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)

5'-Nucleotidase has been purified from rat glioblastoma cells (Rugli cells). The enzyme has been solubilized from plasma membranes by using Triton X-100 and CHAPS. Two affinity chromatographies on concanavalin A and 5'-AMP-Sepharose render the purified enzyme with a high specific activity (76.36 mumol AMP.min-1.mg-1). The purified enzyme gives a single polypeptide band on SDS-PAGE with an apparent molecular mass of 74 kDa. Active forms with an apparent molecular mass of 135 kDa and 268 kDa are observed when the purified enzyme is analyzed by gel filtration in the presence of either 0.6% sodium deoxycholate or 0.1% Triton X-100, respectively. The purified 5'-nucleotidase presents optimum activity at pH 7.8-8.1 either in the presence or in the absence of Mg2+. A linear Arrhenius plot is observed in the 25-46 degrees C temperature range and an activation energy of 33.7 KJ/mol is calculated. The enzyme is inhibited by EDTA; the activity is partially restored by different divalent cations as Zn2+, Mn2+, and Co2+. The hydrolysis of nucleosides 5'-monophosphate shows Michaelis kinetic. The enzyme is inhibited by nucleosides di- and triphosphate. 5'-Nucleotidase is a glycoprotein, being its activity inhibited at different extent by various lectins.
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PMID:Isolation and characterization of the ecto-5'-nucleotidase from a rat glioblastoma cell line. 148 Jan 62

Three murine monoclonal antibodies, designated GA-17, GB-4, and GC-3, were prepared by the hybridization of murine myeloma cells (NS-1) and spleen cells of BALB/c mice immunized with the crude membrane fraction of cultured human gliosarcoma cells (GI-1). Two of them (GA-17 and GB-4) reacted exclusively with the membrane of glioma cells, and the other (GC-3) reacted with the membrane of glioma cells and a T cell line (MOLT-4). Although these antibodies reacted with almost all of the gliomas, the reactions differed. GA-17 reacted equally well with all glioblastoma (17 cases) and low-grade astrocytoma (10 cases), whereas GB-4 reacted poorly with 7 cases of glioblastoma and GC-3 did not react with 7 cases of low-grade astrocytoma. The antigens, exclusively expressed on the cell surface, were analyzed by surface labeling with 125I followed by a cell lysis and immunoprecipitation with these antibodies. The findings obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that GA-17, GB-4, and GC-3 reacted with Mr 140,000-145,000, Mr 160,000, and Mr 145,000-150,000 proteins, respectively. Some evidence has been obtained indicating that these antigens are composed of the same polypeptide chain (Mr 120,000) with the carbohydrate chains being different.
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PMID:Human glioma-specific antigens detected by monoclonal antibodies. 158 48

Sialophorin, previously called gpL115, is the heavily sialylated surface protein that is defective in lymphocytes of Wiskott-Aldrich syndrome patients. Using the monoclonal antibody L10 as a probe, sialophorin expression was detected on isolated T lymphocytes and thymocytes, B cell lines, monocytes, neutrophils, and platelets, but not on erythrocytes, fibroblasts, and glioblastoma cells. This unusual distribution pattern suggests that sialophorin is expressed on all circulating cells except erythrocytes. Trace amounts of the sialophorin molecules on lymphocytes are incompletely sialylated, but significant amounts of the molecules on thymocytes are incompletely sialylated. The molecular form of sialophorin on T lymphocytes, thymocytes, and monocytes is the previously characterized species of apparent mol wt 115,000. A newly described sialophorin species of apparent mol wt 135,000 was found on neutrophils and platelets. The 115,000 lymphocyte/monocyte form and the 135,000 platelet/neutrophil form were shown to be substantially similar. The two forms have approximately the same content of sialylated O-linked carbohydrate units since both undergo the same atypical shift in electrophoretic mobility on desialylation. Both contain the epitope recognized by the monoclonal antibody L2 and the epitope recognized by L10 antibody. Moreover, evidence from another study indicates that the polypeptide portions are identical, cumulatively suggesting that 115,000 sialophorin and 135,000 sialophorin are identical except for the presence on the latter of additional neutral saccharide residues.
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PMID:Expression on blood cells of sialophorin, the surface glycoprotein that is defective in Wiskott-Aldrich syndrome. 243 46

The platelet-derived growth factor (PDGF) family consists of three different dimeric forms, AA, BB, and AB, of the two constituent polypeptide chains, A and B. These interact with two different cell surface receptors that, in part, mediate different cellular functions. The various forms of PDGF, as well as the receptors, are expressed at high frequency in glioblastoma multiforme, and it has been suggested that the growth of this tumor might be affected by autocrine loops involving PDGF and its receptors. The present paper focuses on recent discoveries regarding the family of PDGF ligands and receptors, as well as reviews results concerning PDGF-dependent autocrine growth in experimental and spontaneous glioblastoma.
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PMID:Structural and functional aspects of platelet-derived growth factor and its role in the pathogenesis of glioblastoma. 254 95

