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

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

Shedding of membrane type 1 matrix metalloproteinase in a human breast carcinoma cell line

Membrane type 1 matrix metalloproteinase (MT1-MMP) with a transmembrane domain is a new member of the MMP gene family and is expressed on the cell surfaces of many carcinoma cells to activate the zymogen of MMP-2 (gelatinase A). We have previously reported that MT1-MMP is released into culture media in a complex form with tissue inhibitor of metalloproteinases 2 (TIMP-2) from a human breast carcinoma cell line, MDA-MB-231, treated with concanavalin A (Con A). In the present study, we further studied the release mechanism of MT1-MMP. Immunoblot analysis indicated that the amounts of MT1-MMP in culture media increase with the time of exposure and the concentration of Con A, and those in cell lysates conversely decrease in a similar way. Time- and dose-dependent release of MT1-MMP into the media was confirmed by a sandwich enzyme immunoassay specific to MT1-MMP. The molecular weight of the immunoreactive MTI-MMP in the media was Mr 56,000, which was 4,000-Mr smaller than that in the cell lysates. Northern blot analysis demonstrated that the mRNA expression level of MT1-MMP is about 3-fold enhanced after a 24 h-exposure to Con A and this is maintained up to 72-h exposure. The release of MT1-MMP from the Con A-treated cells was inhibited by metalloproteinase inhibitors such as EDTA and o-phenanthroline, but not by MMP inhibitors including TIMP-1, TIMP-2 and BB94 or other proteinase inhibitors of serine, cysteine and aspartic proteinases. During the Con A treatment of the cells, cell viability decreased time- and dose-dependently and dead cells reacted positively in the TdT-mediated dUTP Nick-End Labeling (TUNEL) method. Con A-treated MDA cells showed apoptotic morphology when stained with Hoechst dye and hematoxylin and eosin. DNA ladder formation was detected by electrophoresis of the DNA from Con A-treated MDA cells. These results suggest that MT1-MMP release from Con A-treated cells is due to shedding mediated by metalloproteinase(s) other than MMPs, and is associated with apoptosis.

Regulation of matrix metalloproteinase-2 (MMP-2) by hepatocyte growth factor/scatter factor (HGF/SF) in human glioma cells: HGF/SF enhances MMP-2 expression and activation accompanying up-regulation of membrane type-1 MMP

Hepatocyte growth factor/scatter factor (HGF/SF) contributes to the malignant progression of human gliomas. We investigated the effect of HGF/SF on matrix metalloproteinase-2 (MMP-2), membrane type 1 matrix metalloproteinase (MT1-MMP) and tissue inhibitors of metalloproteinases (TIMPs), expressions of c-Met/HGF receptor-positive human glioblastoma cells. Treatment of U251 human glioblastoma cells with HGF/SF resulted in enhanced secretion of MMP-2 with an increased level of the active form. This was accompanied by enhanced expression (2.5-fold) of mRNA specific for MMP-2. The stimulatory effect of HGF/SF on MMP-2 expression did not occur in the presence of herbimycin A, a protein tyrosine kinase inhibitor. MT1 -MMP, a cell-surface activator of proMMP-2, was also up-regulated by HGF/SF in a dose-dependent manner. By contrast, the level of TIMP- 1 mRNAs was not altered significantly and that of TIMP-2 was reduced mildly by the HGF/SF treatment, suggesting that HGF/SF may eventually modulate a balance between MMP-2 and TIMPs in favor of the proteinase activity in the glioma cell microenvironment. HGF/SF also stimulated MMP-2 expression of other glioblastoma cell lines. Since glioblastomas frequently co-express HGF/SF and its receptor, our results suggest that HGF/SF might contribute to the invasiveness of glioblastoma cells through autocrine induction of MMP-2 expression and activation.

Regulation of matrix metalloproteinase-2 (MMP-2) by hepatocyte growth factor/scatter factor (HGF/SF) in human glioma cells: HGF/SF enhances MMP-2 expression and activation accompanying up-regulation of membrane type-1 MMP

Hepatocyte growth factor/scatter factor (HGF/SF) contributes to the malignant progression of human gliomas. We investigated the effect of HGF/SF on matrix metalloproteinase-2 (MMP-2), membrane type 1 matrix metalloproteinase (MT1-MMP) and tissue inhibitors of metalloproteinases (TIMPs), expressions of c-Met/HGF receptor-positive human glioblastoma cells. Treatment of U251 human glioblastoma cells with HGF/SF resulted in enhanced secretion of MMP-2 with an increased level of the active form. This was accompanied by enhanced expression (2.5-fold) of mRNA specific for MMP-2. The stimulatory effect of HGF/SF on MMP-2 expression did not occur in the presence of herbimycin A, a protein tyrosine kinase inhibitor. MT1 -MMP, a cell-surface activator of proMMP-2, was also up-regulated by HGF/SF in a dose-dependent manner. By contrast, the level of TIMP- 1 mRNAs was not altered significantly and that of TIMP-2 was reduced mildly by the HGF/SF treatment, suggesting that HGF/SF may eventually modulate a balance between MMP-2 and TIMPs in favor of the proteinase activity in the glioma cell microenvironment. HGF/SF also stimulated MMP-2 expression of other glioblastoma cell lines. Since glioblastomas frequently co-express HGF/SF and its receptor, our results suggest that HGF/SF might contribute to the invasiveness of glioblastoma cells through autocrine induction of MMP-2 expression and activation.

Characterization of a truncated recombinant form of human membrane type 3 matrix metalloproteinase

Membrane type 3 matrix metalloproteinase (MT3-MMP), an activator for the zymogen of MMP-2 (proMMP-2, or progelatinase A), is known to be expressed in human placenta, brain, lung and rat vascular smooth muscle cells, but information about its biochemical properties is limited. In the present study, we expressed and purified a truncated form of MT3-MMP lacking the transmembrane and intracytoplasmic domain (DeltaMT3) and characterized the enzyme biochemically. DeltaMT3 digested type III collagen into characteristic 3/4- and 1/4-fragments by cleaving the Gly781-Ile782 and Gly784-Ile785 bonds of alpha1(III) chains. Although DeltaMT3 did not have such an activity against type I collagen, it attacked the Gly4-Ile5 bond of the triple helical portion of alpha2(I) chains, leading to removal of the crosslink containing N-terminal telopeptides. By quantitative analyses of the activities of DeltaMT3 and a similar deletion mutant of MT1-MMP (DeltaMT1), DeltaMT3 was approximately fivefold more efficient at cleaving type III collagen. DeltaMT3 also digested cartilage proteoglycan, gelatin, fibronectin, vitronectin, laminin-1, alpha1-proteinase inhibitor and alpha2-macroglobulin into almost identical fragments to those given by DeltaMT1, although carboxymethylated transferrin digestion by DeltaMT3 generated some extra fragments. The activity of DeltaMT3 was inhibited by tissue inhibitor of metalloproteinases-2 (TIMP-2) and TIMP-3 in a 1 : 1 stoichiometry, but not by TIMP-1. ProMMP-2 was partially activated by DeltaMT3 to give the intermediate form. These results indicate that, like MT1-MMP, MT3-MMP exhibits proteolytic activities against a wide range of extracellular matrix molecules. However, differences in the proMMP-2 activation and tissue distribution suggest that MT3-MMP and MT1-MMP play different roles in the pathophysiological digestion of extracellular matrix.

Enhancement of membrane-type 1-matrix metalloproteinase (MT1-MMP) production and sequential activation of progelatinase A on human squamous carcinoma cells co-cultured with human dermal fibroblasts

Matrix metalloproteinase 2 (MMP-2)/gelatinase A plays an important role in tumour invasion and metastasis. Since MMP-2 is secreted as an inactive form (proMMP-2) from tumour and neighbouring stroma cells, the activation process is necessary to express the enzymic activity for degradation of extracellular matrix components. We herein reported that the activation of proMMP-2 was induced in human squamous carcinoma cells co-cultured with normal human dermal fibroblasts. When A431 cells were co-cultured with human fibroblasts at various cell ratios, 72-kDa proMMP-2 was converted to a 62-kDa active form through the appearance of a 64-kDa intermediate. The activation of proMMP-2 by co-culture was also observed in other carcinoma cell lines, HSC-4 and SAS, but not in normal human keratinocytes. We characterized by in vitro invasion assay that A431 cells in co-culture preferentially invaded through Matrigel and the increased invasive activity was inhibited by exogenously adding tissue inhibitor of metalloproteinases 2. The augmented proMMP-2 activation by co-culture was achieved by the increase in membrane type 1-MMP (MT1-MMP) production along with that of its mRNA level. The predominant appearance of MT1-MMP was immunologically observed in A431 cells, but not human fibroblasts of the co-culture. Furthermore, epidermal growth factor (EGF) enhanced the co-culture-mediated proMMP-2 activation by increasing the production and gene expression of MT1-MMP, and thereby tumour invasive activity was further augmented. These results suggest that the cell-cell contact between carcinoma cells and normal fibroblasts enhances the production of MT1-MMP followed by sequential activation of proMMP-2 on the tumour cell surface, which may be closely implicated in tumour invasion in vivo.

