Cloning of a human gene potentially encoding a novel matrix metalloproteinase having a C-terminal transmembrane domain

Protein Ligation and Labeling Enabled by a C-Terminal Tetracysteine Tag

The hydrazinolysis of S-cyanylated peptide provides an alternative way to afford protein α-hydrazide, a key reagent used in native chemical ligation (NCL), without the aid of any inteins or enzymes. The currently used non-selective S-cyanylation, however, allows no other cysteine in the protein besides the one at the cleavage site. Herein, we report a regioselective S-cyanylation and hydrazinolysis strategy achieved via the fusion of a tetracysteine tag to the C-terminal of the protein of interest. We term it tetracysteine enabled protein ligation (TCEPL). While highly selective, the strategy is applicable for proteins expressed as inclusion bodies, and this was showcased by the efficient semi-synthesis of an iron-sulfur protein rubredoxin and the catalytic and hinge domains of matrix metalloprotease-14 (MMP-14) containing 207 amino acid residues. Furthermore, the TCEPL strategy was exploited for protein C-terminal labeling with amino reagents bearing a variety of functional groups, demonstrating its versatility and generality.

Multicentric osteolytic syndromes represent a phenotypic spectrum defined by defective collagen remodeling

Frank-Ter Haar syndrome (FTHS), Winchester syndrome (WS), and multicentric osteolysis, nodulosis, and arthropathy (MONA) are ultra-rare multisystem disorders characterized by craniofacial malformations, reduced bone density, skeletal and cardiac anomalies, and dermal fibrosis. These autosomal recessive syndromes are caused by homozygous mutation or deletion of respectively SH3PXD2B (SH3 and PX Domains 2B), MMP14 (matrix metalloproteinase 14), or MMP2. Here, we give an overview of the clinical features of 63 previously reported patients with an SH3PXD2B, MMP14, or MMP2 mutation, demonstrating considerable clinical overlap between FTHS, WS, and MONA. Interestingly, the protein products of SH3PXD2B, MMP14, and MMP2 directly cooperate in collagen remodeling. We review animal models for these three disorders that accurately reflect the major clinical features and likewise show significant phenotypical similarity with each other. Furthermore, they demonstrate that defective collagen remodeling is central in the underlying pathology. As such, we propose a nosological revision, placing these SH3PXD2B, MMP14, and MMP2 related syndromes in a novel "defective collagen-remodelling spectrum (DECORS)". In our opinion, this revised nosology better reflects the central role for impaired collagen remodeling, a potential target for pharmaceutical intervention.

Detection of a latent soluble form of membrane type 1 matrix metalloprotease bound with tissue inhibitor of matrix metalloproteinases-2 in periprosthetic tissues and fluids from loose arthroplasty endoprostheses

Membrane type 1 matrix metalloproteinase (MT1-MMP) is implicated in pericellular proteolysis, and, together with tissue inhibitor of matrix metalloproteinases-2 (TIMP-2), in the activation of pro-matrix metalloproteinase-2 on the cell surface. It is expressed on the cell surface either activated or as a proenzyme. A soluble form of MT1-MMP (sMT1-MMP) has been previously identified in periprosthetic tissues and fluid of patients with loose arthroplasty endoprostheses. The aim of this study was to examine periprosthetic tissues and fluids from patients with loose arthroplasty endoprostheses, as well as tissues and fluids from patients with other disorders, for the presence of sMT1-MMP, and to investigate its activation state and possible role. With antibody against MT1-MMP, a protein with molecular mass of ~ 57 kDa was detected by western blotting in all samples tested, representing a soluble form of MT1-MMP, which cannot be ascribed to alternative splicing, as northern blotting showed only one transcript. With various biochemical methods, it was shown that this species occurs in a latent form bearing the N-terminal prodomain, and, additionally, it is bound to TIMP-2, which appeared to be bound via its C-terminal domain to a site different from the active site. Cell ELISA and immunohistochemical analysis revealed that, besides fibroblasts, all other cells, such as inflammatory, epithelial, endothelial, giant and cancer cells, express MT1-MMP on their plasma membrane as a proenzyme. Taking into account the proteolytic abilities of MT1-MMP, the latent sMT1-MMP-TIMP-2 complex could be considered as a new interstitial collagenase. However, the exact role, the production mechanism and the cell origin of this complex remain to be elucidated.

Looking at the proteases from a simple perspective

Proteases have received enormous interest from the research and medical communities because of their significant roles in several human diseases. Some examples include the involvement of thrombin in thrombosis, HIV-1 protease in Acquired Immune Deficiency Syndrome, cruzain in Trypanosoma cruzi infection, and membrane-type 1 matrix metalloproteinase in tumor invasion and metastasis. Many efforts has been undertaken to design effective inhibitors featuring potent inhibitory activity, specificity, and metabolic stability to those proteases involved in such pathologies. Protease inhibitors usually target the active site, but some of them act by other inhibitory mechanisms. The understanding of the structure-function relationships of proteases and inhibitors has an impact on new inhibitor drugs designing. In this paper, the structures of four proteases (thrombin, HIV-protease, cruzain, and a matrix metalloproteinase) are briefly reviewed, and used as examples of the importance of proteases for the development of new treatment strategies, leading to a longer and healthier life.

Matrix metalloproteinase-14 mediates a phenotypic shift in the airways to increase mucin production

RATIONALE

Induced mainly by cigarette smoking, chronic obstructive pulmonary disease (COPD) is a global public health problem characterized by progressive difficulty in breathing and increased mucin production. Previously, we reported that acrolein levels found in COPD sputum could activate matrix metalloproteinase-9 (MMP9).

OBJECTIVES

To determine whether acrolein increases expression and activity of MMP14, a critical membrane-bound endopeptidase that can initial a MMP-activation cascade.

METHODS

MMP14 activity and adduct formation were measured following direct acrolein treatment. MMP14 expression and activity was measured in human airway epithelial cells. MMP14 immunohistochemistry was performed with COPD tissue, and in acrolein- or tobacco-exposed mice.

MEASUREMENTS AND MAIN RESULTS

In a cell-free system, acrolein, in concentrations equal to those found in COPD sputum, directly adducted cysteine 319 in the MMP14 hemopexin-like domain and activated MMP14. In cells, acrolein increased MMP14 activity, which was inhibited by a proprotein convertase inhibitor, hexa-d-arginine. In the airway epithelium of COPD subjects, immunoreactive MMP14 protein increased. In mouse lung, acrolein or tobacco smoke increased lung MMP14 activity and protein. In cells, acrolein-induced MMP14 transcripts were inhibited by an epidermal growth factor receptor (EGFR) neutralizing antibody, EGFR kinase inhibitor, metalloproteinase inhibitor, or mitogen-activated protein kinase (MAPK) 3/2 or MAPK8 inhibitors, but not a MAPK14 inhibitor. Decreasing the MMP14 protein and activity in vitro by small interfering (si)RNA to MMP14 diminished the acrolein-induced MUC5AC transcripts. In acrolein-exposed mice or transgenic mice with lung-specific transforming growth factor-alpha (an EGFR ligand) expression, lung MMP14 and MUC5AC levels increased and these effects were inhibited by a EGFR inhibitor, erlotinib.

CONCLUSIONS

Taken together, these findings implicate acrolein-induced MMP14 expression and activity in mucin production in COPD.

