenase 1B (ADH1B) genes have been implicated in the development of colorectal cancer (CRC). However, the results are inconsistent. In this study, a meta-analysis was performed to assess the associations between the ALDH2 and ADH1B polymorphisms and the risk of CRC.
METHODS: Relevant studies were identified using PubMed, Web of Science and CNKI up to February, 2013. The pooled odds ratio (OR) with a 95% confidence interval (CI) was calculated using the fixed- or random-effects model.
RESULTS: A total of 11 case-controlled studies were selected. Of these, 11 studies included 2,893 cases and 3,817 controls concerning the ALDH2 Glu487Lys polymorphism and six studies included 1,864 cases and 3,502 controls concerning the ADH1B polymorphism. The results indicated that there was a statistically significant link between the ALDH2 polymorphism and the risk of CRC (Glu/Lys+Lys/Lys vs. Glu/Glu: OR=0.87, 95%CI: 0.78-0.96, p=0.10; Glu/Lys vs. Glu/Glu: OR=0.87, 95%CI: 0.77-0.97, p=0.38); however, no significant associations were observed between the ADH1B polymorphism and the risk of CRC win any of the genetic models.
CONCLUSION: This meta-analysis demonstrated that the ALDH2 polymorphism, but not the ADH1B polymorphism, significantly increases the risk of CRC in East Asians.

Crous-Bou M, Rennert G, Cuadras D, et al.
Polymorphisms in alcohol metabolism genes ADH1B and ALDH2, alcohol consumption and colorectal cancer.
PLoS One. 2013; 8(11):e80158 [PubMed] Article available free on PMC after 21/03/2015 Related Publications
BACKGROUND: Colorectal cancer (CRC) is a leading cause of cancer death worldwide. Epidemiological risk factors for CRC included alcohol intake, which is mainly metabolized to acetaldehyde by alcohol dehydrogenase and further oxidized to acetate by aldehyde dehydrogenase; consequently, the role of genes in the alcohol metabolism pathways is of particular interest. The aim of this study is to analyze the association between SNPs in ADH1B and ALDH2 genes and CRC risk, and also the main effect of alcohol consumption on CRC risk in the study population.
METHODOLOGY/PRINCIPAL FINDINGS: SNPs from ADH1B and ALDH2 genes, included in alcohol metabolism pathway, were genotyped in 1694 CRC cases and 1851 matched controls from the Molecular Epidemiology of Colorectal Cancer study. Information on clinicopathological characteristics, lifestyle and dietary habits were also obtained. Logistic regression and association analysis were conducted. A positive association between alcohol consumption and CRC risk was observed in male participants from the Molecular Epidemiology of Colorectal Cancer study (MECC) study (OR = 1.47; 95%CI = 1.18-1.81). Moreover, the SNPs rs1229984 in ADH1B gene was found to be associated with CRC risk: under the recessive model, the OR was 1.75 for A/A genotype (95%CI = 1.21-2.52; p-value = 0.0025). A path analysis based on structural equation modeling showed a direct effect of ADH1B gene polymorphisms on colorectal carcinogenesis and also an indirect effect mediated through alcohol consumption.
CONCLUSIONS/SIGNIFICANCE: Genetic polymorphisms in the alcohol metabolism pathways have a potential role in colorectal carcinogenesis, probably due to the differences in the ethanol metabolism and acetaldehyde oxidation of these enzyme variants.

Brooks PJ, Zakhari S
Acetaldehyde and the genome: beyond nuclear DNA adducts and carcinogenesis.
Environ Mol Mutagen. 2014; 55(2):77-91 [PubMed] Related Publications
The designation of acetaldehyde associated with the consumption of alcoholic beverages as "carcinogenic to humans" (Group 1) by the International Agency for Research on Cancer (IARC) has brought renewed attention to the biological effects of acetaldehyde, as the primary oxidative metabolite of alcohol. Therefore, the overall focus of this review is on acetaldehyde and its direct and indirect effects on the nuclear and mitochondrial genome. We first consider different acetaldehyde-DNA adducts, including a critical assessment of the evidence supporting a role for acetaldehyde-DNA adducts in alcohol related carcinogenesis, and consideration of additional data needed to make a conclusion. We also review recent data on the role of the Fanconi anemia DNA repair pathway in protecting against acetaldehyde genotoxicity and carcinogenicity, as well as teratogenicity. We also review evidence from the older literature that acetaldehyde may impact the genome indirectly, via the formation of adducts with proteins that are themselves critically involved in the maintenance of genetic and epigenetic stability. Finally, we note the lack of information regarding acetaldehyde effects on the mitochondrial genome, which is notable since aldehyde dehydrogenase 2 (ALDH2), the primary acetaldehyde metabolic enzyme, is located in the mitochondrion, and roughly 30% of East Asian individuals are deficient in ALDH2 activity due to a genetic variant in the ALDH2 gene. In summary, a comprehensive understanding of all of the mechanisms by which acetaldehyde impacts the function of the genome has implications not only for alcohol and cancer, but types of alcohol related pathologies as well.

