Role of matrix metalloproteinase-9 dimers in cell migration: design of inhibitory peptides

Acute- and late-phase matrix metalloproteinase (MMP)-9 activity is comparable in female and male rats after peripheral nerve injury

BACKGROUND

In the peripheral nerve, pro-inflammatory matrix metalloproteinase (MMP)-9 performs essential functions in the acute response to injury. Whether MMP-9 activity contributes to late-phase injury or whether MMP-9 expression or activity after nerve injury is sexually dimorphic remains unknown.

METHODS

Patterns of MMP-9 expression, activity and excretion were assessed in a model of painful peripheral neuropathy, sciatic nerve chronic constriction injury (CCI), in female and male rats. Real-time Taqman RT-PCR for MMP-9 and its endogenous inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1) of nerve samples over a 2-month time course of CCI was followed by gelatin zymography of crude nerve extracts and purified MMP-9 from the extracts using gelatin Sepharose-beads. MMP excretion was determined using protease activity assay of urine in female and male rats with CCI.

RESULTS

The initial upsurge in nerve MMP-9 expression at day 1 post-CCI was superseded more than 100-fold at day 28 post-CCI. The high level of MMP-9 expression in late-phase nerve injury was accompanied by the reduction in TIMP-1 level. The absence of MMP-9 in the normal nerve and the presence of multiple MMP-9 species (the proenzyme, mature enzyme, homodimers, and heterodimers) was observed at day 1 and day 28 post-CCI. The MMP-9 proenzyme and mature enzyme species dominated in the early- and late-phase nerve injury, consistent with the high and low level of TIMP-1 expression, respectively. The elevated nerve MMP-9 levels corresponded to the elevated urinary MMP excretion post-CCI. All of these findings were comparable in female and male rodents.

CONCLUSION

The present study offers the first evidence for the excessive, uninhibited proteolytic MMP-9 activity during late-phase painful peripheral neuropathy and suggests that the pattern of MMP-9 expression, activity, and excretion after peripheral nerve injury is universal in both sexes.

Targeting the Hemopexin-like Domain of Latent Matrix Metalloproteinase-9 (proMMP-9) with a Small Molecule Inhibitor Prevents the Formation of Focal Adhesion Junctions

A lack of target specificity has greatly hindered the success of inhibitor development against matrix metalloproteinases (MMPs) for the treatment of various cancers. The MMP catalytic domains are highly conserved, whereas the hemopexin-like domains of MMPs are unique to each family member. The hemopexin-like domain of MMP-9 enhances cancer cell migration through self-interaction and heterointeractions with cell surface proteins including CD44 and α4β1 integrin. These interactions activate EGFR-MAP kinase dependent signaling that leads to cell migration. In this work, we generated a library of compounds, based on hit molecule N-[4-(difluoromethoxy)phenyl]-2-[(4-oxo-6-propyl-1H-pyrimidin-2-yl)sulfanyl]-acetamide, that target the hemopexin-like domain of MMP-9. We identify N-(4-fluorophenyl)-4-(4-oxo-3,4,5,6,7,8-hexahydroquinazolin-2-ylthio)butanamide, 3c, as a potent lead (K_d = 320 nM) that is specific for binding to the proMMP-9 hemopexin-like domain. We demonstrate that 3c disruption of MMP-9 homodimerization prevents association of proMMP-9 with both α4β1 integrin and CD44 and results in the dissociation of EGFR. This disruption results in decreased phosphorylation of Src and its downstream target proteins focal adhesion kinase (FAK) and paxillin (PAX), which are implicated in promoting tumor cell growth, migration, and invasion. Using a chicken chorioallantoic membrane in vivo assay, we demonstrate that 500 nM 3c blocks cancer cell invasion of the basement membrane and reduces angiogenesis. In conclusion, we present a mechanism of action for 3c whereby targeting the hemopexin domain results in decreased cancer cell migration through simultaneous disruption of α4β1 integrin and EGFR signaling pathways, thereby preventing signaling bypass. Targeting through the hemopexin-like domain is a powerful approach to antimetastatic drug development.

Expression of matrix metalloproteinases in Naegleria fowleri and their role in invasion of the central nervous system

Naegleria fowleri is a free-living amoeba found in freshwater lakes and ponds and is the causative agent of primary amoebic meningoencephalitis (PAM), a rapidly fatal disease of the central nervous system (CNS). PAM occurs when amoebae attach to the nasal epithelium and invade the CNS, a process that involves binding to, and degradation of, extracellular matrix (ECM) components. This degradation is mediated by matrix metalloproteinases (MMPs), enzymes that have been described in other pathogenic protozoa, and that have been linked to their increased motility and invasive capability. These enzymes also are upregulated in tumorigenic cells and have been implicated in metastasis of certain tumours. In the present study, in vitro experiments linked MMPs functionally to the degradation of the ECM. Gelatin zymography demonstrated enzyme activity in N. fowleri whole cell lysates, conditioned media and media collected from invasion assays. Western immunoblotting indicated the presence of the metalloproteinases MMP-2 (gelatinase A), MMP-9 (gelatinase B) and MMP-14 [membrane type-1 matrix metalloproteinase (MT1-MMP)]. Highly virulent mouse-passaged amoebae expressed higher levels of MMPs than weakly virulent axenically grown amoebae. The functional relevance of MMPs in media was indicated through the use of the MMP inhibitor, 1,10-phenanthroline. The collective in vitro results suggest that MMPs play a critical role in vivo in invasion of the CNS and that these enzymes may be amenable targets for limiting PAM.

Establishment of oral squamous cell carcinoma cell line and magnetic bead-based isolation and characterization of its CD90/CD44 subpopulations

In this study, we describe the establishment of the human papillomavirus 18-positive, stage II, grade 1, T2N0M0 head and neck tumor primary cell line derived from oral squamous cell carcinoma of a non-smoking patient by using two different protocols. Furthermore, a preparation of subpopulations derived from this primary cell line according to the cluster of differentiation molecules CD44/CD90 status using magnetic bead-based separation and their characterization was performed. Impedance-based real-time cell analysis, enzyme-linked immunsorbant assay (ELISA), wound-healing assay, flow-cytometry, gene expression analysis, and MTT assay were used to characterize these four subpopulations (CD44+/CD90-, CD44-/CD90-, CD44+/CD90+, CD44-/CD90-). We optimised methodics for establishement of primary cell lines derived from oral squamous cell carcinoma tissue samples and subsequent separation of mesenchymal (CD90+) and epithelial (CD90-) types of tumorous cells. Primary cell line prepared by using trypsin proteolysis was more viable than the one prepared by using collagenase. According to our results, CD90 separation is a necessary step in preparation of permanent tumor-tissue derived cell lines. Based on the wound-healing assay, CD44+ cells exhibited stronger migratory capacity than CD44- subpopulations. CD44+ subpopulations had also significantly higher expression of BIRC5 and SOX2, lower expression of FLT1 and IL6, and higher levels of basal autophagy compared to CD44- subpopulations. Furthermore, co-cultivation experiments revealed that CD44-/CD90+ cells supported growth of epithelial tumor cells (CD44+/CD90-). On the contrary, factors released by CD44+/CD90+ type of cells seem to have rather inhibiting effect. The most cisplatin-resistant subpopulation with the shortest doubling time was CD44-/CD90+, but this subpopulation had a low migratory capacity.

Therapeutic Potential of Matrix Metalloproteinase Inhibition in Breast Cancer

Matrix metalloproteinases (MMPs) are a family of zinc endopeptidases that cleave nearly all components of the extracellular matrix as well as many other soluble and cell-associated proteins. MMPs have been implicated in normal physiological processes, including development, and in the acquisition and progression of the malignant phenotype. Disappointing results from a series of clinical trials testing small molecule, broad spectrum MMP inhibitors as cancer therapeutics led to a re-evaluation of how MMPs function in the tumor microenvironment, and ongoing research continues to reveal that these proteins play complex roles in cancer development and progression. It is now clear that effective targeting of MMPs for therapeutic benefit will require selective inhibition of specific MMPs. Here, we provide an overview of the MMP family and its biological regulators, the tissue inhibitors of metalloproteinases (TIMPs). We then summarize recent research from model systems that elucidate how specific MMPs drive the malignant phenotype of breast cancer cells, including acquisition of cancer stem cell features and induction of the epithelial-mesenchymal transition, and we also outline clinical studies that implicate specific MMPs in breast cancer outcomes. We conclude by discussing ongoing strategies for development of inhibitors with therapeutic potential that are capable of selectively targeting the MMPs most responsible for tumor promotion, with special consideration of the potential of biologics including antibodies and engineered proteins based on the TIMP scaffold. J. Cell. Biochem. 118: 3531-3548, 2017. © 2017 The Authors. Journal of Cellular Biochemistry Published by Wiley Periodicals, Inc.

