Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017636 (glioblastoma)
 18,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human U373 glioblastoma/astrocytoma cell line was found to constitutively produce and secrete a plasminogen activator and a plasminogen activator inhibitor. The plasminogen activator was identified as urokinase based on apparent molecular weight, immunoblotting with anti-urokinase antibodies, and Northern blotting with a human urokinase cDNA probe. The inhibitor secreted by U373 cells was found to be related to the PAI-1 molecule based on reactivity with anti-human PAI-1 antibodies, apparent molecular weight, and Northern blot analysis with a human PAI-1 cDNA probe. The expression of both urokinase and the PAI-1-like molecule by U373 cells could be modulated by phorbol myristate acetate or by inflammatory mediators such as interferon-gamma and interleukin-1. In the case of interleukin-1, the alpha form exhibited no detectable effect while the beta form not only elevated inhibitor levels, it also appeared to induce the production of tissue plasminogen activator. Thus, in these cells interleukin-1 beta induces alterations in PA and PAI expression and interleukin-1 alpha does not, even though the two forms are reported to utilize the same cellular receptor.
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PMID:Modulation of plasminogen activator and plasminogen activator inhibitor expression in the human U373 glioblastoma/astrocytoma cell line by inflammatory mediators. 172 61

Changes in the fibrinolytic and coagulation values measured preoperatively in brain tumor patients have not been done systematically using individual rather than global assays. Such measurements can provide meaningful information on the status of tumor-host interactions and could potentially help in predicting thromboembolic and hemorrhagic tendencies. A complete fibrinolytic profile including total fibrinolytic activity (TFA), tissue plasminogen activator (t-PA), plasmin inhibitor (PI), plasminogen activator inhibitor (PAI), protein C (PC) and plasminogen (PLG) was obtained preoperatively in 114 brain tumor patients. PLG and PI did not show much variation among the groups. TFA was slightly reduced (15%) in patients with malignant brain tumors. t-PA, however, was abnormally low in several patients and in almost 40% of patients with brain metastasis. PAI was above the upper limit of normal in approximately 50% of the patients but particularly in glioma, glioblastoma and metastasis patients. Finally, mean PC was abnormally increased in the glioblastoma and metastasis groups (p less than 0.001). This is the first study that has measured protein C in brain tumor patients. In conclusion, plasma fibrinolytic levels show marked changes in a substantial number of brain tumor patients prior to surgery--suggesting an ongoing tumor-host interaction.
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PMID:Plasma fibrinolytic profile in patients with brain tumors. 182 14

Fresh brain-tumor samples were obtained at operation and analyzed for their content of tissue type plasminogen activator (tPA) using an activity assay (gel chromatography zymogram) and an enzyme-linked immunospecific assay. The specimens were taken from 23 glioblastomas, 35 metastatic tumors, 42 meningiomas, 16 low-grade gliomas, and seven acoustic neurinomas; seven specimens were from normal brain. A strong correlation was found between the results of the two assays (r = 0.77, p less than 0.0001). There was a threefold difference in the tPA content of the benign tumors as compared to malignant tumors (p = 0.0006), the latter having less tPA. Histologically benign meningiomas contained higher tPA than malignant meningiomas (p = 0.01); however, the difference between low-grade gliomas and high-grade gliomas was less evident. Overall regression analysis data have shown an inverse relationship between the tissue content in tPA and the presence and degree of tumor necrosis and peritumoral brain edema (p = 0.004 and p = 0.0004, respectively). This finding was most consistent in the glioblastoma group where the correlation coefficient values were r = 0.53 and r = -0.55, respectively. There was no significant correlation between the tissue tPA content and the age and sex, steroid use, or plasma tPA of the patients or the duration of symptoms. In summary, this is the first demonstration of tPA in a large series of human brain tumors and in normal brain. The differences observed have clear biological significance and, although the source of tPA in tumor tissue is still unknown, a relative reduction in tPA in tumor tissue may play an integral role in the development of tissue necrosis and tissue edema. The lack of tPA in tumor necrosis was not due to tissue destruction and cell death since urokinase was readily detectable in that tissue.
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PMID:Biological significance of tissue plasminogen activator content in brain tumors. 189 96

The distribution of tissue plasminogen activator (t-PA) has been studied in a series of 38 human brain tumours and two specimens of cerebral cortex, using the monoclonal antibody ESP6. t-PA was localised in vascular endothelium in the majority of tumours and both the cortical specimens, confirmed by double staining with Ulex europaeus lectin (Uel) and Factor 8-related antigen. Nineteen out of 22 high grade astrocytomas showed strong endothelial staining whereas staining was weak or absent in the four low grade astrocytomas studied. No consistent relationship was found between the pattern of staining and tumour grade in the other tumours, although strong staining of the three metastatic lesions with Uel was observed. Among the astroglial tumours only one glioblastoma showed any tumour cell staining for t-PA, which raises questions concerning the origin of t-PA producing cells derived from human gliomas in vitro. Studies of t-PA in brain tumours should take account of this vascular localisation before concluding that the activity is derived from neoplastic cells.
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PMID:Immunohistochemical localisation of tissue plasminogen activator in human brain tumours. 253 81

We have studied the regulation by glucocorticoids and dibutyryl cAMP of the amounts of urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA) and a Mr approximately 54000 plasminogen activator inhibitor accumulated in serum-free conditioned culture fluid by a human fibrosarcoma, a human glioblastoma and a human melanoma cell line (HT-1080, UCT/gl-1 and Bowes). For the quantitation of u-PA and t-PA, we used sandwich-type ELISA with a combination of polyclonal and monoclonal antibodies. For an estimation of variations in the amount of the inhibitor, we used sodium dodecyl sulphate-polyacrylamide gel electrophoresis followed by Coomassie blue staining of conditioned culture fluid proteins, the inhibitor protein band being identified by its selective removal by passage of the conditioned culture fluids through a column with monoclonal antibodies against the inhibitor. The modulation of the 3 proteins by the hormonal agents varied greatly between the cell lines. The proteins were independently regulated, in the sense that the hormonal agents did not concomitantly change their levels in the direction expected either to increase or decrease total extracellular plasminogen activator activity. In conditioned culture fluids containing both t-PA and inhibitor, the two were present in the medium as a Mr approximately 120 000 complex. In contrast, no u-PA inhibitor complexes were found in conditioned culture fluid from any of the cell lines; this is likely to be due to the occurrence of u-PA in the culture fluid in the one-chain proenzyme form, which, unlike active u-PA, does not react with the inhibitor. These findings illustrate the complexity of the regulation of extracellular plasminogen activator activity, and imply that the presumed functional diversity of u-PA and t-PA may be related to their independent regulation.
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PMID:Hormonal regulation of extracellular plasminogen activators and Mr approximately 54,000 plasminogen activator inhibitor in human neoplastic cell lines, studied with monoclonal antibodies. 301 58

In the human glioblastoma cell line, T-MG1, plasminogen activator activity (PA-activity) was demonstrated by using the chromogenic substrate S-2251. Using monoclonal antibodies against human urokinase type PA (u-PA) and human tissue type PA (t-PA), only u-PA activity was found in T-MG1 cell extracts. The u-PA activity in T-MG1 cells was suppressed in a dose-dependent manner by B-TGF and EGF after 24 hours of exposure to these growth factors. Twenty units of B-TGF caused a decrease in PA-activity of 80%, while 10 ng/ml EGF gave a decrease in PA-activity of 60%. The suppressive effects of B-TGF and EGF were observed after 2 hours and 4 hours of incubation, respectively and sustained for at least 24 hours. The effects of B-TGF and EGF were not antienzymatic, but rather mediated through regulatory mechanisms. In view of the capacity of invasive growth of gliomas and the potential role of PA in invasive growth, the suppression of PA-activity in gliomas by B-TGF and EGF may be of importance.
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PMID:Type beta transforming growth factor and epidermal growth factor suppress the plasminogen activator activity in a human glioblastoma cell line. 326 20

Alkylating agents, mechlorethamine and N-methyl-N'-nitro-N-nitrosoguanidine, induce the production of plasminogen activator in U-87MG cells, an alkylation DNA repair deficient (Mer-) human glioblastoma strain. Enzyme induction was not observed, however, in U-178MG and SH-101 cells, alkylation repair proficient (Mer+) glioblastoma strains, or in HeLa cells, which reactivated and supported well the growth of alkylation damaged adenovirus 3. In the alkylation repair defective U-87MG strain, enhanced production of plasminogen activator occurred in a narrow concentration range of treatment with either alkylating agent, causing a 20 to 50% inhibition of [3H]thymidine incorporation. Maximum plasminogen activator induction was observed between 32 and 48 h after alkylation treatment and the levels of enzyme produced were 5 to 10 times those of untreated control levels. This alkylation dependent enzyme induction required protein synthesis for it did not occur in the presence of cycloheximide. It was hence concluded that plasminogen activator induction in alkylation repair deficient human cells is caused by unrepaired DNA damage and that it may represent an eukaryotic SOS-like function. In addition, plasminogen activator induction may be useful as a sensitive assay for the identification of alkylation repair defective human tumors for which the susceptibility to alkylation chemotherapy should be expected to increase.
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PMID:Induction of plasminogen activator by alkylating agents in a repair defective human glioblastoma cell strain. 369 74

