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)

Monoclonal antibodies to the transferrin receptor or to the T cell antigen, CD5, were chemically linked to mammalian RNase A and found to specifically inhibit protein synthesis in antigen-positive cells. Antibody-mediated specificity of these cytotoxic ribonuclease chimeras (CRCs) was demonstrated in three ways. 1) Toxicity was due to the chemical linkage of RNase to antibody, as the individual components added separately or in combination did not inhibit protein synthesis; 2) the anti-transferrin receptor CRCs inhibited protein synthesis in those cells expressing the human transferrin receptor (K562, U251, Jurkat cells) but had no detectable toxicity to cells lacking the human transferrin receptor (Vero or NIH 3T3 cells); 3) free antibody to either the human transferrin receptor (454A12 or 5E-9) or to the T cell antigen, CD5 (T101), blocked the cytotoxicity of the respective CRC. Two CRC species, designated P1 and P2, that differed in size and stoichiometry of RNase A to antibody, were purified by size-exclusion high performance liquid chromatography. The higher molecular weight P1 conjugate had an IC50 of 20-30 nM, whereas the P2 conjugate had a higher IC50 of 300-500 nM. Bioactivity could be reversibly increased more than 10-fold by freezing. The cytotoxicity of the CRCs was examined in vivo in a solid tumor animal model. Intratumoral injections of an anti-transferrin receptor CRC into established U251 human glioblastoma tumors grown in the flanks of nude mice prevented tumor growth, whereas RNase A mixed with antibody was ineffective. CRCs, therefore, express cytotoxicity in vitro and in vivo. Mammalian nucleases coupled to antibodies may be utilized as cell type-selective cytotoxins and have potential as pharmacologic reagents. The systemic toxicity and immunogenicity observed with mammalian derived cytotoxins may be significantly less than that of the currently employed plant- and bacterial-derived immunotoxins.
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PMID:Cytotoxic ribonuclease chimeras. Targeted tumoricidal activity in vitro and in vivo. 152 74

The cytosol of a human glioblastoma cell line (KNS-42) stimulated the growth of both bovine aortic endothelial cells and smooth muscle cells in a dose-dependent manner. The endothelial cell growth activity eluted at an apparent molecular weight of about 30,000 on a Sephadex G-100 column and bound to a heparin-Sepharose column with high affinity to elute at 1.3-1.7 M NaCl. The growth activity was destroyed by heating at 56 degrees C for 30 min, but not by exposure to trypsin, deoxyribonuclease or ribonuclease at 37 degrees C for 30 min. As this factor stimulated the growth of vascular endothelial cells and smooth muscle cells, and vasoproliferative responses in chick embryo chorioallantoic membranes were apparent, this factor may possibly be related to tumor angiogenesis.
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PMID:Endothelial cell growth factor derived from a human glioblastoma cell line and possible association with tumor angiogenesis. 266 83

The Turcot syndrome (TS) is a rare, probably autosomal recessive, disorder characterized by development of primary neuroepithelial tumors of the central nervous system (CNS) and numerous adenomatous colorectal polyps. To examine the possible involvement of mutations of the APC gene, which is responsible for familial adenomatous polyposis (FAP), in Turcot syndrome, we examined DNAs from TS patients for alterations in this gene by means of ribonuclease protection analysis. Germ-line APC mutations were detected in each of three unrelated cases of TS, and additional (somatic) mutations were observed in colonic adenomas that had developed in one of these patients. However, no somatic mutations in APC were found among 91 neuroepithelial tumors (medulloblastoma, glioblastoma, astrocytoma, and oligodendroglioma), whether sporadic or associated with TS. These results suggest that the APC gene is associated with pathogenesis of one feature of TS, but that at least one other gene is responsible for the genesis of neuroepithelial tumors in the CNS.
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PMID:Germ-line and somatic mutations of the APC gene in patients with Turcot syndrome and analysis of APC mutations in brain tumors. 751 58

We have re-examined whether pp60c-src, the normal cellular homologue of the transforming protein of Rous sarcoma virus, is present in human T cells. By in vitro immune-complex kinase assay or Western blotting with the anti-pp60c-src mAbs 327 or GD11, pp60c-src was found to be present in lysates of T cell lines, including the Jurkat T cell line. The 327 and GD11 mAbs have been reported to be specific for pp60c-src and not to cross-react with other src family members or other kinases. Furthermore, the size of the pp60c-src bands present on Western blotting and in vitro kinase assay were clearly different from those of p56lck or p59fyn. In addition, pp60c-src is detected in the HTLV-I-derived T cell lines S1T and C8, which lack expression of p56lck and p59fyn. RNase protection assays confirmed that pp60c-src mRNA is present in Jurkat T cells. We also found pp60c-src protein to be constitutively present in freshly isolated thymocytes. In contrast, pp60c-src was absent, or present at extremely low levels, in normal, resting peripheral blood T lymphocytes, which is in agreement with previous findings. However, after stimulation of resting T cells with the mitogenic lectin PHA or with Ab to the TCR complex, pp60c-src expression is induced in both CD4+ and CD8+ T cell subsets, with peak expression detectable 12 to 24 h after T cell activation. The levels of pp60c-src are low in all T cells except Jurkat, where levels of pp60c-src are comparable to levels found in a glioblastoma cell line (T98G). Nevertheless, significant levels of pp60c-src kinase activity are readily detectable in thymocytes and activated normal T cells as well as in T cell lines. The finding that pp60c-src is inducible following activation through the TCR suggests that pp60c-src may play a specific role in the normal T cell activation pathway.
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PMID:pp60c-src expression is induced by activation of normal human T lymphocytes. 753 11

