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Song BJ, Abdelmegeed MA, Cho YE, Akbar M, Rhim JS, Song MK, Hardwick JP. Contributing Roles of CYP2E1 and Other Cytochrome P450 Isoforms in Alcohol-Related Tissue Injury and Carcinogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1164:73-87. [PMID: 31576541 DOI: 10.1007/978-3-030-22254-3_6] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The purpose of this review is to briefly summarize the roles of alcohol (ethanol) and related compounds in promoting cancer and inflammatory injury in many tissues. Long-term chronic heavy alcohol exposure is known to increase the chances of inflammation, oxidative DNA damage, and cancer development in many organs. The rates of alcohol-mediated organ damage and cancer risks are significantly elevated in the presence of co-morbidity factors such as poor nutrition, unhealthy diets, smoking, infection with bacteria or viruses, and exposure to pro-carcinogens. Chronic ingestion of alcohol and its metabolite acetaldehyde may initiate and/or promote the development of cancer in the liver, oral cavity, esophagus, stomach, gastrointestinal tract, pancreas, prostate, and female breast. In this chapter, we summarize the important roles of ethanol/acetaldehyde in promoting inflammatory injury and carcinogenesis in several tissues. We also review the updated roles of the ethanol-inducible cytochrome P450-2E1 (CYP2E1) and other cytochrome P450 isozymes in the metabolism of various potentially toxic substrates, and consequent toxicities, including carcinogenesis in different tissues. We also briefly describe the potential implications of endogenous ethanol produced by gut bacteria, as frequently observed in the experimental models and patients of nonalcoholic fatty liver disease, in promoting DNA mutation and cancer development in the liver and other tissues, including the gastrointestinal tract.
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Affiliation(s)
- Byoung-Joon Song
- Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA.
| | - Mohamed A Abdelmegeed
- Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - Young-Eun Cho
- Section of Molecular Pharmacology and Toxicology, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA.,Department of Food Science and Nutrition, Andong National University, Andong, Republic of Korea
| | - Mohammed Akbar
- Division of Neuroscience and Behavior, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA
| | - Johng S Rhim
- Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Min-Kyung Song
- Investigational Drug Branch, National Cancer Institute, NIH, Bethesda, MD, USA
| | - James P Hardwick
- Biochemistry and Molecular Pathology in the Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH, USA
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Castro GD, Castro JA. Alcohol drinking and mammary cancer: Pathogenesis and potential dietary preventive alternatives. World J Clin Oncol 2014; 5:713-29. [PMID: 25300769 PMCID: PMC4129535 DOI: 10.5306/wjco.v5.i4.713] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 01/21/2014] [Accepted: 04/03/2014] [Indexed: 02/06/2023] Open
Abstract
Alcohol consumption is associated with an increased risk of breast cancer, increasing linearly even with a moderate consumption and irrespectively of the type of alcoholic beverage. It shows no dependency from other risk factors like menopausal status, oral contraceptives, hormone replacement therapy, or genetic history of breast cancer. The precise mechanism for the effect of drinking alcohol in mammary cancer promotion is still far from being established. Studies by our laboratory suggest that acetaldehyde produced in situ and accumulated in mammary tissue because of poor detoxicating mechanisms might play a role in mutational and promotional events. Additional studies indicated the production of reactive oxygen species accompanied of decreases in vitamin E and GSH contents and of glutathione transferase activity. The resulting oxidative stress might also play a relevant role in several stages of the carcinogenic process. There are reported in literature studies showing that plasmatic levels of estrogens significantly increased after alcohol drinking and that the breast cancer risk is higher in receptor ER-positive individuals. Estrogens are known that they may produce breast cancer by actions on ER and also as chemical carcinogens, as a consequence of their oxidation leading to reactive metabolites. In this review we introduce our working hypothesis integrating the acetaldehyde and the oxidative stress effects with those involving increased estrogen levels. We also analyze potential preventive actions that might be accessible. There remains the fact that alcohol drinking is just one of the avoidable causes of breast cancer and that, at present, the suggested acceptable dose for prevention of this risk is of one drink per day.
