Abstract
Breast cancer cell metastases to bone result in osteolysis and release of large quantities of Ca2+ into the bone microenviroment. Extracellular Ca2+ (Cao2+) acting through the Ca2+-sensing receptor (CaR), a member of G protein-coupled receptor superfamily, plays an important role in the regulation of multiple signaling pathways. Here, we find that expression of the CaR and Gα12 is significantly up-regulated in breast cancer cells (MDA-MB-231 and MCF-7) compared with nonmalignant breast cells (Hs 578Bst and MCF-10A). Cao2+ induces a significant increase in extracellular [3H]phosphocholine (P-cho) production in breast cancer cells. Using an anti-CaR antibody to block Cao2+ binding to the CaR and small interfering RNA (siRNA) to silence CaR gene expression, our data demonstrate that [3H]P-cho production in response to Cao2+-stimulation is CaR-dependent. By analyzing cellular lipid profiles and using siRNA to silence choline kinase (ChoK) expression, we determine that the production of [3H]P-cho is primarily related to CaR-induced ChoK activation, and not degradation of choline phospholipids. Finally, by pretreatment of the cells with either pertussis toxin or C3 exoenzyme, co-immunoprecipiation of Gαi, Gαq or Gα12 with the CaR, and RhoA translocation, we found that the enhancement of ChoK activation and P-cho production in breast cancer cells occurs via a CaR-Gα12-Rho signaling pathway.
Original language | English (US) |
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Pages (from-to) | 1894-1900 |
Number of pages | 7 |
Journal | Cellular Signalling |
Volume | 21 |
Issue number | 12 |
DOIs | |
State | Published - Dec 2009 |
Keywords
- Breast cancer cells
- Ca-sensing receptor
- Choline kinase
- Gα
- Phosphocholine
ASJC Scopus subject areas
- Cell Biology