Coordinated elevation of membrane type 1-matrix metalloproteinase and matrix metalloproteinase-2 expression in rat uterus during postpartum involution

BACKGROUND

The changes occurring in the rodent uterus after parturition can be used as a model of extensive tissue remodeling. As the uterus returns to its prepregnancy state, the involuting uterus undergoes a rapid reduction in size primarily due to the degradation of the extracellular matrix, particularly collagen. Membrane type-I matrix metalloproteinase (MT1-MMP) is one of the major proteinases that degrades collagen and is the most abundant MMP form in the uterus. Matrix metalloproteinase-2(MMP-2) can degrade type I collagen, although its main function is to degrade type IV collagen found in the basement membrane. To understand the expression patterns of matrix metalloproteinases (MMPs) in the rat uterus, we analyzed their activities in postpartum uterine involution.

METHODS

We performed gelatin zymography, northern blot analysis and immunohistochemistry to compare the expression levels of MT1-MMP, MMP-2, matrix metalloproteinase-9 (MMP-9) and the tissue inhibitors of MMPs-1 and 2 (TIMP-1 and TIMP-2) in the rat uterus 18 h, 36 h and 5 days after parturition with their expression levels during pregnancy (day 20).

RESULTS

We found that both MT1-MMP and MMP-2 localized mainly in the cytoplasm of uterine interstitial cells. The expression levels of MT1-MMP and MMP-2 mRNAs and the catalytic activities of the expressed proteins significantly increased 18 h and 36 h after parturition, but at postpartum day 5, their mRNA expression levels and catalytic activities decreased markedly. The expression levels of MMP-9 increased 18 h and 36 h after parturition as determined by gelatin zymography including the expression levels of TIMP-1 and TIMP-2.

CONCLUSION

These expression patterns indicate that MT1-MMP, MMP-2, MMP-9, TIMP-1 and TIMP-2 may play key roles in uterine postpartum involution and subsequent functional regenerative processes.

Membrane associated proteases and their inhibitors in tumour angiogenesis

Cell surface proteolysis is an important mechanism for generating biologically active proteins that mediate a range of cellular functions and contribute to biological processes such as angiogenesis. Although most studies have focused on the plasminogen system and matrix metalloproteinases (MMPs), recently there has been an increase in the identification of membrane associated proteases, including serine proteases, ADAMs, and membrane-type MMPs (MT-MMPs). Normally, protease activity is tightly controlled by tissue inhibitors of MMPs (TIMPs) and plasminogen activator inhibitors (PAIs). The balance between active proteases and inhibitors is thought to determine the occurrence of proteolysis in vivo. High concentrations of proteolytic system components correlate with poor prognosis in many cancers. Paradoxically, high (not low) PAI-1 or TIMP concentrations predict poor survival in patients with various cancers. Recent observations indicate a much more complex role for protease inhibitors in tumour progression and angiogenesis than initially expected. As knowledge in the field of protease biology has improved, the unforeseen complexities of cell associated enzymes and their interaction with physiological inhibitors have emerged, often revealing unexpected mechanisms of action.

Altered NPY and AgRP in membrane type-1 matrix metalloproteinase-deficient mice

Membrane-type-1 matrix metalloproteinase (MT1-MMP) knockout (KO) mice fail to gain weight and die 3-4 weeks after birth. To understand the wasting phenotype in MT1-MMP-KO mice we studied the expression of some hypothalamic neuropeptides involved in control of appetite and body weight. In MT1-MMP-KO mice, neuronal perikarya in the arcuate nucleus displayed accumulations of NPY and agouti-related protein (AgRP) immunoreactivity (-ir). In contrast, NPY-ir and AgRP-ir were reduced in the projection areas of the arcuate neurons. NPY and AgRP are known to relay metabolic signals from the periphery into the brain to stimulate body weight gain. Their altered subcellular distribution suggests that MT1-MMP is involved in postnatal development of the arcuate NPY/AgRP-system which may contribute to the generation of the wasting phenotype.

Membrane Type 1 Matrix Metalloproteinase Regulates Collagen-Dependent Mitogen-Activated Protein/Extracellular Signal-Related Kinase Activation and Cell Migration

Mitogen-activated protein kinase-extracellular signal-related kinase (ERK) kinase 1 (MEK1)/ERK signaling has been implicated in the regulation of tumor cell invasion and metastasis. Migration of HT1080 cells on type I collagen was suppressed by the matrix metalloproteinase (MMP) inhibitors BB94 and tissue inhibitor of metalloproteinase (TIMP)-2 but not by TIMP-1. TIMP-2-specific inhibition suggests that membrane type 1 MMP (MT1-MMP) is likely involved in this process. Activation of ERK was induced in HT1080 cells adhered on dishes coated with type I collagen, and this was inhibited by BB94. MMP-2 processing in HT1080 cells, which also was stimulated by cultivation on type I collagen, was inhibited by MEK inhibitor PD98059. Expression of a constitutively active form of MEK1 promoted MMP-2 processing concomitant with the increase of MT1-MMP levels, suggesting that MT1-MMP is regulated by MEK/ERK signaling. In addition, expression of the hemopexin-like domain of MT1-MMP in HT1080 cells interfered with MMP-2 processing, ERK activation, and cell migration, implying that the enzymatic activity of MT1-MMP is involved in collagen-induced ERK activation, which results in enhanced cell migration. Thus, adhesion of HT1080 cells to type I collagen induces MT1-MMP-dependent ERK activation, which in turn causes an increase in MT1-MMP levels and subsequent cell migration.

Doxycycline decreases proteinuria in glomerulonephritis

Treatment options for crescentic glomerulonephritis include the use of steroids, cytotoxic therapy, and, in severe cases, intravenous immunoglobulins and plasmapheresis. Injury and lysis of capillary glomerular basement membrane, which is made up of type IV collagen, laminin, fibronectin, and proteoglycans, by serine proteinases and matrix metalloproteinases (MMPs) likely is an important participant in the pathogenesis of crescentic glomerulonephritis. Tetracycline derivatives inhibit not only the activity of MMPs, but also their production, and have been investigated for the treatment of disorders in which the MMP system becomes amplified, such as degenerative osteoarthritis, periodontitis, cancer, and abdominal aortic aneurysm. We report an interesting case of crescentic glomerulonephritis in a young man who was treated with cyclophosphamide and prednisone. The patient developed steroid-induced acne that was treated with long-term oral doxycycline therapy. During the period the patient was administered doxycycline, proteinuria decreased by 70% and recurred when doxycycline was stopped. To our knowledge, this is the first report of possible benefits of a metalloproteinase inhibitor (doxycycline) in glomerulonephritis in humans. Future studies are urgently required to explore the option of metalloproteinase inhibitors in the treatment of proliferative glomerulonephritis.