Decreased homodimerization and increased TIMP-1 complexation of uteroplacental and uterine arterial matrix metalloproteinase-9 during hypertension-in-pregnancy

Preeclampsia is a complication of pregnancy manifested as hypertension-in-pregnancy (HTN-Preg) and often intrauterine growth restriction (IUGR). Placental ischemia could be an initiating event, but the molecular mechanisms are unclear. To test the hypothesis that dimerization of matrix metalloproteinases (MMPs) plays a role in HTN-Preg and IUGR, the levels/activity of MMP-9, tissue inhibitor of metalloproteinase (TIMP-1), and their dimerization forms were measured in the placenta, uterus, and uterine artery of normal pregnant (Preg) rats and a rat model of reduced uteroplacental perfusion pressure (RUPP). Consistent with our previous report, blood pressure (BP) was higher, pup weight was lower, and gelatin zymography showed different gelatinolytic activity for pro-MMP-9, MMP-9, pro-MMP-2 and MMP-2 in RUPP vs Preg rats. Careful examination of the zymograms showed additional bands at 200 and 135kDa. Western blots with MMP-9 antibody suggested that the 200kDa band was a MMP-9 homodimer. Western blots with TIMP-1 antibody as well as reverse zymography suggested that the 135kDa band was a MMP-9/TIMP-1 complex. The protein levels and gelatinase activity of MMP-9 homodimer were decreased while MMP-9/TIMP-1 complex was increased in placenta, uterus and uterine artery of RUPP vs Preg rats. The epidermal growth factor (EGF) receptor blocker erlotinib and protein kinase C (PKC) inhibitor bisindolylmaleimide decreased MMP-9 homodimer and increased MMP-9/TIMP-1 complex in placenta, uterus and uterine artery of Preg rats. EGF and the PKC activator phorbol-12,13-dibutyrate (PDBu) reversed the decreases in MMP-9 homodimer and the increases in MMP-9/TIMP-1 complex in tissues of RUPP rats. Thus, the increased BP and decreased pup weight in placental ischemia model of HTN-Preg are associated with a decrease in MMP-9 homodimer and an increase in MMP-9/TIMP-1 complex in placenta, uterus, and uterine artery, which together would cause a net decrease in MMP-9 activity and reduce uteroplacental and vascular remodeling in the setting of HTN-Preg and IUGR. Enhancing EGFR/PKC signaling may reverse the MMP-9 unfavorable dimerization patterns and thereby promote uteroplacental and vascular remodeling in preeclampsia.

Bifunctional Inhibitors as a New Tool To Reduce Cancer Cell Invasion by Impairing MMP-9 Homodimerization

Protein homodimers play important roles in physiological and pathological processes, including cancer invasion and metastasis. Recently, MMP-9 natural homodimerization via the PEX domain has been correlated with high migration rates of aggressive cancer cells. Here we propose that bifunctional MMP-9 inhibitors designed to impair natural MMP-9 homodimerization promoted by PEX-PEX interactions might be an effective tool to fight cancer cell invasion. Elaborating a previously described dimeric hydroxamate inhibitor 1, new ligands were synthesized with different linker lengths and branch points. Evaluation of the modified bifunctional ligands by X-ray crystallography and biological assays showed that 7 and 8 could reduce invasion in three glioma cell lines expressing MMP-9 at different levels. To rationalize these results, we present a theoretical model of full-length MMP-9 in complex with 7. This pioneering study suggests that a new approach using MMP-9 selective bifunctional inhibitors might lead to an effective therapy to reduce cancer cell invasion.

CO-releasing molecules CORM2 attenuates angiotensin II-induced human aortic smooth muscle cell migration through inhibition of ROS/IL-6 generation and matrix metalloproteinases-9 expression

Ang II has been involved in the pathogenesis of cardiovascular diseases, and matrix metalloproteinase-9 (MMP-9) induced migration of human aortic smooth muscle cells (HASMCs) is the most common and basic pathological feature. Carbon monoxide (CO), a byproduct of heme breakdown by heme oxygenase, exerts anti-inflammatory effects in various tissues and organ systems. In the present study, we aimed to investigate the effects and underlying mechanisms of carbon monoxide releasing molecule-2 (CORM-2) on Ang II-induced MMP-9 expression and cell migration of HASMCs. Ang II significantly up-regulated MMP-9 expression and cell migration of HASMCs, which was inhibited by transfection with siRNA of p47^phox, Nox2, Nox4, p65, angiotensin II type 1 receptor (AT1R) and pretreatment with the inhibitors of NADPH oxidase, ROS, and NF-κB. In addition, Ang II also induced NADPH oxidase/ROS generation and p47^phox translocation from the cytosol to the membrane. Moreover, Ang II-induced oxidative stress and MMP-9-dependent cell migration were inhibited by pretreatment with CORM-2. Finally, we observed that Ang II induced IL-6 release in HASMCs via AT1R, but not AT2R, which could further caused MMP-9 secretion and cell migration. Pretreatment with CORM-2 reduced Ang II-induced IL-6 release. In conclusion, CORM-2 inhibits Ang II-induced HASMCs migration through inactivation of suppression of NADPH oxidase/ROS generation, NF-κB inactivation and IL-6/MMP-9 expression. Thus, application of CO, especially CORM-2, is a potential countermeasure to reverse the pathological changes of various cardiovascular diseases. Further effects aimed at identifying novel antioxidant and anti-inflammatory substances protective for heart and blood vessels that targeting CO and establishment of well-designed in vivo models properly evaluating the efficacy of these agents are needed.

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Angiotensin II can induce HASMCs migration via activating ROS/NF-κB/IL-6/ MMP-9.

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CORM-2 can inhibit Ang II-induced ROS/NF-κB/IL-6/MMP-9-dependent HASMCs migration.

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The blockade of ROS by CORM-2 can be a preventive strategy of cardiovascular diseases.

Plasma matrix metalloprotease 9 correlates with blood lymphocytosis, leukemic cell invasiveness, and prognosis in B-cell chronic lymphocytic leukemia

The complex biology underlying chronic lymphocytic leukemia cell migration and tissue invasiveness is not yet completely understood and might provide novel predictive markers and therapeutic targets. A total of 36 patients out of treatment from at least 3 months were enrolled and followed up for a median period of 44.2 months (range: 4.4–99.2). Matrix metalloprotease 9 and tissue inhibitor of metalloproteases 1 plasma levels and production/release from lymphoid cells were measured by zymography and enzyme-linked immunosorbent assay (ELISA) analysis. Malignant and normal lymphocyte mobility and matrix-degradation capability were studied using a Boyden chamber system, with and without autologous plasma. Free matrix metalloprotease 9 plasma levels were related with blood lymphocytosis, especially in more advanced stages (p = 0.003), and higher concentrations were associated with an increased disease progression risk (hazard ratio = 9.0, 95% confidence interval = 1.5–13.8). Leukemic cells expressed and secreted very little matrix metalloprotease 9. On the contrary, normal lymphocytes derived from the same leukemic patients showed matrix metalloprotease 9 intracellular levels that were lower in subjects with higher blood lymphocytosis (p = 0.024) and more advanced stages (p = 0.03); the released quantities were inversely associated with matrix metalloprotease 9 plasma concentrations (p = 0.035). Leukemic cells had a reduced spontaneous mobility and matrix-degradation capability that were stimulated by autologous plasma (p = 0.001) and normal lymphocytes (p = 0.005), respectively. Matrix metalloprotease 9 affected cell invasiveness depending on concentration and disease stage. In conclusion, chronic lymphocytic leukemia cells have a reduced mobility, matrix-degradation capability, and matrix metalloprotease 9 production compared to their own autologous normal lymphocytes. They are exposed to matrix metalloprotease 9 of prevalently systemic origin whose higher levels are associated with both leukemic and normal lymphocyte accumulation in the peripheral blood and have a negative prognostic value.

