title: Role of PTHrP in human intestinal Caco-2 cell response to oxidative stress.
abstract: We have previously demonstrated that parathyroid hormone (PTH) induces apoptosis in human colon adenocarcinoma Caco-2 cells but the effects of its tumoral analog PTH-related peptide (PTHrP) in this cell line are still unknown. In the present work we investigated whether PTHrP, as PTH, is able to induce Caco-2 cell apoptosis or if it exerts protective effects under apoptotic conditions. Using Caco-2 cells cultured under serum deprivation in the presence or absence of PTHrP we demonstrated that, differently to PTH, its analog employed at the same concentration (10(-8)M) is not a pro-apoptotic hormone. Cells were exposed to an oxidative insult in the form of hydrogen peroxide to induce apoptosis, which leads to a 50% loss of cell viability determined by MTS assay, morphological changes observed under fluorescence microscopy and Western blot analysis. Herein we demonstrate, for the first time, that pre-treatment with PTHrP prior to H2O2 incubation, prevents cell death induced by the apoptotic inductor; and using specific inhibitors we evidenced that protein kinase B (AKT), extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase 1/2 (JNK1/2) and p38 mitogen-activated protein kinase (MAPK) mediate this anti-apoptotic effect. Also, we found that PTHrP decreases the pro-apoptotic protein BAX levels and increases the protein expression of the anti-apoptotic HSP27. Immunoblot analysis revealed that H2O2 increases the phosphorylation levels of AKT and MAPKs, exhibiting a cellular defense response; and consequently increases phospho-BAD levels. The H2O2-induced activation of protein kinases is reverted when cells are pre-treated with PTHrP. Altogether these results evidence a protective effect of PTHrP under apoptotic conditions in intestinal cells, which may be mediated by AKT and MAPKs.
authors.affiliation: Dept. Biología, Bioquímica & Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina.
authors.forename: Virginia
authors.initials: V
authors.lastname: Lezcano
authors.affiliation: Dept. Biología, Bioquímica & Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina.
authors.forename: Claudia
authors.initials: C
authors.lastname: Gentili
authors.affiliation: Dept. Biología, Bioquímica & Farmacia, Universidad Nacional del Sur, Bahía Blanca, Argentina. Electronic address: aboland@criba.edu.ar.
authors.forename: Ana Russo
authors.initials: AR
authors.lastname: de Boland
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D018938:Caco-2 Cells; D002470:Cell Survival / Q000187:drug effects; D020895:Enterocytes / Q000187:drug effects / Q000201:enzymology / Q000473:pathology*; D004789:Enzyme Activation / Q000187:drug effects; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D018832:Molecular Chaperones; D018384:Oxidative Stress / Q000187:drug effects*; D044162:Parathyroid Hormone-Related Protein / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D017304:Annexin A5; D055551:HSP27 Heat-Shock Proteins; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D044162:Parathyroid Hormone-Related Protein; D051028:bcl-2-Associated X Protein; D006861:Hydrogen Peroxide; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D016650:Fluorescein-5-isothiocyanate
keywords: AKT; Apoptosis; Caco-2 cell; MAPK; PTHrP