Membrane-type 1 matrix metalloproteinase: a key enzyme for tumor invasion

Matrix metalloproteinases (MMPs) are believed to play a pivotal role in malignant behavior of cancer cells such as rapid tumor growth, invasion, and metastasis by degrading extracellular matrix (ECM). Different types of synthetic inhibitors against MMPs (MMPIs) were developed as candidates for anti-cancer therapeutics and so far clinical trials had led to no significant success. However, this does not diminish the importance of MMPs in the malignancy of cells. Details about MMPs, specifically when and how they take part in the development of cancer are necessary for more advanced application of MMPIs. In this paper, we summarize recent knowledge about membrane-type 1 matrix metalloproteinase (MT1-MMP) which is expressed on cancer cell surface as an invasion-promoting proteinase. By localizing at the leading edge of invasive cancer cells, MT1-MMP degrades components of the tissue barriers. One of the major targets is type I collagen, the most abundant ECM component. Although MT1-MMP itself cannot degrade type IV collagen in the basement membrane, it binds to and activates proMMP-2, one of the type IV collagenases. However, degradation of the ECM is not the sole function of MT1-MMP. MT1-MMP also regulates cell-ECM interaction by processing cell adhesion molecules such as CD44 and integrin alphav chain, and eventually promotes cell migration as well. In addition to the transcriptional regulation, invasion-promoting activity of the MT1-MMP is also strictly monitored at the post-translational level. Precise knowledge about the regulation will give us insight to develop new methods for treating invasive cancer patients.

The expression of novel membrane-type matrix metalloproteinase isoforms is required for normal development of zebrafish embryos

Matrix metalloproteinases (MMPs) play important roles in the turnover of components of extracellular matrix (ECM) and in the processing of active and latent-signaling molecules bound to the ECM or associated with the cell surface. Through such actions, MMPs regulate a variety of cellular and developmental processes. Membrane-type matrix metalloproteinases (MT-MMPs) are of particular importance because they function in the immediate pericellular environment that modulates both cell-cell and cell-ECM interactions. In this study, we utilized zebrafish as a developmental model to study the role of MT-MMPs during early embryogenesis. We successfully isolated two isoforms of a MT-MMP homologue that are structurally similar to MT1-MMP. They have been named zebrafish MT-MMPalpha and beta. Zebrafish MT-MMPbeta is unique among vertebrate MT-MMPs in that it contains an Arg-Glu-Asp (RED) multiple-repeat motif in its linker region. Whole mount in situ analysis, RT-PCR, immunofluorescence, reporter analysis, Western blot analysis, and zymography indicated that MT-MMPalpha and beta were expressed through at least the first 72 h of development and that this expression was targeted to the cell surface. Functional studies using injection of either mRNA or morpholino antisense oligonucleotides resulted in a truncation of the cranial to caudal axis as monitored through 72 h post fertilization, indicating that zebrafish MT-MMPalpha and beta had an important role in embryonic development. Axis markers indicated that these effects likely involved processes occurring later than 10 h of embryogenesis.

Tetraspanin CD63 promotes targeting and lysosomal proteolysis of membrane-type 1 matrix metalloproteinase

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is known to be internalized from cell surface, however, the fate of internalized MT1-MMP is still unknown. Here we demonstrate that at least a part of internalized MT1-MMP is targeted for lysosomal proteolysis. Treatment with an inhibitor of lysosomal proteinases chloroquine suppressed degradation of internalized MT1-MMP and induced accumulation of MT1-MMP in CD63-positive lysosomes. Ectopic expression of CD63 accelerated degradation of MT1-MMP, which was blocked by chloroquine. MT1-MMP, and CD63 were shown to form a complex through hemopexin-like domain of MT1-MMP and N-terminal region of CD63, and thus accelerated degradation of MT1-MMP was not observed with mutants lacking these domains. CD63 mutant lacking lysosomal targeting motif was unable to promote MT1-MMP degradation. These results suggest that CD63 regulates MT1-MMP by targeting to lysosomes.

The LZT proteins; the LIV-1 subfamily of zinc transporters

Zinc is an essential ion for cells with a vital role to play in controlling the cellular processes of the cell, such as growth, development and differentiation. Specialist proteins called zinc transporters control the level of intracellular zinc in cells. In mammals, the ZIP family of zinc transporters has a pivotal role in maintaining the correct level of intracellular zinc by their ability to transport zinc into cells from outside, although they may also transport metal ions other than zinc. There are now recognised to be four subfamilies of the ZIP transporters, including the recently discovered LIV-1 subfamily which has similarity to the oestrogen-regulated gene LIV-1, previously implicated in metastatic breast cancer. We call this new subfamily LZT, for LIV-1 subfamily of ZIP zinc Transporters. Here we document current knowledge of this previously uncharacterised group of proteins, which includes the KE4 proteins. LZT proteins are similar to ZIP transporters in secondary structure and ability to transport metal ions across the plasma membrane or intracellular membranes. However, LZT proteins have a unique motif (HEXPHEXGD) with conserved proline and glutamic acid residues, unprecedented in other zinc transporters. The localisation of LZT proteins to lamellipodiae mirrors cellular location of the membrane-type matrix metalloproteases. These differences to other zinc transporters may be consistent with an alternative role for LZT proteins in cells, particularly in diseases such as cancer.

MMP-2 protein in invasive breast cancer and the impact of MMP-2/TIMP-2 phenotype on overall survival

Crucial event in the metastasis of cancer cells is the secretion of matrix metalloproteinases (MMPs), which are responsible for the degradation of extracellular matrix (ECM). Among them, matrix metalloproteinase-2 (MMP-2) is a gelatinase, which degrades basement membrane type-IV collagen. Immunohistochemistry was performed to detect MMP-2 protein in 135 infiltrative breast carcinomas. MMP-2 was studied along with clinicopathological parameters (tumor size, histological type, nuclear and histological grade, stage, lymph node status, ER, and PR), patients' survival and tissue inhibitor metalloproteinase-2 (TIMP-2), Ki-67, and p53 proteins. MMP-2 immunoreactivity was detected in the cytoplasm in cancer cells in 102 (75.6%) and in both tumor and tumor stromal cells in 37 (27.4%) of 135 cases respectively. MMP-2 reactivity in cancer cells displayed a statistically significant association with tumor size > 2 cm (p = 0.022). In tumor stromal cells a strong parallel association was observed between the expression of MMP-2 and TIMP-2 (p = 0.015), while an inverse correlation was found between MMP-2 and both Ki-67 and p53 (p = 0.033 and p = 0.034 respectively). In the subgroup with negative lymph nodes MMP-2 was also inversely associated with p53 in cancer cells (p = 0.045). Finally a statistically significant association was revealed using Kaplan-Meier and Cox's proportional hazard regression model between the MMP-2/TIMP-2 phenotype and patients' better survival (p = 0.021). Our results point out the strong relation between MMP-2 and TIMP-2 and the effect of the MMP-2/TIMP-2 phenotype in the patients' overall survival. The inverse correlation between MMP-2 and both Ki-67 and p53 can be explained by the potential inhibition of MMP-2 by TIMP-2. These results suggest the necessity of further investigation.

