title: Dosage-dependent regulation of cell proliferation and adhesion through dual β2-adrenergic receptor/cAMP signals.
abstract: The role of β-adrenergic receptors (β-ARs) remains controversial in normal and tumor breast. Herein we explore the cAMP signaling involved in β-AR-dependent control of proliferation and adhesion of nontumor human breast cell line MCF-10A. Low concentrations of a β-agonist, isoproterenol (ISO), promote cell adhesion (87.5% cells remaining adherent to the plastic dishes following specific detachment vs. 35.0% in control, P<0.001), while increasing concentrations further engages an additional 36% inhibition of Erk1/2 phosphorylation (p-Erk1/2)-dependent cell proliferation (P<0.01). Isoproterenol dose response on cell adhesion was fitted to a 2-site curve (EC50(1): 16.5±11.5 fM, EC50(2): 4.08±3.09 nM), while ISO significantly inhibited p-Erk1/2 according to a 1-site model (EC50: 0.25±0.13 nM). Using β-AR-selective agonist/antagonists and cAMP analogs/inhibitors, we identified a dosage-dependent signaling in which low ISO concentrations target a β2-AR population localized in raft microdomains and stimulate a Gs/cAMP/Epac/adhesion-signaling module, while higher concentrations engage a concomitant activation of another β2-AR population outside rafts and inhibit the proliferation by a Gs/cAMP/PKA-dependent signaling module. Our data provide a new molecular basis for the dose-dependent switch of β-AR signaling. This study also sheds light on a new cAMP pathway core mechanism with a single receptor triggering dual cAMP signaling controlled by PKA or Epac but with different cellular outputs.
authors.affiliation: 2Inserm U1048, Institut des Maladies Métaboliques et Cardiovasculaires, I2MC, 1, avenue Jean-Poulhès, BP84225, 31432 Toulouse Cedex 4, France. celine.gales@inserm.fr.
authors.forename: Ariana
authors.initials: A
authors.lastname: Bruzzone
authors.forename: Aude
authors.initials: A
authors.lastname: Saulière
authors.forename: Frédéric
authors.initials: F
authors.lastname: Finana
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Sénard
authors.forename: Isabel
authors.initials: I
authors.lastname: Lüthy
authors.forename: Céline
authors.initials: C
authors.lastname: Galés
mesh_terms: D002448:Cell Adhesion; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D000242:Cyclic AMP / Q000502:physiology*; D006801:Humans; D018343:Receptors, Adrenergic, beta-2 / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D018343:Receptors, Adrenergic, beta-2; D000242:Cyclic AMP
keywords: Epac; MCF-10A human breast cell line; PKA; signaling compartmentalization