Three-Dimensional Assay for Studying Breast Cancer Cell Invasion

Cancer cell invasion is a complex process that naturally occurs in a three-dimensional (3-D) environment comprised of tumor cells and extracellular matrix components (ECM). Therefore, examining the invasive ability of breast cancer cells in a 3-D assay is imperative to discovering novel treatment strategies aimed at preventing cancer invasion and metastasis. Here, I describe a method to quantitatively measure the number of invaded cancer cells within a 3-D microenvironment and determine the effects of potential drugs on this cellular process.

The Cell Surface Receptor CD44: NMR-Based Characterization of Putative Ligands

The cell surface receptor CD44 is a glycoprotein belonging to the hyaluronan-binding proteins, termed hyaladherins. CD44 is expressed in a wide variety of isoforms in many cells and, in particular, is present on the surface of malignant cells where it is involved in the onset and progression of cancer. In a first attempt to identify novel CD44-binding agents, we first characterized, with NMR spectroscopic techniques, several agents that were reported to bind to human CD44 (hCD44). To our surprise, however, none of these putative CD44-binding agents, including a peptide that is in phase 2 clinical trials (A6 peptide) and a recently reported fragment hit, were found to interact significantly with recombinant hCD44(21-178). Nonetheless, we further report that a fragment-screening campaign, with solution NMR spectroscopy as the detection method, identified a viable fragment hit that bound in a potentially functional pocket on the surface of CD44, opposite to the hyaluronic acid binding site. We hypothesize that this pocket could be indirectly associated with the cellular and in vivo activity of the A6 peptide, which would provide a novel framework for the possible development of therapeutically viable CD44 antagonists.

Multiple myeloma-derived MMP-13 mediates osteoclast fusogenesis and osteolytic disease

Multiple myeloma (MM) cells secrete osteoclastogenic factors that promote osteolytic lesions; however, the identity of these factors is largely unknown. Here, we performed a screen of human myeloma cells to identify pro-osteoclastogenic agents that could potentially serve as therapeutic targets for ameliorating MM-associated bone disease. We found that myeloma cells express high levels of the matrix metalloproteinase MMP-13 and determined that MMP-13 directly enhances osteoclast multinucleation and bone-resorptive activity by triggering upregulation of the cell fusogen DC-STAMP. Moreover, this effect was independent of the proteolytic activity of the enzyme. Further, in mouse xenograft models, silencing MMP-13 expression in myeloma cells inhibited the development of osteolytic lesions. In patient cohorts, MMP-13 expression was localized to BM-associated myeloma cells, while elevated MMP-13 serum levels were able to correctly predict the presence of active bone disease. Together, these data demonstrate that MMP-13 is critical for the development of osteolytic lesions in MM and that targeting the MMP-13 protein - rather than its catalytic activity - constitutes a potential approach to mitigating bone disease in affected patients.

Cell-Surface MMP-9 Protein Is a Novel Functional Marker to Identify and Separate Proangiogenic Cells from Early Endothelial Progenitor Cells Derived from CD133(+) Cells

To develop cell therapies for ischemic diseases, endothelial progenitor cells (EPCs) have been expected to play a pivotal role in vascular regeneration. It is desirable to use a molecular marker that is related to the function of the cells. Here, a quantitative polymerase chain reaction array revealed that early EPCs derived from CD133(+) cells exhibited significant expression of MMP-9. Some populations of early EPCs expressed MMP-9 on the cell surface and others did not. We also attempted to separate the proangiogenic fraction from early EPCs derived from CD133(+) cells using a functional cell surface marker, and we then analyzed the MMP-9(+) and MMP-9(-) cell fractions. The MMP-9(+) cells not only revealed higher invasion ability but also produced a high amount of IL-8. Moreover, the stimulative effect of MMP-9(+) cells on angiogenesis in vitro and in vivo was prohibited by anti-IL-8 antibody. These data indicate that MMP-9 is one of the useful cell surface markers for the separation of angiogenic cells. Our treatment of early EPCs with hyaluronidase caused not only a downregulation of cell-surface MMP-9 but also a decrease in invasion ability, indicating that membrane-bound MMP-9, which is one of the useful markers for early EPCs, plays an important role in angiogenesis. Stem Cells 2016;34:1251-1262.

Neutrophil-Derived Proteases in the Microenvironment of Pancreatic Cancer -Active Players in Tumor Progression

A hallmark of pancreatic ductal adenocarcinoma (PDAC) is the fibro-inflammatory microenvironment, consisting of activated pancreatic stellate cells, extracellular matrix proteins, and a variety of inflammatory cells, such as T cells, macrophages, or neutrophils. Tumor-infiltrating immune cells, which are found in nearly all cancers, including PDAC, often fail to eliminate the tumor, but conversely can promote its progression by altering the tumor microenvironment. Pancreatic cancer cells are able to attract polymorphonuclear neutrophils (PMN) via tumor secreted chemokines and in human PDAC, PMN infiltrates can be observed in the vicinity of tumor cells and in the desmoplastic tumor stroma, which correlate with undifferentiated tumor growth and poor prognosis. The behavior of tumor-infiltrating neutrophils in the tumor micromilieu is not yet understood at a mechanistic level. It has been shown that PMN have the potential to kill tumor cells, either directly or by antibody-dependent cell-mediated cytotoxicity, but on the other side various adverse effects of PMN, such as promotion of aggressive tumor growth with epithelial-to-mesenchymal transition and increased metastatic potential, have been described. Recent therapeutic approaches for PDAC focus not only the tumor cell itself, but also elements of the tumor microenvironment. Therefore, the role of PMN and their derived products (e.g. cytokines, proteases) as a new vein for a therapeutic target should be critically evaluated in this context. This review summarizes the current understanding of the interplay between proteases of tumor-infiltrating neutrophils and pancreatic tumor cells and elements of the desmoplastic stroma.

Pharmacodynamic considerations in the use of matrix metalloproteinase inhibitors in cancer treatment

INTRODUCTION

Matrix metalloproteinases (MMPs) are classified in the family of zinc-dependent endopeptidases, which can degrade various components of an extracellular matrix and a basement membrane. Studies have demonstrated that MMPs relate to the development of malignant tumors and induce angiogenesis, resulting in the invasion and metastasis of tumor cells. MMPs are highly expressed in malignant tumors and are related to cancer patients' malignant phenotype and poor prognosis. Therefore, blocking the expression or activity of MMPs may be a promising strategy for cancer treatment.

AREAS COVERED

This study aimed to explain the MMP structure, regulatory mechanism, and carcinogenic effect; investigate the matrix metalloproteinase-inhibitors (MMPIs) that are currently used in clinical trials for cancer treatment; and summarize the trial results.

EXPERT OPINION

Currently, the results of clinical trials that have used MMPIs as anticancer agents are unsatisfactory. However, MMPs remain an attractive target for cancer treatment. For example, development of the specific peptide or antibodies in targeting the hemopexin domain of MMP-2 may be a new therapeutic direction. The design and development of MMPIs that have selectivity will be the primary focus in future studies.