Tanaka H
Advances in cancer epidemiology in Japan.
Int J Cancer. 2014; 134(4):747-54 [PubMed] Related Publications
Epidemiologists in Japan have been performing calculations to estimate nationwide cancer incidence rates as well as 5-year survival rates using population-based cancer registry data. There have been remarkable changes in cancer incidence and/or mortality in cancers of the lung, liver and stomach, which were thought to be attributed to the changing impact of exposure to cigarette smoking, chronic hepatitis C virus infection and Helicobacter pylori infection, respectively. In systematic reviews providing evidence in risk/protective factors for cancer sites using case-control and cohort studies of the Japanese population, there were associations between cancer sites (esophagus, stomach, colo-rectum, liver, pancreas, lung and breast) and various lifestyle factors. In the past 10 years, a hospital-based case-control study at Aichi Cancer Center provided valuable evidence of gene-environment interaction on the development of cancer [i.e., the effects of aldehyde dehydrogenase-2 (ALDH2) polymorphism and heavy alcohol drinking on esophageal cancer, ALDH2 polymorphism and smoking on lung cancer, methylenetetrahydrofolate reductase polymorphism and heavy alcohol drinking on pancreatic cancer]. The database with stored DNA was also used and identified seven loci containing significant but low-penetrance polymorphisms associated with the development of breast cancer. These findings together with established risk factors are likely to be useful to predict personalized breast cancer risk in East Asian women. In 2005, the Japan Multi-Institution Collaborative Cohort (J-MICC) study was launched to elucidate gene-environment interactions as well as to confirm preclinical diagnostic biomarkers of cancer. J-MICC, which has recruited 92,000 healthy individuals by the end of 2012, will follow the individuals until 2025.

Dura P, Berkers T, van Veen EM, et al.
Polymorphisms in alcohol-metabolizing enzymes and esophageal carcinoma susceptibility: a Dutch Caucasian case-control study.
J Hum Genet. 2013; 58(11):742-8 [PubMed] Related Publications
Esophageal cancer (EC), mainly consisting of squamous cell carcinoma (ESCC) in the Eastern world and adenocarcinoma (EAC) in the Western world, is strongly associated with dietary factors such as alcohol use. We aimed to clarify the modifying role in EC etiology in Caucasians of functional genotypes in alcohol-metabolizing enzymes. In all, 351 Caucasian patients with EC and 430 matched controls were included and polymorphisms in CYP2E1, ADH and near ALDH2 genes were determined. In contrast to the results on ESCC in mainly Asian studies, we found that functional genotypes of alcohol-metabolizing enzymes were not significantly associated with EAC or ESCC in an European population.

González CA, Sala N, Rokkas T
Gastric cancer: epidemiologic aspects.
Helicobacter. 2013; 18 Suppl 1:34-8 [PubMed] Related Publications
A multifactorial and multistep model of gastric cancer (GC) is currently accepted, according to which different environmental and genetic factors are involved at different stages in the cancer process. The aim of this article is to review the most relevant information published on the relative contribution of genetic and environmental factors. Large meta-analyses confirmed the association between IL8, IL10, TNF-b, TP53 and PSCA, while genetic variation at different genes such as XPG, PLCE1, HFE, ERCC5, EZH2, DOC2, CYP19A1, ALDH2, and CDH1 have been reported to be associated with GC risk. Several microRNAs have also been associated with GC and their prognosis. Cohort studies have shown the association between GC and fruit, flavonoid, total antioxidant capacity, and green tea intake. Obesity was associated with cardia GC, heme iron intake from meat with GC risk. Several large meta-analyses have confirmed the positive association of GC with salt intake and pickled foods and the negative association with aspirin use.

Hakenewerth AM, Millikan RC, Rusyn I, et al.
Effects of polymorphisms in alcohol metabolism and oxidative stress genes on survival from head and neck cancer.
Cancer Epidemiol. 2013; 37(4):479-91 [PubMed] Article available free on PMC after 21/03/2015 Related Publications
BACKGROUND: Heavy alcohol consumption increases risk of developing squamous cell carcinoma of the head and neck (SCCHN). Alcohol metabolism to cytotoxic and mutagenic intermediates acetaldehyde and reactive oxygen species is critical for alcohol-drinking-associated carcinogenesis. We hypothesized that polymorphisms in alcohol metabolism-related and antioxidant genes influence SCCHN survival.
METHODS: Interview and genotyping data (64 polymorphisms in 12 genes) were obtained from 1227 white and African-American cases from the Carolina Head and Neck Cancer Epidemiology study, a population-based case-control study of SCCHN conducted in North Carolina from 2002 to 2006. Vital status, date and cause of death through 2009 were obtained from the National Death Index. Kaplan-Meier log-rank tests and adjusted hazard ratios were calculated to identify alleles associated with survival.
RESULTS: Most tested SNPs were not associated with survival, with the exception of the minor alleles of rs3813865 and rs8192772 in CYP2E1. These were associated with poorer cancer-specific survival (HRrs3813865, 95% CI=2.00, 1.33-3.01; HRrs8192772, 95% CI=1.62, 1.17-2.23). Hazard ratios for 8 additional SNPs in CYP2E1, GPx2, SOD1, and SOD2, though not statistically significant, were suggestive of differences in allele hazards for all-cause and/or cancer death. No consistent associations with survival were found for SNPs in ADH1B, ADH1C, ADH4, ADH7, ALDH2, GPx2, GPx4, and CAT.
CONCLUSIONS: We identified some polymorphisms in alcohol and oxidative stress metabolism genes that influence survival in subjects with SCCHN. Previously unreported associations of SNPs in CYP2E1 warrant further investigation.

