New thiol and sulfodiimine metalloproteinase inhibitors and their effect on human microvascular endothelial cell growth

A new synthetic matrix metalloproteinase inhibitor reduces human mesenchymal stem cell adipogenesis

Development of adipose tissue requires the differentiation of less specialized cells, such as human mesenchymal stem cells (hMSCs), into adipocytes. Since matrix metalloproteinases (MMPs) play critical roles in the cell differentiation process, we conducted investigations to determine if a novel mercaptosulfonamide-based MMP inhibitor (MMPI), YHJ-7-52, could affect hMSC adipogenic differentiation and lipid accumulation. Enzyme inhibition assays, adipogenic differentiation experiments, and quantitative PCR methods were employed to characterize this inhibitor and determine its effect upon adipogenesis. YHJ-7-52 reduced lipid accumulation in differentiated cells by comparable amounts as a potent hydroxamate MMPI, GM6001. However, YHJ-7-82, a non-inhibitory structural analog of YHJ-7-52, in which the zinc-binding thiol group is replaced by a hydroxyl group, had no effect on adipogenesis. The two MMPIs (YHJ-7-52 and GM6001) were also as effective in reducing lipid accumulation in differentiated cells as T0070907, an antagonist of peroxisome-proliferator activated receptor gamma (PPAR-gamma), at a similar concentration. PPAR-gamma is a typical adipogenic marker and a key regulatory protein for the transition of preadiopocyte to adipocyte. Moreover, MMP inhibition was able to suppress lipid accumulation in cells co-treated with Troglitazone, a PPAR-gamma agonist. Our results indicate that MMP inhibitors may be used as molecular tools for adipogenesis and obesity treatment research.

Matrix metalloproteinase inhibitors based on the 3-mercaptopyrrolidine core

New series of pyrrolidine mercaptosulfide, 2-mercaptocyclopentane arylsulfonamide, and 3-mercapto-4-arylsulfonamidopyrrolidine matrix metalloproteinase inhibitors (MMPIs) were designed, synthesized, and evaluated. Exhibiting unique properties over other MMPIs (e.g., hydroxamates), these newly reported compounds are capable of modulating activities of several MMPs in the low nanomolar range, including MMP-2 (~2 to 50 nM), MMP-13 (~2 to 50 nM), and MMP-14 (~4 to 60 nM). Additionally these compounds are selective to intermediate- and deep-pocket MMPs but not shallow-pocketed MMPs (e.g., MMP-1, ~850 to >50,000 nM; MMP-7, ~4000 to >25,000 nM). Our previous work with the mercaptosulfide functionality attached to both cyclopentane and pyrrolidine frameworks demonstrated that the cis-(3S,4R)-stereochemistry was optimal for all of the MMPs tested. However, in our newest compounds an interesting shift of preference to the trans form of the mercaptosulfonamides was observed with increased oxidative stability and biological compatibility. We also report several kinetic and biological characteristics showing that these compounds may be used to probe the mechanistic activities of MMPs in disease.

Structural insights into the binding of MMP9 inhibitors

Matrix Metalloproteinase are family of enzymes responsible for degradation of extracellular matrix. MMP9 (gelatinase B) is one of the common matrix metalloproteinase that is associated with tissue destruction in a number of disease states such as rheumatoid arthiritis, fibrotic lung disease, dilated cardiomyopathy, as well as cancer invasion and metastasis. Recent study demonstrates that increased expression of MMP9 results in augmentation of myopathy with increased inflammation and fibernecrosis. Previous studies do not provide any conclusive information related to structural specificity of MMP9 inhibitors towards its active site, but with the availability of experimental structures it is now possible to study the structural specificity of MMP9 inhibitors. In light of availability of this information, we have applied docking and molecular dynamics approach to study the binding of inhibitors to the active site of MMP9. Three categories of inhibitor consisting of sulfonamide hydroxamate, thioester, and carboxylic moieties as zinc binding groups (ZBG) were chosen in the present study. Our docking results demonstrate that thioester based zinc binding group gives favourable docking scores as compared to other two groups. Molecular Dynamics simulations further reveal that tight binding conformation for thioester group has high specificity for MMP9 active site. Our study provides valuable insights on inhibitor specificity of MMP9 which provides valuable hints for future design of potent inhibitors and drugs.

