Therapeutic developments in matrix metalloproteinase inhibition

Biomolecular basis of matrix metallo proteinase-9 activity

Matrix metalloproteinases (MMPs) are structurally related endopeptidases. They are also known as metzincins due to their interaction with zinc ion of the conserved methionine (Met) at the active site. MMPs play an important role in physiological and signaling processes of wound healing, bone resorption and angiogenesis. The structure of MMPs consists of signal peptide, propeptide, catalytic domain, hinge region and hemopexin-like domain. MMP-9 shares high structural and functional similarities with MMP-2, therefore designing selective MMP-9 inhibitors (MMPIs) is challenging. The selectivity can be achieved by targeting S2 subsite of MMP-9 that is having difference with MMP-2. Further, targeting its exosite and protein disulfide isomerase may also provide selective MMPIs. The review highlights the molecular features and basis of MMP-9 enzyme action. The MMPIs reported in the recent years have also been included.

Heteroarylimino-4-thiazolidinones as inhibitors of cartilage degradation

2-Benzo[d]thiazolyl- and 2-benzo[d]isothiazolyl-imino-5-benzylidene-4-thiazolidinone derivatives were investigated as potential metalloproteinases (MMPs) inhibitors and evaluated for their antidegenerative activity on human chondrocyte cultures stimulated by IL-1β, using an experimental model that reproduces the mechanisms involved in osteoarthritic (OA) diseases. Cell viability, the amount of glycosaminoglycans (GAGs) and the production of nitric oxide (NO) were measured. The most potent compound, 5-(4-methoxy-benzylidene)-2-(benzo[d]isothiazol-3-ylimino)-thiazolidin-4-one (4b), a MMP-13 inhibitor at nanomolar concentration (IC(50)=0.036 μM), could be considered as a lead compound for the development of novel clinical agents, inhibitors of cartilage degradation, for the treatment of OA.

Genetic polymorphisms of matrix metalloproteinases and their inhibitors in potentially malignant and malignant lesions of the head and neck

Matrix metalloproteinases (MMPs) are a family of zinc-dependent proteinases that are capable of cleaving all extra cellular matrix (ECM) substrates. Degradation of matrix is a key event in progression, invasion and metastasis of potentially malignant and malignant lesions of the head and neck. It might have an important polymorphic association at the promoter regions of several MMPs such as MMP-1 (-1607 1G/2G), MMP-2 (-1306 C/T), MMP-3 (-1171 5A/6A), MMP-9 (-1562 C/T) and TIMP-2 (-418 G/C or C/C). Tissue inhibitors of metalloproteinases (TIMPs) are naturally occurring inhibitors of MMPs, which inhibit the activity of MMPs and control the breakdown of ECM. Currently, many MMP inhibitors (MMPIs) are under development for treating different malignancies. Useful markers associated with molecular aggressiveness might have a role in prognostication of malignancies and to better recognize patient groups that need more antagonistic treatment options. Furthermore, the introduction of novel prognostic markers may also promote exclusively new treatment possibilities, and there is an obvious need to identify markers that could be used as selection criteria for novel therapies. The objective of this review is to discuss the molecular functions and polymorphic association of MMPs and TIMPs and the possible therapeutic aspects of these proteinases in potentially malignant and malignant head and neck lesions. So far, no promising drug target therapy has been developed for MMPs in the lesions of this region. In conclusion, further research is required for the development of their potential diagnostic and therapeutic possibilities.

Carbamoylphosphonate matrix metalloproteinase inhibitors 6: cis-2-aminocyclohexylcarbamoylphosphonic acid, a novel orally active antimetastatic matrix metalloproteinase-2 selective inhibitor--synthesis and pharmacodynamic and pharmacokinetic analysis

