Expression of membrane-type matrix metalloproteinase-1 in human pancreatic adenocarcinomas

The expression of a new type of matrix metalloproteinase, membrane-type matrix metalloproteinase-1 (MT-MMP-1), was examined in 24 cases of primary pancreatic adenocarcinomas and 9 cases of secondary liver tumors derived from pancreatic adenocarcinomas, using a non-radioactive in situ hybridization and immunohistochemical methods. Out of 24 cases of primary pancreatic adenocarcinomas, 18 showed positive expression of MT-MMP-1 transcripts in cancer cells and 20 of 24 showed positive expression in the tumor stromal cells. The immunoreactivity of the gene products for MT-MMP-1 was demonstrated to be almost the same, as shown by in situ hybridization in these 24 cases. In particular, both the staining intensity for MT-MMP-1 transcripts and the immunoreactivity of the gene products in the tumor stromal cells of mucinous cystadenocarcinomas were significantly weaker than those of common-type ductal adenocarcinomas among the 24 cases. All of the 9 cases of secondary liver tumors derived from pancreatic adenocarcinomas showed positive expression for MT-MMP- transcripts but less immunoreactivity for the gene products. These results suggest that MT-MMP-1 is transcribed and translated in both cancer cells and the tumor stromal cells in human pancreatic adenocarcinomas. Furthermore, considering that common-type ductal adenocarcinoma of the pancreas usually shows a strong desmoplastic reaction, while mucinous cystadenocarcinoma typically does not, MT-MMP-1 expressed in the tumor stromal cells of common-type adenocarcinomas may be involved in processes leading to the desmoplastic reaction.

The Ets-1 and Ets-2 transcription factors activate the promoters for invasion-associated urokinase and collagenase genes in response to epidermal growth factor

Urokinase plasminogen activator (uPA) has been associated with invasion and metastasis in breast cancer. The expression of uPA and 92 kDa type IV collagenase (gelatinase B/MMP-9) is regulated by growth factors, receptor-type tyrosine kinases and cytoplasmic oncoproteins. Here, we have identified transcriptional requirements for the induction of uPA and 92 kDa type IV collagenase by epidermal growth factor (EGF). EGF stimulates the motile and invasive activities specifically in the ErbB-2-overexpressing SK-BR-3 cells. Expression of extracellular matrix-degrading proteases including type I collagenase/MMP-1, 92 kDa type IV collagenase/MMP-9, uPA and uPA receptor were induced. EGF also transiently stimulated expression of the transcription factors Ets-1 and Ets-2. Reporter transfection assays revealed the activation of uPA and MMP-9 collagenase promoters by EGF and the requirement of each of the composite Ets and AP-1 transcription factor binding sites for an EGF response. Most notably, transfections with the Ets-1 and Ets-2 expression vectors potentiated uPA and MMP-9 promoter activation in response to EGF. Mutation of the threonine 75 residue of chicken Ets-2 conserved in the Pointed group of the Ets family proteins abrogated the ability of Ets-2 to collaborate with EGF. Ets-1 and Ets-2 were highly expressed in invasive breast tumor cell lines. Our results suggest that Ets-1 and Ets-2 provide the link connecting EGF stimuli with activation of uPA and 92 kDa type IV collagenase promoters and may contribute to invasion phenotypes.

Membrane-type 1 MMP (MMP-14) cleaves at three sites in the aggrecan interglobular domain

An aggrecan G1-G2 substrate was used to determine sites within the interglobular domain that were susceptible to cleavage by MT1-MMP. Degradation products were identified by Western blotting with neo-epitope antibodies specific for MMP-derived N- and C-terminal sequences. The results showed that MT1-MMP cleaved at the N341-F342 and D441-L442 bonds, as shown for other MMPs, and also at a site 13 amino acids C-terminal to the N341-F342 site. The G2 product of this additional cleavage was identified by sequence analysis and revealed an N-terminus commencing T355VxxPDVELPLP. The data are consistent with MT1-MMP cleavage at three sites in the aggrecan interglobular domain; one at N342-F342, a second at D441-L442 and a third at Q354-T355.

