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)

We sought to characterize the pathway by which the multifunctional cytokine transforming growth factor-beta (TGF-beta) inhibits the proliferation of normal astrocytes, and we analyzed the alterations in the TGF-beta pathway in human glioma cell lines. Upon TGF-beta treatment, primary rat astrocytes showed a significant decrease in DNA synthesis upon thymidine incorporation with a cell cycle arrest in the G(1) phase. Western analysis of the astrocytes revealed that the expression of the cyclin-dependent kinase inhibitor (CdkI) p15(INK4B) was significantly up-regulated upon TGF-beta treatment without a change in other CdkI levels. The retinoblastoma protein (Rb) became hypophosphorylated, and Cdk2 activity decreased. Analysis of Smad3 null mouse astrocytes showed a significant loss of both TGF-beta-mediated growth inhibition and p15(INK4B) induction compared with wild-type mouse astrocytes. Infection of rat astrocytes by SMAD3 and SMAD4 adenoviruses failed to induce increased expression of p15(INK4B), implying indirect transcriptional regulation of p15(INK4B) by SMAD3. High-grade human gliomas secrete TGF-beta, yet are resistant to its growth inhibitory effects. Analysis of the effects of TGF-beta on 12 human glioma cell lines showed that TGF-beta mildly inhibited the growth of six lines, had no effect on four lines, and stimulated the growth of two lines. The majority of glioma lines had homozygous deletions of the p15(INK4B) gene, except for two lines that expressed p15(INK4B) protein, which was induced further upon TGF-beta treatment. Three lines mildly induced CdkI p21(WAF1) expression in response to TGF-beta. Most tumor lines retained other TGF-beta-mediated responses, including extracellular matrix protein and angiogenic factor secretion, which may contribute to increased malignant behavior. This suggests that the loss of p15(INK4B) may explain, in part, the selective loss of growth inhibition by TGF-beta in gliomas to form a more aggressive tumor phenotype.
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PMID:Transforming growth factor-beta-mediated p15(INK4B) induction and growth inhibition in astrocytes is SMAD3-dependent and a pathway prominently altered in human glioma cell lines. 1057 84

Gliomas express a higher amount of Fas than normal brain tissue. It is of interest to know whether expression of the Fas receptor is unfavorable to the antiapoptotic pathways in gliomas. In this study, we introduced the Fas gene via an adenovirus vector (Adeno-Fas) into the A-172, U251, and U-373 MG glioma cell lines, each of which expresses Fas on the cell surface. Infection of Adeno-Fas induced apoptosis in each glioma cell line. In U251 cells and A-172 cells that express the same level of Fas as a result of infection with Adeno-Fas, a much higher percentage of U251 cells underwent apoptosis than did A-172 cells. This suggests that each glioma cell line has its own threshold of Fas expression, above which apoptosis is induced, and that the constitutive expression of Fas is below the level of this threshold. It was found that the constitutive expression of the anti-apoptotic gene Bcl-X(L) is higher in A-172 cells than in U251 cells. Adenovirus-mediated transduction of the Bcl-X(L) gene into U251 cells effectively suppressed Adeno-Fas-mediated apoptosis. These data indicate that the Bcl-X(L) gene is one of the important determinants of the threshold for Fas-mediated apoptosis. When U251 and U-373 MG cells were transduced with the Fas gene controlled by the myelin basic protein promoter, which had been shown to be active in gliomas but not in neural tissues, the cells underwent markedly enhanced apoptosis. Taken together, these results indicate that the overexpression of Fas alone induced apoptosis in each glioma cell line. The degree of Fas-mediated apoptosis was attenuated by the expression of an anti-apoptotic gene, Bcl-X(L). The adenovirus-mediated induction of Fas gene controlled by a tissue-specific promoter (e.g., myelin basic protein promoter) would be a promising therapeutic approach for malignant glioma.
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PMID:Adenovirus-mediated overexpression of Fas induces apoptosis of gliomas. 1077 Jun 30

