Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0017636 (glioblastoma)
 18,345 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To elucidate the mechanism of apoptosis in brain tumors, we analyzed the expression of apoptosis-related gene products in cultured glioma cells and biopsied brain tumor specimens. Fas, Bcl-2 family (Bcl-2, Bcl-x and Bax) and ICE family (ICE, Ich-1) were found to be involved in tumorigenesis of certain brain tumors. It was also clarified that OK-432 activated mononuclear cells could kill T98G glioblastoma cells by apoptotic mechanism through the Fas ligand/Fas system.
 ...
PMID:[Expression of apoptosis-related gene products in human brain tumors and apoptosis-inducing therapy]. 874 89

It is now generally accepted that massive neuronal death due to oxidative stress is a regular feature of brains in neurodegenerative diseases. However, much less attention has been given to the death of glial cells. In this study, we examined p53-sensitive apoptosis of cells by using human glioblastoma A172 cells and p53-deficient mouse astrocytes. In human A172 cells, hydrogen peroxide (H2O2) caused cell death in a time- and concentration-dependent manner, accompanied by nucleosomal DNA fragmentation and chromatin condensation. After treatment with H2O2, p53 protein was highly expressed and protein levels of Bak, p21WAF1/CIP1 and GADD45 were also enhanced. However, the protein levels of Bcl-2 and Bax did not change. On the other hand, primary cultured astrocytes from p53-deficient mouse brain grew faster than wild-type and heterozygous astrocytes. In addition, p53-deficient astrocytes were more resistant to H2O2-induced apoptosis than wild-type and heterozygous astrocytes. These results suggest that glial proliferation and the repair of damaged DNA may be regulated by p53-induced p21WAF1/CIP1 and GADD45, and that glial apoptosis caused by oxidative stress may be mediated by p53-induced Bak.
 ...
PMID:Hydrogen peroxide-induced apoptosis mediated by p53 protein in glial cells. 989 Jun 30

The effectiveness of chemotherapy for human cancers is limited by pharmacokinetic parameters such as variation in metabolism and is determined by the cellular response. In this work, we aimed to gain a more holistic understanding of the molecular basis of glioma response to the DNA-alkylating agent 1, 3-bis(2-chloroethyl)-1-nitrosourea (BCNU) by using a systematic approach: we investigated the expression of 588 genes with various cellular functions in a BCNU-resistant glioblastoma cell line and a BCNU-sensitive subline before and after treatment with BCNU. Our gene expression profiling revealed major differences in gene expression between these two cell lines, especially after treatment with BCNU. One striking example was that BCNU decreased the expression of six DNA-repair genes in sensitive but not in resistant cells. In sensitive cells, BCNU treatment resulted in the induction of two MAP kinase genes; this finding suggests that the specific response to BCNU in sensitive cells may involve the Jun kinase signal transduction pathway. After BCNU treatment, marked induction of tumor necrosis factor was detected only in sensitive cells, suggesting that tumor necrosis factor is a mediator of BCNU-induced cell death. Bcl-2 family members were not altered by BCNU in sensitive cells, suggesting that BCNU-induced cell death may be independent of the bcl-2 pathway. Results of the present study demonstrate that gene expression profiling may facilitate identification of cellular pathways associated with specific responses to chemotherapeutic agents and contribute to an understanding of the molecular basis of drug action.
 ...
PMID:Characterization of cellular pathways involved in glioblastoma response to the chemotherapeutic agent 1, 3-bis(2-chloroethyl)-1-nitrosourea (BCNU) by gene expression profiling. 1002 10

Protein phosphorylation in a human glioblastoma cell line, T98G, was examined after exposure to oxidative stress in vitro. Hydrogen peroxide (1 mM) markedly induced tyrosine phosphorylation of focal adhesion kinase (FAK) and serine phosphorylation of Akt at 1 h after stimulation. Concommitantly, the association of FAK with phosphatidylinositide 3'-OH-kinase (PI 3-kinase) was also observed by the hydrogen peroxide stimulation. When T98G cells were incubated with wortmannin, a PI 3-kinase inhibitor, both PI 3-kinase activity and phosphorylation of Akt were inhibited, whereas apoptosis by oxidative stress was accelerated. Concomitant with apoptosis, elevated level of CPP32 protease activity (caspase-3) was observed, with decreases in Bcl-2 protein and increases in Bax protein. These results suggested that in the signal transduction pathway from FAK to PI 3-kinase, Akt promotes survival. Thus, it became apparent that FAK is the upstream signal protein of the PI 3-kinase-Akt survival pathway in hydrogen peroxide-induced apoptosis in T98G cells.
 ...
PMID:FAK is the upstream signal protein of the phosphatidylinositol 3-kinase-Akt survival pathway in hydrogen peroxide-induced apoptosis of a human glioblastoma cell line. 1018 51