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.

Transformation of epithelial Madin-Darby canine kidney cells with p60(v-src) induces expression of membrane-type 1 matrix metalloproteinase and invasiveness

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is expressed both in carcinoma cells and in surrounding stromal fibroblasts. MT1-MMP localizes to the surface of tumor cells and is thought to play an important role in tumor invasion. To analyze the mechanism of MT1-MMP gene expression in epithelial tumor cells, the dog kidney epithelial cell line Madin-Darby canine kidney (MDCK) was transformed by oncogenes, including v-src, and expression of MT1-MMP was examined. Transformation of MDCK cells with v-src resulted in loss of cell-to-cell contacts and morphological change. Expression of MT1-MMP in v-src-transformed cells was identified by Northern and Western blotting. Gelatin zymography analysis showed that progelatinase A in the culture medium was processed from latent to activated form by MDCK cells transformed with v-src. The MDCK cells transformed by v-src were tumorigenic in the subcutis (ectopic) and kidney (orthotopic) of nude mice and spontaneously metastasized to the lung after orthotopic implantation. These results suggest that MT1-MMP induced by v-src transformation may promote invasiveness of transformed cells.

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.

Ursolic acid-induced down-regulation of MMP-9 gene is mediated through the nuclear translocation of glucocorticoid receptor in HT1080 human fibrosarcoma cells

We have previously reported that ursolic acid, a pentacyclic triterpene acid, inhibited the invasion of HT1080 human fibrosarcoma cells by reducing the expression of matrix metalloproteinase-9. Since the chemical structure of ursolic acid is very similar to that of dexamethasone, a synthetic glucocorticoid, we investigated whether ursolic acid acts through the glucocorticoid receptor. The expression of matrix metalloproteinase-9 is thought to be regulated similarly with matrix metalloproteinase-1 and matrix metalloproteinase-3 as containing common 2-O-tetradecanoylphorbol-acetate responsible region, where AP-1 proteins can bind. Dexamethasone has been studied to repress the 2-O-tetradecanoylphorbol-acetate-induced expression of matrix metalloproteinase-1 and matrix metalloproteinase-3 through a glucocorticoid receptor-mediated manner. In Northern blot analysis, we found that ursolic acid reduced the expression of matrix metalloproteinase-1 and matrix metalloproteinase-3 induced by 2-O-tetradecanoylphorbol-acetate. Similarly, ursolic acid down-regulated 2-O-tetradecanoylphorbol-acetate-induction of matrix metalloproteinase-9 gene in the same manner of dexamethasone. RU486, a potent glucocorticoid receptor antagonist, was used for identifying that ursolic acid-induced down-regulation of matrix metalloproteinase-9 expression is mediated by its binding to glucocorticoid receptor. The effect of ursolic acid on the matrix metalloproteinase-9 expression was blocked by RU486, suggesting that ursolic acid acts via a glucocorticoid receptor in the regulation of matrix metalloproteinase-9. Western blot analysis and immunocytochemistry showed that ursolic acid increased glucocorticoid receptor fraction in the nucleus, although it decreased the synthesis of glucocorticoid receptor mRNA. In addition, ursolic acid did not decrease the expression of c-jun and DNA-binding activity of AP-1 to its cognate sequences. Taken together, we suggest that ursolic acid may induce the repression of matrix metalloproteinase-9 by stimulating the nuclear translocation of glucocorticoid receptor, and the translocated glucocorticoid receptor probably down-modulating the trans-activating function of AP-1 to 2-O-tetradecanoylphorbol-acetate responsible element of matrix metalloproteinase-9 promoter region.

Membrane-type matrix metalloproteinase-1(MT1-MTP) gene is overexpressed in highly invasive hepatocellular carcinomas

BACKGROUND/AIMS

The matrix metalloproteinase (MMP) family play important roles in the invasion of cancer cells by degrading the extracellular matrices. The current study was designed to determine the expression pattern of membrane-type matrix metalloproteinase-1 (MT1-MMP) in hepatocellular carcinomas and its participation in invasion potential.