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Bachar G, Hod R, Goldstein DP, Irish JC, Gullane PJ, Brown D, Gilbert RW, Hadar T, Feinmesser R, Shpitzer T. Outcome of oral tongue squamous cell carcinoma in patients with and without known risk factors. Oral Oncol 2010; 47:45-50. [PMID: 21167767 DOI: 10.1016/j.oraloncology.2010.11.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2010] [Revised: 11/02/2010] [Accepted: 11/02/2010] [Indexed: 11/18/2022]
Abstract
BACKGROUND Tobacco smoking and high alcohol consumption are considered major risk factors of oral tongue squamous cell carcinoma. This study compared disease outcome between patients with and without known risk factors. METHODS Patients with oral tongue squamous cell carcinoma treated at two major medical centers from 1994 to 2008 were identified by cancer registry search. The medical files were reviewed for background-and-disease-related data, risk factors, and outcome. RESULTS The study sample consisted of 291 patients: 175 had a history of heavy tobacco smoking and alcohol abuse and 116 did not. Comparison of the patients without risk factors between the two centers yielded no differences in background features. Men accounted for 74% of the total patients with risk factors and comprised 77% of the risk-factor group. The risk-factor group was characterized by a significantly higher mean tumor grade (p=0.0001) and greater tumor depth of invasion (p=0.022) than the non-risk-factor group. The 5-year local and regional control rates were 85.3% and 74%, respectively, with no significant difference between the groups. The 5-year overall survival rate was 68% in the risk-factor group and 64% in the non-risk-factor group (p=NS). Separate analysis of patients aged <40 years at diagnosis revealed a worse overall (p=0.015) and disease-free survival (p=0.038) in those without risk factors. CONCLUSIONS The outcome of oral tongue carcinoma is similar in patients with and without risk factors. The worse prognosis in younger patients (<40 years) without risk factors suggests that the pathogenesis in these cases involves factors other than smoking and alcohol.
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Affiliation(s)
- G Bachar
- Department of Otolaryngology-Head and Neck Surgery, Rabin Medical Center, Beilinson Campus, Petah Tiqwa 49100, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
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López-Blanc SA, Collet AM, Gandolfo MS, Femopase F, Hernández SL, Tomasi VH, Paparella ML, Itoiz ME. Nucleolar organizer regions (AgNOR) and subepithelial vascularization as field cancerization markers in oral mucosa biopsies of alcoholic and smoking patients. ACTA ACUST UNITED AC 2009; 108:747-53. [PMID: 19748291 DOI: 10.1016/j.tripleo.2009.06.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 05/14/2009] [Accepted: 06/26/2009] [Indexed: 02/04/2023]
Abstract
OBJECTIVE The aim of this study was to show that variations in nucleolar organizer regions (AgNOR) and the increase in subepithelial vascularization could reveal changes related to markers of field cancerization in alcoholic and smoking patients who have not yet expressed clinical or histological malignant lesions. STUDY DESIGN Quantitative variations in epithelial AgNOR and in the vascularization of the underlying connective tissue were assessed by image analysis in histologically normal biopsy specimens from alcohol drinkers and smoking patients (DS). AgNORs were evidenced by silver staining and vessel walls were labeled by immunohistochemical demonstration of the CD34 antigen. Samples of oral mucosa of nonalcoholic, nonsmoking patients (NDS) obtained during surgical procedures served as controls. Eight parameters related to number, volume, and shape of nuclei and AgNORs, and 4 parameters related to number and diameter of vascular sections were evaluated. Differences between DS and NDS groups were statistically evaluated by means of ANOVA test and posterior Bonferroni comparisons. RESULTS The morphometric analysis revealed more irregular-shaped AgNORs in the superficial and suprabasal layers of the oral mucosa of DS patients. The suprabasal layers also exhibited a significantly larger number of AgNORs. The normal oral mucosa of DS patients exhibited a greater vascular density, with predominance of small-caliber blood vessels underlying the basement membrane. CONCLUSION The variations in AgNOR and epithelial vascularization would be practical biomarkers to evaluate changes underlying the augmented risk of cancerization in oral mucosa.
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Affiliation(s)
- Silvia A López-Blanc
- Department of Oral Pathology, Clinical Stomatology, Faculty of Dentistry, National University of Córdoba, Córdoba, Argentina
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Abstract
Chronic consumption of alcoholic beverages is an accepted social custom worldwide. In the upper aerodigestive tract, local morphologic, metabolic and functional alterations are present due to alcohol consumption. A clinical link between the chronic consumption of alcohol and head and neck cancer has been observed for decades. While alcohol was described initially as a risk enhancer only in smokers, a number of epidemiological studies have now provided sufficient evidence that chronic alcohol consumption increases the risk of head and neck cancer independent of exposure to tobacco smoke. The systemic effects of alcohol interact with local changes in the morphology and function of the salivary glands. In addition, alcohol leads to accumulation of pathologic microbes within the mucosa, leading to chronic infection. Susceptibility to carcinogens and cell proliferation in the mucosa are increased, resulting in genetic changes with the development of dysplasia, leukoplacia and carcinoma. Chronic alcohol consumption is correlated with an increased risk of cancer and an increased mortality in a dose-effect relationship. A number of biologically plausible mechanisms exist by which alcohol may cause cancer. These mechanisms are discussed in this article.
