title: Human neutrophils uniquely release TIMP-free MMP-9 to provide a potent catalytic stimulator of angiogenesis.
abstract: Several lines of evidence have implicated matrix metalloproteinase 9 (MMP-9) as a protease inducing an angiogenic switch critical for tumor progression. Among MMP-9-expressing cell types, including cancer cells and tumor-associated leukocytes, inflammatory neutrophils appear to provide an important source of MMP-9 for tumor angiogenesis. However, delivery of MMP-9 by neutrophils has not been mechanistically linked to its catalytic activity at the angiogenic site. By using a modified angiogenic model, allowing for a direct analysis of exogenously added cells and their products in collagen onplants grafted on the chorioallantoic membrane of the chicken embryo, we demonstrate that intact human neutrophils and their granule contents are highly angiogenic. Furthermore, purified neutrophil MMP-9, isolated from the released granules as a zymogen (proMMP-9), constitutes a distinctly potent proangiogenic moiety inducing angiogenesis at subnanogram levels. The angiogenic response induced by neutrophil proMMP-9 required activation of the tissue inhibitor of metalloproteinases (TIMP)-free zymogen and the catalytic activity of the activated enzyme. That the high angiogenic potency of neutrophil proMMP-9 is associated with its unique TIMP-free status was confirmed when a generated and purified stoichiometric complex of neutrophil proMMP-9 with TIMP-1 failed to induce angiogenesis. Recombinant human proMMP-9, operationally free of TIMP-1, also induced angiogenesis at subnanomolar levels, but lost its proangiogenic potential when stoichiometrically complexed with TIMP-1. Similar proMMP-9/TIMP-1 complexes, but naturally produced by human monocytic U937 cells and HT-1080 fibrosarcoma cells, did not stimulate angiogenesis. These findings provide biochemical evidence that infiltrating neutrophils, in contrast to other cell types, deliver a potent proangiogenic moiety, i.e., the unencumbered TIMP-free MMP-9.
authors: Department of Cell Biology, The Scripps Research Institute, 10550 Torrey Pines Road, La Jolla, CA 92037, USA.
authors: Veronica C
authors: VC
authors: Ardi
authors: Tatyana A
authors: TA
authors: Kupriyanova
authors: Elena I
authors: EI
authors: Deryugina
authors: James P
authors: JP
authors: Quigley
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D045744:Cell Line, Tumor; D002642:Chick Embryo; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D061965:Matrix Metalloproteinase Inhibitors; D009389:Neovascularization, Pathologic / Q000201:enzymology*; D018919:Neovascularization, Physiologic; D009504:Neutrophils / Q000201:enzymology*; D011994:Recombinant Proteins / Q000235:genetics / Q000494:pharmacology; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D004792:Enzyme Precursors; D061965:Matrix Metalloproteinase Inhibitors; D011994:Recombinant Proteins; D019715:Tissue Inhibitor of Metalloproteinase-1; C120487:pro-matrix metalloproteinase 9; D020780:Matrix Metalloproteinase 9