cAMP-PKA inhibition of SK3 channel reduced both Ca2+ entry and cancer cell migration by regulation of SK3-Orai1 complex

Pflugers Arch. 2014 Oct;466(10):1921-32. doi: 10.1007/s00424-013-1435-5. Epub 2014 Jan 24.

Abstract

SK3 channel mediates the migration of various cancer cells. When expressed in breast cancer cells, SK3 channel forms a complex with Orai1, a voltage-independent Ca(2+) channel. This SK3-Orai1 complex associates within lipid rafts where it controls a constitutive Ca(2+) entry leading to cancer cell migration and bone metastases development. Since cAMP was found to modulate breast cancer cell migration, we hypothesized that this could be explained by a modulation of SK3 channel activity. Herein, we study the regulation of SK3 channel by the cAMP-PKA pathway and the consequences for SK3-dependent Ca(2+) entry and cancer cell migration. We established that the beta-adrenergic receptor agonist, isoprenaline, or the direct adenylyl cyclase activator forskolin alone or in combination with the PDE4 inhibitor, CI-1044, decreased SK3 channel activity without modifying the expression of SK3 protein at the plasma membrane. Forskolin and CI-1044 reduced the SK3-dependent constitutive Ca(2+) entry and the SK3-dependent migration of MDA-MB-435s cells. PKA inhibition with KT 5720 reduced: (1) the effect of forskolin and CI-1044 by 50 % on Ca(2+) entry and (2) SK3 activity by inhibiting the serine phosphorylation of SK3. These cAMP-elevating agents displaced Orai1 protein outside lipid rafts in contrast to SK3, which remained in the lipid rafts fractions. All together, these results show that activation of the cAMP-PKA pathway decreases SK3 channel and SK3-Orai1 complex activities, leading to a decrease in both Ca(2+) entry and cancer cell migration. This work supports the potential use of cAMP-elevating agents to reduce cancer cell migration and may provide novel opportunities to address/prevent bone metastasis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic beta-Agonists / pharmacology
  • Azepines / pharmacology
  • Calcium / metabolism*
  • Calcium Channels / metabolism*
  • Carbazoles / pharmacology
  • Cell Line, Tumor
  • Cell Movement*
  • Colforsin / pharmacology
  • Cyclic AMP / metabolism*
  • Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
  • Cyclic AMP-Dependent Protein Kinases / metabolism*
  • HEK293 Cells
  • Humans
  • Isoproterenol / pharmacology
  • Membrane Microdomains / metabolism
  • Niacinamide / analogs & derivatives
  • Niacinamide / pharmacology
  • ORAI1 Protein
  • Phosphodiesterase 4 Inhibitors / pharmacology
  • Protein Binding
  • Protein Kinase Inhibitors / pharmacology
  • Pyrroles / pharmacology
  • Small-Conductance Calcium-Activated Potassium Channels / metabolism*

Substances

  • Adrenergic beta-Agonists
  • Azepines
  • Calcium Channels
  • Carbazoles
  • KCNN3 protein, human
  • ORAI1 Protein
  • ORAI1 protein, human
  • Phosphodiesterase 4 Inhibitors
  • Protein Kinase Inhibitors
  • Pyrroles
  • Small-Conductance Calcium-Activated Potassium Channels
  • Colforsin
  • Niacinamide
  • KT 5720
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • Isoproterenol
  • CI 1044
  • Calcium