Year: 2020
Type: article
Abstract: Ca 2+ /calmodulin-dependent protein kinases (CaM Kinases) are intracellular signaling targets of hormones implicated in numerous cancers including breast cancer.The hormone estrogen (E2) or the muscarinic receptor agonist carbachol activate CaM Kinases, ERK and transcription factors to promote cell growth and differentiation.The mechanism by which E2 activates CaM Kinases and their precise intracellular targets that control cancer cell growth and survival remain to be elucidated.We show that E2 treatment of MCF-7 cells activates a CaM KI, ERK and cell growth pathway through the estrogen receptor alpha (ERα).Treatment of MDA-MB-231 (MDA) cells with carbachol also stimulated this pathway.Interestingly, we identified a CaM KI phosphorylation site within the C-terminal region of the tumor suppressor, p53, at serine 366 (S366).Stimulation of cells using either E2 or carbachol triggered phosphorylation of p53 at S366, which was blocked by pretreatment with the CaM KK inhibitor, STO-609 or transfection with siRNAs directed against CaM KI.Cells transfected with constitutively-active CaM KK revealed an elevated level of endogenous p53 phosphorylation at S366.Purified p53 associated with CaM KI from MCF-7 and MDA lysates and immunoprecipitation of transfected Flag-CaM KI revealed the presence of endogenous p53.Evaluation of agonist-stimulated cells using confocal microscopy suggests that endogenous CaM KI and p53 proteins co-localize in the cytoplasm.The p53 inhibitor, Pifithrin-alpha (PFT-α) increased p53 cytoplasmic localization, cell growth and survival.Treatment of MCF-7 or MDA cells with E2 or carbachol promoted cell growth and that was blocked by STO-609 but not PFT-α.This data is the first to suggest CaM KI may phosphorylate and regulate p53 in breast cancer cell growth and survival.
Institution: George Fox University
Language: English
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
Award: G6334516498
OpenAlex ID: W3024045489