Genetic polymorphisms of alcohol and aldehyde dehydrogenases and glutathione S-transferase M1 and drinking, smoking, and diet in Japanese men with esophageal squamous cell carcinoma

Alcohol, ALDH2, and Esophageal Cancer: A Meta-analysis Which Illustrates the Potentials and Limitations of a Mendelian Randomization Approach

Mendelian randomization, the use of common polymorphisms as surrogates for measuring exposure levels in epidemiologic studies, provides one method of assessing the causal nature of some environmental exposures. This can be illustrated by looking at the association between the ALDH2 polymorphism and esophageal cancer. 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 for the increased cancer risk. The ability to metabolize acetaldehyde is encoded by the ALDH2 gene, which is polymorphic in some populations. The ALDH2*2 allele produces an inactive protein subunit, which is unable to metabolize acetaldehyde. An individual's genotype at this locus may influence their esophageal cancer risk through two mechanisms, first through influencing alcohol intake and second through influencing acetaldehyde levels. We have carried out a meta-analysis of studies looking at the ALDH2 genotype and esophageal cancer and found that risk was reduced among *2*2 homozygotes [odds ratio (OR), 0.36; 95% confidence interval (95% CI), 0.16-0.80] and increased among heterozygotes (OR, 3.19; 95% CI, 1.86-5.47) relative to *1*1 homozygotes. This provides strong evidence that alcohol intake increases the risk of esophageal cancer and individuals whose genotype results in markedly lower intake, because they have an adverse reaction to alcohol are thus protected. This meta-analysis also provides evidence that acetaldehyde plays a carcinogenic role in esophageal cancer. The two different processes operating as a result of the ALDH2 genotype have implications for the interpretation of studies using the Mendelian randomization paradigm.

Epidemiological evidence that acetaldehyde plays a significant role in the development of decreased serum folate concentration and elevated mean corpuscular volume in alcohol drinkers

BACKGROUND

Elevated mean corpuscular volume (MCV) is a traditional biological marker for alcohol abuse and alcoholism, but the underlying mechanism is unclear. Three recent epidemiologic studies consistently showed that MCV was elevated by alcohol drinking more markedly among individuals with genetically inactive aldehyde dehydrogenase-2 (ALDH2) (encoded by ALDH2*2 mutant allele) than those with active ALDH2 (encoded by ALDH2*1/2*1 genotype), suggesting that the elevated MCV was etiologically linked to acetaldehyde exposure. The purpose of the present study was to clarify further this relationship by examining the status of folate and vitamin B12.

METHODS

The study participants were 159 men who were aged 40 to 69 years and randomly selected from a Japanese rural population. The genetic polymorphism of ALDH2 was determined by PCR-restriction fragment length polymorphism method; data on alcohol drinking and other lifestyles were collected using a structured questionnaire; serum concentrations of folate and vitamin B12 were measured using the protein competitive reaction method, and blood cell counts were measured by routine methods. A multiple linear regression model was used to analyze the data.

RESULTS

: The relationship between alcohol drinking and serum folate concentration was significantly different between ALDH2 genotypes, indicating that the reduction of serum folate by alcohol drinking was more marked in men with ALDH2*1/2*2 than those with ALDH2*1/2*1. The relationship between alcohol drinking and elevated MCV was significantly stronger in men with ALDH2*1/2*2 than those with ALDH2*1/2*1 even after adjustment for serum folate and vitamin B12 concentrations.

CONCLUSIONS

These findings indicate that acetaldehyde plays a significant role in the development of decreased serum folate concentration and elevated MCV by alcohol drinking.

Esophageal melanosis, an endoscopic finding associated with squamous cell neoplasms of the upper aerodigestive tract, and inactive aldehyde dehydrogenase-2 in alcoholic Japanese men

BACKGROUND

Esophageal melanosis is often observed in alcoholic Japanese men, in whom the prevalence of squamous cell dysplasia and carcinoma (SCC) in the upper aerodigestive tract are high. This study evaluated the associations of esophageal melanosis with these neoplasms, and the factors contributing to the development of esophageal melanosis in this population.

