title: Development and characterization of a stable epithelial cell line from Muta Mouse lung.
abstract: We have isolated and characterized a stable epithelial cell line from Muta Mouse lung that is a suitable complement to the in vivo assay system. The cells are contact inhibited, forming a flat monolayer, and retain several epithelial/pulmonary characteristics. The genome is stable across more than 50 generations, with a modal chromosome number of 78. Spontaneous rates of micronuclei (19.2 +/- 1.4 per 1,000), sister chromatid exchanges (0.25 +/- 0.004 per chromosome), and chromosome aberrations ( approximately 4%) are lower than, or comparable to, other transgenic cell lines currently used in mutagenicity research. Fluorescence in situ hybridization analyses showed that 80% of cells contain three lambdagt10lacZ loci. Slot-blot analyses indicated that the average cell contains approximately 17 transgene monomers. Spontaneous mutant frequency at the lacZ transgene is stable (39.8 +/- 1.1 x 10(-5)), and the direct-acting mutagens N-ethyl-N-nitrosourea and ICR-191 yielded increases in mutant frequency of 6.3- and 3.2-fold above control, respectively. Benzo[a]pyrene (BaP) exposure increased mutant frequency more than 25-fold above control and did not require an exogenous metabolic activation mixture. Inhibition of Cyp1A1 by 5 microM alpha-naphthoflavone eliminated BaP mutagenesis. Activation and mutation induction by the heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine required a low concentration (0.05% v/v) of exogenous rat liver S9. High activity of alpha, micro, and pi glutathione-S-transferase isozymes appears to confer resistance to the cytotoxic effects of xenobiotics. The cell line is a suitable complement to the in vivo Muta Mouse assay, and provides an opportunity for routine in vitro mutagenicity testing using an endpoint that is identical to that employed in vivo.
authors.affiliation: Mutagenesis Section, Safe Environments Program, Health Canada, Ottawa, Ontario, Canada. paul_white@hc-sc.gc.ca
authors.forename: Paul A
authors.initials: PA
authors.lastname: White
authors.forename: George R
authors.initials: GR
authors.lastname: Douglas
authors.forename: John
authors.initials: J
authors.lastname: Gingerich
authors.forename: Craig
authors.initials: C
authors.lastname: Parfett
authors.forename: Phil
authors.initials: P
authors.lastname: Shwed
authors.forename: Vern
authors.initials: V
authors.lastname: Seligy
authors.forename: Lynda
authors.initials: L
authors.lastname: Soper
authors.forename: Lynn
authors.initials: L
authors.lastname: Berndt
authors.forename: Janet
authors.initials: J
authors.lastname: Bayley
authors.forename: Shelley
authors.initials: S
authors.lastname: Wagner
authors.forename: Kathleen
authors.initials: K
authors.lastname: Pound
authors.forename: David
authors.initials: D
authors.lastname: Blakey
mesh_terms: D000818:Animals; D004847:Epithelial Cells / Q000166:cytology; D007763:Lac Operon; D008168:Lung / Q000166:cytology*; D051379:Mice; D008817:Mice, Mutant Strains; D008856:Microscopy, Fluorescence; D009154:Mutation; D019076:Transgenes