Mechanisms in alcohol-associated carcinogenesis.
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Alcohol Dehydrogenase↗
Biomedical subjects
H K Seitz
Publications and source records attributed to H K Seitz.
Genetic damage and repair in human rectal cells for biomonitoring: sex differences, effects of alcohol exposure, and susceptibilities in comparison to peripheral blood lymphocytes.
INTRODUCTION: Cells other than lymphocytes may be preferable as surrogate biomarkers during exposure monitoring. In nutritional toxicology, cells from colorectal tissues are particularly relevant for studying associations between food and cancer. Thus, we have previously shown that colonic cells of males have higher levels of DNA damage than females, which (among other factors) could be due to a higher consumption of alcoholic beverages by males. To test this hypothesis, we have performed a first exploratory study to compare DNA damage in rectal cells from biopsies of male patients with alcohol abuse and of male and female controls. Peripheral blood lymphocytes were additionally monitored to assess systemic exposure loads. METHODS: Cells were isolated and subjected to microgelelectrophoresis +/- endonuclease III to measure DNA breaks and oxidized pyrimidine bases ("comet-assay"). Cell aliquots were treated with H(2)O(2) for 5min in suspension culture and processed immediately or after 60min to determine induced damage and its persistence. RESULTS: Pooled data from subjects of all groups revealed that oxidative DNA damage in rectal cells directly correlated to damage in lymphocytes. Female controls had lower levels of DNA damage than male controls, confirming the previous studies. An unexpected result was that male alcohol abusers had significantly less genetic damage than male controls. Also, repair was detected in lymphocytes of male alcohol abusers and female controls, but not in male controls. CONCLUSION: This is the first time the comet-assay has been used to detect genotoxicity in human rectal cells as a biomonitoring tool. Our pilot study confirms earlier reports on sex differences and indicates a good correlation between damage in rectal cells and damage in lymphocytes and implies that alcohol exposure enhances endogenous defence.
Adult↗
Increased cancer risk in heavy drinkers with the alcohol dehydrogenase 1C*1 allele, possibly due to salivary acetaldehyde.
BACKGROUND: Chronic ethanol consumption is associated with an increased risk of upper aerodigestive tract cancer. As acetaldehyde seems to be a carcinogenic factor associated with chronic alcohol consumption, alcoholics with the alcohol dehydrogenase (ADH) 1C*1 allele seem to be particularly at risk as this allele encodes for a rapidly ethanol metabolising enzyme leading to increased acetaldehyde levels. Recent epidemiological studies resulted in contradictory results and therefore we have investigated ADH1C genotypes in heavy alcohol consumers only. METHODS: We analysed the ADH1C genotype in 107 heavy drinkers with upper aerodigestive tract cancer and in 103 age matched alcoholic controls without cancer who consumed similar amounts of alcohol. Genotyping of the ADH1C locus was performed using polymerase chain reaction based on restriction fragment length polymorphism methods on leucocyte DNA. In addition, ethanol was administered orally (0.3 g/kg body weight) to 21 healthy volunteers with the ADH1C*1,1, ADH1C*1,2, and ADH1C*2,2 genotypes, and 12 volunteers with various ADH genotypes consumed ethanol ad libitum (mean 211 (29) g). Subsequently, salivary acetaldehyde concentrations were measured by gas chromatography or high performance liquid chromatography. RESULTS: The allele frequency of the ADH1C*1 allele was found to be significantly increased in heavy drinkers with upper aerodigestive tract cancer compared with age matched alcoholic controls without cancer (61.7% v 49.0%; p = 0.011). The unadjusted and adjusted odds ratios for all cancer cases versus all alcoholic controls were 1.67 and 1.69, respectively. Healthy volunteers homozygous for the ADH1C*1 allele had higher salivary acetaldehyde concentrations following alcohol ingestion than volunteers heterozygous for ADH1C (p = 0.056) or homozygous for ADH1C*2 (p = 0.011). CONCLUSIONS: These data demonstrate that heavy drinkers homozygous for the ADH1C*1 allele have a predisposition to develop upper aerodigestive tract cancer, possibly due to elevated salivary acetaldehyde levels following alcohol consumption.