METHODS

Endoscopic screening was combined with esophageal iodine staining in 1535 alcoholic Japanese men (aged 40-79 years), of whom 1007 underwent aldehyde dehydrogenase-2 (ALDH2) genotyping.

RESULTS

Fifty patients (3.3%) were diagnosed with esophageal melanosis, which had a higher incidence in those with noncancerous distinct iodine-unstained lesions (DIULs; 16/268; 6.0%), esophageal SCC (9/66; 13.6%), and oropharyngolaryngeal SCC (4/19; 21.1%) than in cancer- and DIUL-free controls (24/1182; 2.0%). The presence of esophageal melanosis was associated with higher risks for noncancerous DIULs, esophageal SCC, and oropharyngolaryngeal SCC (odds ratios, 2.81, 6.54, and 14.77, respectively). Men with the inactive ALDH2*1/2*2 genotype had a higher risk for esophageal melanosis (2.66-fold), as well as for DIULs and SCCs.

CONCLUSIONS

The presence of esophageal melanosis in alcoholic Japanese men could indicate a high risk for DIULs and SCCs in the upper aerodigestive tract. The high incidence of esophageal melanosis may be partially linked to high acetaldehyde exposure, a consequence of drinking alcohol in persons with inactive ALDH2.

Hangover Susceptibility in Relation to Aldehyde Dehydrogenase-2 Genotype, Alcohol Flushing, and Mean Corpuscular Volume in Japanese Workers

BACKGROUND

A study of Asian-American students suggested a positive association between inactive ALDH2*2 and susceptibility to hangover. A biomarker for moderate-to-heavy drinking in persons with inactive aldehyde dehydrogenase-2 (ALDH2) is increased mean corpuscular volume (MCV).

METHODS

Associations between hangover and ALDH2 genotype, alcohol flushing, and MCV were examined for 251 Japanese workers (139 men, 112 women).

RESULTS

Inactive ALDH2*1/2*2 heterozygotes drank less alcohol than active ALDH2*1/2*1 homozygotes (p < 0.0001), but the frequency of hangover did not significantly differ between the two groups for either gender. The amount of drinking reported to lead to hangover was significantly less for male and female ALDH2*1/2*2 heterozygotes than for their ALDH2*1/2*1 homozygous counterparts (p < 0.005). The proportion of men who had hangover three times or more during the past year increased significantly with increased daily alcohol consumption in men with the ALDH2*1/2*2 genotype (p = 0.0002) but not in those with the ALDH2*1/2*1 genotype. For men who usually consumed <44 g of ethanol/day, the median amount of drinking before hangover was significantly lower for ALDH2*1/2*2 men than for ALDH2*1/2*1 men reporting the same level of consumption. Hangover occurred with consistently high frequency among ALDH2*1/2*1 men, regardless of their daily consumption. Similar findings were observed in a comparison of men who never flushed and those who reported current or former flushing, a surrogate marker of inactive ALDH2. Assessment of hangover risk by quartiles of MCV showed that men with MCV of > or =96 had a significantly higher risk of hangover than did men with MCV of <91 (odds ratio = 5.56; 95% confidence interval = 1.69-18.25).

CONCLUSIONS

Inactive heterozygous ALDH2, alcohol flushing, and increased MCV were positively associated with hangover susceptibility in Japanese workers, suggesting that acetaldehyde is etiologically linked to the development of hangover.

Cribado del carcinoma escamoso de esófago en población de riesgo

Together with adenocarcinoma, epidermoid esophageal carcinoma is the most clinically important neoplasm of the esophagus. Because of the low incidence of epidermoid esophageal carcinoma in the general population, strategies for its early diagnosis are not a priority compared with other neoplasms. However, because survival is low when the disease is diagnosed in symptomatic patients (less than 20% at 5 years), methods for its early diagnosis should be investigated. The use of cytology or Lugol chromoendoscopy in countries with a high incidence of epidermoid carcinoma or in individuals at increased risk (mainly alcoholics and smokers) has allowed early diagnosis and potentially curative treatment, substantially increasing life expectancy in this group of patients. These results should stimulate the evaluation and eventual implementation of programs to achieve early diagnosis and therefore greater survival in patients with epidermoid esophageal carcinoma in Western countries.