Collagen binding properties of the membrane type-1 matrix metalloproteinase (MT1-MMP) hemopexin C domain. The ectodomain of the 44-kDa autocatalytic product of MT1-MMP inhibits cell invasion by disrupting native type I collagen cleavage

Up-regulation of the collagenolytic membrane type-1 matrix metalloproteinase (MT1-MMP) leads to increased MMP2 (gelatinase A) activation and MT1-MMP autolysis. The autocatalytic degradation product is a cell surface 44-kDa fragment of MT1-MMP (Gly(285)-Val(582)) in which the ectodomain consists of only the linker, hemopexin C domain and the stalk segment found before the transmembrane sequence. In the collagenases, hemopexin C domain exosites bind native collagen, which is required for triple helicase activity during collagen cleavage. Here we investigated the collagen binding properties and the role of the hemopexin C domain of MT1-MMP and of the 44-kDa MT1-MMP ectodomain in collagenolysis. Recombinant proteins, MT1-LCD (Gly(285)-Cys(508)), consisting of the linker and the hemopexin C domain, and MT1-CD (Gly(315)-Cys(508)), which consists of the hemopexin C domain only, were found to bind native type I collagen but not gelatin. Functionally, MT1-LCD inhibited collagen-induced MMP2 activation in fibroblasts, suggesting that interactions between collagen and endogenous MT1-MMP directly stimulate the cellular activation of pro-MMP2. MT1-LCD, but not MT1-CD, also blocked the cleavage of native type I collagen by MT1-MMP in vitro, indicating an important role for the MT1-MMP linker region in triple helicase activity. Similarly, soluble MT1-LCD, but not MT1-CD or peptide analogs of the MT1-MMP linker, reduced the invasion of type I collagen matrices by MDA-MB-231 cells as did the expression of recombinant 44-kDa MT1-MMP on the cell surface. Together, these studies demonstrate that generation of the 44-kDa MT1-MMP autolysis product regulates collagenolytic activity and subsequent invasive potential, suggesting a novel feedback mechanism for the control of pericellular proteolysis.

Plasma concentration of tissue inhibitor of matrix metalloproteinase 1 in patients with colorectal carcinoma

BACKGROUND

The expression of tissue inhibitor of matrix metalloproteinase (TIMP) 1 in tumour tissue from patients with colorectal carcinoma has been reported to be related to disease progression. However, the clinical significance of plasma TIMP-1 has not been fully elucidated.

METHODS

The plasma level of TIMP-1 protein was determined by enzyme-linked immunosorbent assay in samples from 54 patients who underwent resection of the primary tumour.

RESULTS

Plasma TIMP-1 levels were associated significantly with depth of invasion and metastasis to lymph nodes and liver. Circulating TIMP-1 levels were significantly higher in patients with serosal invasion, liver metastases and Dukes' stage C tumours. Using a cut-off value of 160 ng/ml, serosal invasion and Dukes' C stage could be predicted with an accuracy of 68.5 per cent. With a cut-off value of 170 ng/ml, metastasis to the lymph node and liver could be predicted with an accuracy of 66.7 and 70.4 per cent respectively. These values were greater than those for carcinoembryonic antigen and CA19-9.

CONCLUSION

These data suggest that the plasma concentration of TIMP-1 correlates with both invasion and metastasis in patients with colorectal carcinoma.

Expression of a novel matrix metalloproteinase gene during Cynops early embryogenesis

Matrix metalloproteinases (MMPs) are thought to play important roles in the gastrulation of Cynops pyrrhogaster embryos. MMP cDNAs were cloned from Cynops pyrrhogaster and we report here a novel MMP called CyMMP, which has strong similarity to MMP-21 (XMMP) in Xenopus. Reverse transcription-polymerase chain reaction (RT-PCR) analysis demonstrated that CyMMP mRNA was already present in cleavage stage embryos. The amount of the mRNA then gradually decreased, but increased again starting in late gastrula. There were regional differences in the level of CyMMP mRNA expression at late gastrula: the involved archenteron roof was the predominant site of expression of the gene, while there was weak expression in the neuroectoderm and epidermal ectoderm. We also found that the gene was activated in artificially mesodermalized ectoderm. The present findings indicate that CyMMP mRNA expression is activated in differentiating mesoderm during gastrulation, suggesting that CyMMP plays a role in gastrulation-related cell movement.

Intratumoral concentrations of tissue inhibitor of matrix metalloproteinase 1 in patients with gastric carcinoma a new biomartker for invasion and its impact on survival

BACKGROUND

Previously, the authors clarified that the plasma concentration of tissue inhibitor of matrix metalloproteinase 1 (TIMP-1) in patients with gastric carcinoma was a significant predictor of tumor invasiveness and metastasis.

METHODS

To further clarify the clinical significance of TIMP-1, the authors used an enzyme-linked immunoassay to assess TIMP-1 protein concentrations in samples of tumor tissue from 86 patients who underwent primary resection for gastric carcinoma. Concentrations in samples of normal gastric mucosa from 73 of these patients also were assessed.

RESULTS

Tissue TIMP-1 concentrations were significantly greater in gastric tumors than in normal gastric mucosa and were associated significantly with a variety of pathologic factors, including macroscopic type, depth of tumor invasion in the gastric wall, presence of lymphatic vessel invasion, pattern of tumor infiltration into the surrounding tissue, and disease stage. Significantly greater TIMP-1 concentrations were found in tumors that were exposed to the serosal surface compared with tumors that were limited to the submucosal layer. TIMP-1 protein was significantly greater in tumors with lymphatic vessel invasion, an infiltrative pattern into the surrounding tissue (INF-gamma), and in tumors from patients with Stage III disease. Survival was significantly poorer in patients with TIMP-1 concentrations > or = 10.0 ng/mg total protein. When patients were stratified by disease stage, survival was significantly different in patients with Stage III disease. Multivariate analysis demonstrated that intratumoral concentrations of TIMP-1 were the most significant independent factor for survival.

CONCLUSIONS

These findings suggest that the intratumoral concentration of TIMP-1 protein may be a good indicator of tumor aggressiveness and can serve as a significant independent predictor of survival in patients with gastric carcinoma.

The propeptide domain of membrane type 1-matrix metalloproteinase acts as an intramolecular chaperone when expressed in trans with the mature sequence in COS-1 cells

It has been assumed that cleavage of the N-terminal propeptide domain of membrane type-1 matrix metalloproteinase (MT1-MMP) is required for enzyme function. We recently demonstrated that the propeptide domain of MT1-MMP is not cleaved and actually is required for function of the membrane-bound enzyme in transfected COS-1 cells (Cao, J., Drews, M., Lee, H. M., Conner, C., Bahou, W. F., and Zucker, S. (1998) J. Biol. Chem. 273, 34745-34752). In this report, we have inserted the cDNA encoding the signal and propeptide sequences of MT1-MMP (MT(1-109)) and the cDNA encoding propeptide-deleted mature MT1-MMP (MT delta pro) in expression vectors that were then transfected into matrix metalloproteinase-deficient COS-1 cells. Co-expression of both the mature sequence and the prosequence of MT1-MMP as independent polypeptides (in trans) in COS-1 cells resulted in reconstitution of MT1-MMP function in terms of facilitating (125)I-labeled tissue inhibitor of metalloproteinase 2 binding to transfected cells and subsequent activation of progelatinase A. Transfection of cells with either cDNA alone resulted in non-functional cells. These results are consistent with the propeptide sequence of MT1-MMP functioning as an intramolecular chaperone involved in protein folding and trafficking to the cell surface.

The role of matrix metalloproteinases in autoimmune damage to the central and peripheral nervous system

Members of the family of matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of inflammatory demyelination. MMPs apparently mediate important steps in the genesis of inflammatory demyelination, such as cell migration, blood-brain/nerve barrier breakdown, demyelination, and cytokine activation. This review will highlight in vitro as well as in vivo findings, which support the importance of this group of proteases in the pathogenesis of inflammatory demyelinating disorders of the central and peripheral nervous system.

