Ethanol and acetaldehyde potentiate the clastogenicity of ultraviolet light, methyl methanesulfonate, mitomycin C and bleomycin in Chinese hamster ovary cells

In vivo comet assay of acrylonitrile, 9-aminoacridine hydrochloride monohydrate and ethanol in rats

As part of the Japanese Center for the Validation of Alternative Methods (JaCVAM)-initiative international validation study of the in vivo rat alkaline comet assay, we examined the ability of acrylonitrile, 9-aminoacridine hydrochloride monohydrate (9-AA), and ethanol to induce DNA damage in the liver and glandular stomach of male rats. Acrylonitrile is a genotoxic carcinogen, 9-AA is a genotoxic non-carcinogen, and ethanol is a non-genotoxic carcinogen. Positive results were obtained in the liver cells of male rats treated with known genotoxic compounds, acrylonitrile and 9-AA.

Genome Instability and Bleomycin Sensitivity Test

Procjena individualne osjetljivosti na mutagene često je dio istraživanja u epidemiološkim studijama koje prate pojavnost zloćudnih bolesti u populacijama. Posljedica djelovanja mutagena u genomu izloženih osoba jest nastanak osoba jest nastanak određene, manje ili veće, količine oštećenja, uvjetovane individualnim razlikama u osjetljivosti. Viša razina takve genomske nestabilnosti znači opasnost (rizik) od razvoja zloćudnih bolesti. Interindividualne razlike u odgovoru na mutagene obično se povezuju i s promijenjenom (većinom smanjenom) sposobnosti (kapacitetom) za popravak DNA. Citogenetičke studije su pokazale da je genom tumorskih stanica nestabilniji od normalnih, a time i skloniji akumuliranju oštećenja, bilo da je nestabilnost uzrokovana nasljeđem, izloženošću ili kombinacijom tih dvaju učinaka. U oboljelih ispitanika utvrđena je povećana učestalost kromatidnih i kromosomskih aberacija naspram normalne populacije te sklonost razvoju određenih vrsta neoplazija. U praćenju povezanosti promijenjenog odgovora i pojavnosti tumora služe nam različiti biomarkeri. Kao indirektni pokazatelji uspješnosti popravka DNA često se rabe testovi osjetljivosti na mutagene u kulturama limfocita periferne krvi. Jedan od takvih testova je i bleomicinski test. Radiomimetik i citostatik, a po strukturi glikopeptid, bleomicin se u stanici prevodi u aktivni oblik sposoban cijepati molekulu DNA što uzrokuje brojne jednolančane i dvolančane lomove. Kao jednostavna i jeftina metoda, zasniva se na utvrđivanju ukupnog broja jednolančanih lomova u kromosomima limfocita uzgajanih u staničnoj kulturi koji su u uvjetima in vitro tijekom kasne G2-faze staničnog ciklusa bili izloženi bleomicinu. Ovaj revijalni rad daje pregled utjecaja raznih faktora na rezultate samog testa i pokazuje njegovu široku primjenu u proučavanju genomske nestabilnosti koju najčešće uzrokuje kombinacija raznih faktora.

Nucleolar organizer regions (AgNOR) and subepithelial vascularization as field cancerization markers in oral mucosa biopsies of alcoholic and smoking patients

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.

Alcohol-related diseases of the mouth and throat

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.

Ethanol and aloe emodin alter the p53 mutational spectrum in ultraviolet radiation-induced murine skin tumors

Mutations in the p53 tumor-suppressor gene contribute to the development of skin cancer, and the spectrum of mutations in this gene correlates with specific physical and chemical carcinogens in the environment. Cosmetics may contain alcohols and/or aloe emodin (AE). Although these compounds are not carcinogenic when applied to the skin, they may increase the carcinogenicity of ultraviolet (UV) radiation. We investigated whether ethanol (EtOH) and AE alone or combined with UV radiation cause mutations in the p53 gene. In the absence of UV radiation, C3H/HeN mice chronically treated for up to 33 wk with AE in 25% EtOH-in-water vehicle or vehicle alone failed to develop tumors and had no mutations in exons 4-8 of the p53 gene. UV radiation alone induced skin tumors, which had mutations predominantly in p53 exons 5 and 8. In contrast, mutations arising in UV + EtOH-or UV + AE-treated groups were more broadly distributed throughout the p53 gene. Mutations were found in exons 4, 6, and 7, as well as in exons 5 and 8. This altered distribution of mutations across the p53 DNA sequence more closely resembles the pattern observed in TP53 from human skin tumors at sun-exposed sites than that in the p53 gene of mice treated with UV alone. Thus, treatment with UV radiation in combination with two chemicals not thought to be carcinogenic, alcohol, and AE results in a broader distribution of mutations in a critical tumor-suppressor gene.