Matsuo K, Oze I, Hosono S, et al.
The aldehyde dehydrogenase 2 (ALDH2) Glu504Lys polymorphism interacts with alcohol drinking in the risk of stomach cancer.
Carcinogenesis. 2013; 34(7):1510-5 [PubMed] Related Publications
The impact of alcohol on the risk of stomach cancer is controversial. Although aldehyde dehydrogenase 2 (ALDH2) Glu504Lys (rs671) polymorphism has a strong effect on acetaldehyde metabolism, little is known about its impact on stomach cancer risk when combined with alcohol drinking. This case-control study included a total of 697 incident stomach cancer case subjects and 1372 non-cancer control subjects who visited Aichi Cancer Center between 2001 and 2005. We estimated odds ratios (OR) and 95% confidence intervals (CI) for ALDH2 genotypes and alcohol consumption using logistic regression models after adjustment for potential confounders, including Helicobacter pylori infection. The ALDH2 504Lys allele was associated with the risk of stomach cancer, with adjusted ORs of 1.40 (95% CI, 1.11-1.76) for Glu/Lys and 1.73 (1.12-2.68) for Lys/Lys compared with Glu/Glu. Heavy drinking was associated with risk (OR 1.72, 1.17-2.52) after adjustment for ALDH2 genotype and other confounders. Moreover, ORs for heavy drinking were 1.28 (0.77-2.12) for those with ALDH2 Glu/Glu and 3.93 (1.99-5.79) for those with the ALDH2 Lys allele relative to non-drinkers with the Glu/Glu genotype (P for interaction = 0.0054). In conclusion, ALDH2 and alcohol drinking showed interaction for risk factors of stomach cancer, indicating that acetaldehyde plays a role in stomach carcinogenesis.

Ferrari P, McKay JD, Jenab M, et al.
Alcohol dehydrogenase and aldehyde dehydrogenase gene polymorphisms, alcohol intake and the risk of colorectal cancer in the European Prospective Investigation into Cancer and Nutrition study.
Eur J Clin Nutr. 2012; 66(12):1303-8 [PubMed] Related Publications
BACKGROUND/OBJECTIVES: Heavy alcohol drinking is a risk factor of colorectal cancer (CRC), but little is known on the effect of polymorphisms in the alcohol-metabolizing enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) on the alcohol-related risk of CRC in Caucasian populations.
SUBJECTS/METHODS: A nested case-control study (1269 cases matched to 2107 controls by sex, age, study centre and date of blood collection) was conducted within the European Prospective Investigation into Cancer and Nutrition (EPIC) to evaluate the impact of rs1229984 (ADH1B), rs1573496 (ADH7) and rs441 (ALDH2) polymorphisms on CRC risk. Using the wild-type variant of each polymorphism as reference category, CRC risk estimates were calculated using conditional logistic regression, with adjustment for matching factors.
RESULTS: Individuals carrying one copy of the rs1229984(A) (ADH1B) allele (fast metabolizers) showed an average daily alcohol intake of 4.3 g per day lower than subjects with two copies of the rs1229984(G) allele (slow metabolizers) (P(diff)<0.01). None of the polymorphisms was associated with risk of CRC or cancers of the colon or rectum. Heavy alcohol intake was more strongly associated with CRC risk among carriers of the rs1573496(C) allele, with odds ratio equal to 2.13 (95% confidence interval: 1.26-3.59) compared with wild-type subjects with low alcohol consumption (P(interaction)=0.07).
CONCLUSIONS: The rs1229984(A) (ADH1B) allele was associated with a reduction in alcohol consumption. The rs1229984 (ADH1B), rs1573496 (ADH7) and rs441 (ALDH2) polymorphisms were not associated with CRC risk overall in Western-European populations. However, the relationship between alcohol and CRC risk might be modulated by the rs1573496 (ADH7) polymorphism.

Liu P, Wang X, Hu CH, Hu TH
Bioinformatics analysis with graph-based clustering to detect gastric cancer-related pathways.
Genet Mol Res. 2012; 11(3):3497-504 [PubMed] Related Publications
Despite a dramatic reduction in incidence and mortality rates, gastric cancer still remains one of the most common malignant tumors worldwide, especially in China. We sought to identify a set of discriminating genes that could be used for characterization and prediction of response to gastric cancer. Using bioinformatics analysis, two gastric cancer datasets, GSE19826 and GSE2685, were merged to find novel target genes and domains to explain pathogenesis; we selected differentially expressed genes in these two datasets and analyzed their correlation in order to construct a network. This network was examined to find graph clusters and related significant pathways. We found that ALDH2 and CCNB1 were associated with gastric cancer. We also mined for the underlying molecular mechanisms involving these differently expressed genes. We found that ECM-receptor interaction, focal adhesion, and cell cycle were among the significantly associated pathways. We were able to detect genes and pathways that were not considered in previous research on gastric cancer, indicating that this approach could be an improvement on the investigative mechanisms for finding genetic associations with disease.

