Membrane Type-4 Matrix Metalloproteinase Research Articles

MT4-MMP promotes invadopodia formation and cell motility in FaDu head and neck cancer cells

Hypoxia-inducible factor-1α (HIF-1α) induces cancer metastasis. We previously demonstrated that HIF-1α-induced membrane-type 4 matrix metalloproteinase (MT4-MMP) is involved in hypoxia-mediated metastasis in head and neck squamous cell carcinoma (HNSCC). However, the functions and detailed mechanisms of MT4-MMP in cancer metastasis are not well understood. In this study, we investigated whether MT4-MMP regulates invadopodia formation or individual cell movement—both critical to cancer migration and invasion—in three-dimensional (3D) environments. By expressing MT4-MMP in the HNSCC cell line FaDu, we demonstrated that MT4-MMP increases invadopodia formation and gelatin degradation. Furthermore, the amoeboid-like cell movement on collagen gel was increased by MT4-MMP expression in FaDu cells. Mechanistically, MT4-MMP may induce invadopodia formation by binding with Tks5 and PDGFRα to result in Src activation and promote amoeboid-like movement by stimulating the small GTPases Rho and Cdc42. Altogether, our data indicate that MT4-MMP induces two crucial mechanisms of cancer dissemination, invadopodia formation and amoeboid movement, and elucidate the prometastatic role of MT4-MMP in hypoxia-mediated cancer metastasis.

Developmental expression of membrane type 4-matrix metalloproteinase (Mt4-mmp/Mmp17) in the mouse embryo.

Matrix metalloproteinases (MMPs) constitute a large group of endoproteases that play important functions during embryonic development, tumor metastasis and angiogenesis by degrading components of the extracellular matrix. Within this family, we focused our study on Mt4-mmp (also called Mmp17) that belongs to a distinct subset that is anchored to the cell surface via a glycosylphosphatidylinositol (GPI) moiety and with the catalytic site exposed to the extracellular space. Information about its function and substrates is very limited to date, and little has been reported on its role in the developing embryo. Here, we report a detailed expression analysis of Mt4-mmp during mouse embryonic development by using a LacZ reporter transgenic mouse line. We showed that Mt4-mmp is detected from early stages of development to postnatal stages following a dynamic and restricted pattern of expression. Mt4-mmp was first detected at E8.5 limited to the intersomitic vascularization, the endocardial endothelium and the dorsal aorta. Mt4-mmpLacZ/+ cells were also observed in the neural crest cells, somites, floor plate and notochord at early stages. From E10.5, expression localized in the limb buds and persists during limb development. A strong expression in the brain begins at E12.5 and continues to postnatal stages. Specifically, staining was observed in the olfactory bulb, cerebral cortex, hippocampus, striatum, septum, dorsal thalamus and the spinal cord. In addition, LacZ-positive cells were also detected during eye development, initially at the hyaloid artery and later on located in the lens and the neural retina. Mt4-mmp expression was confirmed by quantitative RT-PCR and western blot analysis in some embryonic tissues. Our data point to distinct functions for this metalloproteinase during embryonic development, particularly during brain formation, angiogenesis and limb development.

MT4-MMP and EGFR expression levels are key biomarkers for breast cancer patient response to chemotherapy and erlotinib

Background:Triple-negative breast cancers (TNBC) are heterogeneous cancers with poor prognosis. We aimed to determine the clinical relevance of membrane type-4 matrix metalloproteinase (MT4-MMP), a membrane type matrix metalloproteinase that interacts with epidermal growth factor receptor (EGFR) overexpressed in >50% of TNBC.Methods:We conducted a retrospective immunohistochemical analysis on human TNBC samples (n=81) and validated our findings in in vitro and in vivo assays.Results:Membrane type-4 matrix metalloproteinase and EGFR are produced in 72.5% of TNBC samples, whereas those proteins are faintly produced by healthy tissues. Unexpectedly, tumour relapse after chemotherapy was reduced in samples highly positive for MT4-MMP. Mechanistically, this is ascribed to a higher sensitivity of MT4-MMP-producing cells to alkylating or intercalating chemotherapeutic agents, as assessed in vitro. In sharp contrast, MT4-MMP expression did not affect tumour cell sensitivity to paclitaxel that interferes with protease trafficking. Importantly, MT4-MMP expression sensitised cancer cells to erlotinib, a tyrosine kinase EGFR inhibitor. In a pre-clinical model, the growth of MT4-MMP overexpressing xenografts, but not of control ones, was reduced by epirubicin or erlotinib. The combination of suboptimal drug doses blocked drastically the growth of MT4-MMP-producing tumours.Conclusions:We demonstrate that MT4-MMP defines a sub-population of TNBC sensitive to a combination of DNA-targeting chemotherapeutic agents and anti-EGFR drugs.

