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)

Alzheimer's disease is characterized by cerebral deposits of amyloid beta-protein (AP) as senile plaque core and vascular amyloid, and a complementary DNA encoding a precursor of this protein (APP) has been cloned from human brain. From a cDNA library of a human glioblastoma cell line, we have isolated a cDNA identical to that previously reported, together with a new cDNA which contains a 225-nucleotide insert. The sequence of the 56 amino acids at the N-terminal of the protein deduced from this insert is highly homologous to the basic trypsin inhibitor family, and the lysate from COS-1 cells transfected with the longer APP cDNA showed an increased inhibition of trypsin activity. Partial sequencing of the genomic DNA encoding APP showed that the 225 nucleotides are located in two exons. At least three messenger RNA species, apparently transcribed from a single APP gene by alternative splicing, were found in human brain. We suggest that protease inhibition by the longer APP(s) could be related to aberrant APP catabolism.
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PMID:Novel precursor of Alzheimer's disease amyloid protein shows protease inhibitory activity. 289 91

Nitric oxide (NO) is a messenger molecule with diverse functions throughout the body. The inducible type of nitric oxide synthase (NOS) is considered to be a key molecule in the immune responses to bacteria, parasites, and tumors, and its gene expression is regulated by cytokines. We isolated 3 overlapping partial inducible NOS cDNA clones from a human glioblastoma cell line A-172 induced by IL-1, TNF-alpha, and IFN-gamma. The 3,963-bp human glioblastoma inducible NOS cDNA contained the longest open reading frame of 3,459 bp, which encoded a polypeptide of 1,153 amino acids with a calculated molecular mass of 131 kDa. This human inducible NOS possessed consensus recognition sites for the cofactors FMN, FAD, and NADPH and calmodulin recognition sites, and displayed 48.1% sequence identity with the endothelial type, 43.1% with the neuronal type, and 99.3% with the inducible type from hepatocytes, and 99.9% with the inducible type from chondrocytes and adenocarcinoma. An expression plasmid consisting of pSG5 expression vector and cDNA containing the entire putative coding sequence was constructed and transfected into COS-1 cells. COS-1 cells showed nitric oxide synthase activity together with a 130 kDa immunoreactive band on Western blot analysis.
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PMID:Cloning and functional expression of human inducible nitric oxide synthase (NOS) cDNA from a glioblastoma cell line A-172. 753 87

A cDNA coding for a human phosphodiesterase 4C (PDE4C2) was isolated from the mRNA prepared from the glioblastoma cell line, U87. The cDNA contained an ORF of 1818 bp corresponding to a 605 amino acid polypeptide. The sequence differed at the 5' end from the human PDE4C previously reported (Engels, P. et al, 1995 FEBs Letters 358, 305-310) indicating that it represents a novel splice variant of the human PDE4C gene. Evidence was also obtained for a third 5' splice variant. The PDE4C2 cDNA was transfected into both COS 1 cells and yeast cells, and shown to direct the expression of an 80 kD polypeptide by Western blotting using a PDE4C specific antiserum. The activity of cell lysates was typical of PDE4 being specific for cAMP and inhibitable by the selective inhibitor, rolipram. However, the Km for cAMP of the enzyme produced in COS cells was 0.6 microM compared to 2.6 microM for the yeast 4C activity. In addition the COS cell PDE4 activity was much more sensitive to R rolipram than the yeast PDE4 enzyme (IC50 of 23 nM compared to 1648 nM). This difference in rolipram sensitivity was associated with the detection of a high affinity [3H] R rolipram binding site on the COS cell 4C enzyme but not on the yeast expressed enzyme. The results indicate that the enzyme can adopt more than one active conformation, which are distinguished by their interaction with rolipram.
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PMID:Molecular cloning and expression of a human phosphodiesterase 4C. 942 61

For glioma- and glioblastoma-specific gene expression, we utilized a nestin regulatory element whose activity was evaluated by the reporter gene lacZ. Nestin is a 38-kDa intermediate filament protein, and is expressed specifically in the neuroepithelial stem cells. Nestin is detected in gliomas and glioblastomas, but not in normal brain tissue. We constructed a nestin gene regulator by placing nestin's second intron before the 5' upstream region (2iNP). To obtain enhanced expression of this tissue-specific regulator, we utilized the adenovirus double-infection method with a Cre-loxP on/off switching system. We constructed a 'regulator' vector, Ax2iNPNCre, which expresses Cre recombinase under the control of the nestin regulatory element, 2iNP. A 'reporter' vector, AxCALNLNZK, expresses lacZ under the control of a strong CAG promoter when the stuffer sequence has been removed by Cre recombinase at a pair of loxP sites. We used seven human glioma/glioblastoma cell lines: U251, KG-1C, NGM5, U87 MG, LN-Z308, NP-2 and T98G. Of these, nestin was expressed highly in U251 and KG-1C, less in NGM5, and undetectably in the other four lines. With the use of the two adenovirus vectors, we found X-gal staining and high nestin regulator-promoted beta-galactosidase activities in four of the seven glioma/glioblastoma cell lines. Staining was strong in U251, KG-1C and NGM5, and less in U87 MG. LacZ expression was nearly undetectable in the non-glioma cell line, HeLa, but a little in COS-7. The adenovirus double-infection method, which uses a nestin regulator, is applicable for glioma/glioblastoma-specific expression.
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PMID:Glioma/glioblastoma-specific adenoviral gene expression using the nestin gene regulator. 1080 92