Wu C, Kraft P, Zhai K, et al.
Genome-wide association analyses of esophageal squamous cell carcinoma in Chinese identify multiple susceptibility loci and gene-environment interactions.
Nat Genet. 2012; 44(10):1090-7 [PubMed] Article available free on PMC after 21/03/2015 Related Publications
We conducted a genome-wide association study (GWAS) and a genome-wide gene-environment interaction analysis of esophageal squamous-cell carcinoma (ESCC) in 2,031 affected individuals (cases) and 2,044 controls with independent validation in 8,092 cases and 8,620 controls. We identified nine new ESCC susceptibility loci, of which seven, at chromosomes 4q23, 16q12.1, 17q21, 22q12, 3q27, 17p13 and 18p11, had a significant marginal effect (P=1.78×10(-39) to P=2.49×10(-11)) and two of which, at 2q22 and 13q33, had a significant association only in the gene-alcohol drinking interaction (gene-environment interaction P (PG×E)=4.39×10(-11) and PG×E=4.80×10(-8), respectively). Variants at the 4q23 locus, which includes the ADH cluster, each had a significant interaction with alcohol drinking in their association with ESCC risk (PG×E=2.54×10(-7) to PG×E=3.23×10(-2)). We confirmed the known association of the ALDH2 locus on 12q24 to ESCC, and a joint analysis showed that drinkers with both of the ADH1B and ALDH2 risk alleles had a fourfold increased risk for ESCC compared to drinkers without these risk alleles. Our results underscore the direct genetic contribution to ESCC risk, as well as the genetic contribution to ESCC through interaction with alcohol consumption.

Guo LK, Zhang CX, Guo XF
Association of genetic polymorphisms of aldehyde dehydrogenase-2 and cytochrome P450 2E1-RsaI and alcohol consumption with oral squamous cell carcinoma.
Zhongguo Yi Xue Ke Xue Yuan Xue Bao. 2012; 34(4):390-5 [PubMed] Related Publications
OBJECTIVE: To investigate the association of the polymorphisms of aldehyde dehydrogenase-2(ALDH2) and CYP2E1-RsaI genes and alcohol consumption with oral squamous cell carcinoma (OSCC).
METHODS: The genetic polymorphisms of ALDH2 and CYP2E1-RsaI were determined by polymorphism-polymerase chain reaction (PCR) technique in the peripheral blood leukocytes of 320 OSCC patients and 320 non-cancer controls.
RESULTS: The frequencies of ALDH2 variant genotypes and CYP2E1-RsaI (c2/c2) were 70.94% and 39.06% in the OSCC group and 43.44% and 20.62% in the control group (both P<0.01). The risk of OSCC with ALDH2 variant genotypes was significantly higher than that in control group (OR=3.178, 95% CI=1.917-4.749), whereas the subjects carried with CYP2E1-RsaI (c2/c2) also had a high risk of OSCC (OR=2.467, 95%CI=1.783-4.045). Combined analysis of the polymorphisms showed that percentage of ALDH2 variant genotypes/CYP2E1-RsaI (c2/c2) in OSCC group and control group was 32.19% and 6.25%, respectively (P<0.01). Carriers of ALDH2 variant genotypes/CYP2E1-RsaI (c2/c2) had a high risk of OSCC (OR=9.792, 95%CI=3.583-12.472). The percentage of alcohol consumption was significantly higher in OSCC group than in the control group (OR=2.861, 95% CI=1.541-4.781, P<0.01), and ALDH2 variant genotypes and CYP2E1-RsaI (c2/c2) showed synergic effects with alcohol consumption for the increased risk of OSCC (OR=41.152, 95%CI=19.903-67.551).
CONCLUSION: The polymorphisms of ALDH2 and CYP2E1-RsaI genes and alcohol consumption, independently and synergically, increase the risk of OSCC.

Wu M, Chang SC, Kampman E, et al.
Single nucleotide polymorphisms of ADH1B, ADH1C and ALDH2 genes and esophageal cancer: a population-based case-control study in China.
Int J Cancer. 2013; 132(8):1868-77 [PubMed] Article available free on PMC after 21/03/2015 Related Publications
Alcohol drinking is a major risk factor for esophageal cancer (EC) and the metabolism of ethanol has been suggested to play an important role in esophageal carcinogenesis. Epidemiologic studies, including genomewide association studies (GWAS), have identified single nucleotide polymorphisms (SNPs) in alcohol dehydrogenases (ADHs) and aldehyde dehydrogenases (ALDHs) to be associated with EC. Using a population-based case-control study with 858 EC cases and 1,081 controls conducted in Jiangsu Province, China, we aimed to provide further information on the association of ADH1B (rs1229984), ADH1C (rs698) and ALDH2 (rs671) polymorphisms with EC in a Chinese population. Results showed that ADH1B (rs1229984) was associated with EC with odds ratios (ORs) of 1.34 [95% confidence interval (CI): 1.08-1.66] for G-allele carriers compared to A/A homozygotes. No heterogeneity was detected on this association across different strata of alcohol drinking and tobacco smoking. Statistical interaction between ALDH2 (rs671) and alcohol drinking on EC susceptibility in both additive and multiplicative scales was observed. Compared to G/G homozygotes, A-allele carriers were positively associated with EC among moderate/heavy drinkers (OR = 1.64, 95% CI: 1.12-2.40) and inversely associated with EC among never/light drinks (OR = 0.75, 95% CI: 0.54-1.03). In addition, statistical interaction between ALDH2 and ADH1B polymorphisms on EC susceptibility among never/light drinkers was indicated. We did not observe association of ADH1C polymorphism with EC. In conclusion, our findings indicated that ADH1B (rs1229984) was associated with EC independent of alcohol drinking and tobacco smoking status and alcohol drinking interacted with ALDH2 (rs671) on EC susceptibility in this high-risk Chinese population.

