Evaluation and characterization of micronuclei induced by the antitumour agent ASE [3 beta-hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lactam-p-bis(2-chloroethyl)amino phenylacetate] in human lymphocyte cultures

3 beta-Hydroxy-13 alpha-amino-13,17-seco-5 alpha-androstan-17-oic-13,17-lac tam-p-bis(2-chloroethyl)amino phenylacetate (ASE) is a homo-aza-steroidal e ster of p-bis(2-chloroethyl) amino phenyl acetic acid and has been shown to display antineoplastic, mutagenic and genotoxic activity, In the present s tudy an effort has been made to evaluate the ability of ASE to induce micro nuclei (MN) in human lymphocytes treated in vitro using the cytokinesis-blo ck assay. Lympocytes mere treated with different concentrations of ASE (0.1 , 0.25, 0.5, 1, 2.5, 5, 10 and 20 mu g/ml) at two different cell culture ti mes, 21 and 41 h after culture initiation. ASE treatment lasted until cell harvest, for 51 and 31 h, respectively. Two types of cultures mere used, wh ole blood and isolated lymphocyte cultures. The content of induced MN was i dentified by FISH analysis, using an a-satellite DNA probe, in binucleate c ells. Our results suggest that ASE is capable of increasing MN frequencies in human lymphocytes under both culture conditions. This increase is relate d to the concentration in a linear dose-dependent manner and is also depend ent on the duration of treatment. FISH analysis has shown that the induced MN resulted mainly from breakage events. Additionally, a weak aneugenic eff ect was found at the higher concentrations in whole blood cultures as well as in isolated lymphocyte cultures. Cytotoxic effects of ASE were observed under both cell culture conditions with a linear dose-dependent relationshi p according to CBPI evaluation and were more pronounced in isolated lymphoc yte cultures.