Inhibitors of human collagenase, MMP1

Different common drugs (Meloxicam, Tenoxicam and Piroxicam, and sodium alendronate) were tested both experimental and theoretically as inhibitors of interstitial human collagenase, also known as matrix metalloproteinase 1 (MMP-1). The in vitro collagenase activity, alone and in the presence of inhibitors, was quantified by the reaction with a fluorescent synthetic substrate and measuring the change of emission. Collagenase-inhibitor interaction was studied theoretically by computational calculations. Three among the four tested substances showed moderate inhibiting activity against the human collagenase.

Inhibition of enzyme activity of and cell-mediated substrate cleavage by membrane type 1 matrix metalloproteinase by newly developed mercaptosulphide inhibitors

MT1-MMP (membrane type 1 matrix metalloproteinase, or MMP-14) is a key enzyme in molecular carcinogenesis, tumour-cell growth, invasion and angiogenesis. Novel and potent MMP inhibitors with a mercaptosulphide zinc-binding functionality have been designed and synthesized, and tested against human MT1-MMP and other MMPs. Binding to the MT1-MMP active site was verified by the competitive-inhibition mechanism and stereochemical requirements. MT1-MMP preferred deep P1' substituents, such as homophenylalanine instead of phenylalanine. Novel inhibitors with a non-prime phthalimido substituent had K(i) values in the low-nanomolar range; the most potent of these inhibitors was tested and found to be stable against air-oxidation in calf serum for at least 2 days. To illustrate the molecular interactions of the inhibitor-enzyme complex, theoretical docking of the inhibitors into the active site of MT1-MMP and molecular minimization of the complex were performed. In addition to maintaining the substrate-specificity pocket (S1' site) van der Waals interactions, the P1' position side chain may be critical for the peptide-backbone hydrogen-bonding network. To test the inhibition of cell-mediated substrate cleavage, two human cancer-cell culture models were used. Two of the most potent inhibitors tested reached the target enzyme and effectively inhibited activation of proMMP-2 by endogenous MT1-MMP produced by HT1080 human fibrosarcoma cells, and blocked fibronectin degradation by prostate cancer LNCaP cells stably transfected with MT1-MMP. These results provide a model for mercaptosulphide inhibitor binding to MT1-MMP that may aid in the design of more potent and selective inhibitors for MT1-MMP.

Catalytic- and ecto-domains of membrane type 1-matrix metalloproteinase have similar inhibition profiles but distinct endopeptidase activities

Membrane type 1-matrix metalloproteinase (MT1-MMP/MMP-14) is a major collagenolytic enzyme that plays a vital role in development and morphogenesis. To elucidate further the structure-function relationship between the human MT1-MMP active site and the influence of the haemopexin domain on catalysis, substrate specificity and inhibition kinetics of the cdMT1-MMP (catalytic domain of MT1-MMP) and the ecto domain DeltaTM-MT1-MMP (transmembrane-domain-deleted MT1-MMP) were compared. For substrate 1 [Mca-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH(2), where Mca stands for (7-methoxycoumarin-4-yl)acetyl- and Dpa for N -3-(2,4-dinitrophenyl)-L-2,3-diaminopropionyl], the activation energy E (a) was determined to be 11.2 and 12.2 kcal/mol (1 cal=4.184 J) for cdMT1-MMP and DeltaTM-MT1-MMP respectively, which is consistent with k (cat)/ K (M) values of 7.37 and 1.46x10(4) M(-1).s(-1). The k (cat)/ K (M) values for a series of similar single-stranded peptide substrates were determined and found to correlate with a slope of 0.17 for the two enzyme forms. A triple-helical peptide substrate was predicted to have a k (cat)/ K (M) of 0.87x10(4) M(-1).s(-1) for DeltaTM-MT1-MMP based on the value for cdMT1-MMP of 5.12x10(4) M(-1).s(-1); however, the actual value was determined to be 2.5-fold higher, i.e. 2.18x10(4) M(-1).s(-1). These results suggest that cdMT1-MMP is catalytically more efficient towards small peptide substrates than DeltaTM-MT1-MMP and the haemopexin domain of MT1-MMP facilitates the hydrolysis of triple-helical substrates. Diastereomeric inhibitor pairs were utilized to probe further binding similarities at the active site. Ratios of K (i) values for the inhibitor pairs were found to correlate between the enzyme forms with a slope of 1.03, suggesting that the haemopexin domain does not significantly modify the enzyme active-site structure.