Expression and Characterization of Membrane-Type 4 Matrix Metalloproteinase (MT4-MMP) and its Different Forms in Melanoma

Background/Aims: Membrane-type matrix metalloproteinases (MT-MMPs) are expressed on the cell surface and hydrolyze extracellular matrix components and signaling molecules by which they influence cancer cell migration and metastasis. Two of the six known MT-MMPs are anchored to the plasma membrane via a GPI anchor, one of which is MT4-MMP. Only little is known about MT4-MMP expression, synthesis, regulation and degradation. Methods: We analyzed several human cancer cell lines as well as tissue homogenates using Western blotting and quantitative PCR for the expression of MT4-MMP. Organelles of SK-Mel-28 cells were separated using continuous Iodixanol gradients. Glycosylation of the SK-Mel-28 protein was studied via glucosidases and site directed mutagenesis of the MT4-MMP cDNA prior to transfection. Results: We found the MT4-MMP highly expressed in human melanoma cell lines as well as skin and melanoma tissue samples. Three forms of MT4-MMP with molecular masses of 45 kDa, 58 kDa and 69 kDa were detected. Further, we demonstrate that the 58 kDa form is the mature protein in the cell membrane, while the 69 kDa form is its precursor found in intracellular compartments. The 69 kDa forms are processed by furin cleavage in the Golgi apparatus. Moreover, we identified Asn³¹⁸ as the single N-glycosylation site of MT4-MMP. Conclusion: We demonstrate the novel expression of MT4-MMP in melanocytic tissues and propose a precursor/product-relationship of the different forms of MT4-MMP in melanoma cells.

Dynamics of internalization and recycling of the prometastatic membrane type 4 matrix metalloproteinase (MT4-MMP) in breast cancer cells.

Membrane type 4 matrix metalloproteinase (MT4-MMP) [matrix metalloproteinase (MMP) 17] is a GPI-anchored membrane-type MMP expressed on the cell surface of human breast cancer cells. In triple-negative breast cancer cells, MT4-MMP promotes primary tumour growth and lung metastases. Although the trafficking and internalization of the transmembrane membrane type 1 MMP have been extensively investigated, little is known about the regulatory mechanisms of the GPI-anchored MT4-MMP. Here, we investigated the fate and cellular trafficking of MT4-MMP by analysing its homophilic complex interactions, internalization and recycling dynamics as compared with an inert form, MT4-MMP-E249A. Oligomeric and dimeric complexes were analysed by cotransfection of cells with FLAG-tagged or Myc-tagged MT4-MMP in reducing and nonreducing immunoblotting and coimmunoprecipitation experiments. The trafficking of MT4-MMP was studied with an antibody feeding assay and confocal microscopy analysis or cell surface protein biotinylation and western blot analysis. We demonstrate that MT4-MMP forms homophilic complexes at the cell surface, and internalizes in early endosomes, and that some of the enzyme is either autodegraded or recycled to the cell surface. Our data indicate that MT4-MMP is internalized by the clathrin-independent carriers/GPI-enriched early endosomal compartments pathway, a mechanism that differs from that responsible for the internalization of other membrane-type MMP members. Although MT4-MMP localizes with caveolin-1, MT4-MMP internalization was not affected by inhibitors of caveolin-1 or clathrin endocytosis pathways, but was reduced by CDC42 or RhoA silencing with small interfering RNA. We provide a new mechanistic insight into the regulatory mechanisms of MT4-MMP, which may have implications for the design of novel therapeutic strategies for metastatic breast cancer.

