Functional Interplay between Type I Collagen and Cell Surface Matrix Metalloproteinase Activity

Abstract

Type I collagen stimulation of pro-matrix metalloproteinase (pro-MMP)-2 activation by ovarian cancer cells involves ␤ 1 integrin receptor clustering; however, the specific cellular and biochemical events that accompany MMP processing are not well characterized. Collagenolysis is not required for stimulation of pro-MMP-2 activation, and denatured collagen does not elicit an MMP-2 activation response. Similarly, DOV13 cells bind to intact collagen utilizing both ␣ 2 ␤ 1 and ␣ 3 ␤ 1 integrins but interact poorly with collagenase-treated or thermally denatured collagen. Antibody-induced clustering of ␣ 3 ␤ 1 strongly promotes activation of pro-MMP-2, whereas ␣ 2 ␤ 1 integrin clustering has only marginal effects. Membrane-type 1 (MT1)-MMP is present on the DOV13 cell surface as both an active 55-kDa TIMP-2-binding species and a stable catalytically inactive 43-kDa form. Integrin clustering stimulates cell surface expression of MT1-MMP and co-localization of the proteinase to aggregated integrin complexes. Furthermore, cell surface proteolysis of the 55-kDa MT1-MMP species occurs in the absence of active MMP-2, suggesting MT1-MMP autolysis. Cellular invasion of type I collagen matrices requires collagenase activity, is blocked by tissue inhibitor of metalloproteinases-2 (TIMP-2) and collagenase-resistant collagen, is unaffected by TIMP-1, and is accompanied by pro-MMP-2 activation. Together, these data indicate that integrin stimulation of MT1-MMP activity is a rate-limiting step for type I collagen invasion and provide a mechanism by which this activity can be down-regulated following collagen clearance.The MMP family is composed of at least 25 zinc-dependent extracellular endopeptidases whose activities are regulated predominantly by expression as inactive precursors, or zymogens (1-3). Although precise physiological activators of MMPs 1 are unknown, a variety of serine proteinases and other MMPs in the extracellular milieu execute the initial propeptide cleavage events in vitro (2). An exception to serine protease activation is pro-MMP-2 (72-kDa gelatinase A), which lacks the necessary basic amino acid cleavage sites in its pro-domain (4). A primary mechanism of pro-MMP-2 activation involves zymogen association with the cell surface via formation of a ternary complex containing tissue inhibitor of metalloproteinase (TIMP)-2 and membrane type 1-MMP (MT1-MMP, MMP-14) (3-6). Following trimeric complex formation, it is hypothesized that a neighboring MT1-MMP molecule that is not associated with TIMP-2 cleaves pro-MMP-2 at the Asn 37 -Leu 38 peptide bond within the pro-domain (7). Intermediately processed MMP-2 (Leu 38 -MMP-2) undergoes further concentration-dependent autolytic cleavage(s) to generate mature enzymes that can be released into the soluble phase or remain surface-associated (8). Although biological mechanisms of active MMP-2 release from the cell surface are not well characterized and dissociation kinetics provide little insight, cellular binding affinities may shift following pro-MMP-2 cleavage.Culturing ...

Rac Affects Invasion of Human Renal Cell Carcinomas by Up-regulating Tissue Inhibitor of Metalloproteinases (TIMP)-1 and TIMP-2 Expression

“…Increased expression or activation of distinct MMPs in response to integrinmediated cell-substrate adhesion has also been reported by others, but the role of Rac was not analyzed in these studies (42,43). Nevertheless, it is remarkable that these effects were partly substrate-specific and depended on the expression of distinct integrin receptors.…”

Integrin Regulation of β-Catenin Signaling in Ovarian Carcinoma

“…Modulation of cell-cell and cell-matrix adhesion are key events in ovarian cancer metastasis, as intraperitoneal adhesion of malignant cells and multicellular aggregates combined with localized integrin-mediated invasion of the collagen-rich submesothelial matrix are necessary to anchor secondary lesions (5,40). Intraperitoneal ovarian cancer metastasis is mediated by adhesion via integrins ␣2␤1 and ␣3␤1 to peritoneal mesothelial cells displaying surface expression of collagen and the exposed interstitial (types I and III) collagen-rich submesothelial matrix, and antibodies directed against these integrins block collagen binding (41)(42)(43)(44)(45)(46)(47). Integrin engagement by a multivalent matrix ligand results in receptor aggregation, functionally coupling the extracellular environment to specific signal transduction pathways that modulate distinct cellular responses, including gene transcription, cell migration, and survival (48).…”

EMT, the cytoskeleton, and cancer cell invasion

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