cis-2-Aminocyclohexylcarbamoylphosphonic acid ( cis-ACCP) was evaluated in vitro and in two in vivo cancer metastasis models. It reduced metastasis formation in mice by approximately 90% when administered by a repetitive once daily dosing regimen of 50 mg/kg via oral or intraperitoneal routes and was nontoxic up to 500 mg/kg, following intraperitoneal administration daily for two weeks. Pharmacokinetic investigation of cis-ACCP in rats revealed distribution restricted into the extracellular fluid, which is the site of action for the antimetastatic activity and rapid elimination ( t 1/2 approximately 19 min) from blood. Sustained and prolonged absorption ( t 1/2 approximately 126 min) occurred via paracellular mechanism along the small and large intestine with overall bioavailability of 0.3%. The in vivo concentrations of cis-ACCP in the blood in rats was above the minimal concentration for antimetastatic/MMP-inhibitory activity, thus explaining the prolonged action following once daily administration. Finally, 84% of the intravenously administered cis-ACCP to rats was excreted intact in the urine.

Therapeutic potential of sulfamides as enzyme inhibitors

Sulfamide, a quite simple molecule incorporating the sulfonamide functionality, widely used by medicinal chemists for the design of a host of biologically active derivatives with pharmacological applications, may give rise to at least five types of derivatives, by substituting one to four hydrogen atoms present in it, which show specific biological activities. Recently, some of these compounds started to be exploited for the design of many types of therapeutic agents. Among the enzymes for which sulfamide-based inhibitors were designed, are the carbonic anhydrases (CAs), a large number of proteases belonging to the aspartic protease (HIV-1 protease, gamma-secretase), serine protease (elastase, chymase, tryptase, and thrombin among others), and metalloprotease (carboxypeptidase A (CPA) and matrix metalloproteinases (MMP)) families. Some steroid sulfatase (STS) and protein tyrosine phosphatase inhibitors belonging to the sulfamide class of derivatives have also been reported. In all these compounds, many of which show low nanomolar affinity for the target enzymes for which they have been designed, the free or substituted sulfamide moiety plays important roles for the binding of the inhibitor to the active site cavity, either by directly coordinating to a metal ion found in some metalloenzymes (CAs, CPA, STS), usually by means of one of the nitrogen atoms present in the sulfamide motif, or as in the case of the cyclic sulfamides acting as HIV protease inhibitors, interacting with the catalytically critical aspartic acid residues of the active site by means of an oxygen atom belonging to the HN-SO2-NH motif, which substitutes a catalytically essential water molecule. In other cases, the sulfamide moiety is important for inducing desired physico-chemical properties to the drug-like compounds incorporating it, such as enhanced water solubility, better bioavailability, etc., because of the intrinsic properties of this highly polarized moiety when attached to an organic scaffold. This interesting motif is thus of great value for the design of pharmacological agents with a lot of applications.

A novel strategy for designing specific gelatinase A inhibitors: potential use to control tumor progression

Matrix metalloproteases (MMPs) are zinc endopeptidases deeply implicated in tumor progression. MMP inhibitors are attractive potential anti-cancer agent. Unfortunately, until now, clinical trials remain disappointing, that could be the result of a lack of selectivity. We propose second generation selective MMPs, directed toward gelatinase A (MMP-2), based on a non-hydroxamate Zn-ligand grafted on the galardin (ilomastat) skeleton.

Genetic determinants of arterial calcification associated with atherosclerosis

Increasing research interest has focused on arterial calcification in the setting of atherosclerosis. Many features of atherosclerosis-related calcification provide useful clinical information. For example, calcium mineral deposits frequently form in atherosclerotic plaque, and intimal arterial calcification can be used as a surrogate marker for atherosclerosis; also, calcium deposits are readily and noninvasively quantified, which is useful because greater amounts of coronary calcification predict a higher risk of myocardial infarction and death. Several mechanisms leading to calcification associated with atherosclerosis have been proposed; however, no direct testing of proposed mechanisms has yet been reported. Studies in genetically altered animals and in humans have shed light on potential genetic determinants, which in turn could form the basis for a more comprehensive understanding of the factors affecting calcification within plaque and the associated pathobiologic implications. We review proposed molecular and cellular mechanisms of atherosclerosis-associated arterial calcification, summarize genetic influences, and suggest areas in which further investigation is needed. Understanding the molecular and genetic determinants of specific structural plaque components such as calcification can provide a solid foundation for the development of novel therapeutic approaches to favorably alter plaque structure and minimize vulnerability to arterial rupture.

