Activation of angiotensin II type I receptor promotes protein kinase C translocation and cell proliferation in human cultured breast epithelial cells.
The effect of angiotensin II (Ang II) on Ca(2+) signalling in human primary cultured breast epithelial cells was investigated by using fura-2 as the Ca(2+) probe. Ang II (0.1-1000 nM) induced an intracellular free calcium ([Ca(2+)](i)) transient peak which was unchanged by external Ca(2+ )removal. In Ca(2+)-free medium pretreatment with thapsigargin abolished Ang II-induced Ca(2+ )release. Suppression of 1,4,5-inositol trisphosphate formation by U73122, a phospholipase C inhibitor, blocked the Ang II-induced Ca(2+) response. Losartan (DuP753), an inhibitor of Ang II type I receptor (AT1), decreased the [Ca(2+)](i) increase evoked by Ang II, while CGP4221A, an inhibitor of Ang II type II receptor (AT2) did not. AT1 desensitisation was demonstrated with respect to the Ca(2+) response after subsequent exposure of cells to Ang II and also after pretreatment for 25 min with 1000 nM phorbol 12-myristate 13-acetate. Staurosporine, an inhibitor of protein kinases C (PKC), inhibited the AT1 desensitisation. Epithelial breast cells expressed PKC-alpha, -beta1, -delta and -zeta isozymes, and Ang II provoked translocation from the cytosol to the membranes of PKC-alpha, -beta1, and -delta (but not -zeta). Ang II was also able to stimulate cell proliferation in a dose-dependent manner; this effect was blocked by Gö 6976, a specific inhibitor of PKC-alpha and -beta1, the Ca(2+)-dependent isozymes. The main conclusion of this study is that the the Ang II signalling mechanism in breast epithelial cells is based on the elevation of [Ca(2+)](i )released from intracellular stores through AT1 activation. In addition, Ang II stimulates cell proliferation by the activation of PKC isozymes.
Greco
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S
Laboratorio di Fisiologia, Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, Università di Lecce, Via Provinciale per Monteroni, 73100 Lecce, Italy.
Muscella
A
A
Elia
M G
MG
Salvatore
P
P
Storelli
C
C
Marsigliante
S
S
D000704:Analysis of Variance; D000804:Angiotensin II / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D001692:Biological Transport / Q000187:drug effects; D001940:Breast / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002227:Carbazoles / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000378:metabolism; D004963:Estrenes / Q000494:pharmacology; D005260:Female; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism*; D019808:Losartan / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011760:Pyrrolidinones / Q000494:pharmacology; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D057911:Angiotensin Receptor Antagonists; D002227:Carbazoles; D004791:Enzyme Inhibitors; D004963:Estrenes; D007211:Indoles; D007527:Isoenzymes; D011760:Pyrrolidinones; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D000804:Angiotensin II; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C081021:Go 6976; D019284:Thapsigargin; D011493:Protein Kinase C; D010738:Type C Phospholipases; D019311:Staurosporine; D019808:Losartan