Macrophage-derived MT1-MMP and increased MMP-2 activity are associated with glomerular damage in crescentic glomerulonephritis

Membrane-type matrix metalloproteinases (MT-MMPs) have been shown to activate pro-MMP-2 on the cell surface and are suggested to be key enzymes in tissue remodelling under various physiological and pathological conditions. To investigate the role of MT-MMP in progressive renal injury, the gene expression and enzymatic activity of MT-MMP were examined in crescentic glomerulonephritis induced by anti-glomerular basement membrane (GBM) antibody in WKY rats. Isolated glomeruli were subjected to RNA and protein extraction 0, 1, 3, 7, 14, and 28 days after intravenous injection of rabbit anti-GBM antibody. Semiquantitative RT-PCR analysis revealed that among the three members of the MT-MMP family, mRNA expression of MT2-MMP remained unchanged and that of MT3-MMP was not observed in glomeruli during the development of nephritis. However, MT1-MMP gene expression increased from day 3 and reached maximum levels at day 7 (5.5+/-0.7-fold increase over day 0), closely associated with macrophage accumulation, crescent formation, and increased proteinuria. Gelatin zymography showed that the active from of MMP-2 emerged from day 7 and remained during the experimental period accompanied by increased proMMP-2, while no active form of MMP-2 was found in control rats. Using an antisense cRNA probe, intense signals of MT1-MMP mRNA were observed mostly in cells within the crescent and in some cells in the mesangial areas. Most of these cells were ED-1-positive macrophages, based on immunostaining of sequential sections. These results suggested that in the MT-MMP family, MT1-MMP was induced in infiltrating macrophages during the development of crescentic glomerulonephritis and possibly contributed to pathological degradation of glomerular extracellular matrices through the activation of proMMP-2.

Cloning of MMP-26. A novel matrilysin-like proteinase

A cDNA encoding a novel human matrix metalloproteinase (MMP), named MMP-26, was cloned from fetal cDNA. The deduced 261-amino-acid sequence is homologous to macrophage metalloelastase (51.8% identity). It includes only the minimal characteristic features of the MMP family: a signal peptide, a prodomain and a catalytic domain. As with MMP-7, this new MMP does not comprise the hemopexin domain, which is believed to be involved in substrate recognition. A study of MMP-26 mRNA steady states levels reveals, among the tissue examined, a specific expression in placenta. MMP-26 mRNA could also be detected in several human cell lines such as HEK 293 kidney cells and HFB1 lymphoma cells. Recombinant MMP-26 was produced in mammalian cells and used to demonstrate a proteolytic activity of the enzyme on gelatin and beta-casein.

Prognostic value of tissue inhibitor of matrix metalloproteinase-1 in plasma of patients with gastric cancer

Tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in plasma has been reported to be related to disease progression in patients with gastric cancer. However, the prognostic significance of plasma TIMP-1 concentrations has not been clarified. Concentrations of TIMP-1 protein were measured by enzyme-linked immuno-sorbent assay in plasma samples of 147 preoperative patients who subsequently underwent gastric resection, and prognosis was compared. The cut-off value of plasma TIMP-1 concentrations was defined as 112.5 ng/ml, referring to the TIMP-1 levels in patients with intramucosal gastric cancer. Twenty-nine out of 147 patients had higher plasma TIMP-1 levels than the cut off value. When the patients were divided into those with elevated values and those with normal TIMP-1, such parameters as age, serosal invasion, metastases to lymph nodes, peritoneum, and liver, lymphatic invasion, curability, and stage were significantly different between the two. By univariate analysis of the factors affecting survival, macroscopic type, histology, serosal invasion, metastasis to lymph node, peritoneum, and liver, vessel invasions, curability, and plasma TIMP-1 were significant. However, multivariate analysis revealed that TIMP-1 was the only significant factor. In patients with gastric cancer, plasma TIMP-1 seem to be an independent and most powerful prognosticator for the survival.

A novel hydra matrix metalloproteinase (HMMP) functions in extracellular matrix degradation, morphogenesis and the maintenance of differentiated cells in the foot process

As a member of Cnidaria, the body wall of hydra is structurally reduced to an epithelial bilayer with an intervening extracellular matrix (ECM). Biochemical and cloning studies have shown that the molecular composition of hydra ECM is similar to that seen in vertebrates and functional studies have demonstrated that cell-ECM interactions are important to developmental processes in hydra. Because vertebrate matrix metalloproteinases (MMPs) have been shown to have an important role in cell-ECM interactions, the current study was designed to determine whether hydra has homologues of these proteinases and, if so, what function these enzymes have in morphogenesis and cell differentiation in this simple metazoan. Utilizing a PCR approach, a single hydra matrix metalloproteinase, named HMMP was identified and cloned. The structure of HMMP was similar to that of vertebrate MMPs with an overall identity of about 35%. Detailed structural analysis indicated some unique features in (1) the cysteine-switch region of the prodomain, (2) the hinge region preceding the hemopexin domain, and (3) the hemopexin domain. Using a bacterial system, HMMP protein was expressed and folded to obtain an active enzyme. Substrate analysis studies indicated that recombinant HMMP could digest a number of hydra ECM components such as hydra laminin. Using a fluorogenic MMP substrate assay, it was determined that HMMP was inhibited by peptidyl hydroxamate MMP inhibitors, GM6001 and matlistatin, and by human recombinant TIMP-1. Whole-mount in situ studies indicated that HMMP mRNA was expressed in the endoderm along the entire longitudinal axis of hydra, but at relatively high levels at regions where cell-transdifferentiation occurred (apical and basal poles). Functional studies using GM6001 and TIMP-1 indicated that these MMP inhibitors could reversibly block foot regeneration. Blockage of foot regeneration was also observed using antisense thio-oligo nucleotides to HMMP introduced into the endoderm of the basal pole using a localized electroporation technique. Studies with adult intact hydra found that GM6001 could also cause the reversible de-differentiation or inhibition of transdifferentiation of basal disk cells of the foot process. Basal disk cells are adjacent to those endoderm cells of the foot process that express high levels of HMMP mRNA. In summary, these studies indicate that hydra has at least one MMP that is functionally tied to morphogenesis and cell transdifferentiation in this simple metazoan.

Activation of human progelatinase A/promatrix metalloproteinase 2 by Escherichia coli-derived serine proteinase

Treatment of human uterine cervical fibroblasts with commercial lipopolysaccharide (LPS) preparations from different serotypes of Escherichia coli effectively augmented the processing of mammalian progelatinase A/promatrix metalloproteinase (proMMP)-2 to a 62-kDa form of MMP-2. When purified proMMP-2 was incubated with LPS preparations, the proenzyme was similarly processed into the 62-kDa active MMP-2 in a time- and dose-dependent manner. By contrast, progelatinase B/proMMP-9 and prostromelysin 1/proMMP-3 were not activated. A serine proteinase inhibitor, phenylmethylsulfonyl fluoride, completely interfered with this LPS-mediated activation of proMMP-2. This is novel evidence that E. coli serine proteinase is a specific activator of proMMP-2. Thus, it is very likely that E. coli infection plays a crucial role in the degradation of connective tissues via the activation of proMMP-2, and the resultant active MMP-2 participates in the dysfunction of connective tissues such as in the preterm rupture of fetal membranes.

