ABSTRACT
Angiogenesis, the formation of new vessels from pre-existing capillaries, is a fundamental physiological process which is also critical for the development of several pathological conditions; thus a diminished angiogenic response is related to ischemic disorders, whereas increased angiogenesis is associated with tumorigenesis and chronic inflammatory diseases. New ways of modulating angiogenesis therefore have potential in the treatment of these diseases. During angiogenesis, normally quiescent endothelial cells (ECs) become migratory and invade the surrounding tissue. To do this, they require a specific enzyme machinery to degrade the tissue barriers presented by the basement membranes and the interstitial matrix. This function is supplied by matrix metalloproteinase (MMP) proteins, a large family of enzymes responsible for degrading a variety of extracellular matrix (ECM) components and for modulating the bioactivity of transmembrane receptors and soluble factors. In this review we examine the participation of MMPs--in particular membrane type 1-matrix metalloproteinase (MT1-MMP)--in the different steps of angiogenesis, and discuss the mechanisms of regulation of MT1-MMP in ECs. Finally, we explore the potential use of MMP inhibitors (MMPI) in the treatment of angiogenesis-related disease, with especial emphasis on novel approaches to the inhibition of MT1-MMP activity in ECs.
Subject(s)
Angiogenesis Inhibitors/pharmacology , Endothelial Cells/drug effects , Enzyme Inhibitors/pharmacology , Matrix Metalloproteinase Inhibitors , Neovascularization, Pathologic/drug therapy , Angiogenesis Inhibitors/therapeutic use , Animals , Cell Movement/drug effects , Endothelial Cells/enzymology , Enzyme Inhibitors/therapeutic use , Extracellular Matrix/metabolism , Humans , Matrix Metalloproteinase 14/metabolism , Matrix Metalloproteinases/metabolism , Neovascularization, Pathologic/enzymology , Neovascularization, Pathologic/physiopathologyABSTRACT
Matrix metalloproteinases are thought to play an important role in endothelial cell migration and matrix remodeling. We have used an in vitro wound healing migration model and newly generated anti-membrane type 1-matrix metalloproteinase (MT1-MMP) monoclonal antibodies (mAbs) to characterize the role of MT1-MMP during this process. First, the expression and shedding of MT1-MMP are up-regulated upon induction of migration in endothelial cells, as demonstrated by flow cytometry and Western blot analysis. Furthermore, MT1-MMP is concentrated at discrete areas in migrating endothelial cells, in contrast to the diffuse pattern observed in confluent cells. Interestingly, migration of endothelial cells results in the stimulation of MT1-MMP activity, as shown by its ability to process pro-MMP-2 and to degrade fibrinogen assessed by zymography. Moreover, MT1-MMP-mediated gelatin degradation is enriched at migration sites. mAbs generated against the MT1-MMP catalytic domain are shown to inhibit MT1-MMP enzymatic activity and to impair both phorbol 12-myristate 13-acetate-induced endothelial migration and invasion of collagen and fibrin gels. Furthermore, a reduction in the formation of capillary tubes in Matrigel is also observed when endothelial cells are pretreated with the blocking anti-MT1-MMP mAbs. Altogether, these data demonstrate that MT1-MMP plays an important role during endothelial cell migration, and its activity can modulate endothelial migration, invasion, and formation of capillary tubes during the angiogenic response.
