title: Increased susceptibility of late passage human diploid fibroblasts to oxidative stress.
abstract: Three strains of human diploid fibroblasts, TIG-3, TIG-7, and MRC-5, were serially cultivated. The susceptibility of early-passage and late-passage cells at 20-30 and 60-70 population doubling levels, respectively, to hydrogen peroxide, the superoxide radical (exposure to the hypoxanthine-xanthine oxidase system), or linoleic acid hydroperoxide was examined for lactate dehydrogenase release. The susceptibility of late-passage cells to such oxidative stress was considerably enhanced compared with early-passage cells. The concentration of reduced glutathione in late-passage cells was lower by 24-44% on a per-cell-number basis and by 86.0-94.5% on a per-protein-quantity basis than in early-passage cells. In addition, the activity of catalase in late-passage cells was lower by 19-46% compared with early-passage cells. There was, however, no difference between the mRNA levels of catalase in early-passage and late-passage cells. The activities and mRNA levels of copper/zinc superoxide dismutase, manganese superoxide dismutase, and glutathione peroxidase in late-passage cells were all higher than in early-passage cells. These results suggest that late-passage cells are more susceptible to oxidative stress than early-passage cells presumably because of decreases in cellular reduced glutathione concentration and catalase activity, and that their primary defense against oxidative stress is reduced glutathione.
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yuan
authors.forename: T
authors.initials: T
authors.lastname: Kaneko
authors.forename: M
authors.initials: M
authors.lastname: Matsuo
mesh_terms: D002374:Catalase / Q000378:metabolism; D016922:Cellular Senescence; D005347:Fibroblasts / Q000502:physiology; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D018384:Oxidative Stress; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D002374:Catalase; D013482:Superoxide Dismutase; D005978:Glutathione