METHODS

MT1-MMP mRNA expression was examined in 25 human hepatocellular carcinoma specimens using Northern blot, and the correlation to clinicopathological features was evaluated. In situ hybridization and immunohistochemistry were performed to study the localization and the cells responsible for the production.

RESULTS

Northern blot analysis revealed high levels of MT1-MMP mRNA expression in tumorous portions in all cases, whereas in non-tumorous portions moderate or faint expression was evident in 22/25 cases. In 21/25 cases, the expression levels in tumorous portion were higher than those in non-tumorous portion. In particular, hepatocellular carcinoma with capsule infiltration demonstrated significantly higher expression than those without (p<0.05). In situ hybridization and immunohistochemical study revealed MT1-MMP transcripts and proteins in cancer cells and stromal cells, respectively. MT1-MMP positive cells were preferentially observed in the invading border of tumor nests. The MMP-2 transcript showed a similar pattern to that of MT1-MMP by in situ hybridization.

CONCLUSION

The present study showed that the MT1-MMP gene is strongly expressed in hepatocellular carcinoma cells and is involved in the invasion potential of hepatocellular carcinoma, and also that MT1-MMP may be one of the key molecules responsible for the invasion potential of hepatocellular carcinoma. Furthermore, the evidence suggests that MT1-MMP and MMP-2 cooperate in the process of cancer invasion.

MT1-MMP and MMP-2 mRNA expression in human ovarian tumors: possible implications for the role of desmoplastic fibroblasts

Expression of activated MMP-2 (72 kDa type IV collagenase) is highly associated with the malignant phenotype in adenocarcinomas, but predominant expression of the mRNA appears to be in stromal cells. MT1-MMP (membrane type 1-matrix metalloproteinase) is implicated in tumor-epithelial cell surface activation of latent pro-MMP-2, indicating a mechanism for tumor-stromal interaction in invasion. We determined the relative mRNA distribution of these MMPs in human ovarian tumors with a view to analyzing potential variations in the epithelial-mesenchymal interactions dictating ovarian tumor cell spread. In situ hybridization using 35S-labeled riboprobes was used to analyze 33 human ovarian tumors and mouse xenografts of human ovarian (DOV 13, SKOV3) and breast (MCF 7) tumor cell lines known to express MT1-MMP and MMP-2. MMP-2 mRNA was expressed in 31 of 33 and MT1-MMP mRNA was expressed in 29 of 33 tumor cases. MMP-2 mRNA was predominantly expressed in desmoplastic fibroblasts and in the subepithelial stroma. MT1-MMP mRNA showed some colocalization with MMP-2 in stromal cells. Neoplastic epithelial cell labeling for MT1-MMP mRNA was present in borderline and malignant tumors but not in benign tumors, and was invariably less than stromal labeling. Xenografts of DOV 13, SKOV 3, and MCF 7 cells showed some stromal localization of MMP-2 mRNA and weak labeling of DOV 13 cells. There was variable labeling for MT1-MMP mRNA in the neoplastic cells only. The colocalization of MT1-MMP and MMP-2 mRNAs in ovarian carcinoma stroma supports the view that MT1-MMP is closely associated with MMP-2 expression and function. It suggests that either additional mechanisms are involved in regulating MMP-2 activation at the tumor cell surface, or more intriguingly, that desmoplastic fibroblasts may be the primary mediators of extracellular matrix remodeling with respect to this system.

Production of membrane-type matrix metalloproteinase-1 (MT-MMP-1) in early human placenta. A possible role in placental implantation?