Cadoni G, Boccia S, Petrelli L, et al.
A review of genetic epidemiology of head and neck cancer related to polymorphisms in metabolic genes, cell cycle control and alcohol metabolism.
Acta Otorhinolaryngol Ital. 2012; 32(1):1-11 [PubMed] Article available free on PMC after 21/03/2015 Related Publications
The purpose of this report is to review the relationship between genetic polymorphisms involved in carcinogen metabolism, alcohol metabolism and cell-cycle control with the risk of head and neck cancer. The review was performed on available studies on genetic polymorphisms and head and neck cancer (HNC) published in PubMed up to September 2011. 246 primary articles and 7 meta-analyses were published. Among these, a statistically significant association was reported for glutathione S-transferases (GSTM1), glutathione S-transferases (GSTT1) and human microsomal epoxide hydrolase (EPHX1) genes. An increased risk for HNC was also associated reported for P53 codon 72 Pro/Pro, ALDH2 and three variants of the ADH gene: ADH1B (rs1229984), ADH7 (rs1573496) and ADH1C (rs698).

Salaspuro M, Mikko S
Interactions of alcohol and tobacco in gastrointestinal cancer.
J Gastroenterol Hepatol. 2012; 27 Suppl 2:135-9 [PubMed] Related Publications
Cancer prevention is based on the identification of specific etiologic factors. Acetaldehyde derived from the alcoholic beverage itself and formed from ethanol endogenously has recently been classified by the International Agency for Research on Cancer/World Health Organization as a group 1 carcinogen to humans. This is based on the uniform epidemiological and biochemical evidence derived from individuals carrying alcohol and aldehyde dehydrogenase gene mutations. After drinking alcohol, these mutations are associated with increased exposure of the upper digestive tract to acetaldehyde and as well with a remarkably increased risk for upper gastrointestinal (GI) tract cancers. Acetaldehyde is the key intermediate in alcoholic fermentation and ethanol oxidation. Therefore, it is widely present in our environment. Furthermore, it is the most abundant carcinogenic compound of tobacco smoke. Most of the known risk factors for upper digestive tract cancer appear to be associated with an enhanced exposure of GI mucosa to locally formed acetaldehyde. In these process microbes, salivary glands and even mucosal cells appear to play an essential role. Consequently, in the presence of ethanol mutagenic acetaldehyde concentrations are found in the saliva, achlorhydric stomach and colon. Equal acetaldehyde concentrations are seen in saliva also during active smoking. ALDH2-deficiency and high active ADH1C result in two- to threefold salivary acetaldehyde concentrations after a dose of alcohol and this prevails for as long as ethanol is present in the blood and saliva. Regarding cancer prevention, the good news is that acetaldehyde exposure can be markedly reduced. This can be achieved by giving high priority for regulatory measures and consumer guidance.

Fang P, Jiao S, Zhang X, et al.
Meta-analysis of ALDH2 variants and esophageal cancer in Asians.
Asian Pac J Cancer Prev. 2011; 12(10):2623-7 [PubMed] Related Publications
Alcohol drinking is considered a risk factor for esophageal cancer, and exposure to high levels of acetaldehyde, the principal metabolite of alcohol, may be responsible. Individuals homozygous for the *2 variant allele of aldehyde dehydrogenase 2 (ALDH2) are unable to metabolize acetaldehyde, which prevents them from alcohol drinking, whereas those with *1/*2 have a 6-fold higher blood acetaldehyde concentration postalcohol consumption with respect to *1*1. We carried out a meta-analysis of ALDH2 and esophageal cancer searching for relevant studies on Asians in Medline and EMbase up to May 2011, and investigated the association between this genotype variation and esophageal cancer risk. A total of 2,697 cases and ,6344 controls were retained for the analysis. The pooled OR (95% CI) for ALDH2*1/*2 was 2.47 (95%CI: 1.76-3.46) compared with ALDH2*1/*1. ALDH2*2/*2 showed a non-significant decreased risk for esophageal cancer with OR of 0.6 (0.26-1.38). ALDH2*1/*2 individuals showed a higher risk of esophageal cancer among moderate and heavy alcohol users [2.17(1.95-2.43) and 3.20(2.78-3.70), respectively]. Moderate drinkers with ALDH2*2/*2 showed strong esophageal cancer risk [OR(95%CI)=8.52(3.81-19.04)] compared with ALDH2*1/*1 carriers among heavy drinkers than non-drinkers and moderate drinkers (OR=7.05). Our finding showed that ALDH2*1/*2 genotype increases the risk of esophageal cancer, while the ALDH2*2/*2 genotype reduces the risk, presumably preventing people from consumption due to discomfort. Drinking clearly modifies the effect of ALDH2 on esophageal cancer risk in Asians.