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Affiliation(s)
- Frank Riedel
- Department of Otolaryngology, Head and Neck, University Hospital Mannheim, Mannheim, Germany.
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Abstract
Maternal alcohol use during pregnancy is associated with a wide range of adverse outcomes for the child. Many women who drink during pregnancy also have male partners who abuse alcohol. Existing data on paternal effects of alcohol abuse during the preconceptual period and at the time of conception are reviewed. Epidemiological data offer some support for a paternal influence on birth weight, congenital heart defects, and some evidence of mild cognitive impairments. Animal data have demonstrated decreased litter size, increased prevalence of low birth weight fetuses and mixed data on risk of malformations. Increased susceptibility to Pseudomonas bacterial infection has been reported. Cognitive and behavioral findings are the most robust effects. These include learning and memory deficits, hyperactivity, and poor stress tolerance. Multiple causal mechanisms for a paternal effect have been suggested, but none seems satisfactory to explain all findings. Further research is needed on paternal effects in animals and human populations. The results of this research may influence prevention activities.
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Affiliation(s)
- Ernest Abel
- Department of Obstetrics and Gynecology, Wayne State University, Detroit, MI 48201, USA.
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Abstract
Chronic consumption of alcoholic beverages is an accepted social custom worldwide. In the upper aerodigestive tract, local morphological, metabolic and functional alterations can be present as a result of alcohol consumption. A clinical link between the chronic consumption of alcohol and head and neck cancer has been observed for decades. While alcohol was described initially as a risk enhancer only in smokers, a number of epidemiological studies have now provided sufficient evidence that chronic alcohol consumption increases the risk of head and neck cancer independent of exposure to tobacco smoke. Systemic effects of alcohol interact with local changes in the morphology and function of the salivary glands. In addition, alcohol leads to the accumulation of pathological microbes within the mucosa, leading to chronic infection. Susceptibility to carcinogens and cell proliferation in the mucosa are increased, resulting in genetic changes with the development of dysplasia, leucoplakia and carcinoma. Chronic alcohol consumption has been correlated with an increased risk of cancer and increased mortality in a dose-effect relationship. A number of biologically plausible mechanisms exist by which alcohol may cause cancer. These mechanisms are discussed in this chapter.
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Affiliation(s)
- Frank Riedel
- Department of Otolaryngology, Head and Neck Surgery, University Hospital Mannheim, Theodor-Kutzer-Ufer, D-68135, Mannheim, Germany.
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Gómez MID, Valles E, Fanelli SL, de Layño AMAD, Castro GD, Castro JA. Alcohol induction of liver nuclear ethanol and N-nitrosodimethylamine metabolism to reactive metabolites. TERATOGENESIS, CARCINOGENESIS, AND MUTAGENESIS 2002; 22:139-45. [PMID: 11835291 DOI: 10.1002/tcm.10009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In previous studies from our laboratory we reported the presence in highly purified liver nuclei, free of contamination with other organelles, of an ethanol metabolizing system (NEMS) able to lead to acetaldehyde and 1-hydroxyethyl free radicals (1HEt). In the present study we tested whether this NEMS is inducible by chronic alcohol administration to rats and whether these nuclei also have increased ability to bioactivate N-nitrosodimethylamine (NDMA). Sprague Dawley male rats (125-150g) were fed with a nutritionally adequate liquid diet containing alcohol to provide 36% of total energy (standard Lieber-De Carli rat diet), for 28 days. Controls received an isocaloric diet without alcohol. Animals were sacrificed, livers were excised and microsomes and purified nuclear fractions were prepared. Both microsomes and nuclei from treated animals had significantly increased ability compared to controls, to biotransform ethanol to acetaldehyde using NADPH as cofactor under an air atmosphere. Both organelles also exhibited significantly increased capacity compared to controls, to bioactivate NDMA to formaldehyde and to reactive metabolites that bind covalently to proteins. Nuclear preparations from control animals were also able to metabolize NDMA to formaldehyde and reactive metabolites. Results indicate that liver nuclei may have a CYP2E1 able to bioactivate both NDMA and EtOH and that these processes are being induced by chronic alcohol drinking. The bioactivation of these xenobiotics to reactive metabolites in the neighborhood of nuclear proteins and DNA might have significant toxicological implications.
