Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this report, we investigated the expression and activation of proteolytic enzymes by mouse T-lymphoma cell lines of differing metastatic potential. In contrast to the low metastatic Eb line, the metastatic variants ESb and ESb-MP secreted urokinase-type plasminogen activator (u-PA), which was present in the culture supernatant predominantly in the active form (ESb, 96%; ESb-MP, 80%). All three T-lymphoma variants expressed a mainly cell surface-associated proteinase, which proved to be immunologically and enzymatically related to the murine T-cell-associated serine proteinase-1 (MTSP-1). Intact lymphoma cells were able to activate the recombinant human proenzyme of u-PA (pro-u-PA) by a plasmin-independent mechanism, because plasmin contamination of the cells was not detectable. When ESb-MP cells were cultured in the presence of inhibitors of MTSP-1, such as antithrombin III, Pro-Phe-Arg-chloromethylketone, or aprotinin, the ratio of endogenously activated murine u-PA to inactive pro-u-PA in conditioned medium was significantly reduced (from 80% to 15%). The most potent inhibitor, antithrombin, did not inhibit plasmin-catalyzed pro-u-PA activation. These results suggest a novel autocrine mechanism of plasmin-independent pro-u-PA activation for metastatic T lymphomas by the production of an MTSP-1-related proteinase. The ability to initiate the proteolytic cascade of plasminogen activation in the absence of plasmin might contribute to the metastatic behavior of these cells observed in vivo.
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PMID:A T-cell-related proteinase expressed by T-lymphoma cells activates their endogenous pro-urokinase. 156 36

Despite the ubiquitous presence of basic fibroblast growth factor (bFGF) in normal tissues, endothelial cell proliferation in these tissues is usually very low, suggesting that bFGF is somehow sequestered from its site of action. Immunohistochemical staining revealed the localization of bFGF in basement membranes of diverse tissues, suggesting that the extracellular matrix (ECM) may serve as a reservoir for bFGF. Moreover, functional studies indicated that bFGF is an ECM component required for supporting endothelial cell proliferation and neuronal differentiation. We have found that bFGF is bound to heparan sulfate (HS) in the ECM and is released in an active form when the ECM-HS is degraded by heparanase expressed by normal and malignant cells (i.e. platelets, neutrophils, lymphoma cells). It is proposed that restriction of bFGF bioavailability by binding to ECM and local regulation of its release provide a novel mechanism for neovascularization in normal and pathological situations. The subendothelial ECM contains also tissue type- and urokinase type-plasminogen activators which participate in cell invasion and tissue remodeling. These results and studies on the properties of other ECM-immobilized enzymes (i.e. thrombin, plasmin, lipoprotein lipase) and growth factors (GM-CSF, IL-3, osteogenin), suggest that the ECM provides a storage depot for biologically active molecules which are thereby stabilized and protected. This may allow a more localized and persistent mode of action, as compared to the same molecules in a fluid phase.
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PMID:Extracellular matrix-resident basic fibroblast growth factor: implication for the control of angiogenesis. 171 29