Acetaldehyde↗
Risk factors in alcohol associated breast cancer: alcohol dehydrogenase polymorphism and estrogens.
Chronic alcohol consumption is associated with an increased risk for breast cancer, even if consumed in moderate doses. Since acetaldehyde is a carcinogenic factor associated with chronic alcohol consumption, individuals with the alcohol dehydrogenase 1C*1 allele (ADH1C*1 allele) seem to be at particular risk, since this allele encodes for a rapidly ethanol metabolizing enzyme leading to increased acetaldehyde levels. Since recent epidemiological studies demonstrated an increased risk for breast cancer for individuals with the ADH1C*1 allele, we have investigated here ADH1C genotypes in moderate alcohol consumers. Furthermore, estradiols are also known risk factors for breast cancer and acute alcohol ingestion in high doses results in increased serum estradiol concentrations. Thus, in the present study, we tested the effect of low ethanol doses on estrogen serum concentrations. We analyzed the ADH1C genotype in 117 moderate alcohol consumers with breast cancer and in 111 age-matched women with alcohol associated diseases without cancer (74 cirrhotics, 22 patients with pancreatitis and 15 alcohol dependent patients). In addition, 107 healthy controls were studied. Genotyping of the ADH1C-locus was performed using polymerase chain reaction-based restriction fragment length polymorphism methods on leukocyte DNA. To study the effects of ethanol on estradiol levels, ethanol in a dose of 0.225 g/kg body weight was given orally to 8 premenopausal women at various time points of their menstrual cycle. Thereafter estradiol serum concentrations were measured over time. The allele frequency of the ADH1C*1 allele was found to be significantly increased in moderate alcohol consumers with breast cancer as compared to age-matched alcoholic controls without cancer (62% vs. 41.9%, p=0.0035). Women with the ADH1C*1,1 genotype were found to be 1.8 times more at risk for breast cancer than those with another genotype (95% CI 1.431-2.330, p<0.001). Oral ethanol increased serum estradiol levels significantly by 27-38%. The data demonstrate that moderate alcohol consumers with the ADH1C*1 allele have an increased risk to develop breast cancer and even small amounts of alcohol increase serum estradiol levels significantly in premenopausal women especially in the midphase of the menstrual cycle.
Adult↗
Review article: Nutritional therapy in alcoholic liver disease.
Chronic alcohol consumption may lead to primary and secondary malnutrition. In particular, protein energy malnutrition not only aggravates alcoholic liver disease but also correlates with impaired liver function and increased mortality. Therefore, in these patients, adequate nutritional support should be implemented in order to improve their prognosis. Clinical trials addressing this issue have shown that nutritional therapy either enterally or parenterally improves various aspects of malnutrition, and there is increasing evidence that it may also improve survival. Therefore, malnourished alcoholics should be administered a diet rich in carbohydrate- and protein-derived calories preferentially via the oral or enteral route. Micronutrient deficiencies typically encountered in alcoholics, such as for thiamine and folate, require specific supplementation. Patients with hepatic encephalopathy may be treated with branched-chain amino acids in order to achieve a positive nitrogen balance. Fatty liver represents the early stage of alcoholic liver disease, which is usually reversible with abstinence. Metadoxine appears to improve fatty liver but confirmatory studies are necessary. S-adenosyl-L-methionine may be helpful for patients with severe alcoholic liver damage, since various mechanisms of alcohol-related hepatotoxicity are counteracted with this essential methyl group donor, while a recent large trial showed that the use of polyenylphosphatidylcholine is of limited efficacy.
Food, Formulated↗
[Alcoholic liver disease--established treatment and new therapeutic approaches].
