Three-dimensional Type I Collagen Lattices Induce Coordinate Expression of Matrix Metalloproteinases MT1-MMP and MMP-2 in Microvascular Endothelial Cells

Abstract

Angiogenesis, which is the formation of new blood vessels from those pre-existing, occurs during development, wound healing, and tumor growth, and in response to stimuli such as exercise and hypoxia (1-3). This process involves complex signaling events that cause the endothelial cells comprising capillaries to initiate proliferative and migratory phenotypes. The sprouting endothelial cells must break through their existing basement membrane and form contacts with and migrate along different extracellular matrix components, finally establishing a new, patent capillary (1, 2).In an effort to define the molecular mechanisms underlying these events, a number of in vitro cell systems have been established. These include growth of endothelial cells or blood vessel fragments in fibrin clots, on amnionic membranes, in collagen matrices, and on Matrigel ® matrices (4-6). These models are characterized by re-organization that requires significant endothelial cell migration and/or invasion, and remodeling of the surrounding matrix molecules. It has been shown that microvascular endothelial cells undergo morphological changes that can include organization into tubelike structures when grown within a type I collagen matrix (7,8). The morphological changes are accompanied by changes in growth factor receptor profiles and extracellular matrix protein production (9, 10).Matrix metalloproteinases (MMPs) 1 belong to a family of enzymes with diverse substrate specificity, ranging from multiple extracellular matrix components to growth factors, cytokines, and other proteinases (11,12). It was first recognized that matrix metalloproteinases play a role in angiogenesis, based on the observation that inhibition of MMP activity by endogenous tissue inhibitors of metalloproteinases or synthetic compounds could inhibit in vitro tube formation (13,14). Several studies have demonstrated that the gelatinases, MMP-2 and MMP-9, are involved in vascular cell migration and invasion assays (15, 16). However, the regulation of MMP expression and activation during angiogenic events is not well understood. The recent cloning of several membrane-type MMPs (MT-MMPs) (17-19) that each contain a putative transmembrane domain and appear to have substrate specificity for the pro-MMP-2 has led to considerable speculation concerning the role of the cell surface in regulating proteolytic activity, and the extent to which MT-MMPs may be involved in controlling proteolytic cascades involving .We hypothesized that the controlled activation of metalloproteinases would be necessary for the in vitro remodeling of endothelial cells cultured in a collagen matrix, and that this activation would require the transcriptional up-regulation of specific MMPs, including MT-MMPs. Utilizing primary cultures of rat microvascular endothelial cells, we demonstrated a coordinate increase in expression of MMP-2 and MT1-MMP (MMP-14) following culture within a type I collagen matrix, and that activation of MMP-2 correlated temporally with MT1-MMP induction. MMP inhibitors blocked t...

Type IV Collagen Induces Matrix Metalloproteinase 2 Activation in HT1080 Fibrosarcoma Cells

“…Altogether, these data suggest that, in contrast to the previously published mechanisms accounting for the induction of MMP-2 activation by ECM components [42][43][44]62], the promoting effect of type IV collagen does involve neither an upregulation of MT1-MMP transcription nor a posttranslational modification of MT1-MMP. It can be hypothesized that type IV collagen mediates its effect by bringing closer cell membrane-associated MT1-MMP/TIMP-2/MMP-2 complexes, therefore promoting the intermolecular autolytic cleavage of intermediate MMP-2 and thus leading to the generation of the fully mature species.…”

Pancreatic Ductal Morphogenesis and the Pdx1 Homeodomain Transcription Factor

“…This suggests that specific type I collagen matrix-PDC interactions are necessary and sufficient to activate as yet undetermined signal transduction pathways that ultimately activate the genetic and biochemical program of branching morphogenesis. Similar specificities for matrix-dependent signal pathway activation cascades have been reported elsewhere, for example, the activation of specific matrix metalloproteinases in response to collagen but not Matrigel matrix in vascular endothelial cells (Haas et al, 1998).…”

Gelatinase-mediated migration and invasion of cancer cells

“…Alternatively, integrin-mediated signals may lead to the increase in MT1-MMP expression and activity and thus contribute to the MMP-2 activation. Endothelial cells cultured in a three-dimensional (3D)-collagen type I matrix express MT1-MMP with concomitant activation of MMP-2 whereas only a minor fraction of MMP-2 is activated in a 2D-collagen culture (Haas et al, 1998). In addition, HT1080 cells cultured on fibronectin, but not on laminin-1 show increased activation of MMP-2.…”