Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.73 (urokinase-type plasminogen activator)
 10,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

High molecular weight urokinase-type plasminogen activator (uPA) in which proteolytic activity was inactivated (diisopropyl fluorophosphate (DFP)-uPA), its amino-terminal fragment (ATF, amino acids (aa) 1-143), and fucosylated and defucosylated growth factor domains (GFD, aa 4-43) were tested for growth-promoting effects and binding in human SaOS-2 osteosarcoma cells and U-937 lymphoma cells. DFP-uPA, ATF, and both the fucosylated and defucosylated GFD were capable of competing with 125I-ATF for binding to both SaOS-2 and U-937 cells. DFP-uPA, ATF, and fucosylated GFD were also mitogenic in SaOS-2 cells and increased cell numbers. However, defucosylated GFD was nonmitogenic in SaOS-2 cells and did not stimulate cell proliferation, even though it bound to these cells in a manner equivalent to the fucosylated GFD. A nonglycosylated high molecular weight uPA expressed and purified from Escherichia coli inhibited 125I-ATF binding to SaOS-2 cells but was also nonmitogenic. No mitogenic activity was observed in U-937 cells treated with the uPA forms capable of eliciting a mitogenic response in SaOS-2 cells. Proteolytically prepared kringle domain (aa 47-135) and low molecular weight uPA (aa 144-411) did not compete for 125I-ATF binding and did not elicit any mitogenic response in either of the cell lines tested. In addition, tissue plasminogen activator (tPA), which has been shown to be homologous to uPA in its growth factor domain and is also fucosylated, did not inhibit 125I-ATF binding nor elicit any mitogenic response. These results demonstrate that the GFD, implicated in binding to the uPA receptor, is also responsible for growth factor like activity in SaOS-2 cells and that the fucosylation at Thr18 within this domain may serve as a molecular trigger in eliciting this response.
 ...
PMID:Structural requirements for the growth factor activity of the amino-terminal domain of urokinase. 132 Nov 37

A variety of treatments, including acid, heparin, and proteases, are known to free insulin-like growth factors (IGFs) from their binding proteins (IGFBPs). However, the physiologically relevant mechanism regulating the interaction of IGFs and IGFBPs is unknown. We report here the ability of plasmin to dissociate IGFs from IGFBPs. In chromatographic experiments, plasmin completely dissociated complexes of [125I] IGF-I-BP and [125I]IGF-II-BP formed with purified decidual IGFBP (hIGFBP-1) or IGFBPs present in medium conditioned by human osteosarcoma MG-63 cells. Plasmin dissociation of IGF-BP complexes was dose dependent. Neither plasminogen nor plasminogen activators (PAs) alone affected dissociation; however, activation of plasminogen to plasmin by either urokinase PA or tissue-type PA resulted in the dissociation of IGF-BP complexes. Plasmin dissociated immunoreactive and bioactive IGF from IGFBP equivalent to approximately 70% and approximately 60% of the acid control value, respectively. In medium conditioned by MG-63 cells, dissociation of IGF-BP complexes was catalyzed by PAs secreted by MG-63 cells, principally urokinase PA. Limited plasmin degradation of IGF was suggested by chromatographic experiments involving [125I] IGF. Treatment of uncomplexed IGF-I with plasmin concentrations equivalent to those in chromatographic experiments did not result in a significant loss of bioactivity, although a 2-fold increase in the plasmin concentration resulted in a approximately 20% loss of activity. Similar plasmin treatment of equimolar concentrations of hIGFBP-1 resulted in a marked degradation of IGFBP, with loss of IGF-binding ability. In vitro experiments confirmed plasmin dissociation of bioactive IGF-I from hIGFBP-1. In MG-63 cells, IGFBPs can form an IGF reservoir in the pericellular space surrounding the cells by combining IGFs with IGF-BP to form complexes that are incapable of binding to the IGF receptors. The secretion of PAs by osteosarcoma cells and the availability of plasminogen in the extravascular tissues indicate the possibility of a regulatory system in osteosarcoma cells in which pericellular plasmin affects the availability of IGFs to their membrane receptors.
 ...
PMID:Involvement of the plasmin system in dissociation of the insulin-like growth factor-binding protein complex. 137 48

Soluble chromium (VI) compounds either alone or in combination with 3-methylcholanthrene (MC) were used to transform non-tumorigenic osteoblast-like human osteosarcoma cells (HOS TE85). The Cr(VI) compounds were highly toxic to these cells with LC50 values in the range of approximately 0.5-1.0 microM. Continuous passaging of the treated cells resulted in sustained increase in anchorage-independent (AI) colony formation. Treatment with Cr(VI) and MC resulted in substantial increase in AI growth. At the XVth passage, a number of individual AI colonies were expanded in culture and used for further studies. The cells are refractory in appearance and grow as 'nests' rather than as monolayers. The cell lines have relatively high plating efficiency (PE) in soft agar and respond to promotional effect of phorbol-12-myristate-13-acetate by an increase in PE and in the size and number of AI colonies. While the isolated cells are not tumorigenic when tested in athymic nude mice, most of the lines possess higher levels of plasminogen activator (PA) activity, considered as one of the markers of transformation. This is also reflected in the increase in the steady state level of urokinase type PA mRNA. These results show that Cr(VI) compounds are capable of promoting human cells to an altered phenotype characteristic of a stage in the carcinogenesis cascade.
 ...
PMID:Transformation of non-tumorigenic osteoblast-like human osteosarcoma cells by hexavalent chromates: alteration of morphology, induction of anchorage-independence and proteolytic function. 142 71

Transforming growth beta (TGF-beta) has been proposed to have a role in bone remodeling by affecting the differentiation and activity of osteoblasts and osteoclasts and by inhibiting the production of proteinases, such as plasminogen activators (PAs). Studies on PAs have largely been based on data from nonhuman and fetal cell lines, however. The purpose of this study was to investigate the effect of TGF-beta on the PA activity of normal human osteoblast-like cells and to compare this with its action on the human osteosarcoma cell line MG-63. The action of interleukin-1 beta (IL-1 beta) was also assessed because it has been shown to increase PA activity in other connective tissue cell types. Normal osteoblast-like cells had low to undetectable basal urokinase (uPA) and tissue plasminogen activator (tPA) activity, which was significantly stimulated by TGF-beta 1. This action was shown to be dependent on transcription and new protein synthesis. TGF-beta 2 had a similar action. IL-1 beta did not stimulate PA activity. In contrast, the MG-63 cell line had high basal tPA and uPA activities. TGF-beta 1 decreased basal PA activity, the effect being most marked for uPA activity. IL-1 beta stimulated uPA and tPA activity. TGF-beta 1 inhibited IL-1 beta-stimulated uPA activity, but the effect on tPA was more variable. This study has shown that TGF-beta has opposite effects on the PA activity of the two osteoblast-like cell types studied. Care must therefore be used before extrapolating data from one cell type to another.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:The effect of transforming growth factor beta on the plasminogen activator activity of normal human osteoblast-like cells and a human osteosarcoma cell line MG-63. 148 22

The possible carcinogenicity of insoluble chromium (VI) compound, PbCrO4, in human cells has been tested using a nontumorigenic human osteosarcoma cell line (HOS, TE 85). Electron microscopic studies show that PbCrO4 is phagocytosed by HOS cells and accumulates within the vacuoles in the cytoplasm. A number of cell lines have been isolated following multiple treatment of HOS cells with PbCrO4. These cell lines are morphologically different from HOS cells, form anchorage-independent colonies in soft agar and form quickly regressing small tumor nodules in athymic nude mice. The cellular and secreted plasminogen activator (PA) levels of 5 cell lines isolated after PbCrO4 treatment are increased up to 8 fold and up to 10 fold respectively as compared to untreated HOS controls. SDS-PAGE analysis in the presence of copolymerized substrates is consistent with increase in 55 kDa urokinase-type PA (u-PA) and 68 kDa tissue-type PA (t-PA). These results show that PbCrO4 treatment leads to stable phenotypic changes indicative of the transformation of HOS cells.
 ...
PMID:Induction of morphological transformation, anchorage-independent growth and plasminogen activators in non-tumorigenic human osteosarcoma cells by lead chromate. 188 37

Production of proteolytic enzymes by osteoblasts is considered to be important for the initiation of osteoclastic bone resorption. We examined the production of tissue-type (tPA) and urokinase-type plasminogen activator (uPA) activity by three types of osteoblast-like cells (normal rat osteoblasts, rat and human osteosarcoma cells) using a quantitative spectrophotometric assay and a qualitative gel overlay technique. All 3 types of cells released both types of PA-activity into the medium, but normal rat osteoblasts released uPA probably in an inactive form. Treatment with different concentrations of the bone resorbing factors bovine Parathyroid Hormone [1-84], synthetic human Parathyroid Hormone-Like Protein [1-34]. Prostaglandin E2, Interleukin-1 beta, Tumor Necrosis Factor alpha and 1,25-dihydroxyvitamin D3 increased in general the production of both PA's by all three cell types. However, there were differences in the relative potencies of these factors. In contrast, Transforming Growth Factor beta, which inhibits bone resorption, decreased PA-activity in osteoblast-like cells. In all three types of cells, under control as well as under stimulated conditions, a high molecular weight form of PA was demonstrated by the gel overlay technique, most likely a complex of tPA with the PA-inhibitor PAI-1. The uniform increase in production of PA's by osteoblast-like cells in response to bone resorbing factors and its decrease by TGF beta supports the notion that PA's are involved in bone resorption. The exact mechanism however, remains to be elucidated.
 ...
PMID:Regulation of the production of plasminogen activators by bone resorption enhancing and inhibiting factors in three types of osteoblast-like cells. 193 92