Zhou D, Xiao L, Zhang Y, et al.
Genetic polymorphisms of ALDH2 and ADH2 are not associated with risk of hepatocellular carcinoma among East Asians.
Tumour Biol. 2012; 33(3):841-6 [PubMed] Related Publications
The aldehyde dehydrogenase 2 (ALDH2) and alcohol dehydrogenase 2 (ADH2) genes have been implicated in the development of hepatocellular carcinoma (HCC). However, the results have been inconsistent. In this study, we performed a meta-analysis to clarify the associations between polymorphisms of ALDH2 and ADH2 genes and HCC. Published literatures from PubMed and Embase were retrieved. Pooled odds ratio (OR) with 95% confidence interval (CI) was calculated using fixed- or random-effects model. Ten studies including 1,231 HCC cases and 1,849 controls were included in the meta-analysis of the association between ALDH2 polymorphism and HCC risk. The results indicated that ALDH2 polymorphism was not significantly associated with risk of HCC (homogeneous co-dominant model: OR = 0.99, 95% CI 0.72-1.34; heterogeneous co-dominant model: OR = 0.90, 95% CI 0.75-1.08; dominant model: OR = 0.91, 95% CI 0.70-1.18; recessive model: OR = 1.11, 95% CI 0.66-1.87). In addition, four studies including 518 cases and 607 controls were included in the meta-analysis of the association between ADH2 polymorphism and HCC risk. There was no association between ADH2 polymorphism and HCC risk (homogeneous co-dominant model: OR = 0.93, 95% CI 0.58-1.51; heterogeneous co-dominant model: OR = 1.39, 95% CI 0.87-2.23; dominant model: OR = 1.19, 95% CI 0.76-1.88; recessive model: OR = 0.91, 95% CI 0.54-1.54). Further analysis suggested that the ALDH2 polymorphism-alcohol interaction was marginally associated with HCC risk under the dominant model (OR = 2.05, 95% CI 1.01-4.17). However, the result was not robust by sensitivity analysis. The results from the present meta-analysis indicated that there was no significant association between ALDH2 polymorphism, ADH2 polymorphism, or ALDH2 polymorphism-alcohol intake interaction and HCC risk in the East Asians.

Muzio G, Maggiora M, Paiuzzi E, et al.
Aldehyde dehydrogenases and cell proliferation.
Free Radic Biol Med. 2012; 52(4):735-46 [PubMed] Related Publications
Aldehyde dehydrogenases (ALDHs) oxidize aldehydes to the corresponding carboxylic acids using either NAD or NADP as a coenzyme. Aldehydes are highly reactive aliphatic or aromatic molecules that play an important role in numerous physiological, pathological, and pharmacological processes. ALDHs have been discovered in practically all organisms and there are multiple isoforms, with multiple subcellular localizations. More than 160 ALDH cDNAs or genes have been isolated and sequenced to date from various sources, including bacteria, yeast, fungi, plants, and animals. The eukaryote ALDH genes can be subdivided into several families; the human genome contains 19 known ALDH genes, as well as many pseudogenes. Noteworthy is the fact that elevated activity of various ALDHs, namely ALDH1A2, ALDH1A3, ALDH1A7, ALDH2*2, ALDH3A1, ALDH4A1, ALDH5A1, ALDH6, and ALDH9A1, has been observed in normal and cancer stem cells. Consequently, ALDHs not only may be considered markers of these cells, but also may well play a functional role in terms of self-protection, differentiation, and/or expansion of stem cell populations. The ALDH3 family includes enzymes able to oxidize medium-chain aliphatic and aromatic aldehydes, such as peroxidic and fatty aldehydes. Moreover, these enzymes also have noncatalytic functions, including antioxidant functions and some structural roles. The gene of the cytosolic form, ALDH3A1, is localized on chromosome 17 in human beings and on the 11th and 10th chromosome in the mouse and rat, respectively. ALDH3A1 belongs to the phase II group of drug-metabolizing enzymes and is highly expressed in the stomach, lung, keratinocytes, and cornea, but poorly, if at all, in normal liver. Cytosolic ALDH3 is induced by polycyclic aromatic hydrocarbons or chlorinated compounds, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin, in rat liver cells and increases during carcinogenesis. It has been observed that this increased activity is directly correlated with the degree of deviation in hepatoma and lung cancer cell lines, as is the case in chemically induced hepatoma in rats. High ALDH3A1 expression and activity have been correlated with cell proliferation, resistance against aldehydes derived from lipid peroxidation, and resistance against drug toxicity, such as oxazaphosphorines. Indeed, cells with a high ALDH3A1 content are more resistant to the cytostatic and cytotoxic effects of lipidic aldehydes than are those with a low content. A reduction in cell proliferation can be observed when the enzyme is directly inhibited by the administration of synthetic specific inhibitors, antisense oligonucleotides, or siRNA or indirectly inhibited by the induction of peroxisome proliferator-activated receptor γ (PPARγ) with polyunsaturated fatty acids or PPARγ transfection. Conversely, cell proliferation is stimulated by the activation of ALDH3A1, whether by inhibiting PPARγ with a specific antagonist, antisense oligonucleotides, siRNA, or a medical device (i.e., composite polypropylene prosthesis for hernia repair) used to induce cell proliferation. To date, the mechanisms underlying the effects of ALDHs on cell proliferation are not yet fully clear. A likely hypothesis is that the regulatory effect is mediated by the catabolism of some endogenous substrates deriving from normal cell metabolism, such as 4-hydroxynonenal, which have the capacity to either stimulate or inhibit the expression of genes involved in regulating proliferation.