Regulation of Membrane-Type 4 Matrix Metalloproteinase by SLUG Contributes to Hypoxia-Mediated Metastasis

The hypoxic tumor environment has been shown to be critical to cancer metastasis through the promotion of angiogenesis, induction of epithelial-mesenchymal transition (EMT), and acquisition of invasive potential. However, the impact of hypoxia on the expression profile of the proteolytic enzymes involved in invasiveness is relatively unknown. Membrane-type 4 matrix metalloproteinase (MT4-MMP) is a glycosyl-phosphatidyl inositol-anchored protease that has been shown to be overexpressed in human cancers. However, detailed mechanisms regarding the regulation and function of MT4-MMP expression in tumor cells remain unknown. Here, we demonstrate that hypoxia or overexpression of hypoxia-inducible factor-1alpha (HIF-1alpha) induced MT4-MMP expression in human cancer cells. Activation of SLUG, a transcriptional factor regulating the EMT process of human cancers, by HIF-1alpha was critical for the induction of MT4-MMP under hypoxia. SLUG regulated the transcription of MT4-MMP through direct binding to the E-box located in its proximal promoter. Short-interference RNA-mediated knockdown of MT4-MMP attenuated in vitro invasiveness and in vivo pulmonary colonization of tumor cells without affecting cell migratory ability. MT4-MMP promoted invasiveness and pulmonary colonization through modulation of the expression profile of MMPs and angiogenic factors. Finally, coexpression of HIF-1alpha and MT4-MMP in human head and neck cancer was predictive of a worse clinical outcome. These findings establish a novel signaling pathway for hypoxia-mediated metastasis and elucidate the underlying regulatory mechanism and functional significance of MT4-MMP in cancer metastasis.

Membrane‐type 4 matrix metalloproteinase (MT4‐MMP) induces lung metastasis by alteration of primary breast tumour vascular architecture

The present study aims at investigating the mechanism by which membrane-type 4 matrix metalloproteinase (MT4-MMP), a membrane-anchored MMP expressed by human breast tumour cells promotes the metastatic dissemination into lung. We applied experimental (intravenous) and spontaneous (subcutaneous) models of lung metastasis using human breast adenocarcinoma MDA-MB-231 cells overexpressing or not MT4-MMP. We found that MT4-MMP does not affect lymph node colonization nor extravasation of cells from the bloodstream, but increases the intravasation step leading to metastasis. Ultrastructural and fluorescent microscopic observations coupled with automatic computer-assisted quantifications revealed that MT4-MMP expression induces blood vessel enlargement and promotes the detachment of mural cells from the vascular tree, thus causing an increased tumour vascular leak. On this basis, we propose that MT4-MMP promotes lung metastasis by disturbing the tumour vessel integrity and thereby facilitating tumour cell intravasation.

Serum or Plasma Samples?

Dysregulations of the synthesis and breakdown of the extracellular matrix (ECM) is a key processes in the physiopathology of vascular remodeling and the development of atherothrombotic syndromes.1–4 Matrix metalloproteinases (MMPs) are endopeptidases, belonging to the matrixin family that can degrade almost all the ECM components.5 Although there is little doubt that MMPs are an important components in cancer invasion and metastasis,6 they are also regarded as key regulatory molecules in degenerative processes and inflammation,5,7 as playing roles also in physiopathological remodeling of the vascular wall2,8 and as the pathogenesis of cardio- and cerebrovascular diseases.9,10 Thus, MMPs have emerged as potential biomarkers of atherothrombotic risk and predictors of coronary and cerebrovascular disease recurrence.8 ATVB 2008;28:e15–e16. Normal and diseased blood vessel wall cells may upregulate and activate MMPs in a multistep fashion, driven in part by soluble cytokines and cell–cell interactions with platelets and white blood cells. Enhanced MMP activation (alone or in concert with the fibrinolytic system) contributes to increased matrix turnover, which may have beneficial effects (eg, in vascular repair and atherosclerotic plaque stabilization)11 but also detrimental effects (eg, in vascular intimal thickening, atherosclerosis, and in thrombotic syndromes).12 Because the changes on the cellular level are reflected in body fluids, determination of MMPs in blood have been recommended as noninvasive tools in the diagnosis and monitoring of several diseases.13 It has been demonstrated repeatedly that both the MMP/tissue inhibitor of matrix metalloproteinase (TIMP) assay and zymography essentially depend on the blood sampling procedures, with some MMPs and TIMPs having higher concentrations in serum than in plasma.14–41 Although assays for an ever-increasing number of MMPs are now commercially available, the …