A Disintegrin and Metalloproteinase with Thrombospondin Motifs-5 (ADAMTS-5) Forms Catalytically Active Oligomers

The metalloproteinase ADAMTS-5 (A disintegrin and metalloproteinase with thrombospondin motifs) degrades aggrecan, a proteoglycan essential for cartilage structure and function. ADAMTS-5 is the major aggrecanase in mouse cartilage, and is also likely to be the major aggrecanase in humans. ADAMTS-5 is a multidomain enzyme, but the function of the C-terminal ancillary domains is poorly understood. We show that mutant ADAMTS-5 lacking the catalytic domain, but with a full suite of ancillary domains inhibits wild type ADAMTS activity, in vitro and in vivo, in a dominant-negative manner. The data suggest that mutant ADAMTS-5 binds to wild type ADAMTS-5; thus we tested the hypothesis that ADAMTS-5 associates to form oligomers. Co-elution, competition, and in situ PLA experiments using full-length and truncated recombinant ADAMTS-5 confirmed that ADAMTS-5 molecules interact, and showed that the catalytic and disintegrin-like domains support these intermolecular interactions. Cross-linking experiments revealed that recombinant ADAMTS-5 formed large, reduction-sensitive oligomers with a nominal molecular mass of ∼ 400 kDa. The oligomers were unimolecular and proteolytically active. ADAMTS-5 truncates comprising the disintegrin and/or catalytic domains were able to competitively block full-length ADAMTS-5-mediated aggrecan cleavage, measured by production of the G1-EGE(373) neoepitope. These results show that ADAMTS-5 oligomerization is required for full aggrecanase activity, and they provide evidence that blocking oligomerization inhibits ADAMTS-5 activity. The data identify the surface provided by the catalytic and disintegrin-like domains of ADAMTS-5 as a legitimate target for the design of aggrecanase inhibitors.

Role of Nonmuscle Myosin II in Migration of Wharton's Jelly-Derived Mesenchymal Stem Cells

It is the promise of regeneration and therapeutic applications that has sparked an interest in mesenchymal stem cells (MSCs). Following infusion, MSCs migrate to sites of injury or inflammation by virtue of their homing property. To exert optimal clinical benefits, systemically delivered MSCs need to migrate efficiently and in adequate numbers to pathological areas in vivo. However, underlying molecular mechanisms responsible for MSC migration are still not well understood. The Wharton's jelly (WJ) of the umbilical cord is an attractive source of MSCs for stem cell therapy because of its abundant availability and painless collection. In this study, we attempted to identify the role of nonmuscle myosin II (NMII), if any, in the migration of WJ-derived MSCs (WJ-MSCs). Expression of NMII isoforms, NMIIA, and NMIIB was observed both at RNA and protein levels in WJ-MSCs. Inhibition of NMII or its regulator ROCK, by pharmacological inhibitors, resulted in significant reduction in the migration of WJ-MSCs as confirmed by the scratch migration assay and time-lapse microscopy. Next, trying to dissect the role of each NMII isoform in migration of WJ-MSCs, we found that siRNA-mediated downregulation of NMIIA, but not NMIIB expression, led to cells failing to retract their trailing edge and losing cell-cell cohesiveness, while exhibiting a nondirectional migratory pathway. Migration, moreover, is also dependent on optimal affinity adhesion, which would allow rapid attachment and release of cells and, hence, can be influenced by extracellular matrix (ECM) and adhesion molecules. We demonstrated that inhibition of NMII and more specifically NMIIA resulted in increased gene expression of ECM and adhesion molecules, which possibly led to stronger adhesions and, hence, decreased migration. Therefore, these data suggest that NMII acts as a regulator of cell migration and adhesion in WJ-MSCs.

Matrix metalloproteinases as breast cancer drivers and therapeutic targets

Members of the matrix metalloproteinase (MMP) family have been identified as poor prognosis markers for breast cancer patients and as drivers of many facets of the tumor phenotype in experimental models. Early enthusiasm for MMPs as therapeutic targets was tempered following disappointing clinical trials that utilized broad spectrum, small molecule catalytic site inhibitors. However, subsequent research has continued to define key roles for MMPs as breast cancer promoters, to elucidate the complex roles that that these proteins play in breast cancer development and progression, and to identify how these roles are linked to specific and unique biochemical features of individual members of the MMP family. Here, we provide an overview of the structural features of the MMPs, then discuss clinical studies identifying which MMP family members are linked with breast cancer development and new experimental studies that reveal how these specific MMPs may play unique roles in the breast cancer microenvironment. We conclude with a discussion of the most promising avenues for development of therapeutic agents capable of targeting the tumor-promoting properties of MMPs.

Failure of matrix metalloproteinase-9 dimer induction by phorbol 12-myristate 13-acetate in normal human cell lines

Increasing experimental and clinical data has identified an association between increased levels of matrix metalloproteinase (MMP)-9 and shortened patient survival, cancer progression and metastasis. MMP-9 has a significant role in tumor cell invasion and metastasis, as it digests the basement membrane and components of the extracellular matrix. MMP-9 is secreted in either a monomeric or dimeric form. Although limited evidence exists concerning MMP-9 dimers, certain studies have demonstrated that the dimer is associated with aggressive tumor progression. This is believed to be due to the fact that cellular migration depends upon the MMP-9 dimer, and not the monomer. Our previous study revealed that cancer cell MMP-9 dimer secretion patterns could be divided into different categories, and that high MMP-9 and MMP-9 dimer secretion levels were correlated with the most aggressive cancer cell lines. It has been established that signal transduction pathways and cytokines, including those activated by phorbol 12-myristate 13-acetate (PMA), regulate the expression of MMPs. The aim of the present study was to analyze the expression patterns of MMP-2, MMP-9 and MMP-9 dimer in normal human cells from a number of tissues treated with PMA. Muscle, epithelial and connective tissues were selected for use in the present study, since adenosarcomas, carcinomas and sarcomas are derived from these tissue types, respectively. The cell lines were first cultured in 24-well tissue culture plates containing recommended media that was supplemented with 10% fetal bovine serum and antibiotics. When at confluency, the cells were washed and fresh medium was added. In addition, a parallel set of cultures was treated with PMA. Subsequent to a 24-h incubation period, the media were collected and analyzed using gelatinase zymography for the expression of MMP-2 and MMP-9 monomer and dimer forms. The results revealed that the cellular expression of MMP-2 and MMP-9 was dependent upon the primary tissue subtype. All cell lines, regardless of tissue origin, expressed MMP-2. PMA induced the expression of MMP-9 in muscle tissue, glandular epithelia and supportive connective tissue cell lines. By contrast, cell lines of endothelial origin and proper connective tissue were insensitive to treatment with PMA. MMP-9 dimer secretion was not observed in any of the cell lines, which indicated that cellular migration is not supported by these cells.

Matrix metalloproteinase-9 expression is enhanced in renal parietal epithelial cells of zucker diabetic Fatty rats and is induced by albumin in in vitro primary parietal cell culture

As a subfamily of matrix metalloproteinases (MMPs), gelatinases including MMP-2 and MMP-9 play an important role in remodeling and homeostasis of the extracellular matrix. However, conflicting results have been reported regarding their expression level and activity in the diabetic kidney. This study investigated whether and how MMP-9 expression and activity were changed in glomerular epithelial cells upon albumin overload. In situ zymography, immunostaining and Western blot for renal MMP gelatinolytic activity and MMP-9 protein expression were performed in Zucker lean and Zucker diabetic rats. Confocal microscopy revealed a focal increase in gelatinase activity and MMP-9 protein in the glomeruli of diabetic rats. Increased glomerular MMP-9 staining was mainly observed in hyperplastic parietal epithelial cells (PECs) expressing claudin-1 in the diabetic kidneys. Interestingly, increased parietal MMP-9 was often accompanied by decreased staining for podocyte markers (nephrin and podocalyxin) in the sclerotic area of affected glomeruli in diabetic rats. Additionally, urinary excretion of podocyte marker proteins was significantly increased in association with the levels of MMP-9 and albumin in the urine of diabetic animals. To evaluate the direct effect of albumin on expression and activity of MMP-9, primary cultured rat glomerular PECs were incubated with rat serum albumin (0.25 - 1 mg/ml) for 24 - 48 hrs. MMP-9 mRNA levels were significantly increased following albumin treatment. Meanwhile, albumin administration resulted in a dose-dependent increase in MMP-9 protein and activity in culture supernatants of PECs. Moreover, albumin activated p44/42 mitogen-activated protein kinase (MAPK) in PECs. Inhibition of p44/42 MAPK suppressed albumin-induced MMP-9 secretion from glomerular PECs. Taken together, we have demonstrated that an up-regulation of MMP-9 in activated parietal epithelium is associated with a loss of adjacent podocytes in progressive diabetic nephropathy. Albumin overload may induce MMP-9 expression and secretion by PECs via the activation of p44/42 MAPK pathway.