Like most cells in culture, stably transfected COS-1 cells (CF18) that constitutively overexpress basic fibroblast growth factor (FGF2) do not release the growth factor into conditioned media. Yet, when cells were biotinylated, 30% of the total cell-associated immunoreactive FGF2 was detected on the cell surface. Under similar conditions, up to 70% of the total immunoreactive FGF2 in transfected endothelial cells (MAE ZIP) or untransfected rat (C6) and human (U87MG) glioblastoma cell lines was detected on their cell surface. When peripheral plasma membrane proteins were removed from the cell surface with 0.1 M sodium carbonate, the amount of exported FGF2 was significantly reduced, whereas cell viability was unaffected. FGF2 then reappeared on the cell surface in a time-dependent manner. Ouabain, a cardenolide previously shown to inhibit the export of FGF2 from transiently transfected COS-1 cells, blocked the appearance of FGF2 onto the surface of transfected CF18 cells and MAE ZIP cells but had no detectable effect on C6 and U87MG cells. The observation that the translocation of FGF2 onto the cell surface is dissociated from its release into conditioned medium is consistent with FGF2's being rarely found in biological fluids but always cell associated and in the extracellular matrix. The findings point to a role played by the protein export pathway in controlling FGF2 activity and the normal physiological function that this growth factor plays in cell growth and differentiation. The widely accepted presumption that the absence of FGF2 in conditioned media reflects its inability to exit the cell needs to be reevaluated.
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PMID:Translocation of FGF2 to the cell surface without release into conditioned media. 1102 48

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is a membrane-associated MMP that has been recently reported to have a central role in tumour cell invasion. Here we report that both the native and overexpressed recombinant forms of MT1-MMP are highly enriched in low-density Triton X-100-insoluble membrane domains that contain the caveolar marker protein caveolin 1. Moreover, the MT1-MMP-dependent activation of proMMP-2 induced by concanavalin A and cytochalasin D was correlated with the processing of MT1-MMP to its proteolytically inactive 43 kDa fragment in U-87 glioblastoma and HT-1080 fibrosarcoma tumour cell lines; this processing was also preferentially observed within the caveolar fraction. Interestingly, whereas the expression of caveolin 1 had no effect on the MT1-MMP-dependent activation of proMMP-2, its co-expression with MT1-MMP antagonized the MT1-MMP-increased migratory potential of COS-7 cells. Taken together, our results provide evidence that MT1-MMP is preferentially compartmentalized and proteolytically processed in caveolae of cancer cells. The inhibition of MT1-MMP-dependent cell migration by caveolin 1 also suggests that the localization of MT1-MMP to caveolin-enriched domains might have an important function in the control of its enzymic activity.
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PMID:Localization of membrane-type 1 matrix metalloproteinase in caveolae membrane domains. 1117 Oct 51

The extracellular domain of receptor protein tyrosine phosphatase beta (RPTPbeta) is composed of several domains which mediate its interactions with distinct ligands present on the surface of either neurons or glial cells. Here, we demonstrate that the fibronectin type III domain (FNIII) of RPTPbeta binds to glial tumor-derived cell lines and primary astrocytes. We used affinity purification to isolate several proteins that specifically bind to the FNIII domain of RPTPbeta. One of these, a 240 kDa protein that was purified from U118MG glioblastoma cell, was identified as tenascin C based on the amino acid sequence of several tryptic peptides. The interaction of RPTPbeta with tenascin C was found to mediate cell adhesion. Adhesion and spreading of SF763T astrocytoma cells expressing RPTPbeta on tenascin C was specifically abolished by the addition of a soluble fragment containing the FNIII domain of the receptor. RPTPbeta-dependent cell adhesion was mediated by binding to the alternatively spliced FNIII repeats A1,2,4 (TnfnA1,2,4) of tenascin C. Furthermore, COS cells expressing RPTPbeta adhere to TnfnA1,2,4, while the parental cells did not. These results demonstrate that the FNIII domain of RPTPbeta binds to tenascin C and suggest that RPTPbeta present on glial tumor cells is a primary adhesion receptor system to the extracellular matrix.
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PMID:Glial tumor cell adhesion is mediated by binding of the FNIII domain of receptor protein tyrosine phosphatase beta (RPTPbeta) to tenascin C. 1131 93