Phase I/II enzyme gene polymorphisms and esophageal cancer risk: A meta-analysis of the literature

AIM: Phase I/II enzymes metabolize environmental carcin-ogens and several functional polymorphisms have been reported in their encoding genes. Although their significance with regard to esophageal carcinogenicity has been examined epidemiologically, it remains controversial. The present systematic review of the literature was performed to clarify associations.

METHODS: Eligible studies were case-control or cohort studies published until September 2004 that were written in any language. From PubMed and a manual review of refe-rence lists in relevant review articles, we obtained 16 studies related to the CYP1A1 Ile-Val substitution in exon 7, CYP1A1 MspI polymorphisms, CYP2E1 RsaI polymorphisms, GSTM1 null type, GSTT1 null type and GSTP1 Ile104Val. All were of case-control design. Summary statistics were odds ratios (ORs) comparing heterozygous-, homozygous-non-wild type or these two in combination with the homozygous wild type, or the null type with the non-null type for GSTM1 and GSTT1. A random effect model was used to estimate the summary ORs. A meta-regression analysis was applied to explore sources of heterogeneity.

RESULTS: Individuals with the Ile-Val substitution in CYP1A1 exon 7 had increased esophageal cancer risk, with ORs (95%CI) compared with Ile/Ile of 1.37 (1.09-1.71), 2.52 (1.62-3.91) and 1.44 (1.17-1.78) for Ile-Val, Val/Val genotype and the combined group. No significant association was found between esophageal cancer risk and the other genetic parameters.

CONCLUSION: A significant association exists between the CYP1A1 Ile-Val polymorphism and risk of esophageal cancer. Polymorphisms that increase the internal exposure to activated carcinogens may increase the risk of esophageal cancer.

Mean Corpuscular Volume and ADH1C Genotype in White Patients With Alcohol-Associated Diseases

BACKGROUND

Alcohol abuse is associated with several gastrointestinal diseases, such as esophageal carcinoma, chronic alcoholic pancreatitis, and liver cirrhosis. Increased mean corpuscular volume (MCV) has been recognized as a biomarker for alcohol abuse and heavy drinkers. Recent studies from Japan revealed that macrocytosis is related to ALDH-2/2 genotype, leading to increased acetaldehyde accumulation. It has also demonstrated that increased MCV values could also be an independent biomarker for esophageal cancer in Asians. Therefore, the aim of the current study was to investigate possible associations of MCV value with polymorphisms of ADH1C in white patients with alcohol-associated esophageal carcinoma, chronic alcoholic pancreatitis, and alcoholic cirrhosis as well as in heavy drinkers without organ damage.

METHODS

In this study, a total of 510 alcoholic patients were enrolled with esophageal cancer (n = 98), chronic pancreatitis (n = 98), alcoholic liver cirrhosis (n = 151), and alcohol abuse without gastrointestinal disease (n = 163). ADH1C genotyping was performed by PCR-based restriction fragment length polymorphism (PCR-RFLP) analysis from whole blood. The relation between MCV and ADH1C gene polymorphisms (ADH1C*1 and 1C*2) controlled for the amount of drinking, smoking, and age were investigated using both univariate and multivariate analysis.

RESULTS

In univariate analysis, higher alcohol consumption was associated with increased MCV. Other variables were not associated with macrocytosis. In multiple linear regression analysis, after adjustment for age and smoking, higher alcohol consumption and female sex were independently associated with higher MCV values. No other variables, including which alcohol-associated disease the patient had, had an independent effect. Adding ADH genotype rendered no independent significant effect on MCV value.