The effect of plasminogen on the ability of highly metastatic ESb mouse lymphoma cells to degrade heparan sulfate (HS) in the subendothelial extracellular matrix (ECM) was studied. A metabolically sulfate-labeled ECM was incubated with the lymphoma cells, and labeled degradation products were analyzed by gel filtration on Sepharose 6B. Heparanase-mediated release of low-Mr (0.5 less than Kav less than 0.85) HS cleavage products was stimulated fourfold in the presence of plasminogen. Incubation of plasminogen alone with the ECM resulted in its conversion into plasmin, which released high-Mr (Kav less than 0.33) labeled proteoglycans from the ECM. Heating the ECM (80 degrees C, 1 hr) abolished its ability to convert plasminogen into plasmin, yet plasminogen stimulated, through its activation by the ESb plasminogen activator, heparanase-mediated release of low-Mr HS fragments. Heparin inhibited both the basal and plasminogen-stimulated degradation of HS side chains but not the total amount of labeled material released from the ECM. In contrast, aprotinin inhibited the plasminogen-stimulated release of high- as well as low-Mr material. In the absence of plasminogen, degradation of heated ECM by ESb cells was completely inhibited by aprotinin, but there was only a partial inhibition of the degradation of native ECM and no effect on the degradation of soluble HS proteoglycan. These results demonstrate that proteolytic activity and heparanase participate synergistically in the sequential degradation of ECM HS and that the ESb proteolytic activity is crucial for this degradation when the ECM-associated protease is inactivated. Plasminogen may serve as a source for the proteolytic activity that produces a more accessible substrate to the heparanase.
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PMID:Involvement of both heparanase and plasminogen activator in lymphoma cell-mediated degradation of heparan sulfate in the subendothelial extracellular matrix. 242 87

A highly metastatic variant (ESb) of a methylcholanthrene-induced T lymphoma elaborates a heparan sulfate (HS) degrading endoglycosidase (heparanase) to a much higher extent than its non-metastatic parental subline (Eb). Whereas a serum-free medium conditioned by either subline contained a trypsin-like serine protease, heparanase activity was detected only in the ESb-conditioned medium (CM). ESb CM was incubated with a naturally produced, sulfate-labelled subendothelial extracellular matrix (ECM) or with a soluble, high-MW labelled proteoglycan first released from the ECM by incubation with Eb CM or with the partially purified ESb protease. Sulfate labelled degradation products were analyzed by gel filtration on Sephrose 6B. The optimal pH for degradation of ECM-bound HS was 6.2 as compared to pH 5.2 for degradation of the soluble proteoglycan. Heparanase-mediated degradation of both ECM-bound and soluble HS was inhibited by heparin. Addition of either trypsin, plasmin or to a lower extent, the purified ESb protease, stimulated between 5- and 20-fold the ESb CM-mediated degradation of ECM-bound HS but had no effect on heparanase-mediated degradation of the soluble proteoglycan. This stimulation was inhibited in the presence of heparin or protease inhibitors. These results indicate that both a protease and heparanase are involved in the ESb-mediated degradation of ECM-bound HS and that one enzyme produces a more accessible substrate for the next enzyme. This sequential cleavage is characteristic of degradation of a multimolecular structure such as the subendothelial ECM and hence cannot be detected in studies with its isolated constituents.
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PMID:Sequential degradation of heparan sulfate in the subendothelial extracellular matrix by highly metastatic lymphoma cells. 315 49

The plasminogen activator (PA) produced by freshly purified human monocytes-macrophages and histiocytic, lymphoma-derived U 937 cells was analyzed by zymography after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and found to migrate with an apparent Mr of 55,000, identical to that of urokinase (Uk). By immunoprecipitation with antibodies specific for the two different types of PA, the enzyme was shown to be immunologically related to urokinase, and not to tissue PA. Urokinase was secreted in the form of the inactive Mr 55,000 zymogen prourokinase , and could be converted to the active Mr 55,000 enzyme by limited proteolysis with plasmin. Conditioned media from cultures of U 937 cells and monocytes-macrophages inhibited the fibrinolytic activity of exogenously added urokinase. Using [125I]-labeled urokinase we observed the formation of an enzyme-ligand complex, which was not dissociated by boiling in SDS and migrated with an apparent Mr 40,000 daltons higher than the free enzyme; since complexed urokinase was functionally inactivated as a PA, the ligand is an inhibitor of urokinase. This inhibitor is different from fibroblast-produced protease- nexin , in that it did not interact with thrombin. These results suggest that plasminogen activation by mononuclear phagocytes can be modulated through the secretion of both (pro)enzyme and a specific inhibitor.
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PMID:Concomitant secretion of prourokinase and of a plasminogen activator-specific inhibitor by cultured human monocytes-macrophages. 637 11

