Tissue Inhibitor Of Metalloprotease Research Articles

Luteinization and proteolysis in ovarian follicles of Meishan and Large White gilts during the preovulatory period

This experiment was conducted to determine why follicles luteinize faster in the Meishan breed than in the Large White breed of pig. Follicles were recovered during the late follicular phase from ovaries of both breeds before and after administration of hCG given to mimic the LH surge. First, the patterns of cholesterol transporters (high and low density lipoproteins: HDL and LDL) were compared. Cholesterol transporters detected in follicular fluid consisted of HDL only. Similar amounts of Apolipoprotein A-I were found in all samples. There was no obvious breed effect on minor lipoproteins found in the HDL-rich fraction, and this pattern was altered similarly by hCG in the two breeds. The LDL-rich samples of serum from both breeds contained similar amounts of protein. Second, three steroidogenic enzymes, adrenodoxin, 17 alpha-hydroxylase-lyase (P450(17) alpha) and 3 beta-hydroxysteroid-dehydrogenase (3 beta-HSD) were detected by immunohistochemistry and quantified by image analysis on sections of the two largest follicles. Before hCG treatment, theca interna cells demonstrated immunoreactivities for adrenodoxin (strong), P450(17) alpha and 3 beta-HSD (very strong), whereas granulosa cells displayed immunoreactivities for adrenodoxin only. After hCG treatment, the localization of the enzymes was unchanged but the staining intensity of adrenodoxin on granulosa cells and 3 beta-HSD on theca cells increased (P < 0.01 and P < 0.05, respectively). Breed effects were detected for the amounts of adrenodoxin in theca cells (Meishan > Large White; P < 0.05) and of 17 alpha-hydroxylase (Large White > Meishan, P < 0.01). Breed x treatment interactions were never detected. Finally, gelatinases, plasminogen activator, plasminogen activator inhibitor, tissue inhibitors of metalloproteases (TIMP-1 and TIMP-2) were visualized by direct or reverse zymography or western blotting. Whatever the stage relative to LH administration, follicular fluid from Large White gilts contained more TIMP-1, and TIMP-2 (P < 0.02 and P < 0.01, respectively). No breed effect was detected for the amounts of gelatinases and plasminogen activator inhibitor 1. However, for these parameters, a significant breed x time interaction was obvious, as the Meishan follicles had a greater response to hCG (P < 0.01). Since proteolysis plays a key role in the bioavailability of growth factors such as insulin-like growth factor 1, fibroblast growth factor and transforming growth factor beta, which have the ability to alter gonadotrophin-induced progesterone production in pigs, the differences observed in its control in the present study may explain, at least in part, the different patterns of luteinization observed in Meishan and Large White follicles.

Effects of colony stimulating factor-1 on human extravillous trophoblast growth and invasion.

Colony stimulating factor (CSF)-1 has been localized in a variety of tissues and shown to influence proliferation and differentiation of numerous cell types. Messenger RNA and protein products of CSF-1 and its receptor (c-fms) have been identified in the human placenta and decidua. We examined whether CSF-1 and c-fms mRNA and protein are expressed by normal human first trimester invasive extravillous trophoblast (EVT) cells propagated in culture and whether CSF-1 influences proliferation and/or invasion of these cells. CSF-1 mRNA and protein expression was determined by RT-PCR and immunofluorescence microscopy. Proliferation was assessed by the cellular uptake of tritiated thymidine and invasion was evaluated by Matrigel invasion assay as well as Northern blot analysis of mRNA expression for invasion-associated enzymes and their inhibitors. Results revealed that normal invasive EVT cells in culture express both CSF-1 and c-fms mRNA and protein. Under serum-free conditions, exogenous CSF-1 greatly stimulated the proliferation of these cells. CSF-1 neutralizing and c-fms receptor blocking antibody (Ab) each abolished the growth stimulatory effects of CSF-1, indicating that CSF-1 and c-fms interaction was responsible for these effects. In fact, c-fms Ab alone reduced proliferation to below background levels. While exogenous CSF-1 failed to influence EVT cell invasiveness, Northern blot analysis of mRNA indicated a slight upregulation of the invasion-associated enzyme 72 kDa type IV collagenase as well as its natural inhibitor tissue inhibitor of metalloprotease (TIMP)-1, so that the balance between the two remained unaltered. These findings suggest that CSF-1 may represent an autocrine (and possibly paracrine) growth stimulatory factor for the invasive trophoblast cells in situ with no net effect on their invasiveness.

