Progress in matrix metalloproteinase research. Mol Aspects Med. 2008;29:290-308. [PMID: 18619669 DOI: 10.1016/j.mam.2008.05.002]

Matrix metalloproteinases as novel biomarkers and potential therapeutic targets in human cancer

The matrix metalloproteinase (MMP) family of enzymes is comprised of critically important extracellular matrix remodeling proteases whose activity has been implicated in a number of key normal and pathologic processes. The latter include tumor growth, progression, and metastasis as well as the dysregulated angiogenesis that is associated with these events. As a result, these proteases have come to represent important therapeutic and diagnostic targets for the treatment and detection of human cancers. In this review, we summarize the literature that establishes these enzymes as important clinical targets, discuss the complexity surrounding their choice as such, and chronicle the development strategies and outcomes of their clinical testing to date. The status of the MMP inhibitors currently in US Food and Drug Administration approved clinical trials is presented and reviewed. We also discuss the more recent and successful targeting of this enzyme family as diagnostic and prognostic predictors of human cancer, its status, and its stage. This analysis includes a wide variety of human cancers and a number of human sample types including tissue, plasma, serum, and urine.

Matrix metalloproteinases as novel biomarkers and potential therapeutic targets in human cancer

The matrix metalloproteinase (MMP) family of enzymes is comprised of critically important extracellular matrix remodeling proteases whose activity has been implicated in a number of key normal and pathologic processes. The latter include tumor growth, progression, and metastasis as well as the dysregulated angiogenesis that is associated with these events. As a result, these proteases have come to represent important therapeutic and diagnostic targets for the treatment and detection of human cancers. In this review, we summarize the literature that establishes these enzymes as important clinical targets, discuss the complexity surrounding their choice as such, and chronicle the development strategies and outcomes of their clinical testing to date. The status of the MMP inhibitors currently in US Food and Drug Administration approved clinical trials is presented and reviewed. We also discuss the more recent and successful targeting of this enzyme family as diagnostic and prognostic predictors of human cancer, its status, and its stage. This analysis includes a wide variety of human cancers and a number of human sample types including tissue, plasma, serum, and urine.

Cell Guidance by 3D-Gradients in Hydrogel Matrices: Importance for Biomedical Applications

Concentration gradients of soluble and matrix-bound guidance cues in the extracellular matrix direct cell growth in native tissues and are of great interest for design of biomedical scaffolds and on implant surfaces. The focus of this review is to demonstrate the importance of gradient guidance for cells as it would be desirable to direct cell growth onto/into biomedical devices. Many studies have been described that illustrate the production and characterization of surface gradients, but three dimensional (3D)-gradients that direct cellular behavior are not well investigated. Hydrogels are considered as synthetic replacements for native extracellular matrices as they share key functions such as 2D- or 3D-solid support, fibrous structure, gas- and nutrition permeability and allow storage and release of biologically active molecules. Therefore this review focuses on current studies that try to implement soluble or covalently-attached gradients of growth factors, cytokines or adhesion sequences into 3D-hydrogel matrices in order to control cell growth, orientation and migration towards a target. Such gradient architectures are especially desirable for wound healing purposes, where defined cell populations need to be recruited from the blood stream and out of the adjacent tissue, in critical bone defects, for vascular implants or neuronal guidance structures where defined cell populations should be guided by appropriate signals to reach their proper positions or target tissues in order to accomplish functional repair.

Collagen I regulates matrix metalloproteinase-2 activation in osteosarcoma cells independent of S100A4