The extracellular matrix proteolytic machinery is known to play a major role in trophoblast invasion, a process that shares similar features with the pathology of tumor invasion. In this study we investigated the expression of the recently described membrane-type matrix metalloproteinase-1 (MT-MMP-1; MMP-14) in early human placenta and decidual membrane to determine whether it might play a role in invasion. With in situ hybridization, the cytotrophoblasts of trophoblastic columns and the infiltrating intermediate trophoblasts in the decidual membrane were found to be the main producers of MT-MMP-1 mRNA. Gene expression was also seen in the villous double-layered trophoblastic epithelium and in the decidual cells of the decidual membrane. In endothelial and fibroblastic cells, however, the hybridization signal was either very weak or nonexistent. Immunohistochemical analysis and immunoelectron microscopy correlated well with the in situ hybridization findings. The most significant exception to this consisted of pericytes of spiral arteries, which appeared to lack MT-MMP-1 mRNA but showed intensive intracytoplasmic staining for the antigen. Our results show that MT-MMP-1 mRNA production is highly characteristic of intermediate trophoblasts, and MT-MMP-1 may have general importance in the tissue organization of early human placenta. We propose that MT-MMP-1 could be one of the key enzymes in the process of trophoblast invasion, acting alone or as a cell-surface activator of other proteinases.

Tumor cell contact mediated transcriptional activation of the fibroblast matrix metalloproteinase-9 gene: involvement of multiple transcription factors including Ets and an alternating purine-pyrimidine repeat

The 92-kDa type IV collagenase (MMP-9) is a metalloproteinase frequently localized in both tumor stroma and in tumor cells, particularly at the tumor invasion front. To explore the factors regulating transcriptional activation of MMP-9 in stromal cells, we used a model system in which fibroblast MMP-9 expression can be upregulated by cell-cell contact with metastatic transformed rat embryo cells. Using transient transfection of reporter gene constructs containing 5'-deleted or mutated MMP-9 promoter fragments, as well as electrophoretic mobility shift assays, the upstream NFkappaB, SP-1, and Ets sites and the downstream AP-1 site and retinoblastoma binding element were shown to be necessary for basal transcriptional activity of fibroblast MMP-9. In contrast only Ets or SP-1 appeared to be involved in contact-mediated induction of MMP-9. Mutation of the upstream AP-1 site increased both basal and contact-stimulated promoter activation. Deletion of the alternating purine-pyrimidine repeat in the downstream promoter decreased transcriptional activity. Together these findings suggest that Ets and SP-1 are the central transcriptional activators of MMP-9 gene expression in fibroblasts specifically responding to tumor cell contact, and that promoter conformation may regulate MMP-9 expression.

Elevated cyclic AMP suppresses ConA-induced MT1-MMP expression in MDA-MB-231 human breast cancer cells

We have previously reported that induction of MMP-2 activation by Concanavalin A (ConA) in MDA-MB-231 human breast cancer cells involves both transcriptional and post-transcriptional mechanisms, and that the continuous presence of ConA is required for MMP-2 activation (Yu et al. Cancer Res, 55, 3272-7, 1995). In an effort to identify signal transduction pathways which may either contribute to or modulate this mechanism, we found that three different cAMP-inducing agents, cholera toxin (CT), forskolin (FSK), and 3-isobutyl-1-methylxanthine (IBMX) partially inhibited ConA-induced MT1-MMP expression and MMP-2 activation in MDA-MB-231 cells. Combinations of CT or FSK with IBMX exhibited additive effects on reduction of MT1-MMP mRNA expression and MMP-2 activation. Agents which increase cAMP levels appeared to target transcriptional aspects of ConA induction, reducing MT1-MMP mRNA and protein in parallel with the reduced MMP-2 activation. In the absence of ConA, down-regulation of constitutive production of MT1-MMP mRNA and protein was observed, indicating that cAMP acts independently of ConA. These observations may help to elucidate factors regulating MT1-MMP expression, which may be pivotal to the elaboration of invasive machinery on the cell surface.