Fibrinolytic factors, matrix metalloprotease-1, and tissue inhibitor of metalloproteinase-1 in gastric carcinoma

The invasion and metastasis of carcinoma cells require the action of tumor-associated proteases and their inhibitors, which may also may be involved in the stages of carcinogenesis. In the present study, we evaluated the levels of fibrinolytic factors, urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA), type-1 plasminogen activator inhibitor (PAI-1), and u-PA specific receptor (u-PAR) as well as matrix metalloprotease-1 (MMP-1) and its tissue inhibitor of metalloprotease-1 (TIMP-1) in extracts of human gastric carcinoma tissues and their corresponding normal mucosas. The antigen levels of u-PA, PAI-1, and TIMP-1 were significantly higher in carcinomas than normal mucosas, while those of u-PAR were not changed as much. Thus, the increase of u-PAR ligand u-PA and its inhibitor PAI-1 may be important in carcinoma tissues. In addition, the amidolytic activity with S-2444 of carcinomas was significantly higher than that of normal tissue indicating that u-PA but not t-PA was involved in the fibrinolytic activity of carcinoma tissues. However, the relationships between any two factors among these components were not clear. From these findings, it is also confirmed that u-PA and PAI-1 are the major regulators of human gastric cancer cells. In addition, since both MMP-1 and TIMP-1 were found to be higher in the carcinomas than the normal mucosas, it is suggested that this matrix enzyme and inhibitor are also up-regulated in carcinomas, the pathway of which is independently linked to fibrinolytic system.

Expression of matrix-degrading enzymes in pulmonary vascular remodeling in the rat.

Exposure of rats to hypoxia causes pulmonary arterial remodeling, which is partly reversible after return to air. We hypothesized that degradation of excess collagen in remodeled pulmonary arteries in the posthypoxic period is mediated by endogenous matrix metalloproteinases (MMPs). Total proteolytic, collagenolytic, and gelatinolytic activities, levels of stromelysin-1 and tissue inhibitor of metalloprotease-1 (TIMP-1), and immunolocalization of stromelysin-1 in main pulmonary arteries were determined after exposure of rats to 10% O2 for 10 days followed by normoxia. We observed transient increases in total proteolytic, collagenolytic, and gelatinolytic activities and expression of approximately 72-, 68-, and 60-kDa gelatinases by zymography within 3 days of cessation of hypoxic exposure. The level of TIMP-1 increased as the stromelysin-1 level increased. Immunoreactive stromelysin-1 was localized predominantly in the luminal region of normal and hypertensive pulmonary arteries. These results are consistent with the notion that endogenous MMPs may mediate the breakdown of excess collagen in remodeled pulmonary arteries during the early posthypoxic period.

Expression of Matrix Metalloproteinases and Their Tissue Inhibitors in Human Brain Tumors

In this study, we investigated the expression patterns of 15 matrix metalloproteinases (MMPs) and three tissue inhibitors of metalloproteinase in gliomas, medulloblastomas, and normal brain tissue. By Northern blot analysis we found increased levels of mRNAs encoding for gelatinase A, gelatinase B, two membrane-type MMPs (mt1- and mt2-MMP), and tissue inhibitors of metalloproteinase-1 in glioblastomas and medulloblastomas. We observed a significant increase of mt1-MMP, gelatinase A, gelatinase B, and tissue inhibitors of metalloproteinase-1 in glioblastomas as compared with low-grade astrocytomas, anaplastic astrocytomas, and normal brain. In medulloblastomas, the expression of mt1-MMP, mt2-MMP, and gelatinase A were also increased, but to a lesser extent than that observed in glioblastomas. These data were confirmed at the protein level by immunostaining analysis. Moreover, substrate gel electrophoresis showed that the activated forms of gelatinases A and B were present in glioblastomas and medulloblastomas. These results suggest that increased expression of mt1-MMP/gelatinase A is closely related to the malignant progression observed in gliomas. Furthermore, the present study demonstrates, to our knowledge for the first time, that medulloblastomas express high levels of MMP.

SV40 Tag transformation of the normal invasive trophoblast results in a premalignant phenotype. I. Mechanisms responsible for hyperinvasivess and resistance to anti‐invasive action of TGFβ

Invasion of the uterus by first trimester human placental extravillous trophoblast (EVT) cells depends on mechanisms shared by malignant cells. However, unlike tumor invasion, trophoblast invasion of the uterus is stringently controlled in situ by local molecules such as transforming growth factor (TGF)β. Since EVT cells possess active invasion-associated genes but are nontumorigenic, our objective was to induce premalignant and then malignant phenotype into a normal EVT cell line in order to identify the molecular basis of tumor progression. Simian virus 40 large T antigen (SV40 Tag) was introduced into a normal human first trimester invasive EVT cell line, HTR8, established in our laboratory. Since the HTR8 line has a limited in vitro lifespan of 12–15 passages, SV40 Tag-transformed cells were selected on the basis of extended lifespan. A long-lived line, RSVT-2, was produced and an immortalized subclone, RSVT2/C, was further derived under a forced crisis regimen. We examined transformation-induced alterations in proliferative and invasive abilities, responses to the invasion and proliferation-regulating growth factor TGFβ and changes in gene expression for invasion-associated enzymes or enzyme inhibitors. RSVT-2 and RSVT2/C cell lines were hyperproliferative and hyperinvasive when compared with the parental HTR8 cell line. They were also variably resistant to the anti-proliferative and anti-invasive signals from TGFβ. Since both cell lines remained non-tumorigenic in nude mice, these properties indicate that they attained a premalignant phenotype. Both cell lines showed reduced expression of tissue inhibitor of metalloproteases (TIMP)-1, while TIMP-2 and plasminogen activator inhibitor (PAI)-1 expression was was also reduced in RSVT2/C cells, thus contributing to their hyperinvasiveness. Their resistance to the anti-invasive action of TGFβ was explained by the failure of TGFβ to upregulate TIMPs and PAI-1, in contrast to the TGFβ-induced upregulation noted in parental HTR8 cells. Int. J. Cancer 77:429–439, 1998.© 1998 Wiley-Liss, Inc.

SV40 Tag transformation of the normal invasive trophoblast results in a premalignant phenotype. I. Mechanisms responsible for hyperinvasiveness and resistance to anti-invasive action of TGFbeta.

Invasion of the uterus by first trimester human placental extravillous trophoblast (EVT) cells depends on mechanisms shared by malignant cells. However, unlike tumor invasion, trophoblast invasion of the uterus is stringently controlled in situ by local molecules such as transforming growth factor (TGF)beta. Since EVT cells possess active invasion-associated genes but are nontumorigenic, our objective was to induce premalignant and then malignant phenotype into a normal EVT cell line in order to identify the molecular basis of tumor progression. Simian virus 40 large T antigen (SV40 Tag) was introduced into a normal human first trimester invasive EVT cell line, HTR8, established in our laboratory. Since the HTR8 line has a limited in vitro lifespan of 12-15 passages, SV40 Tag-transformed cells were selected on the basis of extended lifespan. A long-lived line, RSVT-2, was produced and an immortalized subclone, RSVT2/C, was further derived under a forced crisis regimen. We examined transformation-induced alterations in proliferative and invasive abilities, responses to the invasion and proliferation-regulating growth factor TGFbeta and changes in gene expression for invasion-associated enzymes or enzyme inhibitors. RSVT-2 and RSVT2/C cell lines were hyperproliferative and hyperinvasive when compared with the parental HTR8 cell line. They were also variably resistant to the anti-proliferative and anti-invasive signals from TGFbeta. Since both cell lines remained non-tumorigenic in nude mice, these properties indicate that they attained a premalignant phenotype. Both cell lines showed reduced expression of tissue inhibitor of metalloproteases (TIMP)-1, while TIMP-2 and plasminogen activator inhibitor (PAI)-I expression was was also reduced in RSVT2/C cells, thus contributing to their hyperinvasiveness. Their resistance to the anti-invasive action of TGFbeta was explained by the failure of TGFbeta to upregulate TIMPs and PAI-I, in contrast to the TGFbeta-induced upregulation noted in parental HTR8 cells.

Interleukin (IL)-6 and Its Soluble Receptor Induce TIMP-1 Expression in Synoviocytes and Chondrocytes, and Block IL-1-induced Collagenolytic Activity

To define the potential role of interleukin-6 (IL-6) and its soluble receptor alpha in cartilage metabolism, we analyzed their effects on tissue inhibitor of metalloproteases (TIMP) synthesis by synoviocytes and chondrocytes. TIMP-1 production by isolated human articular synovial fibroblasts and chondrocytes, stimulated by IL-6 and/or its soluble receptor, was first assayed by specific enzyme-linked immunosorbent assay; the slight stimulatory effect of IL-6 on TIMP-1 production by both types of cells was markedly amplified by the addition of soluble receptor, the maximal secretion being observed only at 96 h. TIMP-1 mRNA expression, determined by ribonuclease protection assay, was induced by IL-6 together with its soluble receptor, but TIMP-2 and -3 mRNAs were not affected by these factors. A specific neutralizing antibody abolished the effects of the soluble receptor. Finally, supernatant from synoviocytes stimulated by IL-6 plus its soluble receptor blocked almost completely the collagenolytic activity of supernatant from IL-1-induced synoviocytes. These observations indicate that IL-6 and its soluble receptor have a protective role in the metabolism of cartilage. Given the high levels of soluble receptor in synovial fluid and the marked induction of IL-6 by IL-1 or TNF-alpha, it is likely that IL-6 and its soluble receptor are critical in controlling the catabolic effects of pro-inflammatory cytokines.

Molecular changes during the genesis of human gliomas.

Neoplastic transformation in the normal human brain occurs as a result of the accumulation of a series of genetic alterations. These genetic alterations include the loss, gain or amplification of different chromosomes which lead to altered expression of proteins that play important roles in the regulation of cell proliferation. Several common genetic alterations at the chromosomal level (loss of 17p, 13q, 9p, 19, 10, 22q, 18q and amplification of 7 and 12q) have been observed. These alterations lead to changes in the expression of several genes; protein 53 (p53), retinoblastoma (RB), interferon (INF) alpha/beta, cyclic AMP dependent kinase number 2 (CDKN2), mutated in multiple advanced cancers 1 (MMAC1), deleted-in-colon carcinoma (DCC), epidermal growth factor receptor (EGFR), platelet derived growth factor (PDGF), platelet derived growth factor receptor (PDGFR), MDM2, GL1, CDK4 and SAS during the genesis and progression of human gliomas. Recent studies suggest that altered expression of several other genes [MET; MYC; transforming growth factor beta (TGF beta); CD44; vascular endothelial growth factor (VEGF); human neurological-related cell adhesion molecule (hNr-CAM); neuroglial cell adhesion molecule (NCAM L1); p21waf1/Cip1; TRKA; mismatch repair genes (MMR); C4-2; D2-2] and proteins [e.g., cathepsins, tenascin, matrix metalloproteases, tissue inhibitors of metalloproteases, nitric oxide synthase, integrins, interleukin-13 receptor (IL-13R), Connexin43, urokinase-type plasminogen activator receptors (uPARs), extracellular matrix proteins and heat shock proteins] are associated with the genesis of human gliomas. Taken together, these findings point to the accumulation of multiple genetic mutations coupled with extensive changes in gene expression in the etiology of human gliomas.

Stimulation of collagen expression and glycosaminoglycan synthesis by midkine in human skin fibroblasts.