Alcoholic liver disease is the most frequent organ damage encountered in chronic alcoholics and the annual death rate attributed to alcohol-induced end-stage liver disease exceeds that of car accidents. Alcoholic liver damage occurs mainly due to the toxicity of its first metabolite acetaldehyde, and due to interactions with numerous macro- and micronutrients. Established treatment options comprise psychotherapy aiming to achieve abstinence, nutritional therapy, management of hepatological complications, and liver transplantation in selected individuals. Since these therapeutic approaches are unsuccessful in many patients, pharmacological therapies of alcoholic liver disease are being investigated. Many drugs failed to be beneficial or have even shown toxicity. However, some agents are promising, such as S-adenosyl-L-methionine (SAMe), pentoxifylline, metadoxin, polyenylphosphatidylcholine or inhibitors of the cytochrome P450 2E1 isoenzyme. In severely ill patients with alcoholic hepatitis, drugs with anti-tumor necrosis factor alpha activity are currently investigated in clinical trials. If and how far corticosteroids are beneficial remains controversial and their use should be restricted to selected patients. Anabolic steroids used to enhance the nutritional status may lead to serious side effects while having a marginal benefit. Silymarin has not been proven efficacious in alcoholic cirrhosis and clinical trials are ongoing which aim to elucidate its therapeutic value in less advanced stages of liver disease.
Clinical Trials as Topic↗
[Review "Kava, kavapyrones and toxic liver injury" by R Teschke, Hanau Zeitschrift für Gastroenterologie 2003, 41:395-404].
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Anti-Anxiety Agents↗
Acute hepatitis induced by Greater Celandine (Chelidonium majus).
We report on two cases of acute liver injury along with the intake of Greater Celandine (Chelidonium majus), a well-known herbal remedy frequently used for irritable bowel syndrome. All other possible causes of acute liver damage were excluded in both patients. In one patient, cholestatic hepatitis recurred rapidly after involuntary re-exposition. Both patients fully recovered after the withdrawal of Greater Celandine. The two cases add to the existing database about the potential hepatotoxicity of drugs containing Greater Celandine and raise the question whether the approval of this drug should be re-evaluated in the light of lacking evidence for a therapeutic benefit.
Adult↗
Inhibition of alcohol-associated colonic hyperregeneration by alpha-tocopherol in the rat.
BACKGROUND: Chronic alcohol consumption results in colorectal mucosal hyperregeneration, a condition associated with an increased risk for colorectal cancer. Possible mechanisms may involve the effects of acetaldehyde and/or free radicals generated during alcohol metabolism. Vitamin E is part of the antioxidative defense system, and its concentration is decreased or its metabolic utilization increased in various tissues after chronic alcohol consumption. We wondered whether alpha-tocopherol supplementation may prevent ethanol-induced colorectal cell cycle behavior and whether these changes were related to alterations in protein synthesis. METHODS: Five groups of male Wistar rats, each consisting of 14 animals, received liquid diets as follows: group 1, alcohol; group 2, alcohol + alpha-tocopherol; group 3, control (i.e., isocaloric glucose); group 4; control (i.e., isocaloric glucose) + alpha-tocopherol. Group 5 was fed a solid chow diet ad libitum. After 4 weeks of feeding, immunohistology was performed with anti-proliferating cell nuclear antigen (PCNA) or anti-BCL2 antibodies. Fractional (k(s)) and absolute (V(s)) rates of protein synthesis and rates of protein synthesis relative to RNA (k(RNA)) and DNA (k(DNA)) were measured with a flooding dose of L-[4-3H] phenylalanine with complementary analysis of protein and nucleic acid composition. RESULTS: The PCNA index was increased significantly in the colon after ethanol administration compared with controls (ethanol, 10.3 +/- 2.3 vs. control, 6.51 +/- 1.6% PCNA positive cells, p < 0.05), although neither the protein, RNA, and DNA concentrations nor k(s), k(RNA), k(DNA), and V(s) were affected. This increase in PCNA index was significantly diminished by coadministration of alpha-tocopherol (ethanol + alpha tocopherol, 7.86 +/- 1.71% PCNA positive cells, p < 0.05) without significant alterations in protein synthetic parameters. A similar result was obtained for the PCNA index in the rectal mucosa (ethanol, 14.6 +/- 4.4 vs. control, 12.1 +/- 4.2% PCNA positive cell), although this did not reach statistical significance. Neither ethanol nor alpha tocopherol feeding had any significant effect on BCL-2 expression in the colorectal mucosa. As with the colon, protein synthetic parameters in the mucosa were not affected by alcohol feeding at 4 weeks. These effects on colonic cell turnover without corresponding changes in protein synthesis thus represent a specific localized phenomenon rather than a general increase in anabolic processes in the tissue and reaffirm the hyperregenerative properties of chronic alcohol consumption. CONCLUSIONS: Alcohol-associated hyperproliferation could be prevented, at least in part, by supplementation with alpha-tocopherol. This may support the hypothesis that free radicals are involved in the pathogenesis of alcohol-associated colorectal hyperproliferation.
