title: Inhibition of phosphatidylinostol 3-kinase uncouples H2O2-induced senescent phenotype and cell cycle arrest in normal human diploid fibroblasts.
abstract: Exposure of WI38 human diploid fibroblasts (HDFs) to hydrogen peroxide (H2O2) induced premature senescence. The senescent HDFs were permanently arrested and exhibited a senescent phenotype including enlarged and flattened cell morphology and increased senescence-associated beta-galactosidase (SA-beta-gal) activity. The induction of HDF senescence was associated with an activation of p53, increased expression of p21Cip1/WAF1, and hypophosphorylation of retinoblastoma protein (Rb), while no changes in the expression of p16Ink4a, p27Kip1, and p14Arf were observed. Exposure of WI38 cells to H2O2 also selectively activated phosphatidylinostol 3-kinase (PI3 kinase) and mitogen-activated protein kinase (MAPK) kinase (MEK), while no changes in p38 MAPK and Jun kinase (JNK) activities were observed. Selective inhibition of PI3 kinase activity with LY294002 abrogated H2O2-induced cell enlargement and flattened morphology and significantly attenuated the increase in SA-beta-gal activity, but did not affect H2O2-induced cell cycle arrest. In contrast, selective inhibition of MEK and p38 MAPK with PD98059 and SB203580, respectively, produced no significant effect on H2O2-induced senescent phenotype and cell cycle arrest. These findings demonstrate that expression of the senescent phenotype can be uncoupled from cell cycle arrest in prematurely senescent cells induced by H2O2 and does not contribute to the maintenance of permanent cell cycle arrest.
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston 29425, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Aimin
authors.initials: A
authors.lastname: Meng
authors.forename: Daohong
authors.initials: D
authors.lastname: Zhou
mesh_terms: D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D048429:Cell Size / Q000187:drug effects / Q000502:physiology; D016922:Cellular Senescence / Q000187:drug effects / Q000502:physiology*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D004171:Diploidy; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D018816:Genes, cdc / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D016160:Retinoblastoma Protein / Q000187:drug effects / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D001616:beta-Galactosidase / Q000187:drug effects / Q000378:metabolism
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D006861:Hydrogen Peroxide; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53; D001616:beta-Galactosidase; C493956:CDKN1A protein, human; C482125:MAP2K1 protein, human