Human tissue plasminogen activator (t-PA) was shown to bind specifically to human osteosarcoma cells (HOS), and human epidermoid carcinoma cells (A-431 cells). Crosslinking studies with DTSSP demonstrated high molecular weight complexes (130,000) between 125I-t-PA and cell membrane protein on human umbilical vein endothelial cells (HUVEC), HOS, and A-431 cells. A 48-65,000 molecular weight complex was demonstrated after crosslinking t-PA peptide (res. 7-20) to cells. Ligand blotting of cell lysates which had been passed over a t-PA affinity column revealed binding of t-PA to 54,000 and 95,000 molecular weight proteins. Several t-PA binding proteins were identified in immunopurified cell lysates, including tubulin beta chain, plasminogen activator inhibitor type 1 and single chain urokinase.
 ...
PMID:Characterization of tissue plasminogen activator binding proteins isolated from endothelial cells and other cell types. 212 40

The secretion of elevated levels of proteinases is considered to be a distinct property of most transformed cells. The cellular and secreted levels of plasminogen activators and collagenases have been examined in the nonmalignant human osteosarcoma (HOS), the malignant Kirsten murine sarcoma virus transformed (KHOS/NP), the temperature sensitive revertant of virus transformed HOS (KHOS-240S) and N-methyl-N'-nitro-N-nitrosoguanidine transformed HOS (MNNG/HOS) clones. Virus and MNNG transformed clones exhibit 100- and 7-fold higher cellular and and 270- and 30-fold higher extracellular plasminogen activator (PA) activity as compared with untransformed HOS controls. The cellular PA activity of the revertant clone is similar to but the secreted level is slightly higher than the HOS controls. SDS-PAGE in the presence of casein and plasminogen is consistent with the major PA species of urinary type (u-PA) and with the absence of PA inhibitor in the parent and revertant clones. The cellular levels of active collagenase are low in all the clones. However, on activation by trypsin, the two active collagenase bands of similar intensity are observed for all the lines in SDS-PAGE in the presence of gelatin. While there appears to be some elevation of secreted collagenase prior to trypsin activation, the activated collagenases appear to have the same size and activity in all of the clones.
 ...
PMID:Synthesis and secretion of plasminogen activators and collagenases in human cells transformed by Kirsten murine sarcoma virus and N-methyl-N'-nitro-N-nitrosoguanidine. 256 62

The use of totally implantable right atrial catheters was evaluated in pediatric oncology patients. From September 15, 1987 to March 31, 1989, 26 catheters were inserted in patients (1 year to 20 years of age) with the following diagnosis: acute leukemia (6), osteosarcoma (5), lymphoma (4), central nervous system tumors (6), osteosarcoma (5), lymphoma (4), central nervous system tumors (6) and other solid tumors (5). Total number of catheter days was 5,475. The catheters were maintained for a mean of 210 days (range 10-534). Complications included: documented local infection in 1 patient, successfully treated with antibiotics without removing the catheter and transient obstructions resolved with injection of heparin or urokinase in other children. The use of these right atrial catheters has been widely accepted by patients and families as well as by the health team. Complications have been minimal. Our experience confirms that these catheters contribute to improving quality of life in pediatric patients with neoplasms.
 ...
PMID:[Use of central venous catheters implanted subcutaneously in children with neoplasms]. 279 84

Plasmin-mediated extracellular proteolysis has been implicated in the degradation of bone in normal and pathological conditions. Normal and malignant osteoblasts can produce both tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA). We have used the osteosarcoma cell line MG63 to address the question of whether the enhanced bone turnover in osteosarcomas is mediated by t-PA or by u-PAA and to study the effect of the cytokine interleukin-1 alpha (IL-1 alpha), known to influence bone degradation, on the plasminogen activator production and extracellular matrix degradation in malignant osteoblastic cells. Furthermore, the effect of IL-1 alpha on the synthesis of matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) was analyzed. u-PA production by MG63 was high (approximately 180 ng/10(6) cells/24 h). Also t-PA and PAI-1 production was observed. u-PA production was rapidly increased in MG63 by IL-1 alpha (10 ng/ml), whereas an effect on t-PA production was only found after a prolonged incubation and hardly any effect of IL-1 alpha on PAI-1 production was observed. mRNA analysis revealed similar effects. u-PA receptor (u-PAR) mRNA was detectable in MG63 cells and could be increased by IL-1 alpha after 24 h. In MG63, u-PA-mediated extracellular matrix degradation was detectable, and IL-1 alpha increased the u-PA-mediated matrix degradation (approximately 2-fold). Under control conditions in MG63, only MMP-2, TIMP-1, and TIMP-2 mRNA could be observed. After the addition of IL-1 alpha, a very rapid increase in MMP-1 and MMP-3 mRNA could be observed as well as a moderate increase in TIMP-1 mRNA. The presence of MMP-2 was demonstrated by gelatin zymography. These results show that IL-1 alpha can stimulate u-PA production and can regulate extracellular proteolytic activity mainly via u-PA induction in the MG63 osteosarcoma cell line. Furthermore, IL-1 alpha has a strong stimulating effect on the production of MMP-1 and MMP-3. These findings suggest that u-PA and possibly MMP-1 and MMP-3 play an important role in the process of bone turnover in osteosarcomas.
 ...
PMID:Regulation of plasminogen activation, matrix metalloproteinases and urokinase-type plasminogen activator-mediated extracellular matrix degradation in human osteosarcoma cell line MG63 by interleukin-1 alpha. 750 10


1 2 3 4 5 Next >>