Chromosomal Aberrations in Peripheral Lymphocytes of Abstinent Alcoholics

Evidence of genotoxicity in lymphocytes of non-smoking alcoholics

Alcohol abuse is a significant public health issue. Epidemiological studies conducted on different populations consistently showed that consumption of alcoholic beverages is associated with cytogenetic damages and higher risk for several types of cancer. However, the interpretation of many cytogenetic studies resulted complicated because some confounding factors, such as smoking habit, are not always taken into account. In the present study, the frequency of sister chromatid exchanges (SCEs), chromosome aberrations (CAs) and micronuclei (MNs) in cultured human lymphocytes was assessed on 15 alcoholic and 15 non-alcoholic control male subjects. Moreover, considering the implication of the Glutathione S-transferases gene polymorphisms in the genetic susceptibility to alcoholic liver diseases, we considered an important issue to evaluate the relationship between these gene polymorphisms and the cytogenetic damage. In our sample we exclusively considered individuals that did not smoke nor consume drugs for a period of at least 2 years prior to the analysis. Statistically significant differences were found between alcoholics and controls in the frequency of SCEs/cell (P = 0.001), RI value (P = 0.001), CAs (P = 0.002) and CAB (P = 0.002). Vice versa, no significant differences were found between alcoholics and controls in terms of MNs frequency and CBPI value. In both samples, no statistically significant association was found between the analysed GSTs gene polymorphisms and the frequencies of MNs, SCEs and CAs. Finally, among alcoholics we found a positive correlation between SCEs and CAs frequencies and the duration of alcohol abuse.

Clastogenic effect of ethanol in chronic and abstinent alcoholics

Alcoholism is one of the main causes of damage for human health, being relevant to study the induction of chromosomal aberrations (CA) by ethanol, and to investigate the individual susceptibility to diseases caused by alcoholism. A cytogenetic study was performed in human peripheral blood lymphocytes of 29 heavy chronic alcoholics, 11 alcoholics in abstinence, and 10 controls. The values of the chromosomal aberrations, mitotic indexes (MI) and proliferation indexes (PI) were determined. A molecular cytogenetic study was also carried out using fluorescence in situ hybridization (FISH) method with DNA library probes for chromosomes 1, 3 and 6, in lymphocytes from chronic alcoholic individuals in comparison with a control group. The results showed that the CA frequencies for chronic alcoholics (5.15 CA/100 cells) and alcoholics in abstinence (3.87 CA/100 cells) were higher than those obtained for control individuals (1.72 CA/100 cells). The mean translocation frequencies (equivalent to the genome) were calculated for six chronic alcoholics (0.267 translocations/100 cells) and six alcoholics in abstinence (0.167 translocations/100 cells), whose values were significantly higher than those observed for six control individuals (0.067 translocations/100 cells). The CA frequencies were not statistically different when smoker and non-smoker alcoholics were compared, indicating that although the smoking habit had significantly increased (four-fold) the CA frequency in healthy control individuals, a lack of interaction effect was observed within the group of alcoholics when smokers and non-smokers were compared. The CA frequencies presented by alcoholics in abstinence were similar to those obtained for chronic alcoholics. Therefore, chronic ethanol intoxication can lead to chromosome damage and disturbances in the metabolism of endogenous and exogenous compounds, which may persist for a long time, and constitute a relevant factor of risk for the development of neoplasias.

Biomarkers to assess the genetic damage induced by alcohol abuse in human lymphocytes

Alcohol abuse is a major risk factor for cancer of the upper alimentary tract, the upper respiratory tract, and liver. Chromosome damage is used as early effect biomarker in the surveillance of human exposure to genotoxic carcinogens. In the present study, two genetic markers, namely chromosome aberrations (CAs) and micronuclei (MN), were used to evaluate genetic damage in peripheral lymphocytes from 20 alcoholics, 20 abstinent alcoholics, and 20 controls. Composition of the three groups was fairly similar as regards sex, age and smoking habits. A highly significant increase was observed in the frequencies of CA and MN in lymphocytes of alcoholics as compared both with controls and abstinent alcoholics. However, no correlation was found between the length of alcohol abuse and the frequencies of either biomarkers in alcoholics. CA and MN frequencies in abstinent alcoholics were similar than those in controls. Our data indicate that CA and MN can be two useful biomarkers to assess genetic damage associated with alcohol abuse. They could be included in programs for cancer prevention in alcoholics. Abstinence appears to normalize the frequency of both MN and CA. This could offer therapists another tool to help alcoholics change their lifestyle.