Stimulation of beta-adrenergic receptors inhibits the proliferation and increases the adhesion of MCF-10A human breast cells: evidence for cAMP-dependant effects via distinct signaling pathways

BRUZZONE A; PARIS H; SENARD JM; LUTHY IA

Copenhagen , Dinamarca

Congreso; 16 th World Congress on Basic and Clinical Pharmacology; 2010

IUPHAR

The â-adrenergic receptors are known to inhibit the growth of human breast cancer cells but their effects have never been examined in non-tumoral cells. The objective of the present work was to study the effect of â-agonist treatment on the proliferation and adhesion of non-tumoral human breast cells, MCF-10A, and to investigate the signaling pathways involved in these actions. The treatment of MCF-10A with 0.2 ìM isoproterenol caused a significant diminution of cell proliferation (37% reduction after 48h), that correlated with a large decrease of the level of Erk1/2 phosphorylation. This effect was blocked by H-89 (PKA inhibitor) and mimicked by forskolin (direct activator of adenylyl cyclase) or 8-Br-cAMP (activator of PKA and Epac) or 6-Bnz-cAMP (specific activator of PKA) but not by 8-CPT-2'-O-Me-cAMP (specific activator of Epac), indicating involvement of PKA. The exposure of MCF-10A cells to isoproterenol for 4h caused a significant enhancement of cell adhesion (74% vs 12% adherent cells after trypsin-EDTA treatment). Isoproterenol effect was not blunted by H-89. Cells treated with 8-CPT-2'-O-Me-cAMP, but not 6-Bnz-cAMP, exhibited enhanced adhesion, demonstrating involvement of Epac. As assessed by immuno-cytology the effect of isoproterenol was related with a redistribution of integrin-â1 and with reinforced cell-cell contacts. The present study demonstrates that â-adrenergic stimulation of MCF-10A cells attenuates cell proliferation and enhances cell adhesion. Both effects are cAMP-dependant, however whereas growth inhibition is mediated via the PKA-Erk1/2 pathway, enhancement of adhesion is due to Epac activation and subsequent redistribution of â1 integrin.