Recruitment of Matrix Metalloproteinase-9 (MMP-9) to the Fibroblast Cell Surface by Lysyl Hydroxylase 3 (LH3) Triggers Transforming Growth Factor-β (TGF-β) Activation and Fibroblast Differentiation

Solid tumor growth triggers a wound healing response. Similar to wound healing, fibroblasts in the tumor stroma differentiate into myofibroblasts (also referred to as cancer-associated fibroblasts) primarily, but not exclusively, in response to transforming growth factor-β (TGF-β). Myofibroblasts in turn enhance tumor progression by remodeling the stroma. Among proteases implicated in stroma remodeling, matrix metalloproteinases (MMPs), including MMP-9, play a prominent role. Recent evidence indicates that MMP-9 recruitment to the tumor cell surface enhances tumor growth and invasion. In the present work, we addressed the potential relevance of MMP-9 recruitment to and activity at the surface of fibroblasts. We show that recruitment of MMP-9 to the fibroblast cell surface occurs through its fibronectin-like (FN) domain and that the molecule responsible for the recruitment is lysyl hydroxylase 3 (LH3). Functional assays suggest that both pro- and active MMP-9 trigger α-smooth muscle actin expression in cultured fibroblasts, reflecting myofibroblast differentiation, possibly as a result of TGF-β activation. Moreover, the recombinant FN domain inhibited both MMP-9-induced TGF-β activation and α-smooth muscle actin expression by displacing MMP-9 from the fibroblast cell surface. Together our results uncover LH3 as a new docking receptor of MMP-9 on the fibroblast cell surface and demonstrate that the MMP-9 FN domain is essential for the interaction. They also show that the recombinant FN domain inhibits MMP-9-induced TGF-β activation and fibroblast differentiation, providing a potentially attractive therapeutic reagent toward attenuating tumor progression where MMP-9 activity is strongly implicated.

Circular trimers of gelatinase B/matrix metalloproteinase-9 constitute a distinct population of functional enzyme molecules differentially regulated by tissue inhibitor of metalloproteinases-1

Gelatinase B/matrix metalloproteinase-9 (MMP-9) (EC 3.4.24.35) cleaves many substrates and is produced by most cell types as a zymogen, proMMP-9, in complex with the tissue inhibitor of metalloproteinases-1 (TIMP-1). Natural proMMP-9 occurs as monomers, homomultimers and heterocomplexes, but our knowledge about the overall structure of proMMP-9 monomers and multimers is limited. We investigated biochemical, biophysical and functional characteristics of zymogen and activated forms of MMP-9 monomers and multimers. In contrast with a conventional notion of a dimeric nature of MMP-9 homomultimers, we demonstrate that these are reduction-sensitive trimers. Based on the information from electrophoresis, AFM and TEM, we generated a 3D structure model of the proMMP-9 trimer. Remarkably, the proMMP-9 trimers possessed a 50-fold higher affinity for TIMP-1 than the monomers. In vivo, this finding was reflected in a higher extent of TIMP-1 inhibition of angiogenesis induced by trimers compared with monomers. Our results show that proMMP-9 trimers constitute a novel structural and functional entity that is differentially regulated by TIMP-1.

Targeting Matrix Metalloproteinases in Cancer: Bringing New Life to Old Ideas

Since the identification of matrix metalloproteinases (MMPs), a family of zinc-dependent endopeptidases, as being a driving factor for cancer progression and patient prognosis, MMPs have been studied extensively. Although early programs targeting MMPs were largely unsuccessful in clinical trials, they remain a viable and highly desirable therapeutic target based on preclinical studies and their role in disease progression. As information regarding the structure and function of these proteinases is compiled and biotechnology evolves, tools to develop better inhibitors is within our grasp. Improved methods for high throughput screening and in silico drug design programs have identified compounds which are highly potent, have high binding affinities, and exhibit favorable pharmacokinetic profiles. More recently, advances in drug delivery methods or compounds which bind outside the active site have brought new light to the field. In this review, we highlight the role of MMPs in cancer, clinical trials for MMP inhibitors, and novel approaches to targeting MMPs in cancer.

Tumor cell-produced matrix metalloproteinase 9 (MMP-9) drives malignant progression and metastasis of basal-like triple negative breast cancer

Matrix metalloproteinases (MMPs) have been implicated in diverse roles in breast cancer development and progression. While many of the different MMPs expressed in breast cancer are produced by stromal cells MMP-9 is produced mainly by the tumor cells themselves. To date, the functional role of tumor cell-produced MMP-9 has remained unclear. Here, we show that human breast cancer cell-produced MMP-9 is specifically required for invasion in cell culture and for pulmonary metastasis in a mouse orthotopic model of basal-like breast cancer. We also find that tumor cell-produced MMP-9 promotes tumor vascularization with only modest impact on primary tumor growth, and that silencing of MMP-9 expression in tumor cells leads to an altered transcriptional program consistent with reversion to a less malignant phenotype. MMP-9 is most highly expressed in human basal-like and triple negative tumors, where our data suggest that it contributes to metastatic progression. Our results suggest that MMP9 may offer a target for anti-metastatic therapies for basal-like triple negative breast cancers, a poor prognosis subtype with few available molecularly targeted therapeutic options.

Platelet-rich plasma (PRP) promotes fetal mesenchymal stem/stromal cell migration and wound healing process

Numerous studies have shown the presence of high levels of growth factors during the process of healing. Growth factors act by binding to the cell surface receptors and contribute to the subsequent activation of signal transduction mechanisms. Wound healing requires a complex of biological and molecular events that includes attraction and proliferation of different type of cells to the wound site, differentiation and angiogenesis. More specifically, migration of various cell types, such as endothelial cells and their precursors, mesenchymal stem/stromal cells (MSCs) or skin fibroblasts (DFs) plays an important role in the healing process. In recent years, the application of platelet rich plasma (PRP) to surgical wounds and skin ulcerations is becoming more frequent, as it is believed to accelerate the healing process. The local enrichment of growth factors at the wound after PRP application causes a stimulation of tissue regeneration. Herein, we studied: (i) the effect of autologous PRP in skin ulcers of patients of different aetiology, (ii) the proteomic profile of PRP, (iii) the migration potential of amniotic fluid MSCs and DFs in the presence of PRP extract in vitro, (iv) the use of the PRP extract as a substitute for serum in cultivating AF-MSCs. Considering its easy access, PRP may provide a valuable tool in multiple therapeutic approaches.

Targeting the Wnt/β-catenin pathway in endometriosis: a potentially effective approach for treatment and prevention

Endometriosis is a chronic, estrogen-dependent disease associated with infertility and pelvic pain. Endometriosis is defined by the presence of extra-uterine endometrial tissue. It affects approximately 10% of reproductive-aged women. However, the underlying etiology, pathogenesis and pathophysiology remain to be fully elucidated. Knowledge of these factors is indispensable for the development of targeted therapies for prevention and treatment of endometriosis. Several studies, including those from our laboratory, have suggested that aberrant activation of the Wnt/β-catenin pathway may be involved in the pathophysiology of endometriosis. This is a review of the literature focused on the aberrant activation of the Wnt/β-catenin pathway in patients with endometriosis, and on how targeting the Wnt/targeting pathway may be a potentially effective approach for treating and/or preventing endometriosis.

Targeting the Wnt/β-catenin pathway in endometriosis: a potentially effective approach for treatment and prevention

Endometriosis is a chronic, estrogen-dependent disease associated with infertility and pelvic pain. Endometriosis is defined by the presence of extra-uterine endometrial tissue. It affects approximately 10% of reproductive-aged women. However, the underlying etiology, pathogenesis and pathophysiology remain to be fully elucidated. Knowledge of these factors is indispensable for the development of targeted therapies for prevention and treatment of endometriosis. Several studies, including those from our laboratory, have suggested that aberrant activation of the Wnt/β-catenin pathway may be involved in the pathophysiology of endometriosis. This is a review of the literature focused on the aberrant activation of the Wnt/β-catenin pathway in patients with endometriosis, and on how targeting the Wnt/targeting pathway may be a potentially effective approach for treating and/or preventing endometriosis.