CONCLUSIONS

In a white population, MCV values were not associated with genotype polymorphisms of ADH1C. In contrast to findings in Asians, macrocytosis does not seem to be an independent biomarker for esophageal cancer. The role of ADH1C polymorphism in increasing MCV and the potential use of MCV as a marker for esophageal carcinoma are still pending.

The etiology of alcohol-induced breast cancer

Breast cancer is the most common cancer in women in the United States, and it is second among cancer deaths in women. Results of most epidemiologic studies, as well as of most experimental studies in animals, have shown that alcohol intake is associated with increased breast cancer risk. Alcohol consumption may cause breast cancer through different mechanisms, including through mutagenesis by acetaldehyde, through perturbation of estrogen metabolism and response, and by inducing oxidative damage and/or by affecting folate and one-carbon metabolism pathways. Alcohol-metabolizing enzymes are present in human breast tissue. Acetaldehyde is a known, although weak, mutagen. However, results of some studies with human subjects implicate this agent in the context of genetic susceptibilities to increased ethanol metabolism. Reactive oxygen species, resulting from ethanol metabolism, may be involved in breast carcinogenesis by causing damage, as well as by generating DNA and protein adducts. Alcohol interferes with estrogen pathways in multiple ways, influencing hormone levels and effects on the estrogen receptors. With regard to one-carbon metabolism, alcohol can negatively affect folate levels, and the folate perturbation affects DNA methylation and DNA synthesis, which is important in carcinogenesis. Some study results indicate that genetic variants of one-carbon metabolism genes might increase alcohol-related breast cancer risk. For all these pathways, genetic polymorphisms might play a role in increasing further a woman's risk for breast cancer. Additional studies are needed to determine the relative importance of these pathways, as well as the modifying influence by genetic variation.

Alcohol, vitamin A, and cancer

Chronic and excessive alcohol intake is associated with an increased risk of a variety of cancers (e.g., oral cavity, larynx, esophagus, liver, lung, colorectal, and breast). Retinoids (vitamin A and its derivatives) are known to exert profound effects on cellular growth, cellular differentiation, and apoptosis, thereby controlling carcinogenesis. Lower hepatic vitamin A levels have been well documented in alcoholics. Substantial research has been done, investigating the mechanisms by which excessive alcohol interferes with retinoid metabolism. More specifically, (1) alcohol acts as a competitive inhibitor of vitamin A oxidation to retinoic acid involving alcohol dehydrogenases and acetaldehyde dehydrogenases; (2) alcohol-induced cytochrome P450 enzymes (CYP), particularly CYP2E1, enhance catabolism of vitamin A and retinoic acid; and (3) alcohol alters retinoid homeostasis by increasing vitamin A mobilization from liver to extrahepatic tissues. As a consequence, long-term and excessive alcohol intake results in impaired status of retinoic acid, the most active derivative of vitamin A and a ligand for both retinoic acid receptors and retinoid X receptors. Moreover, this alcohol-impaired retinoic acid homeostasis interferes with (1) retinoic acid signaling (e.g., down-regulates retinoid target gene expression) and (2) retinoic acid "cross-talk" with the mitogen-activated protein kinase [(MAPK), including Jun N-terminal kinase, extracellular signal-regulated kinase, and p38 kinase] signaling pathway. In addition, restoration of retinoic acid homeostasis by retinoic acid supplementation restored the normal status of both retinoid and MAPK signaling, thereby maintaining normal cell proliferation and apoptosis in alcohol-fed animals. These observations would have implications for the prevention of alcohol-promoted liver (and peripheral tissue) carcinogenesis. However, a better understanding of the alcohol-retinoid interaction and the molecular mechanisms involved is needed before retinoids can be pursued in the prevention of alcohol-related carcinogenesis in human beings, particularly regarding the detrimental effects of polar metabolites of vitamin A.