Human membrane type-2 matrix metalloproteinase is defective in cell-associated activation of progelatinase A

Transfection of the mouse membrane type-2 matrix metalloproteinase (MT2-MMP) gene into COS-1 cells resulted in activation of progelatinase A; however, that of the human gene had no effect. Expression of human and mouse MT2-MMP chimeric proteins revealed the defect of human MT2-MMP which resides in the region between amino acid (aa) residues 155 and 271. Seven aa residues in this region were not conserved between human and mouse MT2-MMP. Substitution with the corresponding mouse residue, proline-183 to serine and glutamine-185 to aspartic acid, recovered cell-associated progelatinase A activation function. These residues are located in the insertion sequence-2 (IS-2), which was conserved in six clones of the human MT2-MMP gene from different sources, except that of proline-183 which was substituted with serine from HT1080 cells. These results indicate that human MT2-MMP is defective in cell-associated activation of progelatinase A, and this is attributed to IS-2. These findings emphasize the importance of IS-2 in MT2-MMP functionality.

Role of membrane-type matrix metalloproteinase 1 (MT-1-MMP), MMP-2, and its inhibitor in nephrogenesis

Extracellular matrix (ECM) proteins, their integrin receptors, and matrix metalloproteinases (MMPs), the ECM-degrading enzymes, are believed to be involved in various biological processes, including embryogenesis. In the present study, we investigated the role of membrane type MMP, MT-1-MMP, an activator pro-MMP-2, in metanephric development. Also, its relationship with MMP-2 and its inhibitor, TIMP-2, was studied. Since mRNAs of MT-1-MMP and MMP-2 are respectively expressed in the ureteric bud epithelia and mesenchyme, they are ideally suited for juxtacrine/paracrine interactions during renal development. Northern blot analyses revealed a single approximately 4.5-kb mRNA transcript of MT-1-MMP, and its expression was developmentally regulated. Inclusion of MT-1-MMP antisense oligodeoxynucleotide (ODN) in the culture media induced dysmorphogenetic changes in the embryonic metanephros. MMP-2 antisense ODN also induced similar changes, but they were relatively less; on the other hand TIMP-2 antisense ODN induced a mild increase in the size of explants. Concomitant exposure of MT-1-MMP and MMP-2 antisense ODNs induced profound alterations in the metanephroi. Treatment of TIMP-2 antisense ODN to metanephroi exposed to MT-1-MMP/MMP-2 antisense notably restored the morphology of the explants. Specificity of the MT-1-MMP antisense ODN was reflected in the selective decrease in its mRNA and protein expression. The MT-1-MMP antisense ODN also resulted in a failure in the activation of pro-MMP-2 to MMP-2. These findings suggest that the trimacromolecular complex of MT-1-MMP:MMP-2:TIMP-2 modulates the organogenesis of the metanephros, conceivably by mediating paracrine/juxtacrine epithelial:mesenchymal interactions.

Tissue inhibitor of matrix metalloproteinase-1 in the plasma of patients with gastric carcinoma. A possible marker for serosal invasion and metastasis

BACKGROUND

Expression of the tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in tumor tissue from patients with gastric carcinoma has been reported to be related to disease progression. However, to the authors' knowledge the clinical significance of plasma TIMP-1 concentrations in these patients has not been clarified.

METHODS

Concentrations of TIMP-1 protein were examined by enzyme-linked immunoadsorbent assay in plasma samples from 149 patients who underwent resection of their primary tumors and from 18 patients with nonresected or recurrent disease.

RESULTS

In the 149 patients whose primary tumors were resected, plasma TIMP-1 concentration was associated significantly with a variety of pathologic factors including macroscopic type, depth of invasion, lymph node and peritoneal metastases, vessel invasion, pattern of tumor infiltration into surround ing tissue, and disease stage. Plasma TIMP-1 concentration was significantly higher in patients with serosal invasion, lymph node metastasis, peritoneal dissemination, or liver metastasis than in those without these factors. Neither carcinoembryonic antigen (CEA) nor CA 19-9 concentrations appeared to be related to these measures of disease progression. In the 18 patients with nonresected or recurrent disease, TIMP-1, CEA, and CA 19-9 were similarly sensitive in predicting peritoneal, liver, and lymph node metastases. The combination of these three factors was able to detect 73.3% of patients with peritoneal metastasis, 83.3% of patients with liver metastasis, and 88.9% of patients with disease recurrence.

CONCLUSIONS

In patients with gastric carcinoma, plasma concentration of TIMP-1 appears to correlate with both serosal invasion and metastasis.

Expression of Mmp-9 and related matrix metalloproteinase genes during axolotl limb regeneration

One of the earliest events in limb regeneration is the extensive remodeling of the extracellular matrix (ECM). Matrix metalloproteinases (MMPs) are a family of matrix degrading enzymes that have been identified in both normal and disease states. Using RT-PCR and cDNA library screening, we have isolated sequences homologous to four different Mmp genes. The spatial and temporal expression of one of these, Mmp-9, has been analyzed during axolotl limb regeneration. Northern blot analysis identifies a 3.8 kb transcript that is abundantly expressed during regeneration, and whole-mount in situ hybridization has uncovered an unusual bi-phasic expression pattern. The first phase begins at 2 hours after amputation, and expression is confined to the healed wound epithelium. This phase continues for 2 days, showing peak expression at 14 hours after amputation. This early phase may be needed to retard reformation of the basal lamina of the epidermis, and thereby facilitate the epidermal-mesenchymal interactions required for successful regeneration. The second phase begins a few days later when a small blastema has formed. During this phase, expression is in the mesenchyme, localized to cells around the tips of the cut skeletal elements. This expression is maintained through several stages until redifferentiation begins. The timing and position of the second phase of expression is consistent with a role for Mmp-9 in the removal of damaged cartilage matrix. We have also discovered that the time of onset of Mmp-9 expression is sensitive to denervation, which causes a delay of several hours. Finally, retinoids, known for their dramatic effects on the pattern of regenerating limbs, can cause a down regulation of Mmp-9 expression. Dev Dyn 1999;216:2-9.

Membrane-type matrix metalloproteinase-1 expression and activation of gelatinase A as prognostic markers in advanced pediatric neuroblastoma

BACKGROUND

Recently a novel membrane-type matrix metalloproteinase-1 (MT-MMP-1) was discovered to be a specific activator of progelatinase A, and was correlated with tumor invasion. To the authors' knowledge, no information regarding the expression of MT-MMP-1 has been reported in childhood malignancies. In this study, the authors attempted to elucidate the specific mechanisms that underlay the invasive behavior of neuroblastoma (NB) cells with respect to the expression of MT-MMP-1 and its determined prognostic value, especially in pediatric patients with advanced Evans' Stage IV NB.

METHODS

Thirty specimens from surgically excised NB (mainly Stage IV) were collected retrospectively. The total levels of progelatinase A (68 kilodaltons [kD]) and its activated form (62 kD) in the tumor lysates were quantified by gelatin zymography. The expression of MT-MMP-1 was estimated by immunostaining with a monoclonal antibody (113-5B7).