Most transmembrane proteins are subjected to limited proteolysis by cellular proteases, and stimulation of cleavage of membrane proteins by calmodulin (CaM) inhibitors was recently shown. The present study investigated the ability of several CaM inhibitors to induce the proteolytic cleavage of the membrane type-1 matrix metalloproteinase (MT1-MMP) from the cell surface of highly invasive U-87 glioblastoma cells. Although no shedding of a soluble MT1-MMP form was induced by CaM inhibitors in the conditioned media, we showed that these inhibitors induced MT1-MMP proteolytic processing to the 43 kDa membrane-bound inactive form that was not correlated with an increase in proMMP-2 activation but rather with an increase in tissue inhibitor of MMPs (TIMP)-2 expression levels. Moreover, this proteolytic processing was sensitive to marimastat suggesting the involvement of MMPs. Interestingly, CaM inhibitors antagonized concanavalin A- and cytochalasin D-induced proMMP-2 activation, and affected the cytoskeletal actin organization resulting in the loss of migratory potential of U-87 glioblastoma cells. Cytoplasmic tail-truncated MT1-MMP constructs expressed in COS-7 cells were also affected by CaM inhibitors suggesting that these inhibitors stimulated MT1-MMP proteolytic processing by mechanisms independent of the CaM-substrate interaction. We also propose that TIMP-2 acts as a negative regulator of MT1-MMP-dependent activities promoted by the action of CaM inhibitors in U-87 glioblastoma cells.
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PMID:Calmodulin inhibitors trigger the proteolytic processing of membrane type-1 matrix metalloproteinase, but not its shedding in glioblastoma cells. 1158 78

We have recently shown that green tea polyphenols, and especially (-)-epigallocatechin 3-gallate (EGCg), acted as potent inhibitors of matrix metalloproteinase activities as well as of proMMP-2 activation (M. Demeule, M. Brossard, M. Page, D. Gingras, R. Beliveau, Biochim. Biophys. Acta 1478 (2000)). In the present work, we sought to examine the involvement of MT1-MMP in the EGCg-induced inhibition of proMMP-2 activation. The incubation of U-87 glioblastoma cells in the presence of concanavalin A or cytochalasin D, two potent activators of MT1-MMP, resulted in proMMP-2 activation that was correlated with the cell surface proteolytic processing of MT1-MMP to its inactive 43 kDa form. Addition of EGCg strongly inhibited the MT1-MMP-dependent proMMP-2 activation. The inhibitory effect of EGCg on MT1-MMP was also demonstrated by the down-regulation of MT1-MMP transcript levels and by the inhibition of MT1-MMP-driven cell migration of transfected COS-7 cells. These observations suggest that this catechin may act at both the MT1-MMP gene and protein expression levels. In addition, treatment of cells with non-cytotoxic doses of EGCg significantly reduced the amount of secreted proMMP-2, and led to a concomitant increase in intracellular levels of that protein. This effect was similar to that observed using well-characterized secretion inhibitors such as brefeldin A and manumycin, suggesting that EGCg could also potentially act on intracellular secretory pathways. Taken together, these results indicate that EGCg targets multiple MMP-mediated cellular events in cancer cells and provides a new mechanism for the anticancer properties of that molecule.
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PMID:Green tea polyphenol (-)-epigallocatechin 3-gallate inhibits MMP-2 secretion and MT1-MMP-driven migration in glioblastoma cells. 1185 93

The putative alpha-secretase cleaves the amyloid precursor protein (APP) of Alzheimer's disease in the middle of the amyloid beta peptide (Abeta) domain. It is generally thought that the alpha-secretase pathway mitigates Abeta formation in the normal brain. Several studies have suggested that ADAM9, ADAM10, and ADAM17 are candidate alpha-secretases belonging to the ADAM (a disintegrin and metalloprotease) family, which are membrane-anchored cell surface proteins. In this comparative study of ADAM9, ADAM10, and ADAM17, we examined the physiological role of ADAMs by expressing these ADAMs in COS-7 cells, and both "constitutive" and "regulated" alpha-secretase activities of these ADAMs were determined. We tried to suppress the expression of these ADAMs in human glioblastoma A172 cells, which contain large amounts of endogenous alpha-secretase, by lipofection of the double-stranded RNA (dsRNA) encoding each of these ADAMs. The results indicate that ADAM9, ADAM10, and ADAM17 catalyze alpha-secretory cleavage and therefore act as alpha-secretases in A172 cells. This is the first report that to suggest the endogenous alpha-secretase is composed of several ADAM enzymes.
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PMID:Putative function of ADAM9, ADAM10, and ADAM17 as APP alpha-secretase. 1253 68


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