Duell EJ, Sala N, Travier N, et al.
Genetic variation in alcohol dehydrogenase (ADH1A, ADH1B, ADH1C, ADH7) and aldehyde dehydrogenase (ALDH2), alcohol consumption and gastric cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort.
Carcinogenesis. 2012; 33(2):361-7 [PubMed] Related Publications
Studies that have examined the association between alcohol consumption and gastric cancer (GC) risk have been inconsistent. We conducted an investigation of 29 genetic variants in alcohol metabolism loci (alcohol dehydrogenase, ADH1 gene cluster: ADH1A, ADH1B and ADH1C; ADH7 and aldehyde dehydrogenase, ALDH2), alcohol intake and GC risk. We analyzed data from a nested case-control study (364 cases and 1272 controls) within the European Prospective Investigation into Cancer and Nutrition cohort. Single nucleotide polymorphisms (SNPs) were genotyped using a customized array. We observed a statistically significant association between a common 3'-flanking SNP near ADH1A (rs1230025) and GC risk [allelic odds ratio (OR)(A v T) = 1.30, 95% confidence interval (CI) = 1.07-1.59]. Two intronic variants, one in ADH1C (rs283411) and one in ALDH2 (rs16941667), also were associated with GC risk (OR(T v C) = 0.59; 95% CI = 0.38-0.91 and OR(T v C) = 1.34; 95% CI = 1.00-1.79, respectively). Individuals carrying variant alleles at both ADH1 (rs1230025) and ALDH2 (rs16941667) were twice as likely to develop GC (OR(A+T) = 2.0; 95% CI = 1.25-3.20) as those not carrying variant alleles. The association between rs1230025 and GC was modified by alcohol intake (<5 g/day: OR(A) = 0.89, 95% CI = 0.57-1.39; ≥5 g/day: OR(A) = 1.45, 95% CI = 1.08-1.94, P-value = 0.05). The association was also modified by ethanol intake from beer. A known functional SNP in ADH1B (rs1229984) was associated with alcohol intake (P-value = 0.04) but not GC risk. Variants in ADH7 were not associated with alcohol intake or GC risk. In conclusion, genetic variants at ADH1 and ALDH2 loci may influence GC risk, and alcohol intake may further modify the effect of ADH1 rs1230025. Additional population-based studies are needed to confirm our results.

Tomoda T, Nouso K, Sakai A, et al.
Genetic risk of hepatocellular carcinoma in patients with hepatitis C virus: a case control study.
J Gastroenterol Hepatol. 2012; 27(4):797-804 [PubMed] Related Publications
BACKGROUND AND AIM: Chronic hepatitis C virus (HCV) infection is a well known risk factor for hepatocellular carcinoma (HCC). The aim of this study is to elucidate the genetic risk of development and recurrence of HCC in patients with HCV.
METHODS: A total of 468 patients with HCV, including 265 with HCC were enrolled. We genotyped 88 single nucleotide polymorphisms (SNPs) in 81 genes expected to influence hepatocarcinogenesis using the iPLEX assay. Risk of HCC was clarified by stratifying patients into risk groups based on the multiplied odds ratio (MOR) for SNPs associated with HCC, and the cumulative effects on the development and recurrence of HCC were analyzed.
RESULTS: Six SNPs associated with risk of HCC were identified (OR range: 0.29-1.76). These included novel SNPs for hepatocarcinogenesis with HCV CCND2 rs1049606, RAD23B rs1805329, CEP164 rs573455, and GRP78rs430397 in addition to the known SNPs MDM2 rs2279744 and ALDH2 rs671. MOR analysis revealed that the highest risk group exerted about a 19-fold higher relative OR compared with the lowest risk group (P = 1.08 × 10(-5)). Predicted 10-year HCC risk ranged from 1.7% to 96% depending on the risk group and the extent of fibrosis. Recurrence-free survival of radiofrequency ablation-treated HCC in the high risk group (n = 53) was lower than that of low risk group (n = 58, P = 0.038).
CONCLUSION: Single nucleotide polymorphisms of CCND2, RAD23B, GRP78, CEP164, MDM2, and ALDH2 genes were significantly associated with development and recurrence of HCC in Japanese patients with HCV.

Matsuo K, Rossi M, Negri E, et al.
Folate, alcohol, and aldehyde dehydrogenase 2 polymorphism and the risk of oral and pharyngeal cancer in Japanese.
Eur J Cancer Prev. 2012; 21(2):193-8 [PubMed] Related Publications
Folate consumption is inversely associated with the risk of oral and pharyngeal cancer (OPC) and potentially interacts with alcohol drinking in the risk of OPC. Aldehyde dehydrogenase 2 (ALDH2) gene polymorphism is known to interact with alcohol consumption. The aim of this study was to investigate potential interaction between folate, alcohol drinking, and ALDH2 polymorphism in the risk of OPC in a Japanese population. The study group comprised 409 head and neck cancer cases and 1227 age-matched and sex-matched noncancer controls; of these, 251 cases and 759 controls were evaluated for ALDH rs671 polymorphism. Associations were assessed by odds ratios and 95% confidence intervals in multiple logistic regression models. We observed an inverse association between folate consumption and OPC risk. The odds ratio for high folate intake was 0.53 (95% confidence interval: 0.36-0.77) relative to low intake (P trend=0.003). This association was consistent across strata of sex, age, smoking, and ALDH2 genotypes. Interaction between folate consumption, drinking, and ALDH2 genotype was remarkable (three-way interaction, P<0.001). We observed significant interaction among folate, drinking, and ALDH2 genotype in the Japanese population.