Midkine is a retinoid-inducible regulator of cell differentiation and cell growth in developing embryonic tissues. The effects of midkine on the expression of the extracellular matrix components, collagens and glycosaminoglycans, in dermal fibroblasts were studied. Midkine did not alter fibroblast proliferation. Collagen synthesis was stimulated in a dose- and exposure time-dependent manner and the maximum two-fold stimulation was achieved at a concentration of 100 ng/ml for 72 h treatment. Midkine increased the synthesis of type I and III collagens to the same extent. Glycosaminoglycan synthesis was also stimulated two-fold, mainly accounted for by an increase in hyaluronan synthesis. Midkine enhanced mRNA levels of alpha 1 (I), alpha 1 (III), alpha 1 (VI) collagens, transforming growth factor beta 1 and matrix metalloprotease-2 but did not alter the mRNA levels of elastin, MMP-1 and tissue inhibitor of metalloproteases-1. These results suggest that midkine is a potent stimulator of collagen and glycosaminoglycan synthesis and may prove useful in the therapy of delayed wound healing.

Regulation of c-fos and c-jun expression by calcitonin in human breast cancer cells.

Breast cancer cells (BCC) have calcitonin (CT) receptors, yet the action of the hormone on these cells is largely unknown. We found that CT produced a strong and transient time- and dose-dependent increase in c-fos mRNA in BCC lines. This event was prevented by a protein kinase A (PKA) inhibitor, H89. CT alone did not influence the expression of c-jun and of the tissue inhibitors of metalloproteases (timp) -1 and -2 mRNAs; however, it reduced the induction of these mRNAs by the protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA), without apparent changes in the half-life of the mRNA (measured for c-jun). Along the same line, CT reduced the c-jun induction and T-47D growth stimulation by epidermal growth factor (EGF) and insulin. These effects were mimicked by forskolin and/or prevented by H89, suggesting that PKA activation was involved. These results indicate that CT modulates in BCC the mRNA levels of two important growth-related early response genes (c-fos and c-jun) and of two other genes (timp-1 and -2) involved in the control of metastatic events.

Purification, cDNA cloning, and developmental changes in the steady-state mRNA level of rat testicular tissue inhibitor of metalloproteases-2 (TIMP-2).

Using multiple high-performance liquid chromatography (HPLC) steps and high-performance electrophoresis chromatography (HPEC) in conjunction with an [125I]collagen film assay to identify inhibitors of metalloproteases, we have purified a 22-kDa polypeptide to apparent homogeneity from primary Sertoli cell-enriched culture medium. Partial N-terminal amino acid sequence analysis revealed that this protein is similar to the human tissue inhibitor of metalloproteases-2 (TIMP-2). To determine the similarity of rat testicular TIMP-2 to the human homolog, a full-length cDNA coding for rat testicular TIMP-2 was isolated from a rat Sertoli cell cDNA expression library and sequenced. Analysis of the nucleotide sequence and the deduced amino acid sequence of the rat testicular TIMP-2 cDNA revealed an 84 and 98% homology with the human TIMP-2 nucleotide and amino acid sequences, respectively. A survey of its mRNA transcripts in different tissues by northern blots revealed the presence of two mRNA species of 3.7 and 1.3 kb in the testis and brain but not in the kidney, spleen, epididymis, and liver in adult male rats. Studies using polymerase chain reaction (PCR) and Southern blot to detect the TIMP-2 mRNA using total RNA isolated from germ cells, Sertoli cells, and Leydig cells have shown that only Sertoli and Leydig cells expressed TIMP-2 mRNA. These results indicate that Sertoli cells are the major source of TIMP-2 in the testis behind the blood-testis barrier (seminiferous tubule barrier). During testicular development from 3 to 60 days of age, the testicular steady-state TIMP-2 mRNA level increased steadily with an advancement of age. Such an increase in the steady-state testicular TIMP-2 mRNA level apparently is not the result of an up-regulation by germ cells because germ cells cocultured with Sertoli cells failed to elicit an increase in the Sertoli cell steady-state TIMP-2 mRNA level. The results of this study suggest that TIMP-2 secreted by Sertoli cells may play a role in tissue restructuring and germ cell migration during spermatogenesis.

Tumor necrosis factor alpha and lymphotoxin stimulate human myeloblastic leukemia cell (ML-1) invasion through a reconstituted basement membrane (Matrigel) with concomitant induction of 92 kDa gelatinase secretion

We have examined the effects of tumor necrosis factor alpha (TNF) and lymphotoxin (LT) on gelatinase (72 kDa and 92 kDa) and tissue inhibitor of metalloprotease 1 (TIMP1) secretion by human myeloblastic leukemia cells (ML-1) in vitro. TNF (0.1–30 ng/ml) significantly stimulated 92 kDa gelatinase secretion in a dose-dependent manner, but did not significantly stimulate 72 kDa gelatinase secretion. LT also significantly stimulated 92 kDa gelatinase secretion, but the stimulation was less effective compared to TNF. TNF, but not LT, concentrations at 30 ng/ml slightly stimulated TIMP1 secretion. Because 92 kDa gelatinase is thought to play a pivotal role in tumor invasion, we examined the effect of TNF or LT on ML-1 cell invasion through a reconstituted basement membrane (Matrigel). Exposure of ML-1 cells to TNF (3, 10, and 30 ng/ml) or LT (3, 10, and 30 ng/ml) stimulated ML-1 cell invasion through Matrigel in a dose-dependent manner in vitro. The data suggest that TNF- and LT-stimulated 92 kDa gelatinase secretion could play an important role in TNF-or LT-stimulated ML-1 cell invasion.

Tumor necrosis factor alpha and lymphotoxin stimulate human myeloblastic leukemia cell (ML-1) invasion through a reconstituted basement membrane (Matrigel) with concomitant induction of 92 kDa gelatinase secretion

We have examined the effects of tumor necrosis factor alpha (TNF) and lymphotoxin (LT) on gelatinase (72 kDa and 92 kDa) and tissue inhibitor of metalloprotease 1 (TIMP1) secretion by human myeloblastic leukemia cells (ML-1) in vitro. TNF (0.1-30 ng/ml) significantly stimulated 92 kDa gelatinase secretion in a dose-dependent manner, but did not significantly stimulate 72 kDa gelatinase secretion. LT also significantly stimulated 92 kDa gelatinase secretion, but the stimulation was less effective compared to TNF. TNF, but not LT, concentrations at 30 ng/ml slightly stimulated TIMP1 secretion. Because 92 kDa gelatinase is thought to play a pivotal role in tumor invasion, we examined the effect of TNF or LT on ML-1 cell invasion through a reconstituted basement membrane (Matrigel). Exposure of ML-1 cells to TNF (3, 10, and 30 ng/ml) or LT (3, 10, and 30 ng/ml) stimulated ML-1 cell invasion through Matrigel in a dose-dependent manner in vitro. The data suggest that TNF- and LT-stimulated 92 kDa gelatinase secretion could play an important role in TNF- or LT-stimulated ML-1 cell invasion.

Expression of matrix-metalloproteinases and their inhibitors in human cholesteatomas.

The proteolytic erosion of the temporal bone is the key event in the pathognomonic course of cholesteatoma progression. The molecular mechanisms of bone resorption, endangering the ossicles, the inner ear, the facial nerve, large vessels or the brain, are not understood. Recently, a new family of proteolytic enzymes, the matrix-metalloproteinases (MMP's) has been described and identified, which seems to play a pivotal role in matrix- and bone homeostasis and inflammatory osteolytic diseases, e.g. osteoarthritis and periodontitis. These enzymes are sophisticatedly controlled by specific inhibitors and activation cascades. We investigated whether human cholesteatoma tissue expresses MMP's and MMP-inhibitors. By immunocytochemistry of cholesteatoma-cryosections, the expression of MMP-2 (72 kD collagenase), MMP-9 (92 kD collagenase), and MMP-3 (stromelysin-1) could be seen to be strictly confined to the basal and suprabasal cell layer of the cholesteatoma epithelium. The neutrophil collagenase (MMP-8) showed a more disseminated expression in the epithelium and the granulation tissue as well. The tissue inhibitor of metalloproteases, TIMP-1, could be detected only in very limited areas of the granulation tissue in a quite randomized manner. Therefore, a derailment in favor of proteolysis of the normally tightly controlled MMP-system might be postulated. The results indicate that members of the MMP-family could play an active role in the molecular mechanisms of cholesteatoma invasion into the temporal bone. This offers new insights into the pathophysiology of the disease and of potential therapeutic approaches.

Interleukin-1 beta induction of tissue inhibitor of metalloproteinase (TIMP-1) is functionally antagonized by prostaglandin E2 in human synovial fibroblasts.

Elevated levels of tissue inhibitor of metalloproteases-1 (TIMP-1) have been demonstrated in inflamed synovial membranes, and it is believed that the inhibitor may play a critical role in the regulation of connective tissue degradation. The present study was undertaken to define the cellular mechanism of action of the inflammatory mediators, interleukin-1 beta (IL-1 beta) and prostaglandin E2 (PGE2), in the control of TIMP-1 synthesis and expression in human synovial fibroblasts. Recombinant human IL-1 beta induced a time- and dose-dependent saturable response in terms of TIMP-1 mRNA expression (effective concentration for 50% maximal response, EC50 = 31.5 +/- 3.3 pg/ml) and protein synthesis (EC50 = 30 +/- 3.3 pg/ml). The protein kinase C (PKC) inhibitors, H-7, staurosporine, and calphostin C, reversed the rhIL-1 beta induction of TIMP-1 mRNA. PGE2 also inhibited rhIL-1 beta-stimulated TIMP-1 mRNA expression and protein secretion in a dose-dependent fashion. The concentration of PGE2 necessary to block 50% of rhIL-1 beta-stimulated TIMP-1 secretion, IC50, was 1.93 ng/ml (4.89 nM). Forskolin, and other stable derivatives of cAMP, mimicked, to a large extent, the effects of PGE2. The phorbol ester, PMA, up-regulated considerably the mRNA expression of TIMP-1 but had no effect on protein production. Calphostin C substantially reduced PMA-activated TIMP-1 expression. Staurosporine, calphostin C, H-7, and substances that elevate cellular levels of cAMP, like PGE2, also reduced basal expression and synthesis of TIMP-1. Taken together, the data suggest that PKA and C may mediate opposing effects in terms of TIMP-1 expression and secretion in human synovial fibroblasts.

Interferon-γ Coordinately Upregulates Matrix Metalloprotease (MMP)-1 and MMP-3, But Not Tissue Inhibitor of Metalloproteases (TIMP), Expression in Cultured Keratinocytes

Matrix metalloproteases (MMP) constitute a family of proteolytic enzymes degrading extracellular matrix components. Their activity is inhibited by tissue inhibitors of metalloproteases (TIMP). Previous studies have demonstrated that various cytokines can modulate MMP and TIMP gene expression. In this study, we demonstrate that interferon-gamma coordinately upregulates MMP-1 (interstitial collagenase) and MMP-3 (stromelysin-1) gene expression in cultured keratinocytes, as determined at the mRNA steady-state levels, and this effect is dependent on on-going protein synthesis. In contrast, there was no effect on TIMP-1 gene expression. Enhanced MMP-1 expression by IFN-gamma was also demonstrated at the protein level by Western analysis. Transient transfections with MMP-1 and MMP-3 promoter/reporter gene constructs revealed no response to IFN-gamma, whereas incubation of keratinocytes with this cytokine appeared to stabilize the MMP-1 mRNA, resulting in reduced turnover of the transcript. These data suggest that IFN-gamma enhances MMP gene expression at the post-transcriptional level. The altered MMP expression by IFN-gamma without concomitant effect on TIMP gene expression potentially leads to imbalance between these proteases and their inhibitors, and enhanced proteolytic activity may play a role in the remodeling of cutaneous tissue involving inflammatory processes, such as wound healing.