Transforming growth factor (TGF)-beta 1 is a polypeptide that is assumed to play a fundamental role in the growth of both normal and neoplastic cells. TGF-beta 2 is a closely related polypeptide, originally described as glioblastoma cell-derived T cell suppressor factor (G-TsF) due to its immunosuppressive activity. Expression of the genes for TGF-beta 1 and G-TsF/TGF-beta 2 was examined in tumor cells and was found to be different in several cell lines and tissues that were tested. Whereas two glioblastoma cell lines expressed both TGF-beta 1 and G-TsF/TGF-beta 2 mRNA, one melanoma and neuroblastoma cell lines showed only TGF-beta 1 mRNA which in the case of the neuroblastoma required cycloheximide treatment for its detection. The coordinate expression of the genes for TGF-beta 1 and G-TsF/TGF-beta 2 in glioblastoma was not paralleled by secretion of both polypeptides as only G-TsF/TGF-beta 2 but not TGF-beta 1 was identified in supernatants of glioblastoma cells. These data provide evidence for a post-transcriptional level of regulation for production of the two forms of TGF-beta. As mRNA for G-TsF/TGF-beta 2 was also identified in fresh surgically removed human glioblastoma tissue, G-TsF/TGF-beta 2 may also be secreted within the tumor in vivo. Unlike glioblastoma, human fetal brain tissues or adult brain specimens studied did not express detectable levels of TGF-beta mRNA. Impaired cell-mediated immunity is an established finding in patients with glioblastoma. Secretion of G-TsF/TGF-beta 2 by tumor cells in vivo may contribute to decreased immune surveillance for tumor development, as well as neovascularization of the tumor tissue.
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PMID:Immunosuppression and transforming growth factor-beta in glioblastoma. Preferential production of transforming growth factor-beta 2. 280 98

The protein encoded by the neu protooncogene (human gene symbol NGL for neuro/glioblastoma-derived) is a member of the surface receptor/tyrosine kinase family. Though its structure suggests that it can transduce a transmembrane signal, neither its extracellular ligand nor its critical intracellular substrates are known. To explore the functional properties of the protein encoded by neu, we created a fusion gene that joins the cytoplasmic domain of neu to the extracellular portion of an immunoglobulin heavy chain. The localization of the fusion polypeptide can then be controlled by coexpression with immunoglobulin light chain. In the absence of light chain, the heavy chain-neu polypeptide is expressed intracellularly and has no transforming activity. By contrast, in the presence of light chain the fusion polypeptide is expressed at the cell surface and produces tumorigenic foci. Thus, transformation apparently requires expression at the cell surface, where the neu intracellular domain can interact with components that are localized to the plasma membrane. The fusion protein is active in cellular transformation when the transmembrane domain is derived either from neu or from immunoglobulin, indicating that the neu transmembrane domain is not specifically required for transformation, although neu activation in tumors is known to result from a point mutation in this region. The extracellular immunoglobulin heavy and light chain domains of the fusion protein form a functional binding site that allows antigen to modulate its activity, reversing the transforming effect.
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PMID:neu protooncogene fused to an immunoglobulin heavy chain gene requires immunoglobulin light chain for cell surface expression and oncogenic transformation. 290

Using immunohistochemistry, well-preserved neuronal cell bodies and fibres containing neuropeptide Y, somatostatin, and cholecystokinin immunoreactivity have been identified in all seven supratentorial anaplastic astrocytomas studied. These neurones have been shown not only on the edge but also in the depth of the neoplastic tissue. These neuropeptides were not present in 18 other intracranial tumours (3 astrocytomas, 1 subependymoma, 8 glioblastoma multiformes, 1 meningioma, and 5 metastases). In all 25 intracranial tumours studied, no immunoreactivity was found for vasoactive intestinal polypeptide, substance P, methionine-enkephalin, leucine-enkephalin, synenkephalin, neurophysin I-II, and corticotropin releasing factor.
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PMID:Neuropeptide Y, somatostatin, and cholecystokinin neurone preservation in anaplastic astrocytomas. 290 6

The immunohistochemical localization of the calcium-binding protein, S100 beta, in human nervous system tumors has been examined by using a monoclonal antibody with specificity for the S100 beta polypeptide. S100 beta-specific immunoreactivity is detected in astrocytoma, glioblastoma, Schwannoma, ependymoma, and craniopharyngioma, whereas no reactivity is seen in oligodendroglioma, meningioma, neuroblastoma, or medulloblastoma. These data suggest that analysis of S100 beta localization with these monoclonal antibodies may be useful for research or diagnostic purposes.
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PMID:Immunohistochemical localization of S100 beta in human nervous system tumors by using monoclonal antibodies with specificity for the S100 beta polypeptide. 373 19

Immunoprecipitation of proteins extracted from metabolically labeled human glioblastoma and fibrosarcoma cells with antiserum to platelet-derived growth factor (PDGF) showed that these cells express and secrete proteins that are recognized specifically by the antiserum. The molecular masses of immunoprecipitated proteins in the lysates of the malignant cells ranged from 16 kDa to 140 kDa. Both cell lines secreted a 31-kDa polypeptide with structural, immunological, and biological properties similar to those of human PDGF. These cell lines were shown to synthesize a 4.4-kb mRNA that contained sequences from all the six currently identified exons of the human c-sis gene. These data suggest that the PDGF-like proteins in the two mesenchyme-derived transformed cells are encoded at least in part by the c-sis locus.
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PMID:Synthesis and secretion of proteins resembling platelet-derived growth factor by human glioblastoma and fibrosarcoma cells in culture. 385 90

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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