Monolayer cultures of human epithelial and endothelial cells were used to study the association of latent transforming growth factor-beta 1 (TGF-beta 1) to extracellular matrices and its release and activation during matrix degradation. Human umbilical vein endothelial cells and embryonic lung fibroblasts produced relatively high levels of TGF-beta 1, its propeptide (beta 1-latency-associated protein), and latent TGF-beta-binding protein and incorporated latent TGF-beta 1 into their matrices as shown by immunoblotting. Amnion epithelial cells produced lower levels of these proteins. Confluent cultures of epithelial cells were exposed to matrix-degrading proteases and glycosidases. Mast cell chymase, leukocyte elastase, and plasmin efficiently released matrix-bound latent TGF-beta 1 complexes, while chondroitinase ABC and heparitinases were ineffective. The ability of the proteases to activate recombinant latent TGF-beta 1 was tested using growth inhibition assays and a novel sodium deoxycholate-polyacrylamide gel electrophoresis followed by immunoblotting. Sodium deoxycholate solubilized M(r) 25,000 TGF-beta 1 but did not dissociate high M(r) latent TGF-beta 1 complexes, allowing separation of these forms by polyacrylamide gel electrophoresis. Mast cell chymase and leukocyte elastase did not activate latent TGF-beta 1, suggesting that its release from matrix and activation are controlled by different mechanisms. The release of TGF-beta from the matrix by leukocyte and mast cell enzymes may contribute to the accumulation of connective tissue in inflammation.

Human fibroblasts and HT-1080 fibrosarcoma cells express membrane-type-1 matrix metalloproteinase (MT1-MMP), the cell surface activator of gelatinase A, in separate forms of 63 kDa, 60 kDa and in some cases 43 kDa. In the present work the interrelationships between MT1-MMP processing and gelatinase A activation were analysed using HT-1080 fibrosarcoma cells as a model. It was found that MT1-MMP was synthesized as a 63 kDa protein, which was constitutively processed to a 60 kDa active enzyme with N-terminal Tyr112, as shown by immunoprecipitation, immunoblotting and sequence analyses. Co-immunoprecipitation results indicated that only the active 60 kDa form of MT1-MMP bound gelatinase A at the cell surface. Both the activation of pro-MT1-MMP and the membrane binding of the tissue inhibitor of metalloproteinases type 2 (TIMP-2) and gelatinase A, and subsequent activation of gelatinase A, were inhibited by calcium ionophores. Although the active MT1-MMP was required for cell surface binding and activation of gelatinase A, it was inefficient in activating gelatinase A in fibroblasts or in control HT-1080 cells alone. Low expression levels of TIMP-2 and rapid synthesis of MT1-MMP were found to be critical for gelatinase A activation. In HT-1080 cells, MT1-MMP was further processed to an inactive, 43 kDa cell surface form when overexpressed, or when the cells were treated with PMA. Under these conditions, the activated gelatinase A was detected in the culture medium, in cell membrane extracts and in MT1-MMP-containing complexes. These results indicate that proteolytic processing (activation and degradation/inactivation) of MT1-MMP and MT1-MMP/TIMP-2 relationships at the cell surface are important regulatory levels in the control of gelatinolytic activity.