Animals↗
Cocarcinogenic effects of alcohol in hepatocarcinogenesis.
Alcohol is a major aetiological factor in hepatocarcinogenesis but our understanding of its importance as a modulating factor is just beginning to emerge. In the present review, a number of possible cofactors and mechanisms are discussed by which alcohol may enhance the development of hepatoma. These include dietary or environmental carcinogens ingested along with alcoholic beverages, alcoholic cirrhosis as a precancerous condition, and the effects of alcohol metabolism.
Acetaldehyde↗
Serum collagen type VI and XIV and hyaluronic acid as early indicators for altered connective tissue turnover in alcoholic liver disease.
Hepatic fibrosis in alcoholic liver disease often heralds progression to cirrhosis and, therefore, noninvasive parameters are required for early diagnosis and follow-up. Collagens VI and XIV, procollagen-III-N-propeptide, hyaluronic acid, and active transforming growth factor-beta1 (TGF-beta1) were measured in healthy volunteers, patients with alcoholic cirrhosis, and heavy drinkers without cirrhosis. Noncirrhotic alcoholics were assigned to two groups with either normal aspartate aminotransferase or levels > or = 2 normal. Collagens VI and XIV were elevated in all alcoholic patients compared to controls (P < 0.0001, all instances). Procollagen-III-N-propeptide and hyaluronic acid levels were higher in alcoholic patients with elevated liver enzymes and in cirrhotics as compared to controls. Procollagen-III-N-propeptide revealed a significant correlation with serum levels of TGF-beta1 (P < 0.0001). Collagens VI, and XIV, procollagen-III-N-propeptide, and hyaluronic acid appear to be sensitive markers indicating fibrotic transformation in alcoholics. The correlation between procollagen-III-N-propeptide and TGF-beta1 emphasizes its role in hepatic fibrogenesis.
Adult↗
Ethanol enhances retinoic acid metabolism into polar metabolites in rat liver via induction of cytochrome P4502E1.
BACKGROUND & AIMS: Long-term and excessive ethanol intake results in decreased plasma and hepatic levels of retinoic acid (RA), the most active derivative of vitamin A. The decrease of RA by ethanol treatment has been proposed to be a cytochrome P450 enzyme (CYP)-dependent process. However, the role of the major ethanol-induced CYP, CYP2E1, in the metabolism of RA has not been defined. METHODS: In vitro incubations of RA with microsomal fractions of liver tissue containing CYPs from either ethanol-exposed or non-ethanol-exposed rats were carried out using chemical inhibitors and antibodies against various CYPs. In vivo, both ethanol-exposed and non-ethanol-exposed rats were treated with or without chlormethiazole, a specific CYP2E1 inhibitor, for 1 month. RA and its catabolic metabolites were analyzed by high-performance liquid chromatography and spectral analysis. RESULTS: Incubation of RA with the liver microsomal fraction from ethanol-exposed rats resulted in greater disappearance of RA and increased appearance of 18-hydroxy-RA and 4-oxo-RA compared with control rat liver microsomal fractions. The enhancement of RA catabolism by ethanol was inhibited by both CYP2E1 antibody and specific inhibitors (allyl sulfide and chlormethiazole) in a dose-dependent fashion, whereas the metabolism of RA into polar metabolites was abolished completely by nonspecific CYP inhibitors (disulfiram and liarozole). Furthermore, treatment with chlormethiazole in ethanol-fed rats in vivo restored both hepatic and plasma RA concentrations to normal levels. CONCLUSIONS: Ethanol-induced CYP2E1 plays a major role in the degradation of RA, which may provide a possible biochemical mechanism for chronic and excessive ethanol intake as a risk for both hepatic and extrahepatic cell proliferation and carcinogenesis.