This work investigates the effect of cell-collagen I interactions on the synthesis and activation of MMP-2, as well as synthesis of MT1-MMP and TIMP-1, by using an in vitro model with 3D fibrillar and 2D monomeric collagen. In order to reveal whether the metastasis-associated protein S100A4 can influence the cell's response to the two forms of collagen, osteosarcoma cell lines with high and low endogenous levels of S100A4 were used. Attachment of osteosarcoma cells to 3D fibrillar and 2D monomeric collagen resulted in opposite effects on MMP-2 activation. Attachment to 3D fibrillar collagen decreased activation of proMMP-2, with a corresponding reduction in MT1-MMP. By contrast, attachment to monomeric collagen increased the amount of fully active MMP-2. This was caused by a reduction in TIMP-1 levels when cells were attached to monomeric 2D collagen. The effect of collagen on proMMP-2 activation was independent of endogenous S100A4 levels, whereas synthesis of TIMP-1 was dependent on S100A4. When cells were attached to monomeric collagen, cells with a high level of S100A4 showed a greater reduction in the synthesis of TIMP-1 than did those with a low level of S100A4. Taken together, this study shows that synthesis and activation of MMP-2 is affected by interactions between osteosarcoma cells and collagen I in both fibrillar and monomeric form.

Matrix metalloproteinase-2 inhibitors from Clinopodium chinense var. parviflorum

From the aerial parts of Clinopodium chinense var. parviflorum, nine new phenylpropanoids, clinopodic acids A-I (2-10), were isolated together with a known phenylpropanoid, rosmarinic acid (1). The structures of these new compounds were elucidated on the basis of spectroscopic analysis. Clinopodic acid C (4) showed MMP-2 inhibitory activity (IC(50) 3.26 microM).

Skp2 overexpression increases the expression of MMP-2 and MMP-9 and invasion of lung cancer cells

Skp2 is one of the components of the E3 ubiquitin ligase which is required for the degradation of tumor suppressor p27. Overexpression of this oncogene is frequently found in human cancers and has been shown to be associated with poor prognosis. In addition to induce p27 degradation and enhance cellular proliferation, Skp2 also plays a role in promoting tumor metastasis. However, the underlying mechanism is unclear. In this study, we established Skp2-overexpressing stable transfectants from A549 human lung cancer cells. We found that these stable transfectants exhibited increased migratory and invasive abilities. In addition, expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 was up-regulated. Enzymatic assay and gelatin zymography confirmed the increase of MMP-2 and MMP-9 activity and neutralization of these two MMPs by antibodies reduced cell invasion. Our results also revealed that Sp1 was involved in the induction of MMP-2 and MMP-9 by Skp2 because treatment of mithramycin or knockdown of Sp1 by small interference RNA attenuated their expressions. Collectively, we provide the first evidence that up-regulation of MMP-2 and MMP-9 is one of the mechanisms by which Skp2 promotes cell invasion.

Identification of specific hemopexin-like domain residues that facilitate matrix metalloproteinase collagenolytic activity

Collagen serves as a structural scaffold and a barrier between tissues, and thus collagen catabolism (collagenolysis) is required to be a tightly regulated process in normal physiology. In turn, the destruction or damage of collagen during pathological states plays a role in tumor growth and invasion, cartilage degradation, or atherosclerotic plaque formation and rupture. Several members of the matrix metalloproteinase (MMP) family catalyze the hydrolysis of collagen triple helical structure. This study has utilized triple helical peptide (THP) substrates and inhibitors to dissect MMP-1 collagenolytic behavior. Analysis of MMP-1/THP interactions by hydrogen/deuterium exchange mass spectrometry followed by evaluation of wild type and mutant MMP-1 kinetics led to the identification of three noncatalytic regions in MMP-1 (residues 285-295, 302-316, and 437-457) and two specific residues (Ile-290 and Arg-291) that participate in collagenolysis. Ile-290 and Arg-291 contribute to recognition of triple helical structure and facilitate both the binding and catalysis of the triple helix. Evidence from this study and prior studies indicates that the MMP-1 catalytic and hemopexin-like domains collaborate in collagen catabolism by properly aligning the triple helix and coupling conformational states to facilitate hydrolysis. This study is the first to document the roles of specific residues within the MMP-1 hemopexin-like domain in substrate binding and turnover. Noncatalytic sites, such as those identified here, can ultimately be utilized to create THP inhibitors that target MMPs implicated in disease progression while sparing proteases with host-beneficial functions.