Molecular processes resulting in the malignant transformation from low- to high-grade astrocytoma remain poorly understood. Using reverse transcriptase PCR, we identified a gene that is differentially expressed in normal brain and low-grade astrocytoma compared to glioblastoma tissues. This gene is identical to human beta 2-chimaerin, which encodes a 468-amino acid GTPase-activating protein for p21rac. The gene was localized to human chromosome 7p15.3 by fluorescence in situ hybridization mapping. Human beta 2-chimaerin is expressed in a variety of human tissues, with the highest expression level detected in human brain and pancreas. RNase protection assays indicated that the expression level of this gene is high in all the normal brain and low-grade astrocytoma samples tested compared to malignant gliomas. The down-regulation of beta 2-chimaerin expression in the high-grade gliomas suggests that decreased expression of this gene may be a feature of progression in the development of malignant glioma.
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PMID:Identification and characterization of human beta 2-chimaerin: association with malignant transformation in astrocytoma. 761 86

We have previously isolated two different aFGF cDNA clones from kidney and brain. The two corresponding mRNA, designated aFGF 1.A and 1.B, are the predominant species in kidney and brain, respectively. During the characterization of aFGF mRNA in glioblastoma cells, we demonstrated that aFGF mRNA in U1242MG and D65MG glioblastoma cells contain 5'-untranslated sequences different from those of 1.A and 1.B. Through a strategy combining chromosome walking, identification and sequencing of evolutionarily conserved DNA regions, and a reverse transcription and polymerase chain reaction (RT-PCR)-based assay for RNA expression, we have isolated two novel aFGF cDNA clones. The cDNA clone representing aFGF mRNA 1.C was isolated from U1242MG cells; another aFGF cDNA, designated 1.D, was isolated from D65MG cells. Promoter 1C has extensive sequence homology to the hamster aFGF gene promoter that was shown to respond to testosterone stimulation by chloramphenicol acetyltransferase reporter gene assays. Using RT-PCR, we showed that normal, benign and cancerous prostate tissues do not express aFGF 1.C mRNA. In contrast, a prostate carcinoma cell line (PC-3) expresses 1.C mRNA. RT-PCR using 1.D-specific primers showed that kidney, brain and prostate do not express 1.D mRNA even though kidney and brain are the most abundant source for aFGF protein. RNase protection analysis further showed that 1.D mRNA is the predominant aFGF transcript in D65MG glioblastoma cells and in NFF-6 neonatal foreskin fibroblast cells. The genomic DNA corresponding to these two cDNA clones and the 5'-flanking regions were also isolated and their sequences determined. These DNA clones will provide important reagents for studying the regulatory elements of aFGF gene expression.
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PMID:Cloning of two novel forms of human acidic fibroblast growth factor (aFGF) mRNA. 768 Jan 20

Human JC virus (JCV) is a neurotropic human polyomavirus that was found in the plaques and oligodendroglial cells of the brains of patients with the fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML). Transgenic mice expressing JCV large tumor (T)-antigen from integrated DNA showed dysmyelination in the central nervous system. However, the role of T-antigen from episomal DNA in the demyelination in PML remains unclear. In this report, we examined the effect of episomally expressed JCV T-antigen on the expression of myelin basic protein (MBP) in U-87 MG human glioblastoma cells to study the mechanism of demyelination. Expression assays of the MBP promoter in U-87 MG detected a 2.5-fold reduction in cells expressing intact T-antigen. Next, U-87 MG expressing T-antigen were examined by RNase protection assays for mRNA accumulation from the endogenous MBP promoter. Also, the expression of the MBP promoter plasmid was determined using in vitro transcription assays with extracts from T-antigen expressing cells. Both assays found a similar down-regulation of the MBP promoter by T-antigen, confirming that negative regulation occurred at the transcriptional level for the endogenous and exogenous MBP promoters. Furthermore, in situ immunofluorescence assays and quantitative Western blot analysis provided convincing evidence of a similar reduction in the level of MBP produced from the functional endogenous gene in U-87 MG glioblastoma cells expressing T-antigen. Thus, we provide evidence for the role of T-antigen in a transcriptional control mechanism for the demyelination that is caused by JCV in PML patients.
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PMID:Evidence for a mechanism of demyelination by human JC virus: negative transcriptional regulation of RNA and protein levels from myelin basic protein gene by large tumor antigen in human glioblastoma cells. 881 66