Calmodulin antagonists increase the expression of membrane-type-1 matrix metalloproteinase in human uterine cervical fibroblasts

The treatment of human uterine cervical fibroblasts with concanavalin A (ConA), or a specific calmodulin antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) or trifluoperazine resulted in accumulation of an active form of matrix metalloproteinase 2 (MMP-2, gelatinase A). In contrast, N-(6-aminohexyl)-1-naphthalenesulfonamide (W-5), a weaker antagonist of calmodulin, did not modulate the activation of proMMP-2. The activation of proMMP-2 was confirmed by the enhanced activity on gelatin and the conversion of proMMP-2 to a 62-kDa form by zymography and western blotting. The plasma membrane, but not the conditioned medium, of the W-7- or trifluoperazine-treated cells activated proMMP-2; this activation was blocked by membrane-type-1 MMP (MT1-MMP) antibody and EDTA. The plasma membrane from trifluoperazine- or ConA-treated cells contained MT1-MMP and tissue inhibitor of metalloproteinases 2. Both trifluoperazine treatment and ConA treatment increased the steady-state levels of MT1-MMP mRNA and proMMP-2 mRNA. These results, together with our previous observations on the production of proMMP-1 (interstitial procollagenase) and proMMP-3 (prostromelysin 1) [Ito, A., Sato, T., Ojima, Y., Chen, L.-C., Nagase, H. & Mori, Y. (1991) J. Biol. Chem. 266, 13598-13601], suggest that calmodulin negatively regulates the matrix turnover by suppressing the production of a number of proMMPs including proMMP-1, proMMP-3 and MT1-MMP, and the activation of proMMP-2 in human uterine cervical fibroblasts.

Expression and localization of membrane type matrix metalloproteinase-1 (MT1-MMP) in trophoblast cells of cultured mouse blastocysts and ectoplacental cones

Membrane type matrix metalloproteinases (MT-MMPs) possess a C-terminal transmembrane domain and are expressed on the cell membrane. It was suspected, therefore, that MT1-MMP might play an important role in the trophoblastic invasion during implantation. The patterns of expression and localization of membrane type matrix metalloproteinase-1 (MT1-MMP) were examined immunocytochemically in cultured mouse blastocysts and excised extoplacental cones (EPCs). MT1-MMP immuno-reactivity was present in the giant trophoblast cells located at the periphery of the spreading trophoblast of cultured blastocysts and the outgrowths of cultured EPCs, but not in the densely packed trophoblast cells in both the blastocysts and the EPCs. It appears likely that MT1-MMP expressed on the edge of the invading trophoblast facilitates the trophoblastic invasion by cleaving proMMP-2, a known substrate of MT1-MMP, in the decidua. Immunohistochemical examination of early conceptuses confirmed that the trophoblast cells actively invading the endometrium in vivo express MT1-MMP strongly. It is suggested, furthermore, that the expression of MT1-MMP might be downregulated by cell-cell contact in mouse trophoblast cells, as in the mouse mammary epithelial cell line HC11.

Dual expression of matrix metalloproteinase-2 and membrane-type 1-matrix metalloproteinase in fibrotic human livers

We have previously reported increased expression of matrix metalloproteinase-2 (MMP-2) using a rat model of liver fibrosis. However we did not clarify how the precursor of MMP-2 (proMMP-2) was activated. Therefore, we used human liver specimens with chronic hepatitis (CH) and liver cirrhosis (LC) to examine expression of membrane-type-1-MMP (MT1-MMP), which has recently been determined to activate proMMP-2. Northern hybridization studies showed a 5.4- and 1.4-fold increase in MMP-2 expression in CH and LC, respectively, as compared with normal liver. MT1-MMP gene expression simultaneously increased 4.0- and 1.4-fold in CH and LC, respectively. In situ hybridization using 35S-cRNA probes of MMP-2 and MT1-MMP showed prominent silver granules in elongated cells found in the lobules, periportal areas, and fibrous septa of CH and LC samples. These elongated cells expressed alpha-smooth muscle actin by immunohistochemistry. Immunoelectron microscopic examination localized MMP-2 and MT1-MMP to the rough endoplasmic reticulum of stellate cells located in the lobules and periportal areas, or to fibroblasts in the fibrous septa, suggesting that MMP-2 and MT1-MMP were produced by these cells. In addition, cytoplasmic and membranous immunodeposits of both MMPs were found in endothelial cells, Kupffer cells, capillary endothelial cells, and lymphocytes, indicating that activation of proMMP-2 occurs locally. Increased expression of MMP-2 and MT1-MMP was detected in CH and LC, while dual over-expression was found in stellate cells and fibroblasts, possibly resulting in the increase of active MMP-2 in and around these cells. These findings suggest that activated MMP-2 may remodel liver parenchyma during the process of liver fibrosis.