ADAMTS5-mediated aggrecanolysis in murine epiphyseal chondrocyte cultures

Aggrecan degradation by aggrecanases [a disintegrin and metalloproteinase with thrombospondin-like motifs (ADAMTS) 1, 4, 5, 8, 9, 15] is considered to initiate much of the cartilage pathology seen in human arthritis, however, the proteinase responsible and its mode of control is unclear. The present work was done to examine mechanisms of aggrecanase control in a novel murine epiphyseal cell system and to determine whether ADAMTS5 alone is responsible for aggrecanolysis by these cells. Epiphyseal cells from 4-day-old mice (wild type, TS-5 (-/-), CD44(-/-), syndecan-1(-/-), membrane type-4 matrix metalloproteinase [MT4MMP(-/-)]) were maintained in non-adherent aggregate cultures and aggrecanolysis studied by biochemical and histochemical methods. Confocal immunolocalization analyses were done with specific probes for ADAMTS5, hyaluronan (HA) and aggrecanase-generated fragments of aggrecan. Aggrecanolysis by these cells was specifically aggrecanase-mediated and it occurred spontaneously without the need for addition of catabolic stimulators. Chondrocytes from ADAMTS5-null mice were aggrecanase-inactive whereas all other mutant cells behaved as wild type in this regard suggesting that ADAMTS5 activity is not controlled by CD44, syndecan-1 or MT4MMP in this system. Immunohistochemical analysis supported the central role for ADAMTS5 in the degradative pathway and indicated that aggrecanolysis occurs primarily in the HA-poor pericellular region in these cultures. These findings are consistent with published in vivo studies showing that single-gene ADAMTS5 ablation confers significant protection on cartilage in murine arthritis. We propose that this culture system and the analytical approaches described provide a valuable framework to further delineate the expression, activity and control of ADAMTS-mediated aggrecanolysis in human arthritis.

ADAMTS4 (Aggrecanase-1) Activation on the Cell Surface Involves C-terminal Cleavage by Glycosylphosphatidyl Inositol-anchored Membrane Type 4-Matrix Metalloproteinase and Binding of the Activated Proteinase to Chondroitin Sulfate and Heparan Sulfate on Syndecan-1

C-terminal truncation of ADAMTS-4 from the p68 form to the p53 form is required for activation of its capacity to cleave the Glu(373)-Ala(374) interglobular domain bond of aggrecan. In transfected human chondrosarcoma cells, this process is not autoproteolytic because the same products form with an inactive mutant of ADAMTS4 (a disintegrin and metalloproteinase with thrombospondin-like motif 4) and truncation is completely blocked by tissue inhibitor of metalloproteinase-1. Instead, activation can be mediated by glycosylphosphatidyl inositol-anchored membrane type 4-matrix metalloproteinase (MT4-MMP, MMP-17) because co-transfection with the active form of MT4-MMP markedly enhanced activation, whereas an inactive mutant of MT4-MMP was ineffective. Treatment of co-transfected cells with phosphatidylinositol-specific phospholipase C liberated the complex of MT4-MMP and p68 ADAMTS4 from the cell membrane, but the p53 ADAMTS4 remained associated. Specific glycosaminoglycan lyase digestions, followed by product analyses using fluorescence-assisted carbohydrate electrophoresis and immunoprecipitation experiments, showed that the p53 form is associated with syndecan-1 through both chondroitin sulfate and heparan sulfate. We conclude that ADAMTS-4 activation in this cell system involves the coordinated activity of both glycosylphosphatidyl inositol-anchored MT4-MMP and the proteoglycan form of syndecan-1 on the cell surface.