Significance of membrane type 1 matrix metalloproteinase expression in breast cancer

Expression of matrix metalloproteinases (MMPs) plays an essential role in tumor metastasis and invasion through the degradation of extracellular matrix (ECM). MT1-MMP (membrane type 1 matrix metalloproteinase), a membrane-type MMP, is responsible for the activation of MMP2. In this study the significance of MT1-MMP expression in human breast tumors was investigated by immunocytochemical assay, and its correlation with clinicobiological features was analyzed. MT1-MMP expression was detected in tumor cells and/or stromal cells, and there was a strong correlation between the expressions of MT1-MMP in the two cell types. Out of 183 primary tumors, 103 (56.2%) showed positive staining of MT1-MMP in tumor cells. MT1-MMP expression showed no significant correlation with any of the clinicobiological parameters examined, including hormone receptor status and angiogenesis. In postoperative survival analysis, MT1-MMP expression itself was not a significant prognostic factor. However, in the particular subgroup with the accumulation of thymidine phosphorylase (TP)-positive stromal cells, which have been activated by various stimuli, such as cytokines and hypoxia, MT1-MMP expression had a significant prognostic value. These data suggested that MT1-MMP might function cooperatively with tumor-associated stromal cells for the progression of breast cancer.

Overexpression of tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) in metastatic MDCK cells transformed by v-src

This article discusses the transformation of epithelial Madin-Durby canine kidney (MDCK) cells with v-src induced expression of membrane-type 1-matrix metalloproteinase (MT1-MMP) and metastatic growth in nude mice (Kadono Y et al., Cancer Res 1998; 58: 2240-44). To analyze genes associated with invasive phenotype of v-src MDCK cells, mRNA differential display was performed between control and the transformed cells. A clone 12', the expression of which was clearly up-regulated in the transformed cells, encoded a protein 81% homologous to human tissue inhibitor of matrix metalloproteinases-1 (TIMP-1). Northern hybridization showed that only MT1-MMP expression was enhanced and other matrix metalloproteinases (MMPs) were undetectable or rather repressed in the transformed cells. Proteolytic activity against type I gelatin was observed in v-src MDCK cells, which was inhibited only by TIMP-2 but not by TIMP-1. MDCK cells stably transfected with the MT1-MMP gene also degraded gelatin, which was selectively inhibited by TIMP-2. These results suggest that MT1-MMP, the expression of which is induced in v-src MDCK cells, degrades extracellullar matrix by itself rather than through the activation of progelatinase A, which in turn contributes to the metastasis of the transformed cells.

Differentiation-dependent expression of gelatinase B/matrix metalloproteinase-9 in trophoblast cells

The purpose of this study was to evaluate the Rcho-1 trophoblast culture system as a model for studying trophoblast invasion and to examine stage-specific expression of enzyme(s) potentially participating in rat trophoblast giant cell invasive behavior. The invasive behavior of the differentiating Rcho-1 trophoblast cells was demonstrated using Matrigel invasion chambers. Gelatin zymography and Western blot analysis of conditioned medium from differentiating Rcho-1 trophoblast cell cultures and rat ectoplacental cone outgrowths revealed a differentiation-dependent increase in gelatinase B/matrix metalloproteinase (MMP-9). Nothern blot and reverse transcriptase polymerase chain reaction (RT-PCR) analyses of Rcho-1 trophoblast or ectoplacental cone cells also showed increasing expression of MMP-9 accompanying cell differentiation. Rcho-1 trophoblast cells stably transfected with MMP-9 promoter/luciferase reporter constructs exhibited a differentiation-dependent increase in MMP-9 promoter activation. In conclusion, trophoblast giant cell differentiation is characterized by transcriptional activation of the MMP-9 gene and appearance of the invasive phenotype.