Tyrosine phosphorylation mediates ConA-induced membrane type 1-matrix metalloproteinase expression and matrix metalloproteinase-2 activation in MDA-MB-231 human breast carcinoma cells

ConA-induced cell surface activation of pro-matrix metalloproteinase-2 (pro-MMP-2) by MDA-MB-231 human breast cancer cells is apparently mediated by up-regulation of membrane type 1 MMP (MT1-MMP) through transcriptional and posttranscriptional mechanisms. Here, we have explored the respective roles of cell surface clustering and protein tyrosine phosphorylation in the ConA-induction effects. Treatment with succinyl-ConA, a variant lacking significant clusterability, partially stimulated MT1-MMP mRNA and protein levels but did not induce MMP-2 activation, suggesting that clustering contributes to the transcriptional regulation by ConA but appears to be critical for the nontranscriptional component. We further found that genistein, an inhibitor of tyrosine phosphorylation, blocked ConA-induced pro-MMP-2 activation and ConA-induced MT1-MMP mRNA level in a dose-dependent manner, implicating tyrosine phosphorylation in the transcriptional aspect. This was confirmed by the dose-dependent promotion of pro-MMP-2 activation by sodium orthovanadate in the presence of suboptimal concentrations of ConA (7.5 microg/ml), with optimal effects seen at 25 microg/ml orthovanadate. Genistein did not inhibit the ConA potentiation of MMP-2 activation in MCF-7 cells, in which transfected MT1-MMP is driven by a heterologous promoter, supporting the major implication of phosphotyrosine in the transcriptional component of ConA regulation. These data describe a major signaling event upstream of MT1-MMP induction by ConA and set the stage for further analysis of the nontranscriptional component.

Regulation of collagenase-3 expression in human breast carcinomas is mediated by stromal-epithelial cell interactions

Collagenase-3 (MMP-13) is a recently identified member of the human matrix metalloproteinase gene family that is expressed in breast carcinomas and in articular cartilage from arthritic patients. Here, we have studied the cellular origin of this enzyme in breast carcinomas by in situ RNA hybridization, and we found that collagenase-3 is expressed by stromal cells immediately adjacent to epithelial tumor cells but not by the tumor cells themselves; nor is it expressed by the normal breast glandular epithelium. Consistent with this observation, coculture experiments using human fibroblasts and MCF-7 breast cancer cells revealed that conditioned medium from breast cancer cells stimulated the fibroblastic expression of collagenase-3 mRNA. In contrast, no stimulatory effect was observed when medium from fibroblast cells was added to breast cancer cells. These results strongly suggest that transcription of collagenase-3 in stromal cells is activated by diffusible factors released from epithelial breast cancer cells. A survey of a series of cytokines and growth factors known for their ability to induce collagenase-3 expression in human fibroblasts identified interleukin-1alpha and interleukin-1beta as potential candidates for inducing the expression of this MMP gene in breast carcinomas. According to these results, collagenase-3 should be included among the molecular factors that are detected during the stromal reaction to invasive breast cancer and that, by concerted action, may be essential for tumor growth and progression.

Suppression of matrix metalloproteinase-3 synthesis by interleukin-4 in human articular chondrocytes

OBJECTIVE

To evaluate the effect of interleukin-4 (IL-4) on IL-1 induced matrix metalloproteinase-3 (MMP-3) and tissue inhibitor of metalloproteinase-1 (TIMP-1) production by human articular chondrocytes.