Risk of multiple squamous cell carcinomas both in the esophagus and the head and neck region

While multiple squamous cell carcinomas are often observed in the esophagus and the head and neck region and confound us about the favorable treatments, the reason why some patients are more likely to develop multiple cancers remains obscure. We statistically analyzed clinical factors in 203 patients with newly diagnosed squamous cell carcinoma, to assess the risk of multiple cancers for the establishment of an effective prevention and screening programs. Widespread epithelial oncogenic alterations were assessed as multiple lugol-voiding lesions (multiple LVL) using lugol chromoendoscopy. Genetic polymorphisms of alcohol dehydrogenase type 3 (ADH3) and aldehyde dehydrogenase type 2 (ALDH2) were identified by PCR-restriction fragment length polymorphism analysis. Forty patients had synchronous multiple cancers and the remaining 163 had solitary cancer. Presence of multiple LVL was the only independent risk factor for multiple cancers [relative risk (RR) = 67; 95%CI, 15-310]. Multiple LVL was observed in only smoking drinkers. Among them, a multivariate analysis demonstrated that the ALDH2 deficiency allele (RR = 5.7; 95%CI, 2.8-11.6) and the slow metabolizing ADH3 allele (RR = 1.9; 95%CI, 1.1-7.9) were the independent risk factors for multiple LVL. Combination of these alleles lead to increase the risk of multiple LVL. In conclusion, an episode of multiple LVL is a remarkable high risk for multiple cancers both at the esophagus and the head and neck region. The interaction between drinking and the ALDH2 deficiency allele increases the risk. In addition, the slow metabolizing ADH3 allele enhances the risk. Prohibiting the use of alcohol and early detection of cancer are strongly recommended for such individuals.

Moderate alcohol consumption and diseases of the gastrointestinal system: a review of pathophysiological processes

BACKGROUND/AIMS

Alcohol drinking is responsible for a number of gastrointestinal diseases and cancers. Although heavy drinking episodes and chronic drinking are well linked to mechanisms of disease, moderate alcohol consumption and its effects are less well known. This review attempts to fill a gap in the literature surrounding moderate alcohol consumption.

METHODS

A systematic review of the English literature using PubMed was used.

RESULTS

A dose-response risk relationship exists between alcohol consumption and digestive disease risk. Acetaldehyde is the main factor in alcohol-related damage in moderate alcohol consumption and acts through numerous methods to exert damaging effects.

CONCLUSION

Zero alcohol intake is recommended for lowest risk of alcohol-related digestive tract diseases and conditions. However, given the lowest overall mortality is associated with moderate drinking, moderate drinking with no bingeing episodes is recommended.

Genetic polymorphisms in three Iranian populations with different risks of esophageal cancer, an ecologic comparison

The age-standardized incidence of esophageal cancer (EC) varies from 3 to >100/100,000 per year in different provinces of Iran. This striking variation of incidence is associated with differences in ethnic backgrounds, raising the possibility that genetic factors are involved in the pathogenesis of EC. We compared the frequencies of polymorphisms in ten genes that have been hypothesized to have a role in risk of EC (CYP1A1, CYP2A6, CYP2E1, GSTM1, GSTP1, GSTT1, ADH2, ADH3, ALDH2, and O6-MGMT) among three Iranian ethnic groups with highly varying rates of EC. These three groups included high-risk Turkomans, medium-risk Turks, and low-risk Zoroastrian Persians. Compared to Zoroastrians, Turkomans had higher frequency of four alleles that are speculated to favor carcinogenesis (CYP1A1 m1, CYP1A1 m2, CYP2A6*9, and ADH2*1); these results are consistent with an influence of these allele variants on the population risk of EC. However, none of these four alleles had a high enough prevalence in Turkomans to explain the high rates of EC in this group. Three of these four alleles (CYP1A1 m1, CYP1A1 m2, CYP2A6*9) were less frequent among Turkomans than in some Asian populations with lower risks of EC. We conclude that it is unlikely that variations in these polymorphic genes are major contributors to the high incidence of EC among Turkomans in Iran.