Expression of membrane type-4 matrix metalloproteinase (metalloproteinase-17) by human eosinophils

Circulating eosinophils need proteinases to mediate a spatially limited and orientated digestion of the extracellular matrix and to migrate into tissue. Moreover, proteinases are likely involved in tissue remodeling, a crucial feature of chronic diseases including asthma. Eosinophils express matrix metalloproteinase (MMP)-9, which is increased upon stimulation with TNF-α. Other MMPs, the membrane type (MT)-MMPs, likely play a major role in cell invasion and tissue remodeling. MT4-MMP was identified in peripheral blood leukocyte preparations, but it is not known whether eosinophils express MT4-MMP. We investigated the expression of MT4-MMP and its modulation by TNF-α in purified human blood eosinophils. The constitutive expression of MT4-MMP mRNA was detected by RT-PCR in unstimulated eosinophils, lymphocytes, and monocytes, but not neutrophils. Stimulation of eosinophils with TNF-α increased MT4-MMP mRNA expression. This effect appeared at 4 h and reached a maximum at 8 h of incubation. MT4-MMP protein was detected in freshly isolated blood eosinophils by Western blotting and immunocytochemistry. TNF-α increased expression of the MT4-MMP protein. MT4-MMP protein was also detected in nasal polyp eosinophils by immunohistochemistry. In conclusion, eosinophils constitutively express MT4-MMP, which is increased upon stimulation with TNF-α. Consequently, MT4-MMP may be directly involved in the degradation of extracellular matrix components and/or modulate the activity of other proteins implicated in eosinophil migration and tissue remodeling.

Membrane Type 4 Matrix Metalloproteinase (MMP17) Has Tumor Necrosis Factor-α Convertase Activity but Does Not Activate Pro-MMP2

Membrane type 4 matrix metalloproteinase (MT4-MMP) shows the least sequence homology to the other MT-MMPs, suggesting a distinct function for this protein. We have isolated a complete cDNA corresponding to the mouse homologue which includes the signal peptide and a complete pro-domain, features that were lacking from the human form originally isolated. Mouse MT4-MMP (mMT4-MMP) expressed in COS-7 cells is located at the cell surface but does not show ability to activate pro-MMP2. The pro-catalytic domain was expressed in Escherichia coli as insoluble inclusions and active enzyme recovered after refolding. Activity of the isolated catalytic domain against synthetic peptides commonly used for MMP enzyme assays could be inhibited by TIMP1, -2, and -3. The recombinant mMT4-MMP catalytic domain was also unable to activate pro-MMP2 and was very poor at hydrolyzing components of the extracellular matrix with the exception of fibrinogen and fibrin. mMT4-MMP was able to hydrolyze efficiently a peptide consisting of the pro-tumor necrosis factor alpha (TNFalpha) cleavage site, a glutathione S-transferase-pro-TNFalpha fusion protein, and was found to shed pro-TNFalpha when co-transfected in COS-7 cells. MT4-MMP was detected by Western blot in monocyte/macrophage cell lines which in combination with its fibrinolytic and TNFalpha-converting activity suggests a role in inflammation.

Human membrane type-4 matrix metalloproteinase (MT4-MMP) is encoded by a novel major transcript: isolation of complementary DNA clones for human and mouse mt4-mmp transcripts

Five distinct membrane-type matrix metalloproteinases (MT-MMP) have been reported by cDNA cloning. However, the mt4-mmp gene product (MMP-17) has not been identified yet in spite of the cDNA isolation [Puente et al. (1996), Cancer Res. 56, 944–949]. In this study, we re-examined the transcripts for human mt4-mmp by 5′ RACE and identified two types of transcripts. The minor one corresponded to the cDNA reported by Puente et al. and failed to express protein, and the other is the major transcript that has an extended open reading frame and expressed 67 and 71 kDa translation products. Thus, functional mt4-mmp has been identified for the first time.