A protease inhibitor discovery method using fluorescence correlation spectroscopy with position-specific labeled protein substrates

We developed novel substrates for protease activity evaluation by fluorescence correlation spectroscopy (FCS). Substrates were labeled in a position-specific manner with a fluorophore near the N terminus and included a C-terminal, 30 kDa, highly soluble protein (elongation factor Ts [EF-Ts]). The C-terminal protein enhanced the substrate peptide solubility and increased the molecular weight, enabling sensitive detection by FCS. Using the labeled substrates, caspase-3 and matrix metalloproteinase-9 (MMP-9) activities were confirmed by FCS. To demonstrate the suitability of this FCS-based assay for high-throughput screening, we screened various chemical compounds for MMP-9 inhibitors. The screening results confirmed the inhibitory activity of one compound and also revealed another potential MMP-9 inhibitor. Thus, this combination of position-specific labeled protein substrates and FCS may serve as a useful tool for evaluating activities of various proteases and for protease inhibitor screening.

Matrix metalloproteinases: fold and function of their catalytic domains

Matrix metalloproteinases (MMPs) are zinc-dependent protein and peptide hydrolases. They have been almost exclusively studied in vertebrates and 23 paralogs are present in humans. They are widely involved in metabolism regulation through both extensive protein degradation and selective peptide-bond hydrolysis. If MMPs are not subjected to exquisite spatial and temporal control, they become destructive, which can lead to pathologies such as arthritis, inflammation, and cancer. The main therapeutic strategy to combat the dysregulation of MMPs is the design of drugs to target their catalytic domains, for which purpose detailed structural knowledge is essential. The catalytic domains of 13 MMPs have been structurally analyzed so far and they belong to the "metzincin" clan of metalloendopeptidases. These compact, spherical, approximately 165-residue molecules are divided by a shallow substrate-binding crevice into an upper and a lower sub-domain. The molecules have an extended zinc-binding motif, HEXXHXXGXXH, which contains three zinc-binding histidines and a glutamate that acts as a general base/acid during catalysis. In addition, a conserved methionine lying within a "Met-turn" provides a hydrophobic base for the zinc-binding site. Further earmarks of MMPs are three alpha-helices and a five-stranded beta-sheet, as well as at least two calcium sites and a second zinc site with structural functions. Most MMPs are secreted as inactive zymogens with an N-terminal approximately 80-residue pro-domain, which folds into a three-helix globular domain and inhibits the catalytic zinc through a cysteine imbedded in a conserved motif, PRCGXPD. Removal of the pro-domain enables access of a catalytic solvent molecule and substrate molecules to the active-site cleft, which harbors a hydrophobic S(1')-pocket as main determinant of specificity. Together with the catalytic zinc ion, this pocket has been targeted since the onset of drug development against MMPs. However, the inability of first- and second-generation inhibitors to distinguish between different MMPs led to failures in clinical trials. More recent approaches have produced highly specific inhibitors to tackle selected MMPs, thus anticipating the development of more successful drugs in the near future. Further strategies should include the detailed structural characterization of the remaining ten MMPs to assist in achieving higher drug selectivity. In this review, we discuss the general architecture of MMP catalytic domains and its implication in function, zymogenic activation, and drug design.

The effect of a hydroxamic acid-containing polymer on active matrix metalloproteinases

Matrix metalloproteinase (MMP) sequestering polymer microspheres were prepared by a post-polymerization hydroxamic acid derivatization of poly(methyl methacrylate-co-methacrylic acid). The microspheres were designed to selectively bind MMPs from solutions on contact through a direct interaction between the polymer-bound hydroxamic acid groups and the characteristic catalytic site zinc atom common to all MMPs. MMP activity assays showed that the hydroxamic acid microspheres reduce MMP activity on contact in a time and concentration-dependent fashion. This effect was observed for several MMP subclasses (MMP-2, -3, -8 and -13) suggesting that the microspheres possess a broad-spectrum MMP binding capacity. However, inactive pro-forms of MMPs showed little binding affinity for the microspheres indicating that the interaction was dependent on MMP activation. The preferential binding of active MMPs was confirmed by MMP-3 and MMP-8 activation studies, which demonstrated significant increases in microsphere binding on activation. The MMP sequestering effect of the microspheres was also demonstrated in a physiologically relevant solution (human chronic wound fluid extract) indicating that the binding interaction was effective in a multi-component, competitive adsorption environment. Thus, the hydroxamic acid-containing microspheres may find use as localized, broad-spectrum MMP inhibitors for the treatment of a number of disease conditions characterized by elevated MMP activity.