A novel CD44-binding peptide from the pro-matrix metalloproteinase-9 hemopexin domain impairs adhesion and migration of chronic lymphocytic leukemia (CLL) cells

(pro)MMP-9 binds to CLL cells through the PEX9 domain and contributes to CLL progression. To biochemically characterize this interaction and identify potential therapeutic targets, we prepared GST-PEX9 forms containing structural blades B1B2 or B3B4. We recently described a sequence in blade B4 (P3 sequence) that bound α4β1 integrin and partially impaired cell adhesion and migration. We have now studied the possible contribution of the B1B2 region to cell interaction with PEX9. CLL cells bound to GST-B1B2 and CD44 was the primary receptor. GST-B1B2 inhibited CLL cell migration as effectively as GST-B3B4. Overlapping synthetic peptides spanning the B1B2 region identified the sequence FDAIAEIGNQLYLFKDGKYW, present in B1 and contained in peptide P6, as the most effective site. P6 inhibited cell adhesion to PEX9 in a dose-dependent manner and with an IC50 value of 90 μM. P6 also inhibited cell adhesion to hyaluronan but had no effect on adhesion to VCAM-1 (α4β1 integrin ligand), confirming its specific interaction with CD44. Spatial localization analyses mapped P6 to the central cavity of PEX9, in close proximity to the previously identified P3 sequence. Both P6 and P3 equally impaired cell adhesion to (pro)MMP-9. Moreover, P6 synergistically cooperated with P3, resulting in complete inhibition of CLL cell binding to PEX9, chemotaxis, and transendothelial migration. Thus, P6 is a novel sequence in PEX9 involved in cell-PEX9/(pro)MMP-9 binding by interacting with CD44. Targeting both sites, P6 and P3, should efficiently prevent (pro)MMP-9 binding to CLL cells and its pathological consequences.

Neutrophil Gelatinase-Associated Lipocalin (NGAL), Pro-Matrix Metalloproteinase-9 (pro-MMP-9) and Their Complex Pro-MMP-9/NGAL in Leukaemias

Matrix metalloproteinase (MMP)-9 and neutrophil gelatinase-associated lipocalin (NGAL) have gained attention as cancer biomarkers. The inactive zymogen form of MMP-9 (pro-MMP-9) also exists as a disulphide-linked heterodimer bound to NGAL in humans. Leukaemias represent a heterogeneous group of neoplasms, which vary in their clinical behavior and pathophysiology. In this review, we summarize the current literature on the expression profiles of pro-MMP-9 and NGAL as prognostic factors in leukaemias. We also report the expression of the pro-MMP-9/NGAL complex in these diseases. We discuss the roles of (pro)-MMP-9 (active and latent forms) and NGAL in tumour development, and evaluate the mechanisms by which pro-MMP-9/NGAL may influence the actions of (pro)-MMP-9 and NGAL in cancer. Emerging knowledge about the coexpression and the biology of (pro)-MMP-9, NGAL and their complex in cancer including leukaemia may improve treatment outcomes.

Reappraisal of quantitative gel zymography for matrix metalloproteinases

BACKGROUND

The determination of matrix metalloproteases (MMPs) is relevant in many pathophysiological conditions, especially if associated with extracellular matrix remodeling; however, the results obtained are closely linked to the method used and are not directly comparable. The aim of this study was to perform a reappraisal of quantitative gel zymography technique for MMPs in human plasma, to use for comparison with commercially available ELISA and in those experimental conditions where the MMP active form needs to be revealed.

METHODS

The critical methodological parameters of zymography were checked and a comparison with a routinely used ELISA was performed.

RESULTS

Sensitivity and reproducibility levels of zymography are suitable for detection of MMP-9 in human plasma, providing results closely related to those obtained by ELISA.

CONCLUSIONS

Analytical parameters of zymography were suitable for detection of MMPs in human plasma. Quantitative zymography for MMPs is an alternative method for comparing the results of ELISA widely employed for MMP determination, thus reducing the discrepancies between laboratories regarding gelatinase assay.

Gelatinase B/MMP-9 in Tumour Pathogenesis and Progression

Since its original identification as a leukocyte gelatinase/type V collagenase and tumour type IV collagenase, gelatinase B/matrix metalloproteinase (MMP)-9 is now recognised as playing a central role in many aspects of tumour progression. In this review, we relate current concepts concerning the many ways in which gelatinase B/MMP-9 influences tumour biology. Following a brief outline of the gelatinase B/MMP-9 gene and protein, we analyse the role(s) of gelatinase B/MMP-9 in different phases of the tumorigenic process, and compare the importance of gelatinase B/MMP-9 source in the carcinogenic process. What becomes apparent is the importance of inflammatory cell-derived gelatinase B/MMP-9 in tumour promotion, early progression and triggering of the "angiogenic switch", the integral relationship between inflammatory, stromal and tumour components with respect to gelatinase B/MMP-9 production and activation, and the fundamental role for gelatinase B/MMP-9 in the formation and maintenance of tumour stem cell and metastatic niches. It is also apparent that gelatinase B/MMP-9 plays important tumour suppressing functions, producing endogenous angiogenesis inhibitors, promoting inflammatory anti-tumour activity, and inducing apoptosis. The fundamental roles of gelatinase B/MMP-9 in cancer biology underpins the need for specific therapeutic inhibitors of gelatinase B/MMP-9 function, the use of which must take into account and substitute for tumour-suppressing gelatinase B/MMP-9 activity and also limit inhibition of physiological gelatinase B/MMP-9 function.

CD44 targets Na(+)/H(+) exchanger 1 to mediate MDA-MB-231 cells' metastasis via the regulation of ERK1/2

Background:

CD44, a transmembrane glycoprotein expressed in a variety of cells and tissues, has been implicated in tumour metastasis. But the molecular mechanisms of CD44-mediated tumour cell metastasis remain to be elucidated.

Methods:

The downregulation of CD44 was determined by immunofluorescence. Moreover, the motility of breast cancer cells was detected by wound-healing and transwell experiments. Then the spontaneous metastasis of CD44-silenced MDA-MB-231 cells was tested by histology with BALB/c nude mice.

Results:

A positive correlation between CD44 and Na⁺/H⁺ exchanger isoform 1 (NHE1) was found in two breast cancer cells. CD44 downregulation could inhibit the metastasis of MDA-MB-231 cells and the expressions of Na⁺/H⁺ exchanger 1. Moreover, CD44 overexpression upregulated the metastasis of MCF-7 cells, but the elevated metastatic ability was then inhibited by Cariporide. Interestingly, during these processes only the p-ERK1/2 was suppressed by CD44 downregulation and the expression of matrix metalloproteinases and metastatic capacity of MDA-MB-231 cells were greatly inhibited by the MEK1 inhibitor PD98059, which even had a synergistic effect with Cariporide. Furthermore, CD44 downregulation inhibits breast tumour outgrowth and spontaneous lung metastasis.

Conclusions:

Taken together, this work indicates that CD44 regulates the metastasis of breast cancer cells through regulating NHE1 expression, which could be used as a novel strategy for breast cancer therapy.

Indirubin-3'-oxime reverses bone loss in ovariectomized and hindlimb-unloaded mice via activation of the Wnt/β-catenin signaling

Osteoporosis is a major global health issue in elderly people. Because Wnt/β-catenin signaling plays a key role in bone homeostasis, we screened activators of this pathway through cell-based screening, and investigated indirubin-3'-oxime (I3O), one of the positive compounds known to inhibit GSK3β, as a potential anti-osteoporotic agent. Here, we show that I3O activated Wnt/β-catenin signaling via inhibition of the interaction of GSK3β with β-catenin, and induced osteoblast differentiation in vitro and increased calvarial bone thickness ex vivo. Intraperitoneal injection of I3O increased bone mass and improved microarchitecture in normal mice and reversed bone loss in an ovariectomized mouse model of age-related osteoporosis. I3O also increased thickness and area of cortical bone, indicating improved bone strength. Enhanced bone mass and strength correlated with activated Wnt/β-catenin signaling, as shown by histological analyses of both trabecular and cortical bones. I3O also restored mass and density of bone in hindlimb-unloaded mice compared with control, suspended mice, demonstrating bone-restoration effects of I3O in non-aged-related osteoporosis as well. Overall, I3O, a pharmacologically active small molecule, could be a potential therapeutic agent for the treatment and prevention of osteoporosis.

