title: Mannose 6-phosphate/insulin-like growth factor 2 receptor limits cell invasion by controlling alphaVbeta3 integrin expression and proteolytic processing of urokinase-type plasminogen activator receptor.
abstract: The multifunctional mannose 6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2R) is considered a tumor suppressor. We report here that RNA interference with M6P/IGF2R expression in urokinase-type plasminogen activator (uPA)/urokinase-type plasminogen activator receptor (uPAR) expressing human cancer and endothelial cells resulted in increased pericellular plasminogen activation, cell adhesion, and higher invasive potential through matrigel. M6P/IGF2R silencing led also to the cell surface accumulation of urokinase and plasminogen and enhanced expression of alphaV integrins. Genetic rescue experiments and inhibitor studies revealed that the enhanced plasminogen activation was due to a direct effect of M6P/IGF2R on uPAR, whereas increased cell adhesion to vitronectin was dependent on alphaV integrin expression and not uPAR. Increased cell invasion of M6P/IGF2R knockdown cells was rescued by cosilencing both uPAR and alphaV integrin. Furthermore, we found that M6P/IGF2R expression accelerates the cleavage of uPAR. M6P/IGF2R silencing resulted in an increased ratio of full-length uPAR to the truncated D2D3 fragment, incapable of binding most uPAR ligands. We conclude that M6P/IGF2R controls cell invasion by regulating alphaV integrin expression and by accelerating uPAR cleavage, leading to the loss of the urokinase/vitronectin/integrin-binding site on uPAR.
authors.affiliation: Department of Molecular Immunology, Center for Physiology, Pathophysiology and Immunology, Medical University of Vienna, A-1090 Vienna, Austria.
authors.forename: Herbert B
authors.initials: HB
authors.lastname: Schiller
authors.forename: Andreas
authors.initials: A
authors.lastname: Szekeres
authors.forename: Bernd R
authors.initials: BR
authors.lastname: Binder
authors.forename: Hannes
authors.initials: H
authors.lastname: Stockinger
authors.forename: Vladimir
authors.initials: V
authors.lastname: Leksa
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D004705:Endocytosis; D005341:Fibrinolysin / Q000378:metabolism; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D051379:Mice; D009361:Neoplasm Invasiveness; D010958:Plasminogen / Q000378:metabolism; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D034622:RNA Interference; D017527:Receptor, IGF Type 2 / Q000378:metabolism*; D055293:Receptors, Urokinase Plasminogen Activator / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
chemical_list: D039302:Integrin alphaVbeta3; D017527:Receptor, IGF Type 2; D055293:Receptors, Urokinase Plasminogen Activator; D010958:Plasminogen; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator