Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Malignant gliomas infiltrate the brain preferentially along myelinated fiber tracts. Central nervous system (CNS) myelin, however, contains inhibitory proteins that block axon regeneration, neurite outgrowth, and cell spreading of astrocytes and fibroblasts. We tested 5 human brain tumor cell lines, 1 rat brain tumor cell line, and 29 short-term cultured specimens from human brain tumors for their ability to spread and migrate on a CNS myelin substrate. Low-grade and pilocytic astrocytoma, ependymoma, medulloblastoma, and meningioma cell lines as well as primary cultures were strongly sensitive to the inhibitory proteins present in the CNS myelin. In contrast, glioblastomas, anaplastic astrocytomas, and oligodendrogliomas were able to spread and migrate on CNS myelin-coated culture dishes, demonstrating that within the gliomas, the ability to overcome the inhibitory effects of the CNS myelin is correlated with the grade of malignancy of the original tumor. Cell spreading of glioblastomas and anaplastic astrocytomas specifically on a CNS myelin substrate was strongly inhibited by the metalloprotease blocker O-phenanthroline and the peptide derivative carbobenzoxy-Phe-Ala-Phe-Tyr-amide, whereas blockers for serine, aspartyl, and cysteine proteases had no effect. Enzymatic peptide degradation assays revealed the presence of a phosphoramidon-sensitive and thiorphan-insensitive metalloproteolytic activity in the plasma membranes of high-grade glioma cells. These results suggest a crucial involvement of a membrane-bound metalloendoprotease in the process of invasive migration of malignant gliomas along CNS white matter fiber tracts.
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PMID:Spreading and migration of human glioma and rat C6 cells on central nervous system myelin in vitro is correlated with tumor malignancy and involves a metalloproteolytic activity. 942 71

Proteases such as matrix metalloproteinases (MMPs), cysteine- and serine-proteinases are capable of degrading extracellular matrix and basement membranes and have been implicated in human brain tumours. MMPs are a homologous family of zinc-dependent proteases. Within this group, attention has been focused on the gelatinases (MMP-2 and MMP-9) which are thought to play an important role in tumour progression. The cysteine proteinases which have received most attention in relation to tumour progression are cathepsin B (CB) and to a lesser extent cathepsin L (CL). Among the serine proteinases, urokinase plasminogen activator and its receptor have been the subject of much investigation. In the present review, evidence from current literature on the possible role or significance of serine- and cysteine-proteinases and MMPs and their inhibitors in human brain tumours is discussed with special reference to gliomas. Although direct evidence is reported for MMPs and serine proteinases to support their role in glioma invasion, much of the evidence for the involvement of cysteine proteinases remains circumstantial.
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PMID:Proteases and their inhibitors in human brain tumours: a review. 942 49

Dolichyl phosphate, an essential carrier lipid in the biosynthesis of N-linked glycoprotein, has been found to induce apoptosis in rat glioma C6 cells and human monoblastic leukemia U937 cells. In the present study, dolichyl phosphate and structurally related compounds were examined regarding their apoptosis-inducing activities in U937 cells. Dihydroheptaprenyl and dihydrodecaprenyl phosphates, of which isoprene units are shorter than that of dolichyl phosphate, induced apoptosis in U937 cells. This phenomenon occurred in a dose- and time-dependent manner, as seen with dolichyl phosphate-induced apoptosis. Derivatives of the same isoprene units of dolichyl phosphate, such as dolichol, dolichal or dolichoic acid, did not induce DNA fragmentation. Farnesyl phosphate and geranylgeranyl phosphate also failed to induce apoptosis. During apoptosis, the caspase family of cysteine proteases play important roles. We observed that apoptosis induced by dihydroprenyl phosphate was mediated by caspase-3-like (CPP32-like) activation but not by caspase-1-like (ICE-like) activation. This caspase-3-like activation was inhibited by a specific inhibitor of caspase-3, DEVD-CHO, but not by an caspase-1 inhibitor YVAD-CHO. We interpret these results to mean that dihydroprenyl phosphates with more than seven isoprene units have apoptosis-inducing activity and that their signal is mediated by caspase-3-like activation.
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PMID:Dihydroheptaprenyl and dihydrodecaprenyl monophosphates induce apoptosis mediated by activation of caspase-3-like protease. 946 Dec 54

The molecular pathways by which the cyclopentenone prostaglandins (PGA and PGJ series) inhibit cell growth and tumorigenicity are poorly understood. These cellular responses may be caused by specific regulation of growth-related and stress-induced genes. A variety of prostaglandins were tested for their ability to regulate insulin-like growth factor-I (IGF-I) and Waf1 gene expression in C6 rat glioma cells. The prostaglandins (in order of potency) PGJ2 > PGA1 > PGA2, approximately PGD2 >> PGE2 all significantly repressed IGF-I gene expression. With the exception of PGE2, the same prostaglandins that repressed IGF-I also induced Waf1 gene expression. However, the order of potency for Waf1 induction was different than for IGF-I repression: PGA2 > PGA1 approximately PGJ2 > PGD2. The different order of potency of the prostaglandins in regulating IGF-I and Waf1 gene expression suggests that different intracellular signals may be involved in regulating the two genes. Augmentation of glutathione levels by pretreatment of cells with N-acetyl-L-cysteine attenuated the effect of PGA2 on IGF-I and Waf1 gene expression. conversely, depletion of the intracellular glutathione pool by pretreatment with buthionine sulfoximine potentiated the effect of PGA2 on the expression of both genes. These results suggest that conjugation with glutathione prevents the regulation of gene expression by PGA2. We also tested the effect of several simpler compounds that contain a five-membered ring system on IGF-I and Waf1 gene expression. 2-Cyclopenten-1-one, but not cyclopentene or cyclopentene, repressed IGF-I and induced Waf1 gene expression, demonstrating the requirement for an alpha, beta-unsaturated carbonyl for regulation of the two genes. The dione compound 4-cyclopentene-1,3-dione, which has two potentially reactive carbons rather than one, was considerably more potent than 2-cyclopentene-1-one in repressing IGF-I gene expression (IC50 = 30 microM for 4-cyclopentene-1,3-dione as compared with 167 microM for 2-cyclopentene-1-one). Additional results indicated that diethyl maleate, which has two alpha,beta-unsaturated carbonyls in a non-cyclic configuration, also repressed IGF-I gene expression (IC50 = 214 microM) and induced Waf1 gene expression, indicating that the cyclic structure is not required for either effect.
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PMID:Effects of cyclopentenone prostaglandins and related compounds on insulin-like growth factor-I and Waf1 gene expression. 954 24

The relation between the intracellular glutathione (GSH) concentration and hydrogen-peroxide(H2O2)-induced cytotoxicity was investigated. The intracellular GSH concentration in human glioblastoma (T98G, U87MG) and glioma (KG1C) cell lines was one or two orders of magnitude higher than that in a human myelogenous leukemic cell line (HL-60), which showed higher sensitivity to H2O2. Pretreatment of these cell lines with L-buthionine-[S,R]-sulfoximine, which significantly reduced the intracellular GSH concentration, increased their sensitivity against H2O2, whereas pretreatment with N-acetyl-L-cysteine, which did not significantly change the intracellular GSH concentration, only marginally protected the cells from the cytotoxic effect of H2O2. The results suggest that drug sensitivity of tumor cells can be modified by glutathione-modulating compounds.
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PMID:Effect of glutathione-modulating compounds on hydrogen-peroxide-induced cytotoxicity in human glioblastoma and glioma cell lines. 962 Feb 20

Apomorphine cytotoxicity towards rat glioma C6 cells was recently demonstrated to be time- and concentration-dependent. In the present work, the mechanism of cytotoxicity of apomorphine was further studied in the C6 cell line. We showed that bovine serum albumin partially protects C6 cells against apomorphine cytotoxicity. However, serum albumin did not prevent apomorphine autoxidation and melanin formation, suggesting that this protein scavenges apomorphine reactive products formed during its oxidation. The use of radioactive tracers, fluorimetry and protein electrophoresis showed that apomorphine autoxidation products covalently and nonspecifically bind to serum albumin and to rat liver microsomes. L-Cysteine, which is a thiol reagent that inhibits apomorphine autoxidation also prevented the formation of apomorphine-serum albumin adducts. These results suggest that quinone derivatives formation and oxidative stress should be responsible for apomorphine cytotoxicity.
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PMID:Mechanisms of apomorphine cytoxicity towards rat glioma C6 cells: protection by bovine serum albumin and formation of apomorphine-protein conjugates. 1021 2

Increased expression of cathepsin B has been reported in a number of human and animal tumors. This has also been observed in human gliomas where increases in cathepsin B mRNA, protein, activity and secretion parallel malignant progression. In the present study, we showed that cathepsin B was directly involved in glioma cell invasion. Activity of cathepsin B was an order of magnitude higher in glioma tissue than in matched normal brain. Inhibitors of cysteine proteases reduced invasion of glioma cells in two in vitro models: invasion through Matrigel and infiltration of a glioma spheroid into a normal brain aggregate. Glioma spheroids expressed higher levels of cathepsin B than did monolayers and the ability of subclones differing in cathepsin B activity to infiltrate normal brain aggregates paralleled their cathepsin B activity. We confirmed that intracellular staining for cathepsin B occurs at the cell periphery and in cell processes and observed extracellular staining on the cell surface. In addition, we demonstrated that intracellular cathepsin B located at the cell periphery and in processes was active. The cell surface cathepsin B colocalized with areas of degradation of an extracellular matrix component. We hypothesize that the increased expression of active cathepsin B in gliomas leads to increases in invasion in vitro and in vivo and have developed a xenotransplant model in which this hypothesis can be tested.
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PMID:Cathepsin B and glioma invasion. 1057 10