Influence of Genetic Variations of Ethanol-Metabolizing Enzymes on Phenotypes of Alcohol-Related Disorders

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase-2 (ALDH2) play central roles in the metabolism of ethanol and its metabolite, acetaldehyde, in the liver. In ADH2, one nucleotide replacement causes either a super-active beta 2 subunit encoded by the ADH2*2 allele or a less active beta 1 subunit (ADH2*1 allele). In the same way, a G/A replacement at codon 487 of the ALDH2 gene produces an inactive form of the enzyme. Because the geno-types of these genes may explain individual differences in concentration and elimination of ethanol and acetaldehyde in the blood after drinking, they could be used as models to elucidate the contribution of these substances to the development of addiction and various types of organ damage. We have examined the influence of genetic variations of these enzymes on alcohol-related disorders in the Japanese. The results revealed that (1) the less active allele of the ADH2 gene (ADH2*1) is associated with an increased risk for alcohol dependence, alcohol-induced persistent amnestic disorder, alcohol withdrawal syndrome, and cancer of the upper GI tract; (2) the inactive allele of the ALDH2 gene (ALDH2*2) is associated with a decreased risk for alcohol dependence, and an increased risk for alcoholic polyneuropathy and cancer in the same region; and (3) these genetic variations modify clinical features of alcohol dependence. Possible mechanisms of altered risk for these disorders are discussed.

Mean corpuscular volume and the aldehyde dehydrogenase-2 genotype in male Japanese workers

BACKGROUND

Increased mean corpuscular volume (MCV) is common in alcohol abusers and alcoholics. MCV is higher in Japanese heavy drinkers with inactive aldehyde dehydrogenase-2 (ALDH2) encoded by ALDH2*1/2*2 than among those with active ALDH2 encoded by ALDH2*1/2*1. Inactive ALDH2 dramatically increases blood acetaldehyde levels after alcohol intake. Because moderate and heavy drinkers with ALDH2*1/2*2 have very high risks for esophageal cancer, MCV might serve as an indicator of these high-risk drinkers.

METHODS

In this investigation of the association of red cell values with the ALDH2 genotype and possible confounding factors, the drinking, smoking, and dietary habits reported on a structured questionnaire by 163 Japanese working men were subjected to multivariate analyses.

RESULTS

Aging, lower body mass index (BMI), more alcohol consumption, and more smoking were positively associated with increased MCV. Among moderate to heavy drinkers (>or=9 units/week; 1 unit = 22 g of ethanol), both MCV and mean corpuscular hemoglobin were higher and the red cell count was lower in those with ADLH2*1/2*2 than in those with ALDH2*1/2*1. Multiple linear regression analysis after adjustment for age, BMI, and smoking revealed that a positive relationship between the amount of drinking and MCV but inverse relationships for drinking and red cell count, as well as hemoglobin and hematocrit values, were significantly stronger for men with ALDH2*1/2*2 than for those with ALDH2*1/2*1, demonstrating a gene-environment interaction. Drinking accounted for 19.9% of interindividual MCV variance among men with ALDH2*1/*2*2 but for only 1.3% of variance among those with ALDH2*1/2*1. Age, BMI, drinking, and smoking accounted for 52.1 and 34.7% of the variation among those with ALDH2*1/2*2 and ALDH2*1/2*1, respectively. Macrocytosis (MCV >or=100.0 fl) was observed in 18 subjects (11.0%), and use of macrocytosis as a biomarker of moderate to heavy drinkers with ALDH2*1/2*2 had a sensitivity of 54.5% (6 of 11) and a specificity of 92.1% (140 of 152).

CONCLUSIONS

Alcohol-related red cell value changes associated with inactive ALDH2 in Japanese men suggest the importance of acetaldehyde's role in increasing MCV and the potential for using MCV as a marker for high-risk drinkers for esophageal cancer.