The Intermediate S1′ Pocket of the Endometase/Matrilysin-2 Active Site Revealed by Enzyme Inhibition Kinetic Studies, Protein Sequence Analyses, and Homology Modeling

Human matrix metalloproteinase-26 (MMP-26/endometase/matrilysin-2) is a newly identified MMP and its structure has not been reported. The enzyme active site S1' pocket in MMPs is a well defined substrate P1' amino acid residue-binding site with variable depth. To explore MMP-26 active site structure-activity, a series of new potent mercaptosulfide MMP inhibitors (MMPIs) with Leu or homophenylalanine (Homophe) side chains at the P1' site were selected. The Homephe side chain is designed to probe deep S1' pocket MMPs. These inhibitors were tested against MMP-26 and several MMPs with known x-ray crystal structures to distinguish shallow, intermediate, and deep S1' pocket characteristics. MMP-26 has an inhibition profile most similar to those of MMPs with intermediate S1' pockets. Investigations with hydroxamate MMPIs, including those designed for deep pocket MMPs, also indicated the presence of an intermediate pocket. Protein sequence analysis and homology modeling further verified that MMP-26 has an intermediate S1' pocket formed by Leu-204, His-208, and Tyr-230. Moreover, residue 233 may influence the depth of an MMP S1' pocket. The residue at the equivalent position of MMP-26 residue 233 is hydrophilic in intermediate-pocket MMPs (e.g. MMP-2, -8, and -9) and hydrophobic in deep-pocket MMPs (e.g. MMP-3, -12, and -14). MMP-26 contains a His-233 that renders the S1' pocket to an intermediate size. This study suggests that MMPIs, protein sequence analyses, and molecular modeling are useful tools to understand structure-activity relationships and provides new insight for rational inhibitor design that may distinguish MMPs with deep versus intermediate S1' pockets.

Activation of pro-gelatinase B by endometase/matrilysin-2 promotes invasion of human prostate cancer cells

This work has explored a putative biochemical mechanism by which endometase/matrilysin-2/matrix metalloproteinase-26 (MMP-26) may promote human prostate cancer cell invasion. Here, we showed that the levels of MMP-26 protein in human prostate carcinomas from multiple patients were significantly higher than those in prostatitis, benign prostate hyperplasia, and normal prostate glandular tissues. The role of MMP-26 in prostate cancer progression is unknown. MMP-26 was capable of activating pro-MMP-9 by cleavage at the Ala(93)-Met(94) site of the prepro-enzyme. This activation proceeded in a time- and dose-dependent manner, facilitating the efficient cleavage of fibronectin by MMP-9. The activated MMP-9 products generated by MMP-26 appeared more stable than those cleaved by MMP-7 under the conditions tested. To investigate the contribution of MMP-26 to cancer cell invasion via the activation of MMP-9, highly invasive and metastatic human prostate carcinoma cells, androgen-repressed prostate cancer (ARCaP) cells were selected as a working model. ARCaP cells express both MMP-26 and MMP-9. Specific anti-MMP-26 and anti-MMP-9 functional blocking antibodies both reduced the invasiveness of ARCaP cells across fibronectin or type IV collagen. Furthermore, the introduction of MMP-26 antisense cDNA into ARCaP cells significantly reduced the MMP-26 protein level in these cells and strongly suppressed the invasiveness of ARCaP cells. Double immunofluorescence staining and confocal laser scanning microscopic images revealed that MMP-26 and MMP-9 were co-localized in parental and MMP-26 sense-transfected ARCaP cells. Moreover, MMP-26 and MMP-9 proteins were both expressed in the same human prostate carcinoma tissue samples examined. These results indicate that MMP-26 may be a physiological and pathological activator of pro-MMP-9.

