Engaged urokinase receptors enhance tumor breast cell migration and invasion by upregulating αvβ5 vitronectin receptor cell surface expression

Abstract

We have previously shown that urokinase receptor physically and functionally interacts with ␣v␤5 vitronectin receptor, leading to tumor breast cell migration and invasion. Here, the link between these 2 receptors was further investigated by analyzing the expression levels of urokinase receptor and ␣v␤5 integrin in 35 human breast carcinomas and 5 benign breast lesions. The occurrence of a positive correlation between urokinase receptor and ␣v␤5 protein levels in benign and malignant tumor specimens prompted us to investigate whether engaged urokinase receptors might modulate ␣v␤5 expression. Here, we report the receptor-dependent ability of catalytically inactive urokinase to upregulate the ␣v and ␤5 chains in MDA-MB-231 and MCF-7 breast carcinoma cell lines in a time-and concentration-dependent manner. This effect is dependent on protein kinase C activity and requires new protein synthesis. Accordingly, the availability of assembled ␣v␤5 receptors on the cell surface increases upon urokinase treatment, as shown by immunoprecipitation and immunocytochemical analyses. Exposure to urokinase leads to enhanced tumor cell migration and invasion, which is prevented by the "phosphorylation-like" urokinase receptor antagonist His-uPA 138E/303E , the DNA-binding drug mithramycin, the protein kinase C inhibitor calphostin C and anti-␣v␤5 antibodies. Finally, urokinase enables benign breast MCF-10A cells to cross Matrigel in a ␣v␤5-and urokinase receptor-dependent manner, indicating that urokinase controls a regulatory circuitry crucial to breast tumor progression.

Junctional adhesion molecule-A-induced endothelial cell migration on vitronectin is integrin αvβ3 specific

“…Our results show that JAM-A interacts with integrin ␣ v ␤ 3 and induces ␣ v ␤ 3 -dependent HUVEC migration on vitronectin. Integrin ␣ v ␤ 3 has been previously shown to interact with several transmembrane and membrane-associated proteins, and these interactions are important for its function (Barazi et al, 2002;Chellaiah and Hruska, 2003;Hapke et al, 2001;Silvestri et al, 2002;Voura et al, 2001). We find that the interaction of JAM-A with integrin ␣ v ␤ 3 seems to be enhanced upon engagement of its ligand-binding site, as shown by the increased association seen during immunoprecipitation in the presence of RGDS peptide.…”

Cooperation between monocytes and breast cancer cells promotes factors involved in cancer aggressiveness

“…This is explained by an increased invasiveness of cancer cells as membrane-associated u-PA is involved in cancer cell invasion. Urokinase acts by degradation of pericellular matrix, because of proteolytic cascade focused on cell surface leading to plasmin generation and matrix metalloprotease activation (Andreasen et al, 1997) but also by an increased cell migration independent of proteolysis (Silvestri et al, 2002). In addition, in relation to plasmin formation, uPA activates latent growth factors and releases growth factors bound to extracellular matrix (Odekon et al, 1994;Ribatti et al, 1999).…”

Factor XII and uPAR upregulate neutrophil functions to influence wound healing

“…The sum of these activities contributes to neutrophil cell adhesion, migration, and NETosis. uPAR itself modulates integrin affinity and avidity (75)(76)(77). In endothelial cells, occupancy of uPAR by FXII promotes the formation of uPAR-integrin complexes that subsequently activate intracellular signaling pathways (outside-in signaling) through, at least, β 1 integrins (22).…”