METHODS

Monolayer cell culture of chondrocytes was obtained from human articular cartilage from patella within 24 h after death. MMP-3 and TIMP-1 protein levels were determined by ELISA. MMP-3 activity was assayed as caseinase activity. Amounts of MMP-3 and TIMP-1 mRNA were measured by Northern blot analysis.

RESULTS

IL-4 suppressed IL-1 stimulated MMP-3 protein and enzyme activity. Moreover, IL-4 suppressed IL-1 induced MMP-3 mRNA. In contrast, IL-4 did not alter the level of TIMP-1 protein and mRNA.

CONCLUSION

IL-4 may be implicated as a protective mediator of joint destruction seen in inflammatory arthritis.

Calcium influx inhibits MT1-MMP processing and blocks MMP-2 activation

We have previously reported that concanavalin A (ConA)-induced MMP-2 activation involves both transcriptional and non-transcriptional mechanisms. Here we examined the effects of calcium influx on MT1-MMP expression and MMP-2 activation in MDA-MB-231 cells. The calcium ionophore ionomycin caused a dose-dependent inhibition of ConA-induced MMP-2 activation, but had no effect on MT1-MMP mRNA levels. However, Western analysis revealed an accumulation of pro-MT1-MMP (63 kDa), indicating that ionomycin blocked the conversion of pro-MT1-MMP protein to the active 60 kDa form. This suggests that increased calcium levels inhibit the processing of MT1-MMP. This finding may help to elucidate the mechanism(s) which regulates MT1-MMP activation.

Transmembrane/cytoplasmic domain-mediated membrane type 1-matrix metalloprotease docking to invadopodia is required for cell invasion

The invasion of human malignant melanoma cells into the extracellular matrix (ECM) involves the accumulation of proteases at sites of ECM degradation where activation of matrix metalloproteases (MMP) occurs. Here, we show that when membrane type 1 MMP (MT-MMP) was overexpressed in RPMI7951 human melanoma cells, the cells made contact with the ECM, activated soluble and ECM-bound MMP-2, and degraded and invaded the ECM. Further experiments demonstrated the importance of localization of the MT-MMP to invadopodia. Overexpression of MT-MMP without invadopodial localization caused activation of soluble MMP-2, but did not facilitate ECM degradation or cell invasiveness. Up-regulation of endogenous MT-MMP with concanavalin A caused activation of MMP-2. However, concanavalin A treatment prevented invadopodial localization of MT-MMP and ECM degradation. Neither a truncated MT-MMP mutant lacking transmembrane (TM) and cytoplasmic domains (DeltaTMMT-MMP), nor a chimeric MT-MMP containing the interleukin 2 receptor alpha chain (IL-2R) TM and cytoplasmic domains (DeltaTMMT-MMP/TMIL-2R) were localized to invadopodia or exhibited ECM degradation. Furthermore, a chimera of the TM/cytoplasmic domain of MT-MMP (TMMT-MMP) with tissue inhibitor of MMP 1 (TIMP-1/TMMT-MMP) directed the TIMP-1 molecule to invadopodia. Thus, the MT-MMP TM/cytoplasmic domain mediates the spatial organization of MT-MMP into invadopodia and subsequent degradation of the ECM.

Membrane-type matrix metalloproteinases (MT-MMPs) in cell invasion

Activated gelatinase A is reportedly associated with tumor spread. We identified a novel matrix metalloproteinase that localizes on the cell surface and mediate the activation of progelatinase A. Thus, this progelatinase A activator was named membrane-type matrix metalloproteinase (MT1-MMP). Following the first-discovery of MT1-MMP, two other MT-MMPs which can activate progelatinase A were identified (MT2- and MT3-MMP, respectively). Among these three MT-MMPs, MT1-MMP is most often overexpressed in malignant tumor tissues, including lung and stomach carcinomas that contain activated gelatinase A. This suggests that MT1-MMP is most closely associated with the activation of progelatinase A in these tumor tissues. The expression of MT1-MMP also induced binding of gelatinase A to the cell surface by functioning as a receptor. The cell surface localization of proteinases has advantages over pericellular proteolysis. MT1-MMP and its family may play a central role in the cell surface localization and activation of progelatinase A and via this mechanism, tumor cells use exogenous progelatinase A to mediate the proteolysis associated with invasion and metastasis.