We have cloned a new human matrix metalloproteinase (MMP-28, epilysin) from human keratinocyte and testis cDNA libraries. Like most MMPs, epilysin contains a signal sequence, a prodomain with a PRCGVTD sequence, a zinc-binding catalytic domain with an HEIGHTLGLTH sequence, and a hemopexin-like domain. In addition, epilysin has a furin activation sequence (RRKKR) but has no transmembrane sequence. The exon-intron organization and splicing pattern of epilysin differ from that of other MMP genes. It has only 8 exons, and 5 exons are spliced at sites not used by other MMPs. Another novel feature of epilysin is that exon 4 is alternatively spliced to a transcript that does not encode the N-terminal half of the catalytic domain. Northern hybridization of tissue RNA indicated that epilysin is expressed at high levels in testis and at lower levels in lungs, heart, colon, intestine, and brain. RNase protection assay with various cell lines indicated that epilysin was selectively expressed in keratinocytes. Recombinant epilysin degraded casein in a zymography assay, and its proteolytic activity was inhibited by EDTA and by batimastat, a selective MMP inhibitor. Immunohistochemical staining showed expression of epilysin protein in the basal and suprabasal epidermis of intact skin. In injured skin, prominent staining for epilysin was seen in basal keratinocytes both at and some distance from the wound edge, a pattern that is quite distinct from that of other MMPs expressed during tissue repair. These findings suggest that this new MMP functions in several tissues both in tissue homeostasis and in repair. The matrix metalloproteinases (MMPs)1 compose a family of enzymes that share several common structural features and that function both in the turnover and degradation of extracellular matrix proteins and in the processing, activation, or deactivation of a variety of soluble factors (1). MMPs, or matrixins, are a subgroup of the much larger metalloproteinase superfamily, which also includes astacin and ADAM proteinases, among others. To date 23 different MMPs have been cloned, and additional members continue to be identified (2).To be classified as a matrix metalloproteinase, a protein must have conserved features of two domains, namely the prodomain and the catalytic domain. The prodomain of a typical MMP is about 80 amino acids, and all MMPs, except MMP-23 (3), contain the consensus sequence PRCXXPD. As for all metalloproteinases, the catalytic domain contains an active site Zn 2ϩ that binds three conserved histidines in the sequence HEXXHXXGXXH(S/T)XXXXXXM, which also contains a conserved methionine to the carboxyl side of the zinc-binding site (metzincins) (4). In an inactive state, the conserved cysteine residue in the prodomain provides the fourth coordination site for the catalytic zinc ion. In addition, with the exception of matrilysin (MMP-7), endometase/matrilysin-2 (MMP-26), and MMP-23, MMPs have a hinge region, which is often prolinerich, and a so-called hemopexin-like C-terminal domain (3,5,6). Other domains fou...

Summary Since proteolysis of the dermal collagenous matrix and basement membranes is required for local invasive growth and early metastasis formation of cutaneous melanomas, we have analysed the activities/expression levels of certain metalloproteinases in melanomas and cultured melanoma cells by in situ hybridization and Northern analysis. In addition to collagenases-1 and -3 that have been implicated in invasive growth behaviour of various malignant tumours, we analysed the levels of 72-kDa gelatinase and its activators MT1-MMP and TIMP-2 in cultured melanoma cells. The lesions examined included three cases of lentigo maligna and 28 cases of Clark grade I-V melanomas. The premalignant as well as the grade I tumours were consistently negative for collagenase-1 and -3 and TIMP-1 and -3. The collagenases were predominantly expressed in the cancer cells of Clark grade III and IV tumours. TIMP-1 and -3 were abundantly expressed in the cancer and/or stromal cells of grade III and IV melanomas, while TIMP-2 protein was detected also in melanomas representing lower invasive potential. Northern analysis of seven melanoma cell lines showed that the expression of collagenase-1 and TIMPs-1 and -3 was associated with 72-kDa gelatinase positivity. All melanoma cell lines were positive for MTI-MMP and TIMP-2 mRNAs. Our results suggest that overexpression of collagenases-1 and -3 and TIMPs -1 and -3 is induced during melanoma progression. Expression of TIMPs may reflect host response to tumour invasion in an effort to control MMP activity and preserve extracellular matrix integrity. Keywords: MMP; cell invasion; angiogenesis; gelatinase 733British Journal of Cancer (1999) 80(5/6), 733-743 © 1999 Cancer Research Campaign Article no. bjoc.1998 Received 10 September 1998 Revised 3 December 1998 Accepted 3 December 1998Correspondence to: UK Saarialho-Kere type I, II and III collagens. Furthermore, MMP-13 is gelatinolytic and type IV collagenolytic (Knäuper et al, 1996, and MMP-1 has also some activity against full-length type IV collagen (Collier et al, 1988). Our objective was to determine the expression patterns and cellular localization of these MMPs during melanocytic tumour progression. Furthermore, as imbalance between TIMPs and MMPs is an important factor in tumour invasion, the expression levels of collagenase inhibitors TIMP-1 and -3 were also examined. Our results suggest that the induction of MMPs-1 and -13 and their tissue inhibitors is a late event in melanocytic tumour progression, and that these enzymes are involved in the regulation of melanoma invasion. MATERIALS AND METHODS Tissue specimensFormalin-fixed, paraffin-embedded specimens were obtained from the Department of Dermatopathology, Helsinki University Central Hospital, Helsinki, Finland. Invasion levels of the melanomas were determined by Clark's classification: level I with confinement of the malignant melanoma cells to the epidermis and its appendages; level II with extension to the papillary dermis so that only a few melanoma cells extended to the int...

Significant esophageal morbidity associated with EA extends into adulthood. Surgical complications, increasing age, and impaired esophageal motility predict development of epithelial metaplasia after repair of EA.

Overexpression of membrane-type matrix metalloproteinase (MT-MMP-1) results in the activation of both endogenous and exogenous 72-kDa gelatinase. To understand the effects of MT-MMP-1 on 72-kDa gelatinase activation, we analyzed its expression in human fibroblasts and HT-1080 fibrosarcoma cells. Both cell types expressed the MT-MMP-1 mRNA constitutively at a considerable level and treatment of cells with PMA enhanced the expression about 2-3-fold. Concanavalin A treatment increased MT-MMP-1 mRNA levels in fibroblasts about 4-fold. Induction of MT-MMP-1 by phorbol 12-myristate 13-acetate (PMA) required protein synthesis as shown by cycloheximide inhibition. The induction was also inhibited by dexamethasone. Analysis of MT-MMP-1 mRNA stability using actinomycin D indicated that the halflife was rather long and not affected by PMA, suggesting transcriptional regulation. Only HT-1080 cells had significant 72-kDa gelatinase processing activity after treatment with PMA or concanavalin A, while fibroblasts were virtually negative. Immunoblotting analysis of fibroblast lysates indicated that MT-MMP-1 was present mainly in a 60-kDa form. PMA and concanavalin A caused 2-4-fold increases in its protein levels, while in HT-1080 cells PMA, concanavalin A, or overexpression of MT-MMP-1 did not significantly enhance the level of the 60-kDa protein. Instead, an immunoreactive, proteolytically processed 43-kDa form was observed, and its appearance correlated to 72-kDa gelatinase processing activity. Thus 72-kDa gelatinase activation, while enhanced by MT-MMP-1 expression, needs additional co-operating factors.Keywords: matrix metalloproteinase; membrane-type matrix metalloproteinase-l ; 72-kDa gelatinase ; matrix degradation ; cell invasion.Matrix metalloproteinases (MMPs) comprise currently a group of at least 14 distinct enzymes capable of degrading most if not all components of the extracellular matrix (Woessner, 1991;Birkedal-Hansen et al., 1993;Sato et al., 1994; Will and Hinzmann, 1995;Takino et al., 1995;Puente et al., 1996). Physiological processes employing some of the MMPs include growth and differentiation, tissue morphogenesis and remodelling and trophoblast invasion during embryo implantation. Several pathophysiological events depend also on metalloproteinases such as wound healing, periodontitis, rheumatoid arthritis and invasion and metastasis of cancer cells. Even in malignant tumors the invasive process is tightly regulated and involves controlled secretion and activation of proteinases and their inhibitors in order to create an optimal proteolytic balance to allow both adhesion to the extracellular matrix and migration Correspondence to J. Keski-Oja, Dept. of Virology, University of Fax: +358 0 434 6491. Abbreviations. bFGF, basic fibroblast groth factor; ConA, concanavalin A ; EGF, epidermal growth factor; IL-1P, interleukin-1P; MT-MMP-1, membrane-type matrix metalloproteinase-1 ; PMA, phorbol 12-myristate 13-acetate; TGF-P, transforming growth factor-P; TTMP-2, tissue inhibitor of metalloproteinases type 2; ...

Membrane-type-1 matrix metalloproteinase (MT1-MMP) has transmembrane and cytoplasmic domains, which target it to invasive fronts. We analyzed the role of the cytoplasmic tail by expressing wild type MT1-MMP and three mutants with progressively truncated C termini in human Bowes melanoma cells. We examined gelatinase A activation and the localization and processing of recombinant proteins in stable cell clones using gelatin zymography, immunoblotting, and immunofluorescence. Cell invasion was analyzed in vitro by Matrigel invasion assays. Gelatinase A was activated in all cell clones. However, the localization of MT1-MMP to the leading edge of migrating cells and cell invasion through Matrigel were strongly enhanced only in cells expressing either wild type or truncated MT1-MMP lacking 6 C-terminal amino acid residues (⌬577). Truncations of 10 or 16 amino acid residues in the cytoplasmic domain (⌬567 and ⌬573, respectively) disturbed MT1-MMP localization. The expression of wild type and ⌬577 MT1-MMPs induced also their cleavage to 43-kDa cell surface forms and the release of soluble, ϳ20-kDa N-terminal fragments containing the catalytic center. A synthetic MMP inhibitor but not a gelatinase inhibitor prevented the processing, suggesting that autocatalytic cleavage occurs. Purified soluble MT1-MMP was also autoproteolytically processed to 43-and 20-kDa forms in vitro. Our results indicate that the cytoplasmic domain has an important role in cell invasion by controlling both the targeting and degradation/turnover of MT1-MMP.

No abstract