title: Oxidative stress induces premature senescence by stimulating caveolin-1 gene transcription through p38 mitogen-activated protein kinase/Sp1-mediated activation of two GC-rich promoter elements.
abstract: Cellular senescence is believed to represent a natural tumor suppressor mechanism. We have previously shown that up-regulation of caveolin-1 was required for oxidative stress-induced premature senescence in fibroblasts. However, the molecular mechanisms underlying caveolin-1 up-regulation in senescent cells remain unknown. Here, we show that subcytotoxic oxidative stress generated by hydrogen peroxide application promotes premature senescence and stimulates the activity of a (-1,296) caveolin-1 promoter reporter gene construct in fibroblasts. Functional deletion analysis mapped the oxidative stress response elements of the mouse caveolin-1 promoter to the sequences -244/-222 and -124/-101. The hydrogen peroxide-mediated activation of both Cav-1 (-244/-222) and Cav-1 (-124/-101) was prevented by the antioxidant quercetin. Combination of electrophoretic mobility shift studies, chromatin immunoprecipitation analysis, Sp1 overexpression experiments, as well as promoter mutagenesis identifies enhanced Sp1 binding to two GC-boxes at -238/-231 and -118/-106 as the core mechanism of oxidative stress-triggered caveolin-1 transactivation. In addition, signaling studies show p38 mitogen-activated protein kinase (MAPK) as the upstream regulator of Sp1-mediated activation of the caveolin-1 promoter following oxidative stress. Inhibition of p38 MAPK prevents the oxidant-induced Sp1-mediated up-regulation of caveolin-1 protein expression and development of premature senescence. Finally, we show that oxidative stress induces p38-mediated up-regulation of caveolin-1 and premature senescence in normal human mammary epithelial cells but not in MCF-7 breast cancer cells, which do not express caveolin-1 and undergo apoptosis. This study delineates for the first time the molecular mechanisms that modulate caveolin-1 gene transcription upon oxidative stress and brings new insights into the redox control of cellular senescence in both normal and cancer cells.
authors.affiliation: Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.
authors.forename: Arvind
authors.initials: A
authors.lastname: Dasari
authors.forename: Janine N
authors.initials: JN
authors.lastname: Bartholomew
authors.forename: Daniela
authors.initials: D
authors.lastname: Volonte
authors.forename: Ferruccio
authors.initials: F
authors.lastname: Galbiati
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D051242:Caveolin 1 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D016922:Cellular Senescence / Q000187:drug effects / Q000502:physiology; D004789:Enzyme Activation; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D041681:NIH 3T3 Cells; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology; D011401:Promoter Regions, Genetic; D011794:Quercetin / Q000494:pharmacology; D020218:Response Elements; D016329:Sp1 Transcription Factor / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D051242:Caveolin 1; D016877:Oxidants; D016329:Sp1 Transcription Factor; D011794:Quercetin; D006861:Hydrogen Peroxide; D048051:p38 Mitogen-Activated Protein Kinases