Mechanism Of Cell Surface Activation Of 72-kDa Type IV Collagenase: ISOLATION OF THE ACTIVATED FORM OF THE MEMBRANE METALLOPROTEASE

Matrix metalloproteases are secreted by mammalian cells as zymogens and, upon activation, initiate tissue remodeling by proteolytic degradation of collagens and proteoglycans. Activation of the secreted proenzymes and interaction with their specific inhibitors determine the net enzymatic activity in the extracellular space. We have previously demonstrated that 72T4Cl can be activated by a plasma membrane-dependent mechanism specific for this enzyme. Here, we report purification of the membrane activator of 72T4Cl, which is a new metalloprotease identical to a recently cloned membrane-type matrix metalloprotease (MT-MMP). We demonstrate that activated MT-MMP acts as a cell surface tissue inhibitor of metalloprotease 2 (TIMP-2) receptor with Kd = 2.54 x 10(-9) M. The activator.TIMP-2 complex in turn acts as a receptor for 72T4Cl (Kd = 0.56 x 10(-9) M, binding to the carboxyl-end domain of the enzyme. Activation of 72T4Cl on the cell membrane provides a basic mechanism for spatially regulated extracellular proteolysis and presents a new target for prognosis and treatment of metastatic disease. The activation, purified as a tri-molecular complex of MT-MMP.TIMP2.carboxyl-end domain of 72T4Cl, is itself an activated form of MT-MMP, posing the following question: what is the mechanism of the activator's activation?

Gelatinase A activity directly modulates melanoma cell adhesion and spreading.

Interaction of cells with the extracellular matrix (ECM) plays an important role in the regulation of cell behavior. Formation of adhesive contacts leads to transduction of signals into the cell and results in altered gene expression and modulation of the cellular phenotype. Specific adhesive interactions of the fibronectin and vitronectin receptors with their ligands in the matrix modulates expression of ECM-degrading metalloproteases. These proteases are involved in the acquisition of the invasive phenotype by a number of cell types. The activity of matrix metalloproteases (MMPs) is reduced by endogenous inhibitors referred to as tissue inhibitors of metalloproteases (TIMPs). Alterations in the balance between the activity of MMPs and TIMPs alters cellular invasion through effects on matrix degradation. In this study we demonstrate that inhibition of endogenous gelatinase A activity in A2058 human melanoma cells results in enhanced cellular adhesion. To further explore this phenomenon, we have used retroviral infection vectors to control the amount of the MMP inhibitor TIMP-2 in human melanoma A2058 cells. Altering the production of TIMP-2 modulates not only proteolysis of the extracellular matrix, but also the adhesive and spreading properties of the cells and results in altered cell morphology. These effects of TIMP-2 appear to be mediated by inhibition of gelatinase A activity. We conclude that gelatinase A, in addition to contributing to proteolysis of ECM components, also functions to proteolyse cell surface components that mediate attachment of A2058 cells to the ECM. Thus, gelatinase A may function to modulate cell attachment and facilitate cell migration and invasion.

Characterization of a pineal region malignant rhabdoid tumor. Towards understanding brain tumor cell invasion.

The malignant rhabdoid tumor (MRT) of the central nervous system is a highly aggressive neoplasm of early infancy which is characterized by brain invasion and widespread dissemination along cerebrospinal fluid pathways. As the process of tumor invasion is mediated in part by the elaboration of proteases and protease inhibitors by tumor cells, we sought to determine the expression of the type-IV collagenases and their inhibitors (tissue inhibitors of metalloproteases, TIMPs) in an MRT from the pineal region of a 9-month-old male. In addition, as only a few reports exist concerning the cytogenetic abnormalities in MRTs, the cytogenetic features of this MRT were examined. When placed into tissue culture, the MRT grew vigorously in early passages. The cytogenetic analysis of the cells in passage one revealed a near diploid karyotype with some metaphases demonstrating monosomy 22. Northern analysis of type-IV collagenase transcripts revealed that the MRT expressed the highest levels of the 72- and 92-kD type-IV collagenase transcripts of any pediatric brain tumor examined. However, the MRT did not express any significant amounts of the TIMP-1 or TIMP-2 transcripts. By in situ hybridization analysis, the MRT demonstrated marked intratumoral expression of the type-IV collagenase but not TIMP transcripts. The results from this study suggest that this particular MRT may be a highly invasive brain tumor, at least in part on the basis of overexpression of the type-IV collagenases relative to the TIMPs.