Matrix metalloproteinase inhibitors (MMPIs) from marine natural products: the current situation and future prospects

Matrix metalloproteinases (MMPs) are a family of more than twenty five secreted and membrane-bound zinc-endopeptidases which can degrade extracellular matrix (ECM) components. They also play important roles in a variety of biological and pathological processes. Matrix metalloproteinase inhibitors (MMPIs) have been identified as potential therapeutic candidates for metastasis, arthritis, chronic inflammation and wrinkle formation. Up to present, more than 20,000 new compounds have been isolated from marine organisms, where considerable numbers of these naturally occurring derivatives are developed as potential candidates for pharmaceutical application. Eventhough the quantity of marine derived MMPIs is less when compare with the MMPIs derived from terrestrial materials, huge potential for bioactivity of these marine derived MMPIs has lead to large number of researches. Saccharoids, flavonoids and polyphones, fatty acids are the most important groups of MMPIs derived from marine natural products. In this review we focus on the progress of MMPIs from marine natural products.

Matrix metalloproteinase inhibitors (MMPIs) from marine natural products: the current situation and future prospects

Matrix metalloproteinases (MMPs) are a family of more than twenty five secreted and membrane-bound zinc-endopeptidases which can degrade extracellular matrix (ECM) components. They also play important roles in a variety of biological and pathological processes. Matrix metalloproteinase inhibitors (MMPIs) have been identified as potential therapeutic candidates for metastasis, arthritis, chronic inflammation and wrinkle formation. Up to present, more than 20,000 new compounds have been isolated from marine organisms, where considerable numbers of these naturally occurring derivatives are developed as potential candidates for pharmaceutical application. Eventhough the quantity of marine derived MMPIs is less when compare with the MMPIs derived from terrestrial materials, huge potential for bioactivity of these marine derived MMPIs has lead to large number of researches. Saccharoids, flavonoids and polyphones, fatty acids are the most important groups of MMPIs derived from marine natural products. In this review we focus on the progress of MMPIs from marine natural products.

Roles of galectin-9 in the development of experimental allergic conjunctivitis in mice

BACKGROUND

Galectin-9 was recently identified as a ligand for Tim-3, which negatively regulates Th1 cells. Here, we investigated whether administration of anti-galectin-9 antibodies (Abs) affects the development of murine experimental allergic conjunctivitis (EC), a Th2-mediated disease.

METHODS

EC was induced in BALB/c mice by active immunization with ragweed (RW) followed by RW challenge in eye drops. Normal rat IgG (nrIgG) or anti-galectin-9 Ab was injected intraperitoneally into the mice either during the induction phase treatment or effector phase treatment. Alternatively, Abs were injected into the subconjunctival space during the effector phase. To evaluate in vitro effects of anti-galectin-9 Abs, splenocytes from RW-sensitized mice were cultured in vitro with RW in the presence of nrIgG or anti-galectin-9 Abs. To induce EC, these splenocytes were transferred into naïve BALB/c mice followed by RW challenge.

RESULTS

Treatment with anti-galectin-9 Abs in vivo during either the induction or effector phase did not significantly affect the severity of EC. However, when the splenocytes from RW-primed mice treated with anti-galectin-9 Abs during the induction phase were stimulated in vitro and adoptively transferred into naïve recipients, they induced significantly severer EC. In contrast, when RW-primed splenocytes were restimulated in vitro with RW in the presence of anti-galectin-9 Abs and then adoptively transferred, they induced less severe EC and produced significantly less IL-5 and IL-13 and more IFN-gamma compared to nrIgG-treated control splenocytes.

CONCLUSIONS

These observations may reflect the fact that galectin-9 not only regulates T-cell function, it is also involved in many other biological functions.