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Affiliation(s)
- M I Díaz Gómez
- Centro de Investigaciones Toxicológicas (CEITOX), CITEFA/CONICET, Buenos Aires, Argentina
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Bielawski DM, Zaher FM, Svinarich DM, Abel EL. Paternal Alcohol Exposure Affects Sperm Cytosine Methyltransferase Messenger RNA Levels. Alcohol Clin Exp Res 2002. [DOI: 10.1111/j.1530-0277.2002.tb02544.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Castro GD, Delgado de Layño AM, Costantini MH, Castro JA. Cytosolic xanthine oxidoreductase mediated bioactivation of ethanol to acetaldehyde and free radicals in rat breast tissue. Its potential role in alcohol-promoted mammary cancer. Toxicology 2001; 160:11-8. [PMID: 11246119 DOI: 10.1016/s0300-483x(00)00433-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Epidemiological evidence links alcohol intake with increased risk in breast cancer. Not all the characteristics of the correlation can be explained in terms of changes in hormonal factors. In this work, we explore the possibility that alcohol were activated to acetaldehyde and free radicals in situ by xanthine dehydrogenase (XDh) and xanthine oxidase (XO) and/or aldehyde oxidase (AO). Incubation of cytosolic fraction with xanthine oxidoreductase (XDh+XO) (XOR) cosubstrates (e.g. NAD+, hypoxanthine, xanthine, caffeine, theobromine, theophylline or 1,7-dimethylxanthine) significantly enhanced the biotransformation of ethanol to acetaldehyde. The process was inhibited by allopurinol and not by pyrazole or benzoate or desferrioxamine and was not accompanied by detectable formation of 1HEt. However, hydroxylated aromatic derivatives of PBN were detected, suggesting either that hydroxyl free radicals might be formed or that XOR might catalyze aromatic hydroxylation of PBN. No bioactivation of ethanol to acetaldehyde was detectable when a cosubstrate of AO such as N-methylnicotinamide was included in cytosolic incubation mixtures. Results suggest that bioactivation of ethanol in situ to a carcinogen, such as acetaldehyde, and potentially to free radicals, might be involved in alcohol breast cancer induction. This might be the case, particularly also in cases of a high consumption of purine-rich food (e.g. meat) or beverages or soft drinks containing caffeine.
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Affiliation(s)
- G D Castro
- Centro de Investigaciones Toxicológicas (CEITOX)-CITEFA/CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Buenos Aires, Argentina.
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Wight AJ, Ogden GR. Possible mechanisms by which alcohol may influence the development of oral cancer--a review. Oral Oncol 1998; 34:441-7. [PMID: 9930353 DOI: 10.1016/s1368-8375(98)00022-0] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Although pure ethanol has never been shown to be carcinogenic in laboratory experiments, alcoholic beverages are now recognised as being important aetiological factors in the development of oral cancer. Despite this, the exact mechanism by which alcohol may exert an influence upon the oral mucosa has received less attention. An overview of the association of alcohol and oral cancer, both in combination with tobacco and without, is provided and consideration given to some of the pathways by which alcohol exerts its effect upon the oral mucosa.
