Abstract |
Breast cancer cell metastases to bone result in osteolysis and release of large quantities of Ca2+ into the bone microenviroment. Extracellular Ca2+ (Ca(o)2+) acting through the Ca(2+)-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 Galpha(12) is significantly up-regulated in breast cancer cells (MDA-MB-231 and MCF-7) compared with nonmalignant breast cells (Hs 578Bst and MCF-10A). Ca(o)2+ induces a significant increase in extracellular [(3)H] phosphocholine (P-cho) production in breast cancer cells. Using an anti-CaR antibody to block Ca(o)2+ binding to the CaR and small interfering RNA ( siRNA) to silence CaR gene expression, our data demonstrate that [(3)H]P-cho production in response to Ca(o)(2+)-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 Galpha(i), Galpha(q) or Galpha12 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-Galpha12-Rho signaling pathway.
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Authors | Chunfa Huang, Lindsey M Hydo, Shiguo Liu, R Tyler Miller |
Journal | Cellular signalling
(Cell Signal)
Vol. 21
Issue 12
Pg. 1894-900
(Dec 2009)
ISSN: 1873-3913 [Electronic] England |
PMID | 19716891
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
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Chemical References |
- Receptors, Calcium-Sensing
- Phosphorylcholine
- Choline Kinase
- GTP-Binding Protein alpha Subunits, G12-G13
- rho GTP-Binding Proteins
- Calcium
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Topics |
- Breast Neoplasms
(enzymology, genetics)
- Calcium
(metabolism)
- Cell Line
- Cell Line, Tumor
- Choline Kinase
(metabolism)
- Enzyme Activation
- Female
- GTP-Binding Protein alpha Subunits, G12-G13
(genetics, metabolism)
- Gene Expression Regulation, Neoplastic
- Humans
- Phosphorylcholine
(metabolism)
- Receptors, Calcium-Sensing
(genetics, metabolism)
- Up-Regulation
- rho GTP-Binding Proteins
(metabolism)
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