Bcl-2 is an oncogene with antiapoptotic function. However, Bcl-2 is converted to a Bax-like death effector by caspases, suggesting that the expression of Bcl-2 may not favor the growth of cancers. We introduced the Bcl-2 gene to gliomas via adenovirus (Adv; Adv-Bcl-2) with the Adv for Fas (Adv-Fas) and the Adv for Fas ligand (Adv-FL) to evaluate the antiapoptotic function of Bcl-2. In U251 glioblastoma cells, Bcl-2 at a low level of expression repressed apoptosis induced by Adv-Fas and Adv-FL, whereas Bcl-2 at a high level of expression did not. On the other hand, Bcl-X(L) showed antiapoptotic function against Fas-mediated apoptosis, irrespective of its expression level. In glioblastoma cells, induction of Bcl-2 alone at a high level induced apoptosis, whereas induction of Bcl-X(L) alone did not. As the multiplicity of infection of Adv-Bcl-2 was increased, the quantity of a cleaved product of Bcl-2 increased. Induction of caspase-inhibitory genes (CrmA and p35) inhibited apoptosis induced by Adv-Bcl-2. Induction of Bcl-2 led to alteration of the membrane potential and structure of the mitochondria. In summary, although Bcl-2 at a low level of expression was antiapoptotic, Bcl-2 at a high level of expression was proapoptotic to Fas-mediated apoptosis. Overexpression of Bcl-X(L) was consistently antiapoptotic to Fas-mediated apoptosis.
 ...
PMID:Expression level of Bcl-2 determines anti- or proapoptotic function. 1046 17

We identified betulinic acid (BetA) as a new cytotoxic agent active against neuroectodermal tumor cells including neuroblastoma, medulloblastoma, glioblastoma and Ewing's sarcoma cells representing the most common solid tumors of childhood. BetA induced apoptosis independent of wild-type p53 protein and accumulation of death-inducing ligand/receptor systems such as CD95. BetA had a direct effect on mitochondria resulting in the release of soluble apoptogenic factors such as cytochrome c or AIF from mitochondria into the cytosol where they induced activation of caspases. Overexpression of the anti-apoptotic proteins Bcl-2 or Bcl-XL that blocked loss of the mitochondrial membrane potential and cytochrome c release from mitochondria conferred resistance to BetA at the level of mitochondrial dysfunction, protease activation and nuclear fragmentation. Neuroblastoma cells resistant to CD95- or doxorubicin-triggered apoptosis remained sensitive to treatment with BetA suggesting that BetA may bypass some forms of resistance. Moreover, BetA exhibited potent antitumor activity on primary tumor cell cultures from all neuroblastoma (4/4), all medulloblastoma (4/4) and most glioblastoma patients (20/24) ex vivo. These findings suggest that BetA may be a promising new agent in the treatment of neuroectodermal tumors in vivo.
 ...
PMID:Betulinic acid: a new chemotherapeutic agent in the treatment of neuroectodermal tumors. 1047 70