On the structure and functions of gelatinase B/matrix metalloproteinase-9 in neuroinflammation

The blood-brain barrier (BBB) is a specific structure that is composed of two basement membranes (BMs) and that contributes to the control of neuroinflammation. As long as the BBB is intact, extravasated leukocytes may accumulate between two BMs, generating vascular cuffs. Specific matrix metalloproteinases, MMP-2 and MMP-9, have been shown to cleave BBB beta-dystroglycan and to disintegrate thereby the parenchymal BM, resulting in encephalomyelitis. This knowledge has been added to the molecular basis of the REGA model to understand the pathogenesis of multiple sclerosis, and it gives further ground for the use of MMP inhibitors for the treatment of acute neuroinflammation. MMP-9 is associated with central nervous system inflammation and occurs in various forms: monomers and multimers. None of the various neurological and neuropathologic functions of MMP-9 have been associated with either molecular structure or molecular form, and therefore, in-depth structure-function studies are needed before medical intervention with MMP-9-specific inhibitors is initiated.

Effect of a nutrient mixture on matrix metalloproteinase-9 dimers in various human cancer cell lines

Strong clinical and experimental evidence demonstrates association of elevated levels of matrix metalloproteinase MMP-9 with cancer progression, metastasis and shortened patient survival, as it plays a key role in tumor cell invasion and metastasis by digesting the basement membrane and ECM components. MMP-9 is secreted in both the monomeric and dimeric form. Although there is little research on MMP-9 dimers, some studies have shown the dimer to be associated with more aggressive tumor progression. Our objective was to study the relative secretion patterns of MMP-9 monomer and dimer in a variety of cancer cell lines and the effect of a nutrient mixture (NM) containing lysine, proline, ascorbic acid and green tea extract on MMP-9 secretion. The cancer cell lines were grown in their respective media, supplemented with 10% FBS, penicillin (100 U/ml) and streptomycin (100 µg/ml) in 24-well tissue culture plates. At near confluence, the cells were treated with NM at 0,10, 50, 100, 500 and 1000 µg/ml. Parallel sets of cultures were treated with PMA (100 ng/ml) for induction of MMP-9. Cell MMP-9 secretion was assayed by gelatinase zymography. MMP-9 dimer secretion patterns of cancer cells fell into different categories. We observed no MMP-9 dimer in prostate DU-145 and PC-3, pancreatic MIA-Pa-Ca2, colon HCT-116, bladder T-24, head and neck FaDu, glioblastoma A-172, T-98 and LN-18 and leukemia HL-60, Jurkat, and Raji cell lines. MMP-dimer secretion only with PMA induction was seen in breast MCF-7 and MDA-MB-231, uterine SK-UT-1, lung A-549, tongue SC-25, melanoma A2058, osteosarcoma U-2OS, rhabdomyosarcoma, fibrosarcoma HT-1080, chondrosarcoma SW-1350 and liposarcoma SW-872. Cervical HeLa and DoTc 2 4510, renal 786-0 and HCC SK-Hep-1 cells exhibited MMP-9 dimer without PMA treatment and increased secretion with PMA treatment. Sarcomas had the highest levels of MMP-9 monomer and dimer with and without PMA among these cancer cell lines. Cervical, uterine and male breast cancer cell lines showed the next highest levels of MMP-9, followed by breast cancer cell lines. Melanoma, renal, lung, head and neck and HCC showed lower levels and prostate, glioblastoma, bladder and leukemia cell lines the lowest. NM showed dose-dependent inhibition of MMP-9 monomer and dimer in all cell lines tested. In conclusion, high MMP-9 and dimer secretion levels correlated with the most aggressive cancer cell lines. NM was effective in inhibiting MMP-9 and dimer secretion in all cell lines tested, suggesting its therapeutic potential as an antimetastatic agent.

Proteolysis during tumor cell extravasation in vitro: metalloproteinase involvement across tumor cell types

To test if proteolysis is involved in tumor cell extravasation, we developed an in vitro model where tumor cells cross an endothelial monolayer cultured on a basement membrane. Using this model we classified the ability of the cells to transmigrate through the endothelial cell barrier onto the underlying matrix, and scored this invasion according to the stage of passage through the endothelium. Metalloproteinase inhibitors reduced tumor cell extravasation by at least 35%. Visualization of protease and cell adhesion molecules by confocal microscopy demonstrated the cell surface localization of MMP-2, MMP-9, MT1-MMP, furin, CD44 and αvβ3, during the process of transendothelial migration. By the addition of inhibitors and bio-modulators we assessed the functional requirement of the aforementioned molecules for efficient migration. Proteolytic digestion occurred at the cell-matrix interface and was most evident during the migratory stage. All of the inhibitors and biomodulators affected the transition of the tumor cells into the migratory stage, highlighting the most prevalent use of proteolysis at this particular step of tumor cell extravasation. These data suggest that a proteolytic interface operates at the tumor cell surface within the tumor-endothelial cell microenvironment.

Role of L1 cell adhesion molecule (L1CAM) in the metastatic cascade: promotion of dissemination, colonization, and metastatic growth

Expression of the L1 cell adhesion molecule (L1CAM) is frequently increased in cancer patients compared to healthy individuals and also linked with bad prognosis of solid tumours. Previously, we could show that full-length L1CAM promotes metastasis formation via up-regulation of gelatinolytic activity in fibrosarcoma. In this study, we aimed to extend this finding to haematogenous malignancies and carcinomas, and to specifically elucidate the impact of L1CAM on major steps of the metastatic cascade. In a well-established T-cell lymphoma spontaneous metastasis model, silencing of L1CAM significantly improved survival of the mice, while intradermal tumour growth remained unaltered. This correlated with significantly decreased spontaneous metastasis formation. L1CAM suppression abrogated the metastatic potential of T-cell lymphoma as well as carcinoma cells as demonstrated by reduced migration and invasion in vitro and reduced formation of experimental metastasis in vivo. At the molecular level, silencing of L1CAM led to reduced expression of gelatinases MMP-2 and -9 in vitro and decreased gelatinolytic activity in primary tumours and metastases in vivo. In accordance, knock down of L1CAM had similar suppressive effects on migration, invasion and in vivo-gelatinolytic activity as treatment with the specific gelatinase inhibitor SB-3CT. This newly discovered impact of L1CAM on distinct steps of the metastatic cascade and MMP activity highlights the potential of possible L1CAM-directed therapies to inhibit metastatic spread.

MiR-376c down-regulation accelerates EGF-dependent migration by targeting GRB2 in the HuCCT1 human intrahepatic cholangiocarcinoma cell line

MicroRNA miR-376c was expressed in normal intrahepatic biliary epithelial cells (HIBEpiC), but was significantly suppressed in the HuCCT1 intrahepatic cholangiocarcinoma (ICC) cell line. The biological significance of the down-regulation of miR-376c in HuCCT1 cells is unknown. We hypothesized that miR-376c could function as a tumor suppressor in these cells. To test this hypothesis, we sought the targets of miR-376c, and characterized the effect of its down-regulation on HuCCT1 cells. We performed proteomic analysis of miR-376c-overexpressing HuCCT1 cells to identify candidate targets of miR-376c, and validated these targets by 3′-UTR reporter assay. Transwell migration assays were performed to study the migratory response of HuCCT1 cells to miR-376c overexpression. Furthermore, microarrays were used to identify the signaling that were potentially involved in the miR-376c-modulated migration of HuCCT1. Finally, we assessed epigenetic changes within the potential promoter region of the miR-376c gene in these cells. Proteomic analysis and subsequent validation assays showed that growth factor receptor-bound protein 2 (GRB2) was a direct target of miR-376c. The transwell migration assay revealed that miR-376c significantly reduced epidermal growth factor (EGF)-dependent cell migration in HuCCT1 cells. DNA microarray and subsequent pathway analysis showed that interleukin 1 beta and matrix metallopeptidase 9 were possible participants in EGF-dependent migration of HuCCT1 cells. Bisulfite sequencing showed higher methylation levels of CpG sites upstream of the miR-376c gene in HuCCT1 relative to HIBEpiC cells. Combined treatment with the DNA-demethylating agent 5-aza-2′-deoxycytidine and the histone deacetylase inhibitor trichostatin A significantly upregulated the expression of miR-376c in HuCCT1 cells. We revealed that epigenetic repression of miR-376c accelerated EGF-dependent cell migration through its target GRB2 in HuCCT1 cells. These findings suggest that miR-376c functions as a tumor suppressor. Since metastasis is the major cause of death in ICC, microRNA manipulation could lead to the development of novel anti-cancer therapy strategies for ICC.