RESULTS

Progelatinase A and the activated form were detected in each of the 30 specimens. The gelatinase A activation ratio, 62 kD/(62 kD + 68 kD), strongly correlated with the high levels of MT-MMP-1 expression found in specimens of advanced tumor stage. In the patients with advanced Stage IV NB, the activation ratio was strongly associated with unfavorable clinical outcome; the 5-year survival was 88.9% in the patients with a low activation ratio (< or = 26%) versus only 21.2% in the patients with a high activation ratio (>26%).

CONCLUSIONS

Gelatinase A activation correlates with high expression of MT-MMP-1 on NB cells and is associated strongly with advanced stage and poor clinical outcome. These results are consistent with the notion that MT-MMP-1 expression is an important prognostic determinant of the biologic behavior of NB.

Membrane-type matrix metalloproteinases

Matrix metalloproteinases (MMP) degrade components of extracellular matrix (ECM), and thereby regulate formation, remodeling and maintenance of tissue. Abnormal function of cell surface proteases associated with malignant tumors may contribute directly to the invasive and malignant nature of the cells. Among the MMP's associated with the tumor cell surface, gelatinase A is believed to be particularly important, since it degrades type IV collagen, and is activated in a tumor specific manner, correlating with tumor spread and poor prognosis. Activation of pro-gelatinase A is uniquely regulated by a cell-mediated mechanism. This study describes an in vitro model that mimics the cell-surface activation mechanism. The expression of MT-MMP could not be detected in normal epithelial cells, but can be seen in transformed epithelial carcinoma cells.

The propeptide domain of membrane type 1 matrix metalloproteinase is required for binding of tissue inhibitor of metalloproteinases and for activation of pro-gelatinase A

Activation of secreted latent matrix metalloproteinases (MMPs) is accompanied by cleavage of the N-terminal propeptide, thereby liberating the active zinc from binding to the conserved cysteine in the pro-domain. It has been assumed that an analogous mechanism is responsible for the activation of membrane type 1 MMP (MT1-MMP). Using recombinant wild-type MT1-MMP cDNA and mutant cDNAs transfected into COS-1 cells lacking endogenous MT1-MMP, we have examined the function of the propeptide domain of MT1-MMP. MT1-MMP was characterized by immunoblotting, surface biotinylation, gelatin substrate zymography, and 125I-tissue inhibitor of metalloproteinases 2 (TIMP-2) binding. In contrast to wild-type MT1-MMP-transfected COS-1 cells, transfected COS-1 cells containing a deletion of the N-terminal propeptide domain of MT1-MMP or a chimeric construction (substitution of the pro-domain of MT1-MMP with that of collagenase 3) were functionally inactive in terms of binding of 125I-labeled TIMP-2 to the cell surface and initiating the activation of pro-gelatinase A. These results support the concept that in its native plasma membrane-inserted form, the pro-domain of MT1-MMP plays an essential role in TIMP-2 binding and subsequent activation of pro-gelatinase A.

Human AIM-1: cDNA cloning and reduced expression during endomitosis in megakaryocyte-lineage cells

The rat AIM-1 gene encoding an Aurora- and Ipl1-like midbody-associated protein serine/threonine kinase has a mitotic regulator function playing a key role in the onset of cytokinesis during mitosis. This report presents a cDNA sequence and megakaryocytic differentiation-dependent expression profile of the human AIM-1 gene. The nucleotide sequences of the human AIM-1 were identified from cDNAs of three cell lines, including cervical carcinoma HeLa cells, colorectal tumor SW480 cells, and normal human diploid skin fibroblast NHDF cells, and no mutation was found. The expression levels of AIM-1 transcript were markedly reduced during differentiation into megakaryocytic cell lineage in human leukemia cells induced by 12-o-tetradecanoyl-phorbol-13-acetate (TPA), suggesting that the downregulation of AIM-1 contributes to the differentiation by repeated duplication of DNA without cytokinesis (endomitosis).

Membrane type 1-matrix metalloproteinase is involved in the formation of hepatocyte growth factor/scatter factor-induced branching tubules in madin-darby canine kidney epithelial cells

Matrix metalloproteinases (MMPs) are believed to be involved in morphogenesis. Association of MMPs in a model of kidney tubulogenesis was studied using Madin-Darby canine kidney (MDCK) epithelial cells in an in vitro morphogenetic system. MDCK cells form branching tubules in three-dimensional collagen gel matrix in the presence of hepatocyte growth factor (HGF). The addition of specific MMP inhibitor BB-94 and tissue inhibitor MMP (TIMP)-2 but not TIMP-1 to such collagen gel cultures reduced the formation of branching tubules induced by HGF. The induction of membrane-type 1-matrix metalloproteinase (MT1-MMP) mRNA expression was observed in MDCK cells cultured in the collagen gel. Stable expression of MT1-MMP antisense RNA interfered with the tubule formation of MDCK cells induced by HGF-collagen gel culture. These observations implicate MT1-MMP in kidney tubulogenesis and TIMP-2-specific inhibition suggests a direct role of MT1-MMP rather than a gelatinase A-mediated effect.

Protein tyrosine phosphorylation in signalling pathways leading to the activation of gelatinase A: activation of gelatinase A by treatment with the protein tyrosine phosphatase inhibitor sodium orthovanadate

Fibroblasts in monolayer culture secrete gelatinase A (MMP2; 72 kDa type IV collagenase) only in its proenzyme form. Unlike other secreted matrix metalloproteinases, progelatinase A is refractory to activation by serine proteinases. Disparate agents, including monensin, cytochalasin D, and concanavalin A, have been found to mediate the activation of gelatinase A zymogen secreted by fibroblast monolayers. Our finding that monensin-mediated activation can be reversed by the protein tyrosine kinase inhibitor genistein (Li et al., Experimental Cell Research 232 (1997) 332) prompted us to investigate the effect of the specific inhibitor of protein tyrosine phosphatases, sodium orthovanadate, on progelatinase A activation. Treatment of fibroblast monolayers with orthovanadate also results in the secretion of activated gelatinase A. This activation is dose- and time-dependent, requires protein synthesis, and is associated with cell membranes. Vanadate-mediated activation does not occur in the presence of herbimycin A, a protein tyrosine kinase inhibitor. As with progelatinase activation mediated by monensin, concanavalin A, and cytochalasin D, orthovanadate treatment results in increased synthesis of the membrane proteinase MT1-MMP, that can catalyze the activation of progelatinase A. Protein tyrosine kinase inhibitors are able to prevent the increase of MT1-MMP mRNA, as shown by Northern blot and RT-PCR. In addition, orthovanadate potentiates the effects of monensin and concanavalin A. While treatment with monensin or concanavalin A result only in an increase of the putative activator MT1-MMP, orthovanadate also reduces the production of the specific inhibitor TIMP-2. These experiments implicate protein tyrosine phosphorylation in the signal transduction pathways which lead to the activation of progelatinase A.

Tissue inhibitors of metalloproteinases and metalloproteinases in atherosclerosis

The ability of the metalloproteinases to degrade extracellular matrix proteins is essential for the matrix remodelling that occurs during infiltration of inflammatory cells, intimal thickening, angiogenesis and plaque rupture which are a result of atherosclerosis. Increased metalloproteinase activity therefore requires stimulation of metalloproteinase expression by cytokines and growth factors, activation of metalloproteinases, and downregulation of tissue inhibitors of metalloproteinases. In addition, metalloproteinases may influence atherosclerosis by processing of proteins involved in inflammation and cell growth and death and the tissue inhibitors of metalloproteinases may also play a less inhibitory role by influencing cell growth and apoptosis.

