RESUMEN
EMMPRIN/CD147 is mainly known for its protease inducing function but a role in promoting tumor angiogenesis has also been demonstrated. This study provides evidence that EMMPRIN is a new coreceptor for the VEGFR-2 tyrosine kinase receptor in both endothelial and tumor cells, as it directly interacts with it and regulates its activation by its VEGF ligand, signalling and functional consequences both in vitro and in vivo. Computational docking analyses and mutagenesis studies identified a molecular binding site in the extracellular domain of EMMPRIN located close to the cell membrane and containing the amino acids 195/199. EMMPRIN is overexpressed in cancer and hence is able to further potentiate VEGFR-2 activation, suggesting that a combinatory therapy of an antiangiogenic drug together with an inhibitor of EMMPRIN/VEGFR-2 interaction may have a greater impact on inhibiting angiogenesis and malignancy.
Asunto(s)
Basigina/metabolismo , Regulación Neoplásica de la Expresión Génica , Factor A de Crecimiento Endotelial Vascular/metabolismo , Receptor 2 de Factores de Crecimiento Endotelial Vascular/metabolismo , Inhibidores de la Angiogénesis/química , Animales , Sitios de Unión , Línea Celular , Línea Celular Tumoral , Membrana Celular/metabolismo , Movimiento Celular , Sistema Libre de Células , Simulación por Computador , Femenino , Silenciador del Gen , Humanos , Ligandos , Ratones , Ratones Desnudos , Microvasos/citología , Mutagénesis , Mutagénesis Sitio-Dirigida , Trasplante de Neoplasias , Neovascularización Patológica , Fosforilación , Unión Proteica , Estructura Terciaria de Proteína , ARN Interferente Pequeño/metabolismo , Proteínas Recombinantes/metabolismo , Transducción de SeñalRESUMEN
EMMPRIN is known to promote tumor invasion through extracellular matrix (ECM) degradation. Here we report that EMMPRIN can regulate melanoma cell adhesion to the ECM through an interaction with ß1 integrin involving kindlin-3. In this study, EMMPRIN knockdown in the human melanoma cell line M10 using siRNA decreased cell invasion and significantly increased cell adhesion and spreading. A morphological change from a round to a spread shape was observed associated with enhanced phalloidin-labelled actin staining. In situ proximity ligation assay and co-immunoprecipitation revealed that EMMPRIN silencing increased the interaction of ß1 integrin with kindlin-3, a focal adhesion protein. This was associated with an increase in ß1 integrin activation and a decrease in the phosphorylation of the downstream integrin kinase FAK. Moreover, the expression at both the transcript and protein level of kindlin-3 and of ß1 integrin was inversely regulated by EMMPRIN. EMMPRIN did not regulate either talin expression or its interaction with ß1 integrin. These results are consistent with our in vivo demonstration that EMMPRIN inhibition increased ß1 integrin activation and its interaction with kindlin-3. To conclude, these findings reveal a new role of EMMPRIN in tumor cell migration through ß1 integrin/kindlin-3-mediated adhesion pathway.
