title: Genotoxins induce binucleation in L5178Y and TK6 cells.
abstract: Following the initial observation that methyl methanesulphonate induced binucleated cells in the AHH-1 line and a significant number of them contained micronuclei, human lymphoblastoid TK6 and mouse lymphoma L5178Y cells were treated with methyl methanesulphonate, methylnitrosourea, mitomycin C, cytosine arabinoside, colchicine and triton X. All except triton X induced binucleated cells in both lines but an increased micronucleus incidence in them was seen only in TK6. The two lines also differed in the numbers of binucleates in the control cultures with 2.0% and 0.5% in TK6 and L5178Y, respectively, and a much higher proportion of those in TK6 contained micronuclei. The differences in behaviour between the two cell lines could not clearly be ascribed to their P53 status. Colchicine induced binucleates in both cell lines but they did not contain increased numbers of micronuclei. The effect on binucleate incidence was not a non-specific cytotoxic response because no increase was seen with triton X even at highly cytotoxic concentrations. The initial concern that not scoring micronuclei in binucleated cells might lead to erroneous results in in vitro micronucleus tests not using a cytokinesis block, was not proven because all the genotoxins tested here induced significant increases in micronucleus frequency in mononuclear cells. When testing less potently active agents in in vitro micronucleus tests not employing a cytokinesis block, care should be taken to understand better this phenomenon and not to include these damaged cells until we do.
authors.affiliation: Genetic Toxicology, Drug Safety and Metabolism, AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire SK10 4TG, United Kingdom. Electronic address: ann.doherty@astrazeneca.com.
authors.forename: Ann T
authors.initials: AT
authors.lastname: Doherty
authors.affiliation: Genetic Toxicology, Drug Safety and Metabolism, AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire SK10 4TG, United Kingdom.
authors.forename: Amy
authors.initials: A
authors.lastname: Wilson
authors.affiliation: Genetic Toxicology, Drug Safety and Metabolism, AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire SK10 4TG, United Kingdom.
authors.forename: Karolina
authors.initials: K
authors.lastname: Chocian
authors.affiliation: Genetic Toxicology, Drug Safety and Metabolism, AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire SK10 4TG, United Kingdom.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Molloy
authors.affiliation: Institute of Life Sciences, Swansea School of Medicine, Swansea University, United Kingdom.
authors.forename: Margaret
authors.initials: M
authors.lastname: Clatworthy
authors.affiliation: Institute of Life Sciences, Swansea School of Medicine, Swansea University, United Kingdom.
authors.forename: Shareen
authors.initials: S
authors.lastname: Doak
authors.affiliation: Institute of Life Sciences, Swansea School of Medicine, Swansea University, United Kingdom.
authors.forename: Gareth
authors.initials: G
authors.lastname: Jenkins
authors.affiliation: Genetic Toxicology, Drug Safety and Metabolism, AstraZeneca R&D, Alderley Park, Macclesfield, Cheshire SK10 4TG, United Kingdom.
authors.forename: Mike
authors.initials: M
authors.lastname: O'Donovan
mesh_terms: D000818:Animals; D002460:Cell Line; D003078:Colchicine / Q000633:toxicity; D003561:Cytarabine / Q000633:toxicity; D048749:Cytokinesis / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects; D006801:Humans; D008741:Methyl Methanesulfonate / Q000633:toxicity; D008770:Methylnitrosourea / Q000633:toxicity; D051379:Mice; D015162:Micronucleus Tests / Q000379:methods*; D016685:Mitomycin / Q000633:toxicity; D009153:Mutagens / Q000633:toxicity*
chemical_list: D009153:Mutagens; D003561:Cytarabine; D016685:Mitomycin; D008770:Methylnitrosourea; D008741:Methyl Methanesulfonate; D003078:Colchicine
keywords: Binucleation; Genotoxicity; In vitro micronucleus assay