LC-MS Study on the Formation of Cyclic 1,N2-Propano Guanine Adduct in the Reactions of DNA with Acetaldehyde in the Presence of Histone

The formation of cyclic 1,N2-propano guanine (CPr-Gua) adduct is significantly accelerated by the addition of arginine or histone in the reaction of calf thymus DNA with acetaldehyde (AA) or crotonaldehyde (CA). Histone proteins, containing a large amount of basic amino acids such as arginine, are essential as nucleosome cores to package DNA. In the presence of 0.60% (w/v) histone in the reaction mixture, 8-times and 25-times larger amounts of the CPr-Gua adduct were formed in the reaction of the DNA with AA and CA, respectively, compared with those in the absence of histone. Furthermore, for the DNA incubated at 95 degrees C for 10 min and cooled on ice to make the single-stranded moieties, 72-times and 178-times larger amounts of the CPr-Gua adduct were formed by AA and CA, respectively, in the presence of 0.60% (w/v) histone. These results strongly suggest that DNA in vivo should be exposed to a much more dangerous situation, compared with DNA alone, from the viewpoint of reactivity with the aldehydes. During DNA replication and transcriptional events of cells, the danger will be further increased markedly because of opening of double-strands. Semi-micro HPLC-ESI-MS measurements following deprination of DNA samples were performed for quantification of the adduct as the corresponding base form, CPr-Gua, in evaluation of the reactivity of DNA with AA and CA.

Synergistic effect of alcohol drinking and smoking onin vivo acetaldehyde concentration in saliva

Alcohol drinking and smoking are independent risk factors for upper digestive tract cancers. Furthermore, their combined use interacts in a multiplicative way on cancer risk. There is convincing evidence that acetaldehyde, the first metabolite of ethanol and a constituent of tobacco smoke, is a local carcinogen in humans. Therefore, we examined the combined effect of alcohol drinking and tobacco smoking on in vivo acetaldehyde concentration in saliva. Seven smokers and 6 nonsmokers participated in the study. First, to measure the effect of alcohol on salivary acetaldehyde, all volunteers ingested 0.8 g/kg body weight of ethanol and saliva samples were collected every 20 min for 160 min thereafter. After a 3-day washout period, smokers ingested again the same amount of ethanol and smoked one cigarette every 20 min and saliva samples were collected at 10 min intervals for 160 min. Acetaldehyde and ethanol concentrations were analyzed by headspace gas chromatograph. Firstly, smokers without concomitant smoking during ethanol challenge had 2 times higher in vivo salivary acetaldehyde concentrations than nonsmokers after ethanol ingestion (AUC 114.8 +/- 11.5 vs. 54.2 +/- 8.7 microM x hr, respectively; p = 0.002). Secondly, smokers with active smoking during ethanol challenge had 7 times higher in vivo salivary acetaldehyde levels than nonsmokers (AUC 369.5 +/- 12.2 vs. 54.2 +/- 8.7 microM x hr, respectively; p < 0.001). We conclude that this markedly increased exposure of upper digestive tract mucosa to carcinogenic salivary acetaldehyde of smoking and drinking subjects may explain the synergistic and multiplicative risk effect of alcohol drinking and tobacco smoking on upper gastrointestinal tract carcinogenesis.

Genetic polymorphisms in the Hmong population

BACKGROUND

The Hmong, an isolated, agrarian people from southern China, migrated to the mountainous regions of what are today Vietnam, Cambodia, and Laos. Minnesota has the second largest Hmong population in the United States. The authors compared frequencies of common genetic polymorphisms believed to influence risk of malignancy to determine whether frequencies in the Hmong are different from those in other Asian populations and in white Minnesotans.

METHODS

Genotyping for glutathione S-transferase micro1 (GSTM1), glutathione S-transferase theta1 (GSTT1), myeloperoxidase (MPO) (C(-)463T), nicotinamide adenine dinucleotide phosphate:quinone oxidoreductase (NQO1) (C609T), 5,10-methylenetetrahydrofolate reductase (MTHFR) (C677T), MTHFR (A1298C), methionine synthase reductase (MTRR) (A66G), X-ray repair cross complementing 1 (XRCC1) 194 (Arg194Trp), XRCC1 280 (Arg280His), and XRCC1 399 (Arg399Gln) alleles was performed by TaqMan analysis using DNA isolated from newborn heel-stick spots provided by the Minnesota Department of Health.

