Mitogenic signalling by B2 bradykinin receptor in epithelial breast cells

Abstract

The kinin peptides are released during inflammation and are amongst the most potent known mediators of vasodilatation, pain, and oedema. A role in the modulation or induction of healthy breast tissue growth has been postulated for tissue kallikrein present in human milk. Moreover, tissue kallikrein was found in malignant human breast tissue and bradykinin (BK) stimulates the proliferation of immortalised breast cancer cells. Aim of the present article was to investigate whether BK also exerts mitogenic activity in normal breast epithelial cells and partially characterise the signalling machinery involved. Results show that BK increased up to 2-fold the 24 h proliferation of breast epithelial cells in primary culture, and that the BK B2 receptor (not B1) inhibitor alone fully blocked the BK response. Intracellular effects of B2 stimulation were the following: (a) the increase of free intracellular Ca(2+) concentration by a mechanism dependent upon the phospholipase C (PLC) activity; (b) the cytosol-to-membrane translocation of conventional (PKC)-alpha and -beta isozymes, novel PKC-delta, -epsilon, and -eta isozymes; (c) the phosphorylation of the extracellular-regulated kinase 1 and 2 (ERK1/2); and (d) the stimulation of the expression of c-Fos protein. EGF, a well known stimulator of cell proliferation, regulated the proliferative response in human epithelial breast cells to the same extent of BK. The effects of BK on proliferation, ERK1/2 phosphorylation, and c-Fos expression were abolished by GF109203X, which inhibits PKC-delta isozyme. Conversely, Gö6976, an inhibitor of PKC-alpha and -beta isozymes, and the 18-h treatment of cells with PMA, that led to the complete down-regulation of PKC-alpha, -beta, -epsilon, and -eta, but not of PKC-delta, did not have any effect, thereby indicating that the PKC-delta mediates the mitogenic signalling of BK. Phosphoinositide 3-kinase (PI3K), tyrosine kinase of the epidermal growth factor receptor (EGFR), and mitogen activated protein kinase kinases (MEK) inhibitors were also tested. The results suggest that EGFR, PI3K, and ERK are required for the proliferative effects of BK. In addition, the BK induced cytosol-to-membrane translocation of PKC-delta was blocked by PI3K inhibition, suggesting that PI3K is upstream to PKC-delta. In conclusion, BK has mitogenic actions in cultured human epithelial breast cells; the activation of PKC-delta through B2 receptor acts in concert with ERK and PI3K pathways to induce cell proliferation.

Cross-talk between G Protein–Coupled Receptor and Epidermal Growth Factor Receptor Signaling Pathways Contributes to Growth and Invasion of Head and Neck Squamous Cell Carcinoma

“…PGE2 and BK are inflammatory molecules that have been previously reported to contribute to proliferation in breast and colon carcinoma (6,10). The concentration of PGE2 and BK used in these studies was determined by treating HNSCC cells with increasing doses of the ligands.…”

“…PGE2 and BK stimulate HNSCC cell proliferation and invasion via EGFR. PGE2 and BK are inflammatory factors that have been previously reported to stimulate growth of colon or breast cancer cells, respectively (7,10). The effect of PGE2 or BK on the growth of head and neck cancer cells has not been described previously.…”

“…Several recent reports provide evidence linking inflammation and tumor promotion. Inflammatory molecules, such as PGE2 and BK, in the tumor microenvironment have been reported to bind GPCRs and induce mitogenesis and invasion in several cancers, including breast and colon (9,10). GPCR-mediated transactivation of EGFR has been shown to result in downstream activation of p44/42 MAPK (17,30).…”

“…6,9). BK also has been reported to stimulate proliferation in breast cancer cells via EGFR (10). Combined inhibition of EGFR and GPCR may lead to enhanced antitumor effects compared with single agents targeting EGFR alone.…”

Targeting lipid metabolism by the lipoprotein lipase inhibitor orlistat results in apoptosis of B-cell chronic lymphocytic leukemia cells

“…22 The bradykinin receptor B2 is directly interacting with phospholipase C and provides mitogenic stimuli. 23,24 Two genes associated with phospholipase D activity were also identified: first phospholipase D2 (PLD2) catalyzes the hydrolysis of PC to produce phosphatidic acid and choline, PLD2 was shown to prevent apoptosis in cancer cell lines 25,26 and increases Syk-mediated signaling in mast cells. 27 We also identified LPL as CLL-specific expressed gene in agreement with previously published data.…”