Protease-Activated Receptor-2 Is Essential for Factor VIIa and Xa–Induced Signaling, Migration, and Invasion of Breast Cancer Cells

Abstract

Protease-activated receptors (PAR) are G protein-coupled receptors that function as cell-surface sensors for coagulant proteases, as well as other proteases associated with the tumor microenvironment. PAR1 is activated by thrombin whereas the upstream coagulant protease VIIa bound to tissue factor and Xa can activate both PAR1 and PAR2. PAR1 has been implicated in tumor cell growth, migration, and invasion whereas the function of PAR2 in these processes is largely unknown. Towards defining the functional importance of PAR2 in cancer cells, we used small interfering RNAs to deplete highly invasive breast cancer cells of endogenous PAR proteins. Our findings strongly suggest that PAR2 is critical for MDA-MB-231 and BT549 breast cancer cell migration and invasion towards NIH 3T3 fibroblast conditioned medium. To define the relative importance of PAR1 versus PAR2 in mediating factor VIIa and Xa responses, we assessed signaling in cancer cells lacking either endogenous PAR1 or PAR2 proteins. Strikingly, in MDA-MB-231 cells depleted of PAR2, we observed a marked inhibition of VIIa and Xa signaling to phosphoinositide hydrolysis and extracellular signalregulated kinase 1/2 activation whereas signaling by VIIa and Xa remained intact in PAR1-deficient cells. Factor VIIa and Xa-induced cellular migration was also impaired in MDA-MB-231 cells deficient in PAR2 but not in cells lacking PAR1. Together, these studies reveal the novel findings that PAR2, a second protease-activated G protein-coupled receptor, has a critical role in breast cancer cell migration and invasion and functions as the endogenous receptor for coagulant proteases

ORAI1-Mediated Calcium Influx in Lactation and in Breast Cancer

“…Despite the presence of other ORAI isoforms, selective inhibition of ORAI1 is sufficient to alter breast cancer cell properties and the nature of the calcium influx associated with growth factors and proinvasiveness stimuli associated with calcium store mobilization, such as seen in our studies with a PAR-2 activator. PAR-2 is a G-protein coupled receptor activated by specific proteases including trypsin (30), and its activation mobilizes calcium from internal stores and promotes the proliferation and invasion of MDA-MB-231 breast cancer cells (31)(32)(33)(34). The ability of ORAI1 inhibition to modify the nature of calcium responses elicited by growth factors and proinvasion factors points to the need for further exploration of mechanism and potential differences between stimuli, specifically the effects on gene transcription via NFAT, which seems particularly sensitive to changes in sustained calcium influx (5).…”

Gene expression profiling identifies sST2 as an effector of ErbB2-driven breast carcinoma cell motility, associated with metastasis

“…However, among the genes we tested, only F2RL1/PAR2 and sST2 contributed to ErbB2-driven migration. PAR2 activation promotes breast cancer cell migration (Morris et al, 2006;Su et al, 2009). Interestingly, this function could be mediated by transactivation of EGFR/ErbB2 (Caruso et al, 2006;Jarry et al, 2007), suggesting the possibility of a positive feedback loop.…”

Angiogenesis is associated with the onset of hyperplasia in human ductal breast disease

“…Tissue factor is highly expressed in metastatic, but not in non-metastatic breast carcinoma cells (Bluff et al, 2006), and may contribute to the metastatic process directly through the TF-FVIIa complex and/or through downstream generation of active coagulation factors (Booden et al, 2004;Palumbo et al, 2007). Furthermore, TF-FVIIa signalling via PAR-2 has been shown to stimulate breast cancer cell migration (Jiang et al, 2004;Morris et al, 2006), and a humanised anti-TF monoclonal antibody (CNTO 859) inhibited experimental in vivo lung metastasis from invasive breast cancer cells by more than 99%, indicating a role for TF in breast cancer cell metastasis (Ngo et al, 2007).…”