Pathophysiology of plaque rupture and the concept of plaque stabilization

Atherosclerotic coronary artery disease is the major cause of death, in men and women, in the United States and in much of the Western world. Atherosclerosis is responsible for coronary heart disease, limb ischemia, and most strokes. Although luminal narrowing by an atherosclerotic plaque and exaggerated or anomalous vasoconstriction contribute to some of the clinical manifestations of atherosclerotic arterial disease, it is the superim-position of a thrombus over an underlying ruptured or eroded plaque that results in the acute coronary syndromes (unstable angina, acute myocardial infarction, and sudden death) that are the most serious clinical manifestations of this disease.

In situ zymography: a molecular pathology technique to localize endogenous protease activity in tissue sections

Proteases play important roles in modulating a wide range of cellular functions, in the regulation of biologic processes, and in the pathogenesis of various diseases. Several molecular techniques are available to identify and characterize proteases in cells and tissues. Most of these techniques do not provide information on the activity of proteases in tissues. In situ zymography (ISZ) is a relatively low-cost technique that uses specific protease substrates to detect and localize specific protease activities in tissue sections. Used in combination with other techniques, ISZ provides data that further our understanding of the role of specific proteases in various pathologic and physiologic conditions. This review describes the general principle of ISZ and highlights the past and future applications of this technique in molecular pathology.

Metalloproteinases: their role in arthritis and potential as therapeutic targets

Irreversible degradation of articular cartilage is a major feature of the arthritides, and its prevention is a therapeutic goal which has been difficult to achieve. Enzymes from the matrix metalloproteinase and ADAMTS (a disintegrin, a metalloproteinase, and thrombospondin motif) families are key mediators of cartilage extracellular matrix destruction. Inhibition of metalloproteinase activity is therefore a conceptually attractive therapeutic strategy, although clinical efficacy has not yet been demonstrated. This review outlines the biology behind metalloproteinases as drug targets in the arthritides, and poses important questions for the future design of such therapies.

Increased expression of membrane type 3-matrix metalloproteinase in human atherosclerotic plaque: role of activated macrophages and inflammatory cytokines

BACKGROUND

Matrix metalloproteinases (MMPs) are thought to play a prominent role in atherogenesis and destabilization of plaque. Pericellularly localized membrane-type (MT)-MMPs activate secreted MMPs. We investigated the hypothesis that MT3-MMP is expressed in human atherosclerotic plaques and is regulated by locally produced inflammatory cytokines and oxidized low-density lipoprotein (Ox-LDL).

METHODS AND RESULTS

Expression and cellular localization of MT3-MMP in normal and atherosclerotic human coronary arteries were examined using specific antibodies. Abundant MT3-MMP expression was noted in medial smooth muscle cells (SMCs) of normal arteries. In atherosclerotic arteries, MT3-MMP expression was observed within complex plaques and colocalized with SMCs and macrophages (Mphi). Cultured human monocyte-derived Mphi constitutively expressed MT3-MMP mRNA and proteolytically active protein, as demonstrated by mRNA analyses, immunoblotting, and gelatin zymography, respectively. Ox-LDL, tumor necrosis factor-alpha, or macrophage colony-stimulating factor caused dose- and time-dependent increases in steady-state levels of MT3-MMP mRNA in cultured Mphi. This correlated with a 2- to 4-fold increase in levels of MT3-MMP immunoreactive protein and enzymatic activity in Mphi membranes. Confocal microscopy and flow cytometry confirmed induction and spatial distribution of MT3-MMP protein from intracellular domains to the Mphi plasma membrane by Ox-LDL, tumor necrosis factor-alpha, or macrophage colony-stimulating factor.

CONCLUSIONS

MT3-MMP is expressed by SMCs and Mphi in human atherosclerotic plaques. Proinflammatory molecules cause a progressive increase in the expression of MT3-MMP in cultured Mphi. Our results suggest a mechanism by which inflammatory molecules could promote Mphi-mediated degradation of extracellular matrix and thereby contribute to plaque destabilization.