Hakenewerth AM, Millikan RC, Rusyn I, et al.
Joint effects of alcohol consumption and polymorphisms in alcohol and oxidative stress metabolism genes on risk of head and neck cancer.
Cancer Epidemiol Biomarkers Prev. 2011; 20(11):2438-49 [PubMed] Article available free on PMC after 21/03/2015 Related Publications
BACKGROUND: Single-nucleotide polymorphisms (SNP) in alcohol metabolism genes are associated with squamous cell carcinoma of the head and neck (SCCHN) and may influence cancer risk in conjunction with alcohol. Genetic variation in the oxidative stress pathway may impact the carcinogenic effect of reactive oxygen species produced by ethanol metabolism. We hypothesized that alcohol interacts with these pathways to affect SCCHN incidence.
METHODS: Interview and genotyping data for 64 SNPs were obtained from 2,552 European- and African-American subjects (1,227 cases and 1,325 controls) from the Carolina Head and Neck Cancer Epidemiology Study, a population-based case-control study of SCCHN conducted in North Carolina from 2002 to 2006. We estimated ORs and 95% confidence intervals (CI) for SNPs and haplotypes, adjusting for age, sex, race, and duration of cigarette smoking. P values were adjusted for multiple testing using Bonferroni correction.
RESULTS: Two SNPs were associated with SCCHN risk: ADH1B rs1229984 A allele (OR = 0.7; 95% CI, 0.6-0.9) and ALDH2 rs2238151 C allele (OR = 1.2; 95% CI, 1.1-1.4). Three were associated with subsite tumors: ADH1B rs17028834 C allele (larynx, OR = 1.5; 95% CI, 1.1-2.0), SOD2 rs4342445 A allele (oral cavity, OR = 1.3; 95% CI, 1.1-1.6), and SOD2 rs5746134 T allele (hypopharynx, OR = 2.1; 95% CI, 1.2-3.7). Four SNPs in alcohol metabolism genes interacted additively with alcohol consumption: ALDH2 rs2238151, ADH1B rs1159918, ADH7 rs1154460, and CYP2E1 rs2249695. No alcohol interactions were found for oxidative stress SNPs.
CONCLUSIONS AND IMPACT: Previously unreported associations of SNPs in ALDH2, CYP2E1, GPX2, SOD1, and SOD2 with SCCHN and subsite tumors provide evidence that alterations in alcohol and oxidative stress pathways influence SCCHN carcinogenesis and warrant further investigation.

Chiang CP, Jao SW, Lee SP, et al.
Expression pattern, ethanol-metabolizing activities, and cellular localization of alcohol and aldehyde dehydrogenases in human large bowel: association of the functional polymorphisms of ADH and ALDH genes with hemorrhoids and colorectal cancer.
Alcohol. 2012; 46(1):37-49 [PubMed] Related Publications
Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are principal enzymes responsible for metabolism of ethanol. Functional polymorphisms of ADH1B, ADH1C, and ALDH2 genes occur among racial populations. The goal of this study was to systematically determine the functional expressions and cellular localization of ADHs and ALDHs in human rectal mucosa, the lesions of adenocarcinoma and hemorrhoid, and the genetic association of allelic variations of ADH and ALDH with large bowel disorders. Twenty-one surgical specimens of rectal adenocarcinoma and the adjacent normal mucosa, including 16 paired tissues of rectal tumor, normal mucosae of rectum and sigmoid colon from the same individuals, and 18 surgical mixed hemorrhoid specimens and leukocyte DNA samples from 103 colorectal cancer patients, 67 hemorrhoid patients, and 545 control subjects recruited in previous study, were investigated. The isozyme/allozyme expression patterns of ADH and ALDH were identified by isoelectric focusing and the activities were assayed spectrophotometrically. The protein contents of ADH/ALDH isozymes were determined by immunoblotting using the corresponding purified class-specific antibodies; the cellular activity and protein localizations were detected by immunohistochemistry and histochemistry, respectively. Genotypes of ADH1B, ADH1C, and ALDH2 were determined by polymerase chain reaction-restriction fragment length polymorphisms. At 33mM ethanol, pH 7.5, the activity of ADH1C*1/1 phenotypes exhibited 87% higher than that of the ADH1C*1/*2 phenotypes in normal rectal mucosa. The activity of ALDH2-active phenotypes of rectal mucosa was 33% greater than ALDH2-inactive phenotypes at 200μM acetaldehyde. The protein contents in normal rectal mucosa were in the following order: ADH1>ALDH2>ADH3≈ALDH1A1, whereas those of ADH2, ADH4, and ALDH3A1 were fairly low. Both activity and content of ADH1 were significantly decreased in rectal tumors, whereas the ALDH activity remained unchanged. The ADH activity was also significantly reduced in hemorrhoids. ADH4 and ALDH3A1 were uniquely expressed in the squamous epithelium of anus at anorectal junctions. The allele frequencies of ADH1C*1 and ALDH2*2 were significantly higher in colorectal cancer and that of ALDH2*2 also significantly greater in hemorrhoids. In conclusion, ADH and ALDH isozymes are differentially expressed in mucosal cells of rectum and anus. The results suggest that acetaldehyde, an immediate metabolite of ethanol, may play an etiological role in pathogenesis of large bowel diseases.

Disclaimer: This site is for educational purposes only; it can not be used in diagnosis or treatment.

Cite this page: Cotterill SJ. ALDH2, Cancer Genetics Web: Accessed:

Creative Commons License
This page in Cancer Genetics Web by Simon Cotterill is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Note: content of abstracts copyright of respective publishers - seek permission where appropriate.

 [Home]    Page last revised: 17 March, 2015     Cancer Genetics Web, Established 1999