Enhanced tumor growth and invasiveness in vivo by a carboxyl-terminal fragment of alpha1-proteinase inhibitor generated by matrix metalloproteinases: a possible modulatory role in natural killer cytotoxicity

Matrix metalloproteinases (MMPs) are believed to contribute to the complex process of cancer progression. They also exhibit an alpha1-proteinase inhibitor (alphaPI)-degrading activity generating a carboxyl-terminal fragment of approximately 5 kd (alphaPI-C). This study reports that overexpression of alphaPI-C in S2-020, a cloned subline derived from the human pancreas adenocarcinoma cell line SUIT-2, potentiates the growth capability of the cells in nude mice. After stable transfection of a vector containing a chimeric cDNA encoding a signal peptide sequence of tissue inhibitor of metalloproteinase-1 followed by cDNA for alphaPI-C into S2-020 cells, three clones that stably secrete alphaPI-C were obtained. The ectopic expression of alphaPI-C did not alter in vitro cellular growth. However, subcutaneous injection of the alphaPI-C-secreting clones resulted in tumors that were 1.5 to 3-fold larger than those of control clones with an increased tendency to invasiveness and lymph node metastasis. These effects could be a result of modulation of natural killer (NK) cell-mediated control of tumor growth in nude mice, as the growth advantage of alphaPI-C-secreting clones was not observed in NK-depleted mice, and alphaPI-C-secreting clones showed decreased NK sensitivity in vitro. In addition, production of alphaPI and generation of the cleaved form of alphaPI by MMP were observed in various human tumor cell lines and in a highly metastatic subline of SUIT-2 in vitro. These results provide experimental evidence that the alphaPI-degrading activity of MMPs may play a role in tumor progression not only via the inactivation of alphaPI but also via the generation of alphaPI-C.

Expression and tissue localization of membrane-type 1, 2, and 3 matrix metalloproteinases in human astrocytic tumors

Three different membrane-type matrix metalloproteinases (MT1-, MT2-, and MT3-MMPs) are known to activate in vitro the zymogen of MMP-2 (pro-MMP-2, progelatinase A), which is one of the key MMPs in invasion and metastasis of various cancers. In the present study, we have examined production and activation of pro-MMP-2, expression of MT1-, MT2-, and MT3-MMPs and their correlation with pro-MMP-2 activation, and localization of MMP-2, MT1-MMP, and MT2-MMP in human astrocytic tumors. The sandwich enzyme immunoassay demonstrates that the production levels of pro-MMP-2 in the anaplastic astrocytomas and glioblastomas are significantly higher than that in the low-grade astrocytomas (P<0.05 and P<0.01, respectively), metastatic brain tumors (P<0.05), or normal brains (P<0.01). Gelatin zymography indicates that the pro-MMP-2 activation ratio is significantly higher in the glioblastomas than in other astrocytic tumors (P<0.01), metastatic brain tumors (P<0.01), and normal brains (P<0.01). The quantitative reverse transcription polymerase chain reaction analyses demonstrate that MT1-MMP and MT2-MMP are expressed predominantly in glioblastoma tissues (17/17 and 12/17 cases, respectively), and their expression levels increase significantly as tumor grade increases. MT3-MMP is detectable in both astrocytic tumor and normal brain tissues, but the mean expression level is approximately 50-fold lower compared with that of MT1-MMP and MT2-MMP in the glioblastomas. The activation ratio of pro-MMP-2 correlates directly with the expression levels of MT1-MMP and MT2-MMP but not MT3-MMP. In situ hybridization indicates that neoplastic astrocytes express MT1-MMP and MT2-MMP in the glioblastoma tissues (5/5 cases and 5/5 cases, respectively). Immunohistochemically, MT1-MMP and MT2-MMP are localized to the neoplastic astrocytes in glioblastoma samples (17/17 cases and 12/17 cases, respectively), which are also positive for MMP-2. In situ zymography shows gelatinolytic activity in the glioblastoma tissues but not in the normal brain tissues. These results suggest that both MT1-MMP and MT2-MMP play a key role in the activation of pro-MMP-2 in the human malignant astrocytic tumors and that the gelatinolytic activity is involved in the astrocytic tumor invasion.