Design, synthesis, and characterization of potent, slow-binding inhibitors that are selective for gelatinases

Gelatinases have been shown to play a key role in angiogenesis and tumor metastasis. Small molecular weight synthetic inhibitors for these enzymes are highly sought for potential use as anti-metastatic agents. Virtually all of the known inhibitors of matrix metalloproteinases (MMPs) are broad spectrum. We report herein the synthesis and kinetic characterization of two compounds, 4-(4-phenoxyphenylsulfonyl)butane-1,2-dithiol (compound 1) and 5-(4-phenoxyphenylsulfonyl)pentane-1,2-dithiol (compound 2), that are potent and selective gelatinase inhibitors. These compounds are slow, tight-binding inhibitors of gelatinases (MMP-2 and MMP-9) with K(i) values in the nanomolar range. In contrast, competitive inhibition of the catalytic domain of membrane-type 1 metalloproteinase (MMP-14(cat)) with comparable K(i) values (K(i) approximately 200 nm) was observed. Binding to stromelysin (MMP-3) was substantially weaker, with K(i) values in the micromolar range (K(i) approximately 10 microm). No binding to matrilysin (MMP-7) and collagenase 1 (MMP-1) was detected at inhibitor concentrations up to 60 microm. We have previously shown that synthetic MMP inhibitors work synergistically with TIMP-2 in the promotion of pro-MMP-2 activation by MT1-MMP in a process that depends on the affinity of the inhibitor toward MT1-MMP. It is shown herein that the dithiols are significantly less efficient (>100-fold) than marimastat, a broad-spectrum MMP inhibitor, in enhancing pro-MMP-2 activation in cells infected to express MT1-MMP, consistent with the lower affinity of the dithiols toward MT1-MMP. Thus, in contrast to broad-spectrum MMP inhibitors, the dithiols are less likely to promote MT1-MMP-dependent pro-MMP-2 activation in the presence of TIMP-2, while maintaining their ability to inhibit active MMP-2 effectively.

Identification of novel, functional genetic variants in the human matrix metalloproteinase-2 gene: role of Sp1 in allele-specific transcriptional regulation

Matrix metalloproteinase-2 (MMP-2) is an enzyme with proteolytic activity against matrix and nonmatrix proteins, particularly basement membrane constituents. Thus, any naturally occurring genetic variants that directly affect gene expression and/or protein function would be expected to impact on progression of pathological processes involving tissue remodeling. We scanned a 2-kilobase pair promoter region and all 13 exons of the human MMP-2 gene, from a panel of 32 individuals, and we identified the position, nature, and relative allele frequencies of 15 variant loci as follows: 6 in the promoter, 1 in the 5'-untranslated region, 6 in the coding region, 1 in intronic sequence, and 1 in the 3'-untranslated region. The majority of coding region polymorphisms resulted in synonymous substitutions, whereas three promoter variants (at -1306, -790, and +220) mapped onto cis-acting elements. We functionally characterized all promoter variants by transient transfection experiments with 293, RAW264.7, and A10 cells. The common C --> T transition at -1306 (allele frequency 0.26), which disrupts an Sp1-type promoter site (CCACC box), displayed a strikingly lower promoter activity with the T allele. Electrophoretic mobility shift assays confirmed that these differences in allelic expression were attributable to abolition of Sp1 binding. These data suggest that this common functional genetic variant influences MMP-2 gene transcription in an allele-specific manner and is therefore an important candidate to test for association in a wide spectrum of pathologies for which a role for MMP-2 is implicated, including atherogenesis and tumor invasion and metastasis.