Infection of rat RT2 glioma cells in vitro with an adenovirus (ADV-TK) expressing herpes simplex virus (HSV) thymidine kinase (TK) and subsequent exposure to 5-bromo-2'-deoxycytidine (BrdC), which is specifically incorporated into ADV-TK-infected cell DNA as 5-bromo-2'-deoxyuridine (BrdU), results in significant radiosensitization (sensitizer enhancement ratio: 1.4-2.3) compared with Ad beta gal-infected cells. Cell killing correlated well with increased BrdU DNA incorporation and with apoptosis. Whereas radiation (4 Gy) alone was relatively ineffective in inducing apoptosis, treatment with HSV-TK/BrdC resulted in BrdC dose- (10-100 microM) and time-dependent (24-48 hours) increases, and the combination of the two treatments produced a synergistic response (1.5- to 2-fold). To investigate the effects of the ADV-TK/BrdC treatment in vivo, RT2 cells were grown as soft tissue tumors in Fischer 344 rats and conditions for virus infusion were optimized by altering the volume and rate of infusion using a rate-controlled positive pressure device. We found that relatively large volumes (100-150 microL) of virus delivered at rates of < or = 1 microL/minute were optimal and gave uniform and reproducible results. Using these optimal infusion conditions, we were able to achieve 40% adenovirus infection in the tumor. Infection of RT2 tumors with ADV-TK and continuous administration of BrdC from an osmotic pump resulted in significant (.001 < P < .009) tumor regression 6 days after radiation (30 Gy delivered as 2 x 5 Gy over 3 days) compared with controls. In situ staining of sectioned tumors with anti-BrdU antibody or by high-performance liquid chromatography analysis of extracted and hydrolyzed tumor DNA confirmed that we obtained efficient and specific incorporation of BrdU into tumor cells. These results suggest that adenovirus-mediated delivery of HSV-TK in combination with BrdC and radiation can potentially be an efficient combination modality for the treatment of gliomas.
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PMID:Radiosensitization of rat glioma with bromodeoxycytidine and adenovirus expressing herpes simplex virus-thymidine kinase delivered by slow, rate-controlled positive pressure infusion. 1083 Jul 25

We constructed an adeno-associated virus (AAV) vector containing the human interferon-beta (HuIFN-b ) gene (AAV-IFN-beta) and investigated its antitumor effect against human glioma cells (U251-SP) inoculated into the brain of nude mice. Prior to this, we examined human glioma cells transduced with AAV-IFN-beta using video-enhanced contrast differential interference contrast (VEC-DIC) microscopy. Infection of AAV-IFN-beta induced apoptosis and secondary necrosis in human glioma cells. In in vivo experiments, we confirmed production of HuIFN-beta and induction of heat-shock protein (HSP) in glioma cells transduced with AAV-IFN-beta. Growth of the experimental gliomas was completely inhibited by six injections of AAV-IFN-beta, starting 7 days after transplantation of glioma cells. In addition, the survival of mice treated with AAV-IFN-beta was remarkably prolonged. These results indicate that AAV-IFN-beta induces apoptosis of glioma cells and has a strong antitumor effect in this experimental glioma model.
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PMID:Antitumor effect of an adeno-associated virus vector containing the human interferon-beta gene on experimental intracranial human glioma. 1185 87

Matrix metalloproteinase 9 (MMP-9) is known to play a major role in cell migration and invasion in both physiological and pathological processes. Our previous work has shown that increased MMP-9 levels are associated with human glioma tumor progression. In this study, we evaluated the ability of an adenovirus containing a 528 bp cDNA sequence in antisense orientation to the 5' end of the human MMP-9 gene (Ad-MMP-9AS) to inhibit the invasiveness and migratory capacity of the human glioblastoma cell line SBN19 in in vitro and in vivo models. Infection of glioma cells with Ad-MMP-9AS reduced MMP-9 enzyme activity by approximately 90% compared with mock- or Ad-CMV-infected cells. Migration and invasion of glioblastoma cells infected with Ad-MMP-9AS were significantly inhibited relative to Ad-CMV-infected controls in spheroid and Matrigel assays. Intracranial injections of SNB19 cells infected with Ad-MMP-9AS did not produce tumors in nude mice. However, injecting the Ad-MMP-9AS construct into subcutaneous U87MG tumors in nude mice caused regression of tumor growth. These results support the theory that adenoviral-mediated delivery of the MMP-9 gene in the antisense orientation has therapeutic potential for treating gliomas.
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PMID:Adenovirus-mediated expression of antisense MMP-9 in glioma cells inhibits tumor growth and invasion. 1243 51