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Affiliation(s)
- A J Wight
- Unit of Oral Medicine and Oral Surgery, Dundee Dental Hospital and School, University of Dundee, U.K
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12
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Izzotti A, Balansky RM, Blagoeva PM, Mircheva ZI, Tulimiero L, Cartiglia C, De Flora S. DNA alterations in rat organs after chronic exposure to cigarette smoke and/or ethanol ingestion. FASEB J 1998; 12:753-8. [PMID: 9619454 DOI: 10.1096/fasebj.12.9.753] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In spite of the epidemiological evidence supporting a synergism between alcohol consumption and cigarette smoking in the pathogenesis of cancers of the aerodigestive tract, there is a paucity of experimental studies evaluating the effects of these agents under well-controlled conditions and exploring the mechanisms involved. We exposed groups of female BD6 rats, aged 8 months, to ethanol (5% in drinking water for 8 consecutive months) and/or whole-body to mainstream cigarette smoke (1 h/day, 5 days/week for 8 months). DNA was purified from different organs and analyzed for the presence of DNA-protein crosslinks and 32P-postlabeled DNA adducts after butanol enrichment. No significant increase of DNA-protein crosslinks, compared to untreated controls, was induced by any treatment in liver, lung, or heart. 'Spontaneous' nucleotidic modifications were detected by 32P-postlabeling in organs of untreated rats, with the highest levels occurring in the heart. Ingestion of ethanol did not affect DNA adduct levels in any of the organs examined: esophagus, liver, lung, and heart. Exposure to cigarette smoke induced formation of DNA adducts in the lung and heart, but not in the esophagus or liver. The combined ingestion of ethanol resulted in a significant formation of smoke-related DNA adducts in the esophagus and in their further, dramatic increase in the heart. It thus appears that ethanol consumption increases the bioavailability of DNA binding smoke components in the upper digestive tract and favors their systemic distribution. The mechanisms responsible for the interaction between ethanol and smoke and for the selective localization of DNA alterations in different organs are discussed. Formation of DNA adducts in the organs examined may be relevant in the pathogenesis of lung and esophageal cancers as well as in the pathogenesis of other types of chronic degenerative diseases, such as chronic obstructive pulmonary diseases and cardiomyopathies.
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Affiliation(s)
- A Izzotti
- Institute of Hygiene and Preventive Medicine, University of Genoa, Italy
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Wilson DM, Tentler JJ, Carney JP, Wilson TM, Kelley MR. Acute ethanol exposure suppresses the repair of O6-methylguanine DNA lesions in castrated adult male rats. Alcohol Clin Exp Res 1994; 18:1267-71. [PMID: 7847618 DOI: 10.1111/j.1530-0277.1994.tb00117.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Alcohol has clearly been associated with an increase of cancers in numerous tissue, including the respiratory tract, colon, rectum, liver, but especially the esophagus, larynx, pharynx, and mouth. Alcohol alone has not been shown to be a mutagen until it is converted to acetaldehyde and, therefore, alcohol presumably acts as a cocarcinogen. Previous data has shown that alcohol concentrations of 2% or greater inhibits DNA repair, and in light of the widespread consumption of alcoholic beverages with alcohol contents ranging from 4 to 5% (beer and wine coolers) to 50% (whiskey), interest in determining the mechanism(s) responsible for alcohol-induced carcinogenesis has heightened. Although previous studies, in intact rats, have investigated the effects of chronic alcohol exposure on some aspects of DNA repair, we have begun to address the effects of acute or "binge" alcohol exposure on mammalian DNA repair. Toward this end, we report the inhibition of O6-methylguanine-DNA methyltransferase (MGMT) by a single intraperitoneal injection of 30% ethanol in adult male castrated rats. This inhibition lasted for at least 24 hr. We also observed a dose-response effect of ethanol on MGMT activity, again only in the castrated rats. The finding of ethanol's effect on MGMT activity in castrated and not intact rats implies a hormonal component of MGMT DNA repair response, which has only been alluded to in past research.
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Affiliation(s)
- D M Wilson
- Department of Pediatrics, Riley Hospital, Indianapolis, IN 46202
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Jorquera R, Castonguay A, Schuller HM. Effects of age and ethanol on DNA single-strand breaks and toxicity induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone or n-nitrosodimethylamine in hamster and rat liver. Cancer Lett 1993; 74:175-81. [PMID: 8174101 DOI: 10.1016/0304-3835(93)90240-a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The effects of age and ethanol exposure on liver DNA single-strand breaks (SSB) and liver cell injury induced in hamsters and rats by a single equimolar dose (0.39 mmol/kg) of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) or N-nitrosodimethylamine (NDMA) were investigated. NNK induced more DNA SSB (by 10-50%) than NDMA in the liver of adult hamsters and rats, but similar differences were not observed in newborn animals. Nitrosamine-induced hepatic DNA damages was compared in newborn and adult animals. While newborn hamsters were less sensitive to NNK-induced DNA damage than adult hamsters, newborn rats were more sensitive to NDMA-induced DNA damage than adult rats. In utero ethanol exposure did not alter significantly the induction of hepatic DNA SSB by NNK or NDMA compared to newborn hamsters and rats. Interestingly, species differences in the extents of NNK-induced hepatic DNA SSB and toxicity were observed in ethanol-consuming adult hamsters and rats. Ethanol treatment of hamsters caused a significant reduction (by 35%) of the frequency of hepatic DNA SSB and a 3.5-fold enhancement of hepatotoxicity induced by NNK.
