title: Induction of mitotic crossing-over by the topoisomerase II poison DACA (N-[2-dimethylamino)ethyl]acridine-4-carboxamide) in Saccharomyces cerevisiae.
abstract: The antitumor agent DACA (N-[2-dimethylamino)ethyl]acridine-4-carboxamide) a new DNA intercalating topoisomerase II poison, was distinguishable from clinical topoisomerase poisons (amsacrine, daunorubicin, doxorubicin and etoposide) in its induction of aberrant colonies in the yeast Saccharomyces cerevisiae D5. It was not only more recombinogenic, but was recombinogenic at non-toxic drug concentrations. DACA at 680 microM (2-h exposure time), induced 1.2% aberrant colonies of which 0.32% were mitotic crossing-over events. The presence of the rad52 mutation abolished mitotic crossing-over and greatly increased drug toxicity. The concentration for 50% inhibition of survival of the rad52 mutant was 100 microM, as compared with 4900 microM for the wild-type. Drug toxicity was marginally increased by the presence of rad3 and rad18 mutations. Rad3 mutations increased the incidence of crossing-over events but had little effect on other mutagenic or recombinogenic events. In contrast, the rad18 mutation increased the incidence of all types of aberrant colonies. The inclusion of hydroxyurea and caffeine, as non-specific repair inhibitors, caused weak and strong inhibition, respectively, of all types of aberrant colonies. Inclusion of the protein-synthesis inhibitor cycloheximide reduced mitotic cross-over but had little effect on the incidence of other aberrations. It is concluded that DACA induces lesions which are repaired by a recombinational repair pathway involving the RAD52 product, and that RAD3 and RAD18 products are each involved in the generation of recombinational events.
authors.affiliation: Cancer Research Laboratory, University of Auckland School of Medicine, New Zealand.
authors.forename: L R
authors.initials: LR
authors.lastname: Ferguson
authors.forename: P M
authors.initials: PM
authors.lastname: Turner
authors.forename: B C
authors.initials: BC
authors.lastname: Baguley
mesh_terms: D000166:Acridines; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000609:Aminoacridines / Q000737:chemistry / Q000633:toxicity*; D000970:Antineoplastic Agents / Q000633:toxicity*; D002455:Cell Division / Q000187:drug effects; D003434:Crossing Over, Genetic / Q000187:drug effects*; D004265:DNA Helicases; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D005800:Genes, Fungal; D007364:Intercalating Agents / Q000633:toxicity*; D009152:Mutagenicity Tests; D009154:Mutation; D051721:Rad52 DNA Repair and Recombination Protein; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D059005:Topoisomerase II Inhibitors
chemical_list: D000166:Acridines; D000609:Aminoacridines; D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D007364:Intercalating Agents; C063607:RAD18 protein, S cerevisiae; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins; D059005:Topoisomerase II Inhibitors; C058332:N-(2'-(dimethylamino)ethyl)acridine-4-carboxamide; D000251:Adenosine Triphosphatases; C061897:Rad3 protein, S cerevisiae; D004265:DNA Helicases