ERK activation and cell growth require CaM kinases in MCF-7 breast cancer cells.

Abstract

Previous studies on MCF-7 breast cancer cells have shown that the G-protein coupled receptor (GPCR) agonist carbachol increases intracellular calcium levels and the activation of extracellular signal-regulated kinase (ERK). Calcium and calmodulin regulate the calcium/calmodulin-dependent kinase (CaM kinase) family of proteins that have been proposed to regulate ERK and gene transcription. Our results suggest that both estrogen (E2) and carbachol treatment of MCF-7 breast cancer cells trigger phosphorylation of ERK1/2 and the transcription factor Elk-1. Carbachol and estrogen triggered nearly a four- to sixfold increase in MCF-7 cell proliferation by 96 h, respectively. Carbachol-stimulated ERK activation and cell growth was completely blocked by the Muscarinic M(3)-subtype GPCR inhibitor, 4-DAMP, and siRNA against the M(3)-subtype GPCR. Interestingly, blockade of CaM KK with the selective inhibitor STO-609 prevented carbachol activation CaM KI, ERK, Elk-1, and cell growth. Consistent with these observations, knockdown of CaM KKalpha and CaM KIgamma with shRNA-containing plasmids blocked ERK activation by carbachol. In addition, Elk-1 phosphorylation and luciferase activity in response to carbachol treatment was also dependent upon CaM kinases and was inhibited by U0126, STO-609, and siRNA knockdown of CaM kinases and ERK2. Finally, blockade of either CaM KK (with STO-609) or ERK (with U0126) activities resulted in the inhibition of carbachol- and estrogen-mediated cyclin D1 expression and MCF-7 cell growth. Taken together, our results suggest that carbachol treatment of MCF-7 cells activates CaM KI, ERK, the transcription factor Elk-1, cyclin D1, and cell growth through CaM KK.

• Authors: John M Schmitt, Ellen Abell, Andrea Wagner, Monika A Davare
• Journal: Molecular and cellular biochemistry (Mol Cell Biochem) Vol. 335 Issue 1-2 Pg. 155-71 (Feb 2010) ISSN: 1573-4919 [Electronic] Netherlands
• PMID: 19763792 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• ets-Domain Protein Elk-1
• Calcium-Calmodulin-Dependent Protein Kinases
• Extracellular Signal-Regulated MAP Kinases

Topics

• Breast Neoplasms (enzymology)
• Calcium-Calmodulin-Dependent Protein Kinases (metabolism)
• Cell Line, Tumor
• Cell Proliferation
• Extracellular Signal-Regulated MAP Kinases (metabolism)
• Female
• Humans
• ets-Domain Protein Elk-1 (metabolism)