We cloned a previously characterized glioblastoma-derived parent cell line (12-18) in order to obtain a relatively homogenous population of human neural cells of neoplastic origin. These cells reach high densities in culture (over 100,000 cells/cm2) and have a high mean DNA content per cell of 18.1 +/- 0.9 pg. A histogram of the cloned cells' chromosome numbers revealed one peak and a modal near diploid number of 52, whereas the parent cell line had expressed polyploidy, with several peaks (including 52) at population doubling level 16. Several consistent results were obtained by Giemsa staining. A persistent structural alteration was the duplication of the long arm of chromosome #9 on to another arm of #9, and the translocation of the short arm of #9 to chromosome #21. We further observed that these cloned cells secrete a specific protease, a plasminogen activator (PA), into serum-free medium (SFM). This enzyme was assayed by the conversion of purified plasminogen to plasmin and the subsequent degradation by plasmin of 125I-labelled fibrin. Glioblastoma-derived cells had higher levels of cell-associated PA activity (2.9-fold) and released more PA activity into SFM (22-fold) than human fetal neural cells. The presence of this protease suggests a mechanism for the invasive character of these neoplasms (glioblastoma multiforme) in vivo.
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PMID:Properties of cloned human glioblastoma cells. Release of a specific protease. 676 10

Monoclonal antibodies against a human plasminogen activator of M(r) approximately 52,000 (HPA52) were derived by immunization of mice with an impure preparation of the enzyme (urokinase), subsequent hybridization of spleen cells with NSI-Ag4/1 myeloma cells, and cloning of the hybridomas. Selection of mice for hybridization and screening of hybridomas were based solely on direct inhibition of an enzymatic assay of the plasminogen activator with the impure enzyme preparation. A cloned hybridoma produced IgG1 antibodies that bound to and inhibited the enzymatic activity of HPA52 irrespective of whether the HPA52 was derived from urokinase or from human glioblastoma cells, whereas there was no inhibition of or binding to a plasminogen activator of M(r) approximately 70,000 from human melanoma cells or a plasminogen activator of M(r) approximately 36,000 that is a degradation product of HPA52 and present in urokinase. Nor did the anti-HPA52 IgG1 inhibit a murine plasminogen activator of M(r) approximately 48,000 derived from sarcoma virus-transformed cells. By using affinity chromatography with columns of anti-HPA52 IgG1 bound to Sepharose, HPA52 was purified from urokinase to homogeneity as evaluated by NaDodSO(4)/polyacrylamide gel electrophoresis. This study demonstrates that inhibitory monoclonal antibodies against enzymes can be derived with the sole use of impure enzyme preparations and shows how such antibodies subsequently can be used for enzyme purification.
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PMID:Monoclonal antibody that specifically inhibits a human Mr 52,000 plasminogen-activating enzyme. 680 14

Incorporation of the serine protease active site reagent diisopropyl fluorophosphate (DFP) into a plasminogen activator with an Mr of approximately 52000 released from cultured human glioblastoma cells was strongly enhanced by incubation with plasmin. This observation led to the isolation of an inactive form of the enzyme from serum-free conditioned culture fluid by affinity chromatography on a column of a Sepharose-bound monoclonal antibody raised against urokinase. An 831-fold purification was obtained with a yield of 41%. The purified molecule was homogeneous as evaluated by polyacrylamide gel electrophoresis with sodium dodecyl sulfate (NaDodSO4), having one stainable band under nonreducing as well as reducing conditions with an Mr of approximately 52000. It was unable to activate plasminogen, but catalytic amounts of plasmin converted it into active enzyme. After NaDodSO4-polyacrylamide gel electrophoresis, the active enzyme showed one band under nonreducing conditions, but after reduction, two bands with Mr values of approximately 20000 and 32000 were observed. The active enzyme incorporated [3H]DFP into the approximately Mr 32000 band, while no incorporation was observed into the inactive form. These findings show that the Mr 52000 human plasminogen activator exists in a proenzyme form consisting of a single polypeptide chain that by proteolysis between half-cystine residues is converted into the active enzyme consisting of two chains with molecular weights of approximately 20000 and 32000, the active site being on the latter chain. The results are consistent with the active form of the enzyme being identical with the higher molecular weight form of urokinase, and together with recent observations that a murine plasminogen activator is released from sarcoma virus transformed cells as an inactive proenzyme, they suggest that zymogens to plasminogen activators are of more general occurrence.
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PMID:Purification of zymogen to plasminogen activator from human glioblastoma cells by affinity chromatography with monoclonal antibody. 689 Dec 64


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