Enhanced production and activation of progelatinase A mediated by membrane-type 1 matrix metalloproteinase in human papillary thyroid carcinomas

Matrix metalloproteinases (MMPs) are believed to be involved in the invasion and metastasis of various human carcinomas. In the present study, the production levels of seven different MMPs (MMP-1, -2, -3, -7, -8, -9, and -13), the activation of the zymogen of MMP-2 (proMMP-2), the expression of membrane-type MMPs (MT1-, MT2-, and MT3-MMPs), and the tissue localization of the activated enzyme were examined in human invasive papillary thyroid carcinomas. Sandwich enzyme immunoassays revealed that among the MMPs examined, only the MMP-2 production level is significantly enhanced in the carcinoma tissues compared with the follicular adenoma and normal control thyroid tissues. Gelatin zymography indicated that the proMMP-2 activation ratio is considerably higher in carcinomas with lymph node metastasis than it is in those without metastasis, follicular adenomas, or normal controls (P < 0.01). Northern blot analysis of the expression of MT1-, MT2-, and MT3-MMPs, which are known to activate proMMP-2 in vitro, demonstrated the predominant expression of MT1-MMP mRNA in the carcinoma tissues (15 of 15 cases), whereas MT2-MMP expression was confined to 26% of the cases (4 of 15 cases), and no consistent expression of MT3-MMP was observed. MTI-MMP mRNA expression levels correlated with the proMMP-2 activation ratio (r = 0.692; P < 0.01), but such a correlation was not obtained with MT2-MMP. There was also a direct correlation between MT1-MMP expression and lymph node metastasis (P < 0.05). In situ hybridization indicated that both carcinoma and stromal cells express MT1-MMP transcripts (five of six cases). MT1-MMP was also immunolocalized to carcinoma and stromal cells in all of the carcinoma samples (26 of 26 cases), which were positive for MMP-2. In situ zymography indicated definite gelatinolytic activity in the carcinoma cell nests, which was abolished by incubation of the carcinoma samples with a synthetic MMP inhibitor before the reaction. These results suggest for the first time that among seven different MMPs, the production of proMMP-2 and its MT1-MMP-mediated activation in the carcinoma cell nests play an important role in the lymph node metastasis of human invasive papillary thyroid carcinomas.

[Outline of tumor invasion and metastasis]

Analysis of cancer genes and studies of cell growth, apoptosis and immortalization have shed light on how normal cells transform into malignant cancer cells. In addition, our knowledge of the molecular mechanisms by which cancer cells invade and traverse tissues and form distant metastases has been improved greatly. Several new therapeutic methods have been developed based on these new findings, and they are expected to provide patients with better choices.

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.

New collagenolytic enzymes/cascade identified at the pannus-hard tissue junction in rheumatoid arthritis: destruction from above

Our aim was to investigate the collagenolytic potential and localization of matrix metalloproteinase-2 (MMP-2) in relation to its regulatory proteins membrane type MT1-MMP and tissue inhibitor of metalloproteinases-2 (TIMP-2) in rheumatoid arthritis (RA). For this purpose, we have used purification of MMP-2, MMP-8, MMP-9 and interstitial type I, II and III collagens; SDS-PAGE/densitometric collagenase activity assay; zymography; Western blotting; reverse transcriptase polymerase chain reaction; in situ hybridization; and immunofluorescence, ABC, ABC-APAAP double immunostainings. MMP-2 degraded human type II collagen almost as effectively as MMP-8, whereas MMP-9 did not cleave type II collagen. In synovial tissue, MT1-MMP, TIMP-2 and MMP-2 were found in synovial lining in fibroblast- and macrophage-like cells, in stromal cells and in vascular endothelium. MT1-MMP, TIMP-2 and MMP-2 were strongly expressed in the pannocytes of the invasive pannus at the interface, but staining was weak and/or there were few positive cells both "above" and "below" the soft-to-hard tissue (cartilage and/or bone) interface. Rheumatoid synovial tissue extract contained proteolytically active 62/59 kDa MMP-2 and 43 kDa MT1-MMP, but no free TIMP-2. These results indicate that components of the ternary MT1-MMP/TIMP-2/MMP-2 complex are coexpressed in the normal synovial lining and in its pathological extension on the hyaline articular cartilage. MMP-2 may participate in the remodeling of the normal lining and also seems to be localized/focalized to pannocytes at a site critical for tissue destruction in arthritis.