The p75 neurotrophic receptor (p75) shares structural features with the Fas receptor (FasR). Both receptors contain extracellular cysteine-rich repeats, a single transmembrane domain, and intracellular death domains. However, it has not been clearly established whether their death domains are equivalent in their ability to mediate apoptosis. To understand better the role of p75 during apoptosis, we constructed chimeric receptors that contained the extracellular portion of the FasR and the intracellular portion of p75. These chimeric receptors, one containing the p75 transmembrane domain and the other containing the FasR transmembrane portion, as well as wild-type p75 and Fas receptors, were transiently transfected into human U373 glioma cells and human embryonic kidney 293 cells (293 cells), which are both responsive to Fas-mediated apoptosis. Whereas expression of FasR was sufficient to induce apoptosis in U373 and 293 cells, expression of p75 and the chimeric receptors induced only minimal levels of cell death compared to FasR. The results indicate that the magnitudes of FasR- and p75-induced killing are different and suggest that the death domain of p75 does not function in the same manner as the FasR death domain.
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PMID:A comparison of the cytoplasmic domains of the Fas receptor and the p75 neurotrophin receptor. 1057 83

The relation between the effect of glutathione(GSH)-modulating compounds and platinum compounds (Cisplatin, Nedaplatin)-induced cytotoxicity was investigated. Pretreatment of human glioblastoma (T98G, U87MG) and glioma (KG1C) cell lines with L-buthionine-[S,R]-sulfoximine, which decrease the intracellular GSH concentration, remarkably increased their sensitivity against platinum compounds, whereas pretreatment with N-acetyl-L-cysteine, which increase the intracellular GSH concentration, only marginally protected the cells from the cytotoxic effect of platinum compounds. The results suggest that platinum compounds-induced cytotoxicity can be modified by GSH-modulating compounds in glioblastoma and glioma cell lines.
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PMID:Effect of glutathione-modulating compounds on platinum compounds-induced cytotoxicity in human glioma cell lines. 1069 65

RGS proteins comprise a family of proteins named for their ability to negatively regulate heterotrimeric G protein signaling. Biochemical studies suggest that members of this protein family act as GTPase-activating proteins for certain Galpha subunits, thereby accelerating the turn-off mechanism of Galpha and terminating signaling by both Galpha and Gbetagamma subunits. In the present study, we used confocal microscopy to examine the intracellular distribution of several RGS proteins in COS-7 cells expressing RGS-green fluorescent protein (GFP) fusion proteins and in cells expressing RGS proteins endogenously. RGS2 and RGS10 accumulated in the nucleus of COS-7 cells transfected with GFP constructs of these proteins. In contrast, RGS4 and RGS16 accumulated in the cytoplasm of COS-7 transfectants. As observed in COS-7 cells, RGS4 exhibited cytoplasmic localization in mouse neuroblastoma cells, and RGS10 exhibited nuclear localization in human glioma cells. Deletion or alanine substitution of an N-terminal leucine repeat motif present in both RGS4 and RGS16, a domain identified as a nuclear export sequence in HIV Rev and other proteins, promoted nuclear localization of these proteins in COS-7 cells. In agreement with this observation, treatment of mouse neuroblastoma cells with leptomycin B to inhibit nuclear protein export by exportin1 resulted in accumulation of RGS4 in the nucleus of these cells. GFP fusions of RGS domains of RGS proteins localized in the nucleus, suggesting that nuclear localization of RGS proteins results from nuclear targeting via RGS domain sequences. RGSZ, which shares with RGS-GAIP a cysteine-rich string in its N-terminal region, localized to the Golgi complex in COS-7 cells. Deletion of the N-terminal domain of RGSZ that includes the cysteine motif promoted nuclear localization of RGSZ. None of the RGS proteins examined were localized at the plasma membrane. These results demonstrate that RGS proteins localize in the nucleus, the cytoplasm, or shuttle between the nucleus and cytoplasm as nucleo-cytoplasmic shuttle proteins. RGS proteins localize differentially within cells as a result of structural differences among these proteins that do not appear to be important determinants for their G protein-regulating activities. These findings suggest involvement of RGS proteins in more complex cellular functions than currently envisioned.
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PMID:Cytoplasmic, nuclear, and golgi localization of RGS proteins. Evidence for N-terminal and RGS domain sequences as intracellular targeting motifs. 1079 63


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