We monitored 30 laboratory hemostatic parameters in an attempt to better comprehend alterations in coagulation and fibrinolysis in 10 patients with hematological malignancies subjected to autologous peripheral blood stem cell transplantation (APBSCT). These parameters were assessed before and just after high-dose conditioning chemotherapy, on days 1, 7, 14 and 28. Although, clinical manifestations associated with fibrino-coagulation disorders never occurred, including veno-occlusive disease, a statistically significant increase was seen in 7 of 30 parameters, compared to values seen before conditioning chemotherapy. These were subdivided into early and late phase parameters. The early phase parameters, which increased during the first day after the conditioning chemotherapy was given, then returned to baseline values, included protein C, plasma tissue factor and tissue-plasminogen activator. The late phase parameters, which increased over baseline values during days 7 to 28, included free-protein S, fibrinogen, plasmin-alpha2-plasmin inhibitor complex and soluble-thrombomodulin. The increase of early phase parameters, as produced by the liver and by endothelial cells, may reflect tissue damage by conditioning chemotherapy. Late phase parameters increased in parallel with C-reactive protein, which suggests a correlation with the degree of inflammation, such as the presence of infective disease during neutropenia. These subclinical alterations in coagulation and fibrinolysis which take on a biphasic pattern during the course of APBSCT should be kept in mind by the attending physicians during therapy.
Leuk Lymphoma 1998 Jan
PMID:Subclinical alterations in coagulation and fibrinolysis in patients undergoing autologous peripheral blood stem cell transplantation. 951 13

Bleeding complications are often associated with acute promyelocytic leukemia (APL) they occur frequently at the onset of APL and become more serious during chemotherapy. The increased bleeding tendency of APL is caused by a massive proteolytic state, triggered by procoagulant substances, plasminogen activators and proteinases released into the circulation from leukemic cells. The introduction of all-trans-retinoic acid (ATRA) into the treatment of APL has reduced bleeding complications. However the mechanisms of the hemostatic defects in patients with APL and their modifications during ATRA with or without chemotherapy are still incompletely understood. Attempts at characterizing and monitoring these hemostatic abnormalities have been made by using several laboratory parameters. Among them we have studied the structural modifications of von Willebrand Factor (vWF). In APL, plasma vWF is massively degraded, with specific fragments produced by the action of plasmin and elastase. After ATRA therapy, proteolysis diminishes progressively in parallel with the improvement of other hemostatic measurements. We conclude that abnormalities of vWF structure and function might adversely affect hemostasis in APL and that their improvement after ATRA administration might explain in part the effectiveness of this drug in reducing hemorrhagic complications.
Leuk Lymphoma 1998 Nov
PMID:The role of von Willebrand factor in the hemostatic defect of acute promyelocytic leukemia. 992 39

Coagulation disorders are often the reason for fatal bleeding in acute promyelocytic leukemia. Their occurrence as well as pathogenesis and prognostic significance in other subtypes of acute myelogenous leukemia and acute lymphoblastic leukemia is less known. Tests were carried out in 70 patients including 49 with AML and 21 with ALL. In all patients thrombin-antithrombin complexes (TAT), D-dimer (DD) and plasmin-antiplasmin complexes (PAP), antithrombin III activity, fibrinogen/fibrin degradation products, APTT and PT were determined. The tests were performed on diagnosis and after cytostatic treatment. The level of TAT, DD and PAP was elevated in 83% of the patients on diagnosis and in 90% after treatment. The highest values were observed in AML M3 patients. Among leukemic patients with normal levels of TAT, DD and PAP at diagnosis, cytostatic treatment had a negligible effect on the level of these markers. During remission the levels of these markers returned to the normal values while in patients without remission they were either elevated or returned to normal values. No correlation between the levels of activation markers and remission rate was reported. DIC was diagnosed in 13 patients including three after chemotherapy. The DIC was acute or subacute in AML and chronic in ALL patients. In the majority of acute leukemia patients there were already changes on diagnosis indicating coagulation activation. Except for AML M3, these usually had a subclinical course. The TAT, DD and PAP tests are not reliable markers of remission in acute leukemias.
Leuk Lymphoma 1999 Dec
PMID:Assessment of coagulation disorders in patients with acute leukemia before and after cytostatic treatment. 1061 52