In vitro effects of a small-molecule antagonist of the Tcf/ß-catenin complex on endometrial and endometriotic cells of patients with endometriosis

BACKGROUND

Our previous studies suggested that aberrant activation of Wnt/ß-catenin signaling might be involved in the pathophysiology of endometriosis. We hypothesized that inhibition of Wnt/ß-catenin signaling might result in inhibition of cell proliferation, migration, and/or invasion of endometrial and endometriotic epithelial and stromal cells of patients with endometriosis.

OBJECTIVES

The aim of the present study was to evaluate the effects of a small-molecule antagonist of the Tcf/ß-catenin complex (PKF 115-584) on cell proliferation, migration, and invasion of endometrial and endometriotic epithelial and stromal cells.

METHODS

One hundred twenty-six patients (78 with and 48 without endometriosis) with normal menstrual cycles were recruited. In vitro effects of PKF 115-584 on cell proliferation, migration, and invasion and on the Tcf/ß-catenin target genes were evaluated in endometrial epithelial and stromal cells of patients with and without endometriosis, and in endometrial and endometriotic epithelial and stromal cells of the same patients.

RESULTS

The inhibitory effects of PKF 115-584 on cell migration and invasion in endometrial epithelial and stromal cells of patients with endometriosis prepared from the menstrual phase were significantly higher than those of patients without endometriosis. Levels of total and active forms of MMP-9 were significantly higher in epithelial and stromal cells prepared from menstrual endometrium in patients with endometriosis compared to patients without endometriosis. Treatment with PKF 115-584 inhibited MMP-9 activity to undetectable levels in both menstrual endometrial epithelial and stromal cells of patients with endometriosis. The number of invasive cells was significantly higher in epithelial and stromal cells of endometriotic tissue compared with matched eutopic endometrium of the same patients. Treatment with PKF 115-584 decreased the number of invasive endometriotic epithelial cells by 73% and stromal cells by 75%.

CONCLUSIONS

The present findings demonstrated that cellular mechanisms known to be involved in endometriotic lesion development are inhibited by targeting the Wnt/β-catenin pathway.

Molecular design of a highly selective and strong protein inhibitor against matrix metalloproteinase-2 (MMP-2)

Synthetic inhibitors of matrix metalloproteinases (MMPs), designed previously, as well as tissue inhibitors of metalloproteinases (TIMPs) lack enzyme selectivity, which has been a major obstacle for developing inhibitors into safe and effective MMP-targeted drugs. Here we designed a fusion protein named APP-IP-TIMP-2, in which the ten amino acid residue sequence of APP-derived MMP-2 selective inhibitory peptide (APP-IP) is added to the N terminus of TIMP-2. The APP-IP and TIMP-2 regions of the fusion protein are designed to interact with the active site and the hemopexin-like domain of MMP-2, respectively. The reactive site of the TIMP-2 region, which has broad specificity against MMPs, is blocked by the APP-IP adduct. The recombinant APP-IP-TIMP-2 showed strong inhibitory activity toward MMP-2 (Ki(app) = 0.68 pm), whereas its inhibitory activity toward MMP-1, MMP-3, MMP-7, MMP-8, MMP-9, or MT1-MMP was six orders of magnitude or more weaker (IC50 > 1 μm). The fusion protein inhibited the activation of pro-MMP-2 in the concanavalin A-stimulated HT1080 cells, degradation of type IV collagen by the cells, and the migration of stimulated cells. Compared with the decapeptide APP-IP (t½ = 30 min), APP-IP-TIMP-2 (t½ ≫ 96 h) showed a much longer half-life in cultured tumor cells. Therefore, the fusion protein may be a useful tool to evaluate contributions of proteolytic activity of MMP-2 in various pathophysiological processes. It may also be developed as an effective anti-tumor drug with restricted side effects.

Matrix metalloproteinase-2 as a target for head and neck cancer therapy

INTRODUCTION

Matrix metalloproteinase (MMP)-2 is a zinc-dependent proteinase that is capable of cleaving all extracellular matrix (ECM) substrates. Degradation of the matrix is a key event in the progression, invasion, and metastasis of potentially malignant and malignant lesions of the head and neck. Therefore, blocking MMP-2 expression or activity may present a promising strategy for anticancer treatment.

AREAS COVERED

Current understanding of the molecular mechanisms that govern MMP-2 regulation and its tumorigenic effects, and that are involved in the initiation and progression of head and neck cancers, in particular the emerging role of MMP-2 in cell migration, which is a prerequisite for tumor metastasis. MMP-2 gene polymorphisms, cellular substrates, and interacting proteins are summarized. The current state of drugs that target this enzyme, either alone or in combination with other targeted agents are also discussed.

EXPERT OPINION

MMP-2 has long been a drug target. The current status of MMP-2 inhibitors as anticancer agents and their failure in the clinic is discussed in light of new data on the MMP-2s role as a cell surface transducer - data that may lead to the design and development of novel, MMP-2-targeting inhibitors.

Peptide-based selective inhibitors of matrix metalloproteinase-mediated activities

The matrix metalloproteinases (MMPs) exhibit a broad array of activities, some catalytic and some non-catalytic in nature. An overall lack of selectivity has rendered small molecule, active site targeted MMP inhibitors problematic in execution. Inhibitors that favor few or individual members of the MMP family often take advantage of interactions outside the enzyme active site. We presently focus on peptide-based MMP inhibitors and probes that do not incorporate conventional Zn²⁺ binding groups. In some cases, these inhibitors and probes function by binding only secondary binding sites (exosites), while others bind both exosites and the active site. A myriad of MMP mediated-activities beyond selective catalysis can be inhibited by peptides, particularly cell adhesion, proliferation, motility, and invasion. Selective MMP binding peptides comprise highly customizable, unique imaging agents. Areas of needed improvement for MMP targeting peptides include binding affinity and stability.

A new isoform of steroid receptor coactivator-1 is crucial for pathogenic progression of endometriosis

Endometriosis is considered to be an estrogen-dependent inflammatory disease, but its etiology is unclear. Thus far, a mechanistic role for steroid receptor coactivators (SRCs) in the progression of endometriosis has not been elucidated. An SRC-1-null mouse model reveals that the mouse SRC-1 gene has an essential role in endometriosis progression. Notably, a previously unidentified 70-kDa SRC-1 proteolytic isoform is highly elevated both in the endometriotic tissue of mice with surgically induced endometriosis and in endometriotic stromal cells biopsied from patients with endometriosis compared to normal endometrium. Tnf⁻/⁻ and Mmp9⁻/⁻ mice with surgically induced endometriosis showed that activation of tumor necrosis factor a (TNF-α)-induced matrix metallopeptidase 9 (MMP9) activity mediates formation of the 70-kDa SRC-1 C-terminal isoform in endometriotic mouse tissue. In contrast to full-length SRC-1, the endometriotic 70-kDa SRC-1 C-terminal fragment prevents TNF-α-mediated apoptosis in human endometrial epithelial cells and causes the epithelial-mesenchymal transition and the invasion of human endometrial cells that are hallmarks of progressive endometriosis. Collectively, the newly identified TNF-α-MMP9-SRC-1 isoform functional axis promotes pathogenic progression of endometriosis.