Role of PTHrP in human intestinal Caco-2 cell response to oxidative stress

LEZCANO, VIRGINIA; GENTILI CLAUDIA; RUSSO DE BOLAND, ANA

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013 vol. 1833 p. 2834 - 2843

0167-4889

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 these cells are still unknown. In the present work we investigated whether PTHrP, as PTH, is able to induce Caco-2 cells 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 (10-8M) 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 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 the pre-treatment with PTHrP prior to H2O2 incubation, prevents the cell death induced by the apoptotic inductor; and using specific inhibitors we evidenced that AKT, ERK1/2, JNK1/2 and p38 MAPK mediate this anti-apoptotic effect. Also, we found that PTHrP decreases the proapoptotic 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