Proteolytically cleaved human 22 kDa growth hormone (22K hGH) between the amino acid residues 134 and 150 by plasmin or other proteases in vitro has been reported to be most active in growth promoting activity. In this study a deleted mutant hGH lacking amino acid residues from 135 to 146 and having more sensitivity to plasmin digestion was produced using the inverse polymerase chain reaction method and the Escherichia coli expression system. The mutant, hGH delta 135-146, was folded and purified effectively and found to be more sensitive to plasmin cleavage to form the two-chain form in vitro. The biological activities of this plasmin sensitive hGH delta 135-146 were tested by in vitro cell proliferation assays and in vivo growth promoting assay. In Ba/F3-hGHR cells, which express receptors for hGH, hGH delta 135-146 showed 10-20% less growth promoting activity than 22K hGH, but expressed comparable quantities of IGF-I mRNA to that of 22K hGH. In Nb2 rat lymphoma cells, which proliferate in response to hGH via the lactogenic receptors, hGH delta 135-146 showed equivalent activities to those of 22K hGH at lower concentrations. By the body weight gain test using hypophysectomized rats, a lower dose (2.5 nmol kg-1) of hGH delta 135-146 exhibited an equivalent activity to that of wild type 22K hGH, but a higher dose (25 nmol kg-1) of the mutant showed less growth promoting activity than 22K hGH. These results indicated that the plasmin sensitive recombinant hGH delta 135-146 failed to show higher biological activity than the 22K hGH in vivo, suggesting the unsuccessful formation of the active two-chain form in vivo.
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PMID:Synthesis and purification of a deleted human growth hormone, hGH delta 135-146: sensitivity to plasmin cleavage and in vitro and in vivo bioactivities. 1070 10

Current evidence has suggested the possible involvement of ROS as signaling messengers in IL-1beta- or LPS-induced gene expression. We previously reported that both IL-1beta and LPS induce uPA in RC-K8 human lymphoma cells. Here, we provide evidence that ROS-generating anthracycline antibiotics, including doxorubicin and aclarubicin, upregulate uPA expression in 2 human malignant cell lines, RC-K8 and H69 small-cell lung-carcinoma cells. Both doxorubicin and aclarubicin markedly increased uPA accumulation in RC-K8- and H69-conditioned medium in a dose-dependent manner. In each case, maximal induction was observed at a sublethal concentration, i.e., at a concentration where cell growth was slightly inhibited. Both doxorubicin and aclarubicin increased uPA mRNA levels, and induction in each case reached the maximal level 9 hr after stimulation. Doxorubicin barely changed the half-life of uPA mRNA and activated uPA gene transcription. Antioxidants such as NAC and PDTC inhibited doxorubicin-induced uPA mRNA accumulation. Microarray analysis, using Human Cancer CHIP version 2 (Takara Shuzo, Kyoto, Japan), in which 425 human cancer-related genes were spotted on glass plates, revealed that uPA is 1 of 3 genes that were clearly upregulated in H69 cells by doxorubicin stimulation. These findings suggest that the anthracycline induces uPA in human malignant cells by activating gene transcription in which ROS may be involved. Therefore, by upregulating uPA expression, the anthracycline may influence many biologic cell functions mediated by the uPA/plasmin system.
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PMID:Induction of urokinase-type plasminogen activator by the anthracycline antibiotic in human RC-K8 lymphoma and H69 lung-carcinoma cells. 1151 39


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