title: Induction of ouabain-resistance mutation and cycle-dependent transformation of C3H/10T1/2 cells by N-nitroso-2-acetylaminofluorene.
abstract: Ouabain-resistance mutation and cell cycle-dependent transformation were studied concurrently in the C3H/10T1/2 cell line treated with N-nitroso-2-acetylaminofluorene (N-NO-AAF) or N-nitroso-N-2-fluorenylacetamide. N-NO-AAF is a new direct-acting mutagen that exhibits a very short half-life (34 min) in complete medium independent of cell number seeded. With 0.1-0.3 mM of N-NO-AAF, cytotoxicity was noted after exposure for 2 h, but another phase of cytotoxicity was observed between 8 and 24 h. N-NO-AAF was more toxic than its parent compound 2-AAF. Moreover, maximal mutation frequency at the Na+/K(+)-ATPase gene locus (ouar mutation) was attained within 30 or 40 min of exposure, dependent on dosage of N-NO-AAF. With 2-AAF, 2-AF and 2-nitrofluorene, however, no detectable mutants were found under the same conditions. In cell cycle-dependent transformation assays, cells were synchronized by release from confluence-induced arrest of proliferation, 2 concentrations of N-NO-AAF were added for 2 h at various intervals during the cell cycle. The results clearly revealed that cells in 2 specific time intervals were susceptible to malignant transformation, i.e., at 10 and 18 h (early S phase) after release from the block.
authors.affiliation: Institute of Biochemistry, College of Medicine, National Taiwan University, Taipei, China.
authors.forename: J K
authors.initials: JK
authors.lastname: Lin
authors.forename: M L
authors.initials: ML
authors.lastname: Kuo
mesh_terms: D015073:2-Acetylaminofluorene / Q000633:toxicity / Q000031:analogs & derivatives; D000818:Animals; D002453:Cell Cycle / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced*; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D006207:Half-Life; D009153:Mutagens; D009154:Mutation; D009603:Nitroso Compounds / Q000633:toxicity*; D010042:Ouabain / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D009153:Mutagens; D009603:Nitroso Compounds; C057157:N-nitroso-N(2)-fluorenylacetamide; D010042:Ouabain; D015073:2-Acetylaminofluorene