Allyl Compounds↗
[Liver toxicity of drugs of plant origin].
Herbal drugs are widely used and often contain highly active pharmacological compounds. Recently, reports have mounted about hepatotoxicity of herbal remedies which ranges from mild liver enzyme alterations to chronic liver disease and liver failure. Hepatotoxicity of Chinese herbs has been recognized, e.g. during treatment of patients with atopic eczema. However, the toxic compounds remain to be determined. Hepatic veno-occlusive disease may result from pyrrolizidine alkaloids which are contained in numerous plants worldwide. Teucrium chamaedrys, commonly referred to as germander, may cause hepatitis and even liver cirrhosis. Significant hepatotoxicity has also been observed after the ingestion of chaparral. Recently, greater celandine, which is widely used for biliary disorders and dyspepsia, was identified as a cause of cholestatic hepatitis. Hepatotoxic reactions have also been observed after the ingestion of Atractylis gummifera, Callilepsis laureola, Senna, Kavapyrone and Pulegium. The aim of this review is to summarize potentially hepatotoxic herbal remedies, to further elucidate their mechanisms of toxicity and thereby underline the likelihood of plants to be the cause of liver damage.
Chemical and Drug Induced Liver Injury↗
Age and bioavailability of alcohol.
UNLABELLED: It has been shown that advanced age results in a decreased first pass metabolism (FPM) of ethanol with elevated serum ethanol concentrations (SECs). It is still unknown if this is due to age by itself or to other factors like for example atrophic gastritis with decreased activity of alcohol dehydrogenase (ADH). To study the effect of age on SECs and on bioavailability of ethanol, 15 volunteers with a mean age of 71 +/- 1 year (8males and 7 females) and 16 volunteers with a mean age of 37 +/- 2 years (8males and 8 females) showing normal gastric histology received ethanol (0.225 g/kg b. w.) intravenously (iv.) and orally. RESULTS: The difference between the SEC time curves after iv. and oral ethanol administration (so called FPM of ethanol) was significantly increased in elderly subjects (54 +/- 6 vs. 12 +/- 9 %, p < 0.001). The SEC time curves after iv. ethanol application were significantly increased in the elderly (p < 0.001), whereas SECs following oral alcohol administration were significantly lower in elderly as compared to younger individuals (p < 0.02). Peak SECs following iv. application was also significantly elevated with age (52 +/- 4 vs. 31 +/- 1 mg/100 ml, p < 0.001) and occurrence of peak SECs following oral ethanol intake was significantly delayed (47 +/- 4 vs. 28 +/- 4 min, p < 0.001). No gender effect at all was observed. CONCLUSION: FPM of ethanol is inexpectedly increased in elderly with normal gastric morphology compared to young people. The elevation of SECs after iv. ethanol administration in the elderly could be explained by the reduction of the water distribution space with age, whereas the increased FPM of ethanol in elderly subjects with normal gastric morphology is probably due to a deceleration of the speed of gastric emptying leading to an increased contact time of alcohol with gastric alcohol dehydrogenase (ADH). Our data do not confirm results from other research groups showing increased SECs in the elderly after alcohol consumption. Increased SECs are therefore not due to age by itself, but are probably caused by other factors as for example atrophic gastritis which is frequently found in the elderly people and which decreases FPM of ethanol.
Adult↗
Restoration of retinoic acid concentration suppresses ethanol-enhanced c-Jun expression and hepatocyte proliferation in rat liver.