PAX6, a member of the highly conserved paired-type homeobox gene family, is expressed in a spatially and temporally restricted pattern during early embryogenesis, and its mutation is responsible for human aniridia. Here we examined the transcriptional regulation of the PAX6 gene by transient transfection assays and identified multiple cis-regulatory elements that function differently in different cell lines. The transcriptional initiation site was identified by RNase protection and primer extension assay. Examination of the genomic DNA sequence indicated that the PAX6 promoter has a TATA like-box (ATATTTT) at -26 base pairs (bp), and two CCAAT boxes are positioned at -70 and -100 bp. A 38-bp poly(CA) sequence was located 992 bp upstream from the initiation site. Transient transfection assays in glioblastoma cells and leukemia cells indicate that a 92-bp region was required for basal level PAX6 promoter activity. A negative transcriptional element, silencer (bases -1518 to -1268), functioned differently in different cell lines. The activation of the promoter is positively correlated with the expression of PAX6 transcripts in all cells tested. These results indicate that a cis-regulatory element or elements is responsible for selective activation of the PAX6 promoter in cells that can express PAX6 mRNA.
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PMID:Transcriptional regulation of the human PAX6 gene promoter. 901 87

We have cloned the cDNA encoding the voltage-dependent K+ channel Kv2.1 from human brain (hKv2.1). RNase protection and RT-PCR (reverse transcriptase-PCR) experiments reveal abundant Kv2.1 transcripts in human brain with virtually no expression detectable in human heart. hKv2.1 has been stably transfected into a human glioblastoma cell line, and transformed cells display large, slowly activating outward currents. The kinetics, steady-state activation and inactivation parameters, and external tetraethylammonium sensitivity were all similar to those described previously for hKv2.1 channels transiently expressed in Xenopus oocytes or other mammalian cell lines. A number of dopamine receptor antagonist/antipsychotic agents were shown to block hKv2.1. Trifluoperizine, trifluperidol and pimozide produced time-dependent blockade of hKv2.1 with IC50 values of approx. 1-2 microM. The diphenylbutylpiperidine fluspirilene was shown to be 4-5-fold more potent than the other agents tested inhibiting hKv2.1 current with an IC50 value of 297 nM. The block produced by fluspirilene was both time- and frequency-dependent. Furthermore, fluspirilene (1 microM) shifted the midpotential of the hKv2.1 steady-state inactivation curve by approx. 15 mV in the hyperpolarizing direction. These results demonstrate the usefulness of this transfection system for the pharmacological characterization of hKv2. 1. Fluspirilene proved to be a relatively potent blocker of hKv2.1 and may provide a useful starting point for the development of more potent and selective agents active against this brain K+ channel.
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PMID:Stable expression and characterization of the human brain potassium channel Kv2.1: blockade by antipsychotic agents. 924 64

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) have been implicated in the immense invasive potential and neovascularization of primary brain tumors. We investigated the gene expression profiles of MMPs 1, 2, 3, 7, 9, 12, 13, 14, 16 and of TIMPs 1, 2, 3, and 4 in various primary brain tumors (astrocytoma WHO grade I-III, glioblastoma, PNET, ependymoma III and oligoastrocytoma II) using novel RNase protection assay probe sets. In addition, we determined the level and cellular source of gelatinolytic activity and localized gelatinase B and TIMP-1 RNA. Distinct expression patterns of the MMP and TIMP genes were found in the various brain tumors tested. While the WHO grade I and II tumors had MT1/MT3 ratios below 1, the malignant (grade III and IV) tumors had ratios above 1. Strong expression of TIMP-1 RNA was observed in all malignant tumors and in grade I pilocytic astrocytomas and localized to the walls of neovessels. Quantitative analysis of enzymatic activity in the soluble fraction of protein extracts revealed that in most tumors gelatinases remained in the inactive pro-form. In situ zymography revealed net gelatinolytic activity in neurons of normal brain and in tumor cells and vessel walls of all tumors tested. Immunohistochemistry demonstrated that gelatinase B was localized to vessel walls, to neutrophils in areas of hemorrhage, and in glioblastomas to macrophages. Together these data demonstrate that the different primary brain tumors show distinct regulation of MMP and TIMP genes. The localization of the soluble gelatinase B indicates an association with neovascularization, whereas membrane-bound MMPs may account for the invasive potential of the glial tumor cells.
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PMID:Distinct expression patterns and levels of enzymatic activity of matrix metalloproteinases and their inhibitors in primary brain tumors. 1139 36


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