A study of in vitro endpoints of genotoxicity in short-term cultured lymphocytes of smokers

Abstract

In recent years, studies on the genotoxic effects of smoking and its modifying factors have been widely followed with interest. In the present study, we have performed three in vitro endpoints of genotoxicity to assess the effect of substances present in tobacco smoke on the peripheral blood lymphocytes of smokers. Cytokinesis blocked binucleated cells with micronucleus assay for baseline levels 1) Cytokinesis blocked binucleated cells with micronucleus assay for in vitro mutagen exposure 2) Single cell gel electrophoresis 3) Chromosomal aberrations; baseline levels 4) Chromosomal aberrations; following in vitro mutagen exposure The results of the short-term assays of genotoxicity have been summarized as follows: The frequencies of binucleated cells with micronuclei in smokers in terms of baseline and in vitro MMC induced levels were found to be comparable in smokers and non-smokers. The frequencies of baseline chromosome aberrations in short-term cultured blood lymphocytes of a group of cigarette smokers were significantly greater than in a matched group of non-smoking controls (p<0.05). Similarly, when blood lymphocytes cultures from smokers and non-smokers were exposed to Mitomycin-C in vitro, the yields of chromosomal aberration were significantly higher in case of smokers (p<0.05). The DNA damage by single cell gel electrophoresis was found to be significantly higher in the smokers group as compared to non- smokers (p<0.05). The present study suggests that the genetic instability as well as mutagen sensitivity of smoker’s cells is significantly higher as compared to non-smokers. The combination of three different in vitro endpoints of genotoxicity was employed to study the baseline genetic damage as well as following a mutagen challenge. The data provides support to the harmful effects of tobacco smoking on the genetic material in terms of DNA damage and sensitivity to a mutagen exposure; both the phenomena are linked with higher propensity to cancer. The results are inclusive of both the criteria (baseline and induced) in order to assess genetic instability and the mutagen sensitivity respectively.