Chronic and excessive ethanol intake decreases hepatic retinoic acid (RA) concentrations, which may play a critical role in ethanol-induced hyperproliferation in hepatocytes. The present study was conducted to determine whether RA supplementation in chronic ethanol-fed rats could restore hepatic RA concentrations to normal levels and modulate hepatocyte hyperproliferation. Male Sprague-Dawley rats were divided into four groups: control, ethanol-fed, ethanol-fed + 50 microg all-trans-RA/kg body wt and ethanol-fed + 100 microg all-trans-RA/kg body wt. Ethanol was given to rats at 6.2% (v/v) in a liquid diet to provide 36% of total caloric intake. Control animals received the same amount of liquid diet with isocaloric maltodextrin in place of ethanol. Results show that the ethanol treatment in rats for a month significantly increased the mean number of proliferating cell nuclear antigen (PCNA)-positive hepatocytes [4.96 +/- 1.36% (ethanol-fed) versus 0.29 +/- 0.08% (control), P < 0.05]. This increase was associated with the induction of hepatic c-Jun protein (6.5-fold increase) and cyclin D1 protein (3-fold increase) in ethanol-fed animals as compared with controls. Furthermore, activator protein 1 (AP-1) DNA-binding activity was significantly higher in hepatic nuclear extracts from ethanol-fed rats than those from controls. In contrast, RA supplementation in ethanol-fed rats raised hepatic RA concentration to normal levels and almost completely abolished the ethanol-enhanced c-Jun, cyclin D and AP-1 DNA-binding activities. Moreover, RA supplementation at both doses markedly suppressed the ethanol-induced PCNA-positive hepatocytes by approximately 80%. These results demonstrate that the restoration of hepatic RA concentrations by dietary RA supplementation suppresses ethanol-induced hepatocyte proliferation via inhibiting c-Jun overexpression, and suggest that RA may play a role in preventing or reversing certain types of ethanol-induced liver injury.
Animals↗
Alcohol and cancer.
This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Helmut K. Seitz and Shohei Matsuzaki. The presentations were (1) Alcohol dehydrogenase-2 and aldehyde dehydrogenase-2 genotype and cancer risk for upper aerodigestive tract in Japanese alcoholics, by Akira Yokoyama; (2) The role of acetaldehyde in alcohol-associated carcinogenesis, by Nils Homann; (3) High salivary acetaldehyde levels after a moderate dose of alcohol in ALDH2-deficient subjects, by Satu Väkeväinen; (4) Alcohol and vitamin A interactions, by Xian Dong Wang; and (5) Alcohol and colorectal cancer, by Helmut K. Seitz.
Acetaldehyde↗
Viruses and alcohol in the pathogenesis of primary hepatic carcinoma.
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Alcoholism↗
Increased rectal cell proliferation following alcohol abuse.
BACKGROUND: Epidemiological data indicate an increased risk for rectal cancer following chronic alcohol consumption. As chronic ethanol ingestion leads to rectal hyperregeneration in experimental animals, indicating a state of increased susceptibility to carcinogens, we studied cell proliferation in alcohol abusers. METHODS: Rectal biopsies were taken from 44 heavy drinkers and 26 controls. Cell proliferation, including proliferative compartment size, was measured by immunohistological staining for proliferative cell nuclear antigen (PCNA) and Ki67, and by in situ hybridisation for histone H3. Quantification of cell proliferation using PCNA staining was evaluated in 27 alcohol abusers and 12 controls. In addition, immunohistology was performed for cytokeratins and gene products of Rb1, bcl-2, and p53. RESULTS: Heavy drinking resulted in increased cell proliferation of the rectal mucosa, as shown by increased detection of different proliferation markers. However, cell differentiation regarding cytokeratin expression patterns was unchanged as well as regulatory factors involved in carcinogenesis and/or apoptosis. CONCLUSION: Chronic alcohol abuse leads to rectal mucosal hyperproliferation in humans, a condition associated with an increased cancer risk.
Adult↗