RESULTS

The Hmong had significantly higher frequencies of the NQO1 T allele and the XRCC1 Trp polymorphism (Arg194Trp) and had significantly lower frequencies of the G allele in MTRR (A66G) and the T allele in MTHFR (C677T) compared with white Minnesotans. The Hmong also were significantly more likely to lack the GSTM1 and GSTT1 genes compared with whites (82% vs. 54% and 61% vs. 18%, respectively). Genotype frequencies were similar for MTHFR (A1298C), MPO (C(-)463T), and XRCC1 (Arg280His, Arg399Gln). Genotype frequencies at these loci also were compared with those reported for other Asian populations and showed notable differences between the Hmong and Chinese/Taiwanese, Korean, and Japanese populations.

CONCLUSIONS

The genetic differences identified have implications for both cancer etiology and prognosis in this unique population.

Duplex polymerase chain reaction with confronting two-pair primers (PCR-CTPP) for genotyping alcohol dehydrogenase beta subunit (ADH2) and aldehyde dehydrogenase 2 (ALDH2)

AIMS

Alcohol dehydrogenase beta subunit (ADH2) Arg47His and aldehyde dehydrogenase 2 (ALDH2) Glu487Lys were genotyped by a duplex polymerase chain reaction (PCR) with confronting two-pair primers (PCR-CTPP), which allows DNA amplification with one-tube PCR including eight primers, and subsequent electrophoresis.

METHODS

Several PCR conditions were tested to establish the optimal conditions for distinguishing the allele-specific bands for the two polymorphisms. Under the optimal PCR conditions, 454 Japanese health check-up examinees were genotyped.

RESULTS

The allele-specific bands were successfully amplified under the optimal conditions of the duplex PCR-CTPP. The genotype distributions were within the Hardy-Weinberg equilibrium. The bands produced by the duplex PCR-CTPP genotyping were clearer than those produced by PCR-CTPP, conducted solely for ADH2.

CONCLUSIONS

ADH2 Arg47His and ALDH2 Glu487Lys were successfully genotyped by this newly developed duplex PCR-CTPP, an inexpensive and time-saving genotyping tool, which will be useful in epidemiological studies on alcoholism, as well as risk estimation of alcohol-related diseases.

Do the ethanol metabolizing enzymes modify the relationship between alcohol consumption and blood pressure?

BACKGROUND

Several cross-sectional studies have examined whether the relationship between alcohol consumption and blood pressure (alcohol-BP relationship) differs among individuals with different aldehyde dehydrogenase-2 (ALDH2) genotypes, but few studies have examined the association with alcohol dehydrogenase-2 (ADH2), and those have yielded inconsistent results. We examined the potential modulatory effects of ADH2 and ALDH2 genotypes on the alcohol-BP relationship in a cross-sectional sample of a Japanese rural community.

METHODS AND RESULTS

The study subjects were 335 randomly selected men aged 40-69 years, who lived in Shiso, a Japanese rural county, in 1999 or 2000. The genetic polymorphisms of ADH2 and ALDH2 were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methods. The frequencies of ADH21/21 (wild-type), 21/22 (superactive heterozygotes), and 22/22 (superactive homozygotes) were 8.4, 34.9 and 56.7%, respectively; and those of ALDH21/21 (wild-type), 21/22 (inactive heterozygotes), and 22/22 (inactive homozygotes) were 52.8, 40.9, and 6.3%, respectively. A multiple linear regression analysis showed that the relationship between alcohol consumption and diastolic blood pressure was significantly stronger in men with ADH21/21 than those with ADH21/22 or 22/22 (adjusted regression coefficient = 0.0392 versus 0.0113 mmHg for + 1 g ethanol/week, P for difference in slope = 0.018). The strength of the alcohol-BP relationship was similar in all of the ALDH2 genotype groups.

CONCLUSION

The alcohol-BP relationship was significantly stronger in men with ADH21/21 than in men with ADH21/22 or 22/22 in this Japanese rural population. This finding was exactly the opposite of what one previous study suggested.