We examined the impact of purified bacterially synthesized GST-MDA-7 (IL-24) and ionizing radiation on the proliferation and survival of nonestablished human glioblastoma multiforme (GBM) cells. Glioma cell types expressing mutated PTEN and p53 molecules, activated ERBB1VIII, overexpressing wild type ERBB1 or without receptor overexpression were selected. In MTT assays, GST-MDA-7 caused a dose-dependent reduction in the proliferation of nonestablished glioma cells; however only at higher concentrations did GST-MDA-7 reduce cell viability. The anti-proliferative and cytotoxic effects of GST-MDA-7 were enhanced by radiation in a greater than additive fashion that correlated with JNK1/2/3 activation. The reduction in cell growth and enhancement in cell killing by the combination of GST-MDA-7 and radiation were blocked by an ROS scavenger, N-acetyl cysteine (NAC), a JNK1/2/3 inhibitor SP600125, a pan-caspase inhibitor (zVAD) and by an inhibitor of caspase 9 (LEHD), but not by an inhibitor of caspase 8 (IETD). Low concentrations of either GST-MDA-7 or radiation reduced clonogenic survival, however colony formation ability was significantly further decreased when the two treatments were combined, which was also blocked by inhibition of caspase 9 function. In general agreement with activation of the intrinsic caspase pathway, cell death correlated with reduced BCL-XL expression and with increased levels of the pro-apoptotic proteins BAD and BAX. Inhibition of caspase 9 after combination treatment blunted neither JNK1/2/3 activation nor the enhanced expression of BAD and BAX, but did block caspase 3 cleavage, reduced expression of BCL-XL and inhibition of ERK1/2 activity. In contrast, incubation with NAC blocked JNK1/2/3 activation and cell killing, but not the increases in BAD and BAX expression. These findings argue that after combination treatment JNK1/2/3 activation is a primary pro-apoptotic event and loss of BCL-XL expression and ERK1/2 activity are secondary caspase-dependent processes. This data also argues that GST- MDA-7 induces two parallel pro-apoptotic pathways via ROS-dependent and -independent mechanisms. Infection of primary human astrocytes with a recombinant adenovirus to express MDA-7, Ad.mda-7, but not infection with either Ad.cmv or Ad.mda-7SP- lacking MDA-7 secretion, resulted in the suppression of GBM cell colony formation in soft agar overlay assays, an effect that was enhanced in a greater than additive fashion by radiation. Collectively, our findings demonstrate that MDA-7 reduces proliferation and enhances the radiosensitivity of nonestablished human GBM cells in vitro, and when grown in 3 dimensions, and that sensitization occurs independently of basal EGFR/ERK1/2/AKT activity or the functions of PTEN and p53.
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PMID:MDA-7 regulates cell growth and radiosensitivity in vitro of primary (non-established) human glioma cells. 1532 89

Accumulating evidence suggests that glutamate plays a key role in the proliferation and invasion of glioblastoma tumors. Astrocytic tumors have been shown to release glutamate at high levels, which may stimulate tumor cell proliferation and motility via activation of glutamate receptors. Excess glutamate has also been found to facilitate tumor invasion by causing excitotoxic damage to normal brain thereby paving a pathway for tumor migration. Results from tissue microarray analyses showed decreased excitatory amino acid transporter-2 (EAAT-2) expression in high-grade glial tumors compared with low-grade astrocytomas and normal brain. EAAT-2 expression was inversely correlated with tumor grade, implicating its potential role in glial tumor progression, which was reflected by an undetectable level of EAAT-2 protein in glioma cell lines. In this study, we sought to investigate the effect of reconstituted EAAT-2 on glioma cell growth in vitro and in vivo by adenoviral-mediated gene transfer. Infection of glioma cells with Ad-EAAT-2 resulted in a physiologic level of functional EAAT-2, and a subsequent dose-dependent reduction in cell proliferation in all glioma cell lines tested compared with controls. Interestingly, results from analyses of Annexin V staining, detection of poly(ADP-ribose)polymerase cleavage and caspase-3 activation all indicated that Ad-EAAT-2 infection elicited apoptosis in glioma cells. Ex vivo experiments in nude mice showed a total suppression of tumor growth at sites that received Ad-EAAT-2-infected cells. Collectively, our results uncovered a new function of EAAT-2 in controlling glioma proliferation. Further studies will improve our knowledge of the role of glutamate in glioma growth and may provide useful prognostic information and alternative therapeutic targets for the treatment of glioma.
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PMID:The excitatory amino acid transporter-2 induces apoptosis and decreases glioma growth in vitro and in vivo. 1575 93