Expression of membrane-type 1 matrix metalloproteinase and activation of progelatinase A in human osteoarthritic cartilage

Matrix metalloproteinases (MMPs) are expressed in osteoarthritic (OA) cartilage and are thought to be involved in the degradation of cartilage extracellular matrix (ECM). Among these proteinases, MMP-2 (gelatinase A) demonstrates a wide range of substrate specificity against the ECM present in cartilage. Although MMP-2 expression increases in OA cartilage, the activation mechanism of the corresponding zymogen (pro-MMP-2) in cartilage is unknown. In this study, we examined the expression pattern of membrane-type 1 MMP (MT1-MMP) in human OA articular cartilage and its correlation with the activation of pro-MMP-2. Immunohistochemical studies demonstrate that MT1-MMP localizes to the chondrocytes in the superficial and transitional zones in all of the samples examined directly correlating with cartilage degradation. Reverse transcription polymerase chain reaction confirmed the predominant expression of MT1-MMP mRNA in the OA cartilage. In situ hybridization revealed the site of expression of MT1-MMP in OA cartilage to be the chondrocytes. Through gelatin zymography and a sandwich enzyme immunoassay it was demonstrated that OA cartilage explants secrete significantly higher levels of pro-MMP-2 than normal samples. Pro-MMP-2 activation was enhanced in the OA cartilage samples and correlated with MT1-MMP expression in the cartilage. Plasma membranes prepared from cultured chondrocytes with MT1-MMP expression and those directly isolated from OA cartilage could activate pro-MMP-2. MT1-MMP gene expression in cultured chondrocytes was induced by treatment with interleukin-1 alpha and/or tumor necrosis factor-alpha. These data suggest that cytokine-induced MT1-MMP in the chondrocytes may play a key role in the activation of pro-MMP-2 in the OA articular cartilage, leading to cartilage destruction through ECM degradation.

Flow injection analysis for measurement of activity of matrix metalloproteinase-7 (MMP-7)

A simple and convenient method for measuring the activity of a recombinant human matrix metalloproteinase 7 (MMP-7, matrilysin) was developed by flow injection analysis (FIA). For this method, purified recombinant MMP-7 zymogen expressed in E. coli and the substrate peptide (MOCAc-Pro-Leu-Gly-Leu-A2pr(DNP)-Ala-Arg-NH2) were used. Following the incubation of substrate peptide with activated r-proMMP-7, the resulting fluorescent product peptide (MOCAc-Pro-Leu-GLY) was monitored with a fluorescence detector (lambda ex 328 mm, lambda em 393 mm) without chromatographic separation. In this FIA system, the analysis time is 2 min and the standard curve is linear from 5 to 100 pmol of the product peptide injected. In order to use this FIA system as a method for screening inhibitors against MMP-7, the effects of CaCl2, EDTA and of the tissue inhibitor of metalloproteinase-1, and -2, were tested. A synthetic PRCGXPD-containing peptide (BS-10) was also observed to inhibit MMP-7 activity, with an IC50 value of 104 microM. Thus, it was concluded that the activity of r-MMP-7 can be reliably measured by the proposed system. Furthermore, to confirm the utility of this FIA system as a screening method, the inhibitory activity of the MMP-related substance in Joro spider (Nephilia clavata) venom was measured by this method. This inhibitory activity was observed in an extract of a venom diluted 1000-fold. Thus, the FIA method is not only simple and quick, but also sensitive enough to screen and analyze the inhibitory properties of a large number of test compounds.