TY - JOUR
T1 - PKC-ζ Is Required for Angiotensin II-Induced Activation of ERK and Synthesis of C-FOS in MCF-7 Cells
AU - Muscella, Antonella
AU - Greco, Simona
AU - Elia, Maria Giovanna
AU - Storelli, Carlo
AU - Marsigliante, Santo
PY - 2003/10
Y1 - 2003/10
N2 - We examined the signalling pathways responsible for the Ang II induction of growth in MCF-7 human breast cancer cells. Ang II in MCF-7 cells induced: (a) the translocation from the cytosol to membrane and nucleus of atypical protein kinase C-ζ (PKC-ζ) but not of PKC-α, -δ, -ε, and -η; (b) the expression of c-fos mRNA and protein; (c) the phosphorylation of the extracellular signal-regulated protein kinases 1 and 2 (ERK1/2). All these effects were due to the activation of the Ang II type I receptor (AT1) since they were blocked by the AT1 antagonist losartan. The Ang II-stimulated ERK1/2 phosphorylation was blocked by (a) high doses of staurosporine, inhibitor of PKC-ζ, and by a synthetic myristoylated peptide with sequences based on the endogenous PKC-ζ pseudosubstrate region (ζ-PS) ; (b) PD098059, a mitogen-activated protein kinase kinase inhibitor (MAPKK/MEK) ; and, moreover, (c) the inhibitors of phosphoinositide 3-kinases (PI3K), LY294002 and wortmannin, thus indicating that PI3K may act upstream of ERK1/2. The Ang II-evoked c-fos induction was blocked only by high doses of staurosporine and by ζ-PS whilst PD098059, LY294002 and wortmannin were ineffective, thus indicating that c-fos induction is not due to ERK1/2 activity. When the epidermal growth factor-receptor (EGFR) tyrosine kinase activity was inhibited by the use of its inhibitor AG1478, Ang II was still able to induce ERK1/2 phosphorylation and c-fos expression, therefore proving that the transactivation of EGFR was not required for these Ang II effects in MCF-7 cells. The previously reported proliferation of MCF-7 cells induced by Ang II was blocked by PD098059 and by wortmannin in a dose-dependent manner, thereby indicating that in MCF-7 cells the PI3K and ERK pathways mediate the mitogenic signalling of AT1. Our results suggest that in MCF-7 cells Ang II activates multiple signalling pathways involving PKC-ζ, PI3K and MAPK; of these pathways only PKC-ζ appears responsible for the induction of c-fos.
AB - We examined the signalling pathways responsible for the Ang II induction of growth in MCF-7 human breast cancer cells. Ang II in MCF-7 cells induced: (a) the translocation from the cytosol to membrane and nucleus of atypical protein kinase C-ζ (PKC-ζ) but not of PKC-α, -δ, -ε, and -η; (b) the expression of c-fos mRNA and protein; (c) the phosphorylation of the extracellular signal-regulated protein kinases 1 and 2 (ERK1/2). All these effects were due to the activation of the Ang II type I receptor (AT1) since they were blocked by the AT1 antagonist losartan. The Ang II-stimulated ERK1/2 phosphorylation was blocked by (a) high doses of staurosporine, inhibitor of PKC-ζ, and by a synthetic myristoylated peptide with sequences based on the endogenous PKC-ζ pseudosubstrate region (ζ-PS) ; (b) PD098059, a mitogen-activated protein kinase kinase inhibitor (MAPKK/MEK) ; and, moreover, (c) the inhibitors of phosphoinositide 3-kinases (PI3K), LY294002 and wortmannin, thus indicating that PI3K may act upstream of ERK1/2. The Ang II-evoked c-fos induction was blocked only by high doses of staurosporine and by ζ-PS whilst PD098059, LY294002 and wortmannin were ineffective, thus indicating that c-fos induction is not due to ERK1/2 activity. When the epidermal growth factor-receptor (EGFR) tyrosine kinase activity was inhibited by the use of its inhibitor AG1478, Ang II was still able to induce ERK1/2 phosphorylation and c-fos expression, therefore proving that the transactivation of EGFR was not required for these Ang II effects in MCF-7 cells. The previously reported proliferation of MCF-7 cells induced by Ang II was blocked by PD098059 and by wortmannin in a dose-dependent manner, thereby indicating that in MCF-7 cells the PI3K and ERK pathways mediate the mitogenic signalling of AT1. Our results suggest that in MCF-7 cells Ang II activates multiple signalling pathways involving PKC-ζ, PI3K and MAPK; of these pathways only PKC-ζ appears responsible for the induction of c-fos.
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U2 - 10.1002/jcp.10336
DO - 10.1002/jcp.10336
M3 - Article
C2 - 12942541
AN - SCOPUS:0141483551
VL - 197
SP - 61
EP - 68
JO - Journal of cellular and comparative physiology
JF - Journal of cellular and comparative physiology
SN - 0021-9541
IS - 1
ER -