The sensitivity of brain tumour cells to wild-type or recombinant parvoviruses H1-PV and MVMp makes these agents promising candidates for gene therapy of astrocytoma. This application raises the question of whether parvoviruses exert deleterious or bystander effects on normal glial cells surrounding tumours. We addressed this question in the mouse model by using cell cultures derived from BALB/c, C57BL/6 and VM/Dk strains. Astrocytes and a large proportion of microglia cultures were competent for MVMp uptake. Infection was, however, abortive as replication-associated viral proteins synthesis took place in less than 10% of astrocytes and no progeny virions were produced. This restriction was even more pronounced for microglia in which no viral protein expression could be detected, save for a minute fraction of VM/Dk-derived cells. Infection with MVMp had no significant effect on glial cell survival and did not interfere with their immune potential. Indeed, neither the lipopolysaccharide (LPS)/interferon (IFN-gamma)-induced cytotoxicity of VM/Dk-derived microglia towards the mouse glioma (MT539MG) cell line, nor the glial cells capacity for tumour necrosis factor alpha production upon LPS stimulation or LPS/IFN-gamma stimulation were affected by infection with MVMp. Moreover, stimulation with LPS and/or IFN-gamma resulted in a decreased expression of the viral replicative and cytotoxic protein NS1. Together, our data indicate that, in the natural host, a majority of normal glial cells are not competent for MVMp replication and that the abortive infection taking place in a minor fraction of these cells fails to impede their survival and immunocompetence, giving credit to the consideration of autonomous parvoviruses for glioma therapy.
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PMID:Oncolytic murine autonomous parvovirus, a candidate vector for glioma gene therapy, is innocuous to normal and immunocompetent mouse glial cells. 1669 1

Loss of function of the tumor suppressor gene PTEN is more frequently encountered in high-grade malignant gliomas than in low-grade gliomas. High-grade gliomas are characterized by their extremely invasive behavior, suggesting that PTEN is one of the important regulators of cell motility and that alterations of its coding gene contribute to a much more invasive tumor cell phenotype. In order to clarify a role of PTEN in glioma invasion, we introduced the wild-type PTEN gene into human malignant glioma cell lines and investigated their motile and invasive activity in a brain slice model that presents circumstances analogous to normal brain conditions in vivo. In addition, we analyzed biochemical and molecular changes resulting from the transfer of PTEN in the glioma cells. Infection of recombinant replication-defective adenovirus vector containing the wild-type PTEN cDNA (Ad5CMV-PTEN) significantly inhibited the cell migration and invasion activities of PTEN-mutated glioma cell lines in in vitro migration and chemoinvasion assays. In an organotypic brain slice model, co-culture of glioma spheroids and rat brain slices demonstrated that Ad5CMV-PTEN transfected cells failed to invade surrounding normal brain tissues. Ad5CMV-PTEN transfer into the glioma cell lines lacking the wild-type gene product decreased the levels of matrix metalloproteinase (MMP)-2 mRNA and inhibited the enzymatic activities of MMP-2 and MMP-9. In contrast, mRNA expression of tissue inhibitor of metalloproteinase (TIMP)-2 was upregulated by the PTEN gene transfer. Introduction of PTEN gene in glioma cell lines markedly reduced the levels of Rac-GTP and Cdc42-GTP, activated forms of these small GTP-binding proteins, and decreased the phosphorylation levels of focal adhesion kinase. These results suggest that PTEN inhibits glioma cell invasion in two ways: suppressing proteolysis of the extracellular matrix by MMPs and modulating the migratory activity of glioma cells to a less motile nature by inactivating two Rho-family GTP-binding proteins, Rac and Cdc42.
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PMID:PTEN gene transfer suppresses the invasive potential of human malignant gliomas by regulating cell invasion-related molecules. 1677 87

With little improvement in the poor prognosis for humans with high-grade glioma brain tumors, alternative therapeutic strategies are needed. As such, selective replication-competent oncolytic viruses may be useful as a potential treatment modality. Here we test the hypothesis that defects in the interferon (IFN) pathway could be exploited to enhance the selective oncolytic profile of vesicular stomatitis virus (VSV) in glioblastoma cells. Two green fluorescent protein-expressing VSV strains, recombinant VSV and the glioma-adapted recombinant VSV-rp30a, were used to study infection of a variety of human glioblastoma cell lines compared to a panel of control cells, including normal human astrocytes, oligodendrocyte precursor cells, and primary explant cultures from human brain tissue. Infection rate, cell viability, viral replication, and IFN-alpha/beta-related gene expression were compared in the absence and presence of IFN-alpha or polyriboinosinic polyribocytidylic acid [poly(I:C)], a synthetic inducer of the IFN-alpha/beta pathway. Both VSV strains caused rapid and total infection and death of all tumor cell lines tested. To a lesser degree, normal cells were also subject to VSV infection. In contrast, IFN-alpha or poly(I:C) completely attenuated the infection of all primary control brain cells, whereas most glioblastoma cell lines treated with IFN-alpha or poly(I:C) showed little or no sign of protection and were killed by VSV. Together, our results demonstrate that activation of the interferon pathway protects normal human brain cells from VSV infection while maintaining the vulnerability of human glioblastoma cells to viral destruction.
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PMID:Variable deficiencies in the interferon response enhance susceptibility to vesicular stomatitis virus oncolytic actions in glioblastoma cells but not in normal human glial cells. 1710 37


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