Alcohol-related diseases of the mouth and throat

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.

Possible mechanisms by which alcohol may influence the development of oral cancer--a review

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.

Genetic susceptibility to head and neck cancer: interaction between nutrition and mutagen sensitivity

The development of head and neck cancer may depend not only on exposure to environmental carcinogens but also on a genetically based susceptibility to carcinogen-induced damage. This thesis presents a case-control study that demonstrates the significance of mutagen sensitivity, a measure of an individual's intrinsic DNA repair capacity against free radical damage, as a risk factor for the disease. As part of the case-control analysis, 167 previously untreated patients and 177 age- and sex-matched healthy controls were assessed for various lifestyle factors including tobacco and alcohol habits, occupational exposures, and diet. Mutagen sensitivity expressed by each individual was determined by quantifying bleomycin-induced chromosomal breaks within peripheral blood lymphocytes in vitro. Consistent with our initial observations and those of others, mutagen hypersensitivity was strongly associated with increased risk of head and neck cancer (odds ratio, 4.95; 95% confidence interval, 2.67 to 9.17) after adjusting for age, sex, and race. Low intake of vitamins C and E was also associated with an increased risk of disease and was interactive with mutagen sensitivity in risk estimates. Individuals with both a low intake of various antioxidants and increased chromosomal sensitivity to oxidant-induced DNA damage were at greatest risk. This study supports the concept that the risk of head and neck cancer is determined by a balance of factors that either enhance or protect against free radical oxygen damage, including innate capacities for DNA repair.

Morphologic changes in offspring of female mice exposed to ethanol before conception

OBJECTIVE

Our purpose was to evaluate the mutagenic effects of preconceptional ethanol exposure by use of the mouse model.

STUDY DESIGN

Fifty-three adult female CF-1 mice were divided into one of five groups with or without an ethanol diet for 28 days. Mice were then superovulated and mated. On day 14 of gestation all mice were killed and fetuses removed and examined for abnormalities.

RESULTS

The mutation index for the study and mutagen groups was similar (48% vs 41%). The percentage of any anatomic abnormality in any treatment group were between 50% and 100%. Anomalies of the abdominal wall were most commonly seen in the mutagenic groups.

CONCLUSIONS

Chronic ethanol exposure in the female mouse before conception yields anatomic abnormalities in the offspring. These mutagenic effects may be variable in that they may result in a dominant lethal mutation or a delayed interference with organogenesis. Ethanol consumption, whether before or after conception, poses an unfavorable outcome in the offspring produced.

Induction of micronuclei by bleomycin in G0 human lymphocytes: II. Potentiation by radioprotectors

Dimethylsulfoxide (DMSO) and WR-1065 are radioprotectors, in that they reduce the effectiveness with which ionizing radiation causes genetic damage. Unlike their protective effects with radiation, these agents potentiate the induction of micronuclei by bleomycin in the cytokinesis-block assay in G0 human lymphocytes. High concentrations of DMSO (1 M) are required to cause potentiation. In contrast, WR-1065 causes dose-dependent potentiation at relatively low concentrations (1.25 to 10 mM). Cytogenetic analysis supports the results from the micronucleus assay, showing higher levels of genetic damage induced by the combination of bleomycin with DMSO or WR-1065 than by bleomycin alone. Possible mechanisms of potentiation are proposed.

Repair of DNA damage induced by reactive oxygen species

DNA repair limits the mutagenic, and thereby the carcinogenic, effect of DNA modifications. Free radicals, particularly reactive oxygen species, induce all forms of DNA damage, including base modifications, base free sites, strand breakage, and cross-links. These lesions are repaired by a variety of enzymes of partly overlapping substrate specificity, some of which may be induced.

Role of acetoin on the regulation of intermediate metabolism of Ehrlich ascites tumor mitochondria: its contribution to membrane cholesterol enrichment modifying passive proton permeability

Acetoin, an unusual metabolite of highly glycolytic mammalian tumor cells, is synthesized from decarboxylated pyruvate and active acetaldehyde in mitochondria. It plays important roles in the regulation and detoxification of pyruvate metabolism through pyruvate dehydrogenase. We show in this report the inhibitory effect of acetoin on succinate oxidation by Ehrlich tumor cell mitochondria, and thus its regulatory role on intermediate metabolism. Acetoin utilization by Ehrlich mitochondria may lead to small quantities of citrate formation which increase the already increased cholesterol synthesis of cancer cells. Membranes, in particular the inner mitochondrial membrane, flooded with cholesterol, show a proton passive permeability twice as low as that of control mitochondrial membranes, a feature that may be related to drastic changes in membrane potential-dependent metabolism of cancer cells.