Glutamate has been shown to function as a toxic agent in neuronal and glial cells, as well as an excitatory neurotransmitter throughout the central nervous system. In the present study, we examined the effect of increasing glutamate concentration on the induction of apoptosis in the two human glioblastoma cell lines GB-4 and GB-12. Glutamate exposure caused cell death of GB-4 and GB-12 in a dose-dependent manner. The cells were found to die via apoptosis in response to glutamate based on the following criteria: propidium iodide (PI) staining, H-E staining, electron microscopic analysis, and the TdT-mediated dUTP-biotin nick end labeling (TUNEL) method. The glutamate-induced apoptosis appears to involve the modulation of Bcl-2 family gene products such as Bcl-2, Bcl-xL, and Bax-alpha. Both Bcl-2 and Bcl-xL were down-regulated by glutamate at 24 h and further at 48 h. The apoptosis-promoting product p21 Bax-alpha was also down-regulated in GB-12 but slightly up-regulated in GB-4, accompanied by generation of variant form of p18 Bax-alpha in both cell lines. These findings suggest that glutamate toxicity results in cellular death via an apoptotic mechanism which appears to involve the Bcl-2/Bax-alpha molecular complex.
 ...
PMID:Participation of Bcl-2/Bax-alpha in glutamate-induced apoptosis of human glioblastoma cells. 1061 94

Glioblastomas are the most frequent and most malignant astrocytic gliomas. The epidermal growth factor receptor (EGFR) gene is the most frequently amplified and overexpressed in glioblastomas. The expression of bcl-2 and Bax in EGFR-antisense transfected and un-transfected glioblastoma cell line, U87E and U87V was studied by immunohistochemistry and western blotting. Our results show that the expression of Bax was stronger and bcl-2 was weaker in EGFR-antisense transfected cell line than the untransfected control. Bcl-2 and Bax genes are probably involved in the reduction of malignancy of glioblastoma cell caused by the introduction of EGFR-antisense into these tumor cells.
 ...
PMID:Expression of bcl-2 and Bax in EGFR-antisense transfected and untransfected glioblastoma cells. 1062 70

Bcl-2 and Bax proteins are implicated in the regulation of apoptosis. Nuclear matrix has been demonstrated to be associated with a vast array of functional and regulatory properties of cells. NuMA is one member of a class of nuclear matrix proteins that resides in both the nucleus and mitotic apparatus. The nuclear lamins appear to form a thin fibrous structure immediately underlying the inner nuclear membrane of eukaryotic cell nuclei. The association of bcl-2 and Bax protein with nuclear matrix in glioblastoma cell line U343 was studied by confocal microscopy and Western blotting. Confocal microscopic images display that bcl-2 was localized at the peripheral of the nuclear matrix and Bax protein was located in the nuclear matrix. Western blotting detected a 26 kDa bcl-2 band and a specific band of Bax at around 66 kDa in nuclear matrix proteins. Our results suggest that bcl-2 and Bax proteins are nuclear matrix associated proteins.
 ...
PMID:Bcl-2 and Bax proteins are nuclear matrix associated proteins. 1069 75

Ceramide has recently been regarded as a potential mediator of apoptosis. In the present study, the effects of Bcl-2 and Bax on the ceramide-mediated apoptotic pathways were examined in glioma cells overexpressing Bcl-2 or Bax. Etoposide, cisplatin and tumor necrosis factor-alpha induced apoptosis of C6 rat glioma cells which was associated with ceramide formation due to activation of neutral sphingomyelinase, followed by release of mitochondrial cytochrome c into the cytosol and activation of caspases-9 and -3. The growth of C6 cells stably overexpressing either Bcl-2 or Bax was almost equal to that of the vector-transfected cells. Bax overexpression enhanced etoposide-induced apoptosis through acceleration of cytochrome c release and caspases activation. However, Bax had no effect on ceramide formation. Similar findings were obtained in C6 cells and U87-MG human glioblastoma cells which were transiently overexpressed with Bax. In contrast, Bcl-2 overexpression resulted in a retardation of the apoptotic process via prevention of cytochrome c release and caspases activation, and ceramide formation was also blocked when Bcl-2 was highly overexpressed in glioma cells. In addition, transient overexpression of Bcl-xL also exerted inhibitory effects on ceramide formation and apoptotic cell death induced by etoposide. These results indicate that Bax promotes apoptosis regardless of ceramide formation and that Bcl-2 or Bcl-xL prevents ceramide formation by repressing neutral sphingomyelinase as well as ceramide-induced cytochrome c release. Oncogene (2000) 19, 3508 - 3520
 ...
PMID:Influence of Bax or Bcl-2 overexpression on the ceramide-dependent apoptotic pathway in glioma cells. 1091 9


1 2 3 4 5 6 7 8 9 10 Next >>