Immunohistochemical study of MT-MMP tissue status in gastric carcinoma and correlation with survival analyzed by univariate and multivariate analysis

Matrix metalloproteinase (MMP) expression is associated with advanced-stage cancer and contributes to tumor progression, invasion, and metastasis. Membrane type matrix metalloproteinase (MT-MMP) has a potential transmembrane domain at the C terminus and activates pro-MMP-2, which is mainly produced from interstitial fibroblasts. Its expression on the membrane of invasive tumor cells results in the pericellular space degradation at cell-matrix contact sites and renders cancer cells more invasive at the migration front. To elucidate the relationship between MT-MMP expression and metastasis and prognosis in gastric cancer patients, MT-MMP expression was analyzed immunohistochemically in 127 primary tumors and results were correlated with several prognostic parameters and patient's survival. MT-MMP immunoreactivity was stained on the cell membrane of cancer cells and fibroblasts in the invasion front. MT-MMP was detected in 72 tumors (57%) (MT-MMP-positive). MT-MMP expression was closely associated with macroscopically invasive type, nodal involvement, lymphatic invasion, vessel invasion, and peritoneal dissemination. Patients with MT-MMP-positive tumor had a significantly worse prognosis than those with MT-MMP-negative tumor (p<0.001). Multivariate analysis showed MT-MMP overexpression as an independent prognostic factor in gastric cancer patients. Immunohistochemical analysis for MT-MMP may be an indicator of metastatic potential or the prognosis of gastric cancer patients.

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.

Expression and tissue localization of membrane-types 1, 2, and 3 matrix metalloproteinases in human urothelial carcinomas

PURPOSE

Three different membrane-type matrix metalloproteinases (MT1, 2, 3-MMP) which can activate proMMP-2 (progelatinase A) are thought to have an important role in various human carcinoma invasions and metastases. We examined the mRNA expression of MT-MMPs and the tissue immunolocalization of MT1-MMP in human urothelial carcinomas.

MATERIALS AND METHODS

mRNA was extracted from 27 clinical urothelial carcinomas and 10 normal urothelial mucosa tissues remote from the tumor. RT-PCR using specific primers was performed, and PCR products were hybridized to 32P-labeled internal probes and analyzed by a bioimage analyzer. Immunolocalization was studied using a monoclonal antibody against MT1-MMP (114-6G6).

RESULTS

MT1-MMP and MT2-MMP mRNA expressions in urothelial carcinomas were significantly higher than those in the normal mucosa. In contrast, MT3-MMP mRNA was little expressed in both tissues, and the amount of MT3-MMP mRNA appeared to be much lower than MT1-MMP and MT2-MMP in the tissue samples. In terms of the tumor multiplicity, MT1-MMP and MT2-MMP mRNA expressions in the group of multiple tumors were significantly higher than those in the solitary tumor group. The carcinoma cells were immunostained for MT1-MMP predominantly in invasive and superficial carcinoma cells. The immunoreactivity was more intense in the invasive type than in the superficial type.

CONCLUSIONS

It is suggested that MT1-MMP and MT2-MMP play an important role in the development of human urothelial carcinomas and reflect some aspects of the pathogenesis of multifocal occurrence. In spite of the possible contribution to the invasive and metastatic phenotype, MT1-MMP mRNA and its product are thought to be expressed already in the clinical superficial stage in some cases of this tumor type.

Expression of the membrane-type 3 matrix metalloproteinase (MT3-MMP) in human brain tissues

Membrane-type 3 matrix metalloproteinase (MT3-MMP) is a novel MT-MMP which has a transmembrane domain at the C terminus, and mediates activation of pro-gelatinase A, just as does MT1-MMP. Previously, we reported that MT1-MMP was expressed on microglial cells only in the white matter [Yamada T, Yoshiyama Y, Sato H, Seiki M, Shinagawa A, Takahashi M (1995) Acta Neuropathol 90:421-424]. In the present study of both non-neurological and Alzheimer brain tissues, we examined the localization of MT3-MMP by immunohistochemistry. Anti-MT3-MMP antibodies gave positive staining of microglial cells in all brain tissues. Positively stained microglia were found not only in the white matter but also in the gray matter. Reverse transcriptase-polymerase chain reaction for MT3-MMP mRNA showed the same amount of expression in gray and white matters, while that for gelatinase A and MT1-MMP mRNA expressed much higher in the white matter than in the gray matter. These results suggest that MT3-MMP may play a role on microglial cells, although its role may be different from MT1-MMP in the brain.

