title: Hypoxia of endothelial cells leads to MMP-2-dependent survival and death.
abstract: Exposure of endothelial cells (ECs) to hypoxia has separately been shown to induce their angiogenesis or death. Matrix metalloproteinase (MMP)-2 is associated with EC angiogenesis, although recent studies also implicate this molecule in EC death. We studied the effect of hypoxia in the absence or presence of TNF-alpha (characteristic of the inflammatory microenvironment accompanying hypoxia) on MMP-2 expression and its role in angiogenesis (proliferation, migration, and tube formation) and in the death of primary human umbilical vein endothelial cells (HUVECs). Hypoxia alone (24-48 h in 0.3% O(2) in the hypoxic chamber) and furthermore, when combined with TNF-alpha, significantly enhanced MMP-2 expression and activity. Hypoxia also led to a reduction in membrane type 1 MMP (MT1-MMP) and tissue inhibitor of metalloproteinase-2 mRNA and protein while enhancing the expression of alpha(v)beta(3) integrin and the cytoskeletal protein phosphopaxillin. Moreover, hypoxia led to colocalization of alpha(v)beta(3) and MMP-2, but not MT1-MMP, with phosphopaxillin in ECs. These results suggest MT1-MMP-independent activation of MMP-2 during hypoxia and support interactions between the ECM, integrins, and the cytoskeleton in hypoxia-induced MMP-2-related functions. Hypoxia enhanced EC migration in an MMP-2-dependent manner while leading to a reduction of cell number via their apoptosis, which was also dependent on MMP-2. In addition, hypoxia caused an aberrant tubelike formation on Matrigel that appeared to be unaffected by MMP-2. The hypoxia-induced, MMP-2-dependent migration of ECs is in accordance with the proangiogenic role ascribed to MMP-2, while the involvement of this protease in the hypoxia-related death of ECs supports an additional apoptotic role for this protease. Hence, in the hypoxic microenvironment, MMP-2 appears to have a dual autocrine role in determining the fate of ECs.
authors.affiliation: Immunology Research Unit, Carmel Medical Center, 7 Michal St., Haifa 34362, Israel.
authors.forename: Yaara
authors.initials: Y
authors.lastname: Ben-Yosef
authors.forename: Ariel
authors.initials: A
authors.lastname: Miller
authors.forename: Sarah
authors.initials: S
authors.lastname: Shapiro
authors.forename: Nitza
authors.initials: N
authors.lastname: Lahat
mesh_terms: D016923:Cell Death / Q000502:physiology*; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000502:physiology; D042783:Endothelial Cells / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000502:physiology; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis*; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000502:physiology; D010100:Oxygen / Q000502:physiology*; D051419:Paxillin; D010750:Phosphoproteins / Q000502:physiology; D013997:Time Factors; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
chemical_list: D003598:Cytoskeletal Proteins; D039302:Integrin alphaVbeta3; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D014409:Tumor Necrosis Factor-alpha; D019716:Tissue Inhibitor of Metalloproteinase-2; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2; D010100:Oxygen