Differential expression and origin of membrane-type 1 and 2 matrix metalloproteinases (MT-MMPs) in association with MMP2 activation in injured human livers

Matrix metalloproteinase-2 (MMP2) activation is associated with basement membrane remodeling that occurs in injured tissues and during tumor invasion. The newly described membrane-type MMPs (MT-MMPs) form a family of potential MMP2 activators. We investigated the localization and steady-state levels of MT1-MMP and MT2-MMP mRNA, compared with those of MMP2 and tissue inhibitor of MMP-2 in 22 hepatocellular carcinomas, 12 liver metastases from colonic adenocarcinomas, 13 nontumoral samples from livers with metastases, 10 benign tumors, and 6 normal livers. MMP2 activation was analyzed by zymography in the same series. The expression of MT1-MMP mRNA and the activation of MMP-2 were increased in hepatocellular carcinomas, metastases, and cholestatic nontumoral samples. MT2-MMP mRNA was rather stable in the different groups. MT1-MMP mRNA levels, but not MT2-MMP mRNA, correlated with MMP-2 and tissue inhibitor of MMP-2 mRNA levels and with MMP2 activation. In situ hybridization showed that MT1-MMP mRNA was expressed in stromal cells, and MT2-MMP mRNA was principally located in both hepatocytes and biliary epithelial cells. Consistently, freshly isolated hepatocytes expressed only MT2-MMP mRNA, and culture-activated hepatic stellate cells showed high levels of MT1-MMP mRNA. These results indicate that in injured livers, MMP2 activation is related to a coordinated high expression of MMP2, tissue inhibitor of MMP-2, and MT1-MMP. Furthermore, the finding of a preferential expression of MT2-MMP in hepatocytes, together with our previous demonstration that the activation of stellate cell-derived MMP2 in co-culture requires interactions with hepatocytes (Am J Pathol 1997, 150:51-58), suggests that parenchymal cells might play a pivotal role in the MMP2 activation process.

Regulation of matrix metalloproteinase-2 (gelatinase A, MMP-2), membrane-type matrix metalloproteinase-1 (MT1-MMP) and tissue inhibitor of metalloproteinases-2 (TIMP-2) expression by elastin-derived peptides in human HT-1080 fibrosarcoma cell line

Soluble kappa-elastin peptides were shown to stimulate the expression of MMP-2 (but not MMP-9) by human fibrosarcoma HT-1080 cells, both at the protein and mRNA levels; maximal effect being observed at a concentration of 25 microg/ml of kappa-elastin. The stimulatory effect could be reproduced using Val-Gly-Val-Ala-Pro-Gly (VGVAPG) peptide, an elastin-derived hydrophobic hexapeptide which represented the elastin receptor binding sequence of tropoelastin. Furthermore, treatment of cells with lactose (30 mM), which dissociated 67-kDa elastin binding protein (EBP) from cell surfaces, completely abolished this effect, suggesting that the elastin receptor could mediate such a response. Using a specific monoclonal antibody, 67-kDa EBP was detected in HT-1080 membrane preparations by Western immunoblotting. Following treatment with 25 microg/ml kappa-elastin or 200 microg/ml VGVAPG, increased levels of the active 62-kDa form of MMP-2 were found in HT-1080 cell extracts. Stimulation of MT1-MMP mRNA expression by treatment with elastin-derived peptides (EDPs) was shown by competitive polymerase chain reaction (PCR). A reverse zymography analysis revealed that EDPs also stimulated TIMP-2 (but not TIMP-1) production by HT-1080 cells. Competitive PCR confirmed increased TIMP-2 mRNA expression by such treatment. These results suggest that occupancy of the 67-kDa elastin receptor by elastin-derived peptides enhanced both expression and activation of proMMP-2 and consequently, could promote the invasive/metastatic ability of tumor cells expressing this receptor.

Roles of the matrix metalloproteinases in mammary gland development and cancer

Tissue remodeling is a key process involved in normal development, wound healing, bone remodeling, and embryonic implantation, as well as pathological conditions such as tumor invasion and metastasis, and angiogenesis. The degradation of the extracellular matrix that is associated with those processes is mediated by a number of families of extracellular proteinases. These families include the serine proteinases, such as the plasminogen-urokinase plasminogen activator system and leukocyte elastases, the cysteine proteinases, like cathepsin D and L, and the zinc-dependent matrix metalloproteinases (MMPs) [1]. Accumulating evidence has highlighted the central role of MMP-driven extracellular matrix remodeling in mammary gland development and breast cancer.

TIMP-2 promotes activation of progelatinase A by membrane-type 1 matrix metalloproteinase immobilized on agarose beads

Membrane-type 1 matrix metalloproteinase (MT1-MMP)/MMP-14 is the activator of progelatinase A (proGelA)/proMMP-2 on the cell surface. However, it was a paradox that a tissue inhibitor of metalloproteinase-2 (TIMP-2), which is an inhibitor of MT1-MMP, is required for proGelA activation by the cells expressing MT1-MMP. In this study, a truncated MT1-MMP having a FLAG-tag sequence at the C terminus (MT1-F) was immobilized onto agarose beads (MT1-F/B) and used to analyze the role of TIMP-2. The proteolytic activity of MT1-F/B against a synthetic peptide substrate was inhibited by TIMP-2 in a dose-dependent manner. In contrast, TIMP-2 promoted the processing of proGelA by MT1-F/B at low concentrations and inhibited it at higher concentrations. TIMP-2 promoted the binding of proGelA to the MT1-F on the beads by forming a trimolecular complex, which was followed by processing of proGelA. A stimulatory effect of TIMP-2 was observed under conditions in which unoccupied MT1-F was still available. Thus, the ternary complex is thought to act as a means to concentrate the substrate to the bead surface and to present it to the neighboring free MT1-F.

Cloning of three Caenorhabditis elegans genes potentially encoding novel matrix metalloproteinases

Three genes potentially encoding novel matrix metalloproteinases (MMPs) were identified by sequence similarity searching of Caenorhabditis elegans genome database, and cDNAs for these MMPs were cloned. The predicted gene products (MMP-C31,-H19 and -Y19) display a similar domain organization to human MMPs. MMP-H19 and -Y19 are unique in that they have an RXKR motif between the propeptide and catalytic domains that is a furin-like cleavage site, and conserved only in stromelysin-3 and membrane-type MMPs. The amino acid sequence homology with MMP-1/human interstitial collagenase at the catalytic domain is 45%, 34% and 23% for MMP-C31, -H19 and -Y19, respectively. Recombinant proteins of C. elegans MMPs cleaved an MMP peptide substrate with efficiency proportional to their amino acid homology with human MMPs. Digestion of gelatin was observed only with MMP-C31. Enzyme activity of MMP-C31 and -H19 was inhibited by human tissue inhibitor of MMPs (TIMP)-1, TIMP-2 and synthetic MMP inhibitors, BB94 and CT543, indicating that the catalytic sites of these C. elegans MMPs are structurally closely related with those of mammalian MMPs.