Role of tissue inhibitor of metalloproteinases-2 (TIMP-2) in regulation of pro-gelatinase A activation catalyzed by membrane-type matrix metalloproteinase-1 (MT1-MMP) in human cancer cells

To clarify the regulatory mechanism of pro-gelatinase A (proGelA) activation at a cellular level, expression of gelatinase A (GelA), three MT-MMPs, and TIMP-2 was examined with 11 human cancer cell lines cultured in the presence and absence of stimulants. MT1-MMP mRNA was expressed in 8 cell lines, while MT2-MMP and MT3-MMP mRNAs were expressed in fewer cell lines. The cells with high proGelA activation strongly expressed MT1-MMP mRNA but not MT2-MMP and MT3-MMP mRNAs, suggesting that MT1-MMP was responsible for the proGelA activation in the cancer cells. Treatments with concanavalin A (Con A) and a phorbor ester (TPA) enhanced the MT1-MMP expression, but only Con A stimulated the proGelA activation in many cell lines. In HT1080 fibrosarcoma cells, however, TPA also stimulated the activation. The level of TIMP-2 secreted into culture medium inversely correlated with proGelA activation. For example, 2 squamous cell carcinoma lines (HSC-3 and HSC-4) and 3 HT1080 clones, which efficiently activated proGelA, secreted little TIMP-2 into medium, whereas other cell lines and other HT1080 clones, which hardly activated proGelA, secreted TIMP-2 at high levels. When HSC-3 cells were incubated with TIMP-2 protein or transfected with TIMP-2 cDNA, the proGelA activation was strongly inhibited. These results indicated that extracellular TIMP-2 was an important negative regulator of proGelA activation. However, the level of extracellular TIMP-2 was not consistent with that of TIMP-2 mRNA in some cell lines. Other experimental results suggested that TIMP-2 might be rapidly metabolized after binding to MT1-MMP, and Con A treatment might stabilize the complex of TIMP-2 and MT1-MMP on cell membranes.

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.

Expression and tissue localization of membrane-types 1, 2, and 3 matrix metalloproteinases in human invasive breast carcinomas

Activation of the zymogen of matrix metalloproteinase 2 (proMMP-2, progelatinase A) possibly is one of the key steps in invasion and metastasis of various human carcinomas. Three different membrane-type MMPs (MT-MMPs), MT1-, MT2-, and MT3-MMPs are thought to be activators of proMMP-2 in the tissues. MT4-MMP is structurally different from the other three enzymes, and its function as proMMP-2 activator is uncertain. In the present study of human invasive breast carcinomas, we examined a correlation between the expression of MT1-, MT2-, and MT3-MMPs, immunolocalization of MT1- and MT2-MMPs, and proMMP-2 activation. Northern blot analysis demonstrated the predominant expression of MT1-MMP mRNA in carcinoma tissues (20 of 20 cases), whereas MT2-MMP was detected in only 25% of the cases (5 of 20 cases), and no detectable expression of MT3-MMP was observed. The expression levels of MT1-MMP but not MT2-MMP correlated well with the presence of lymph node and distant metastases, clinical stages, and size of tumors. Immunohistochemically, MT1-MMP was localized predominantly in the carcinoma cells in all of the samples (32 of 32 cases). Immunostaining of MT2-MMP in the carcinoma cells was observed in only 38% of the cases (12 of 32 cases). Immunoblot analysis of tumor homogenates confirmed the presence of these MT-MMPs. Activation of proMMP-2 was significantly higher in the carcinoma samples with lymph node or distant metastasis compared to carcinoma without metastasis, normal control, or fibrocystic disease (P < 0.05). An increase in the activation ratio of proMMP-2 correlated directly with the expression of MT1-MMP but not MT2-MMP, as measured by either Northern blot analysis or immunostaining. These results suggest that MT1-MMP may play a key role in human breast carcinoma invasion and metastasis by being predominantly responsible for activation of proMMP-2.