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Affiliation(s)
- R Jorquera
- Laboratory of Cancer Etiology and Chemoprevention, School of Pharmacy, Laval University, QC, Canada
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15
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Mufti SI. Is alcohol a carcinogenic risk? BRITISH JOURNAL OF ADDICTION 1992; 87:937-40. [PMID: 1482487 DOI: 10.1111/j.1360-0443.1992.tb01991.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Odeleye OE, Eskelson CD, Watson RR, Mufti SI, Earnest D, Chvapil M. Effect of ethanol consumption and vitamin E supplementation on in vivo lipid peroxidation in rats. Nutr Res 1991. [DOI: 10.1016/s0271-5317(05)80695-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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17
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Ma XL, Baraona E, Lasker JM, Lieber CS. Effects of ethanol consumption on bioactivation and hepatotoxicity of N-nitrosodimethylamine in rats. Biochem Pharmacol 1991; 42:585-91. [PMID: 1859464 DOI: 10.1016/0006-2952(91)90321-u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
To study the effects of ethanol on the hepatotoxicity of N-nitrosodimethylamine (NDMA), 5 mg NDMA/kg body weight was injected intraperitoneally 3 times a week for 6 weeks into rats pair-fed liquid diets containing 36% of energy either as ethanol or as additional carbohydrates. Another group of rats was pair-fed with the same diets but injected with saline instead of NDMA. Co-administration of ethanol and NDMA produced much higher elevations of serum alanine and aspartate aminotransferase and glutamic dehydrogenase activities than the administration of either agent alone. The combined treatment also slightly increased focal necrosis, whereas other liver lesions (steatosis and fibrosis) and the functional impairment of mitochondrial respiration were not affected significantly. Microsomal low Km NDMA demethylation, as well as NDMA denitrosation, were inhibited markedly by incubation with an antibody against P450IIE1, suggesting the involvement of this alcohol-inducible P450 in both NDMA bioactivation reactions. The addition of ethanol inhibited P450-dependent demethylation and denitrosation of NDMA in liver microsomes, whereas both activities were enhanced markedly by chronic ethanol administration. At ethanol concentrations similar to those prevailing in the blood of alcohol-fed animals at the time of NDMA administration, hepatic microsomal demethylation and denitrosation remained significantly higher in ethanol-fed rats given NDMA than in controls. Our results suggest that bioactivation plays a critical role in the hepatotoxicity of NDMA and its aggravation by chronic alcohol consumption.
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Affiliation(s)
- X L Ma
- Section of Liver Disease and Nutrition, Bronx Veterans Affairs Medical Center, New York, NY 10468
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Abstract
There is a great deal of epidemiological evidence indicating that chronic, excessive alcohol consumption is a major risk factor for cancers in humans. However, the experimental basis for the increased cancer risk associated with alcohol intake is not clear. Since it appears that ethanol alone is not carcinogenic, ethanol effects must be explained in terms of its modifying the actions of other causal agents. Current studies indicate that ethanol and its congeners may act as tumor promoters, thereby enhancing the effect of initiating carcinogens from the environment. Available evidence also shows that ethanol is immunosuppressive. Clearly, cirrhosis due to high, prolonged alcohol intake is an indicator of the immunosuppressive effects of ethanol. It is less clear that more moderate intakes of alcohol could have as profound an effect on immune systems. However, changes do occur yielding alterations in lymphocyte sensitivity to alcohol in vitro and in cell development, as shown by increased NK cell function at low concentrations. Since other conditions, such as cytotoxic drugs which suppress cellular immune functions, are clearly associated with increased cancer risk. It is intriguing to think that prolonged exposure to ethanol-induced immunosuppression may be a cofactor in the promotion of cancer. The tumor promotion may take place via a variety of mechanisms as discussed in this paper, including reduced host defenses by direct effects of ethanol, its metabolites, and/or malnutrition. It may be beneficial to test methods for immunostimulation in prolonged alcohol abusers, where cessation of use is unsuccessful or residual immunosuppression remains, to reduce the risk of development or growth of initiated tumors.
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Affiliation(s)
- S I Mufti
- Department of Pharmacology-Toxicology, College of Pharmacy, University of Arizona, Tucson 85724
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