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)

Hyperthermia has been shown to inhibit glioma growth both in vitro and in vivo, and has been reported to induce apoptosis of a variety of cells. We investigated the role of apoptosis in tumor cell death following hyperthermia in a rat glioma model representing human glioblastoma. Apoptotic cell death was evaluated by terminal deoxyribonucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) and hematoxylin and eosin (H & E) staining. We also examined c-Jun expression immunohistochemically. Apoptotic cell death in rat brain tumors that grew after implantation of C6 glioma cells showed regional differences. In all rats, apoptotic cells, characterized by extreme chromatin condensation and fragmented nuclei with apoptotic bodies in H & E-stained sections, were observed in the gliomas' necrotic cores. TUNEL-positive cells were observed in the border zones between necrotic and vital tumor cells. Before hyperthermia, TUNEL-positive cells were sporadically distributed in the vital tumor tissue. After hyperthermia, the number of TUNEL-positive cells in the peripheral region of the tumor mass increased significantly, reached a peak after 6 h and returned to the basal level within 24 h (P < 0.01). C-Jun protein immunoreactivity was not observed in the cells at the tumor periphery. These data indicate that significantly apoptotic cell death unrelated to c-Jun expression occurs after hyperthermia, and that this form of cell death may be the mechanism of tumor regression following hyperthermia treatment of intracranial gliomas.
 ...
PMID:Apoptotic cell death induced by local brain hyperthermia in a rat glioma model. 979 99

The relationship between malignant potential and apoptosis in astrocytic tumors has not been clearly defined, and further classification of astrocytic tumors is necessary. To elucidate the relationship between the histopathological grade of astrocytic tumors and apoptosis, we studied 25 cases of astrocytic tumors, comprising 10 cases of glioblastoma (GB), 7 cases of anaplastic astrocytoma (AA), and 8 cases of astrocytoma (AC). We detected apoptosis using the TdT-mediated dUTP-biotin nick-end labeling (TUNEL) method. We studied immunohistochemical expression of bcl-2 protein and p53 protein, which are apoptosis-related factors, and cell proliferative activity using Ki-67 antibody. No significant change was noted between apoptotic index and the histological grade of the tumors. In GB, apoptotic cell-rich foci were present at the pseudopalisading necrosis. No correlation between histopathological grades and expression of either p53 or bcl-2 was observed. In GB, however, poor distribution of bcl-2 was found in the areas of pseudopalisade formation. bcl-2 is one of the regulatory factors in the cell cycle and inhibits apoptosis. Expression of apoptosis had no correlation with histopathological grade. However, in GB, the distribution of apoptotic cells showed a correlation with bcl-2-poor foci. It was thought that apoptosis was one of the regulatory factors in the formation of pseudopalisading necrosis in GB.
 ...
PMID:Expression of apoptosis and its related protein in astrocytic tumors. 1053 18

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

We have shown recently that the multifunctional growth factor, scatter factor/hepatocyte growth factor (SF/HGF), and its receptor c-met enhance the malignancy of human glioblastoma through an autocrine stimulatory loop (R. Abounader et al., J. Natl. Cancer Inst., 91: 1548-1556, 1999). This report examines the effects of SF/HGF:c-met signaling on human glioma cell responses to DNA-damaging agents. Pretreating U373 human glioblastoma cells with recombinant SF/HGF partially abrogated their cytotoxic responses to gamma irradiation, cisplatin, camptothecin, Adriamycin, and Taxol in vitro. This cytoprotective effect of SF/HGF occurred at least in part through an inhibition of apoptosis, as evidenced by diminished terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling index and reduced DNA laddering. Anti-c-met U1/ribozyme gene transfer inhibited the ability of SF/HGF to protect against single-strand DNA breakage, DNA fragmentation, and glioblastoma cell death caused by DNA-damaging agents, demonstrating a requirement for c-met receptor function. Phosphorylation of the cell survival-promoting kinase Akt (protein kinase B) resulted from SF/HGF treatment of U373 cells, and both Akt phosphorylation and cell survival induced by SF/HGF were inhibited by phosphatidylinositol 3-kinase inhibitors but not by inhibitors of mitogen-activated protein kinase kinase or protein kinase C. Cytoprotection by SF/HGF in vitro was also inhibited by transient expression of dominant-negative Akt. Transgenic SF/HGF expression by intracranial 9L gliosarcomas reduced tumor cell sensitivity to gamma irradiation, confirming the cytoprotective effect of SF/HGF in vivo. These findings demonstrate that c-met receptor activation by SF/HGF protects certain glioblastoma cells from DNA-damaging agents by activating phosphoinositol 3-kinase-dependent and Akt-dependent antiapoptotic pathways.
 ...
PMID:Scatter factor/hepatocyte growth factor protects against cytotoxic death in human glioblastoma via phosphatidylinositol 3-kinase- and AKT-dependent pathways. 1094 42

Temozolomide is an alkylating cytostatic drug that finds increasing application in the treatment of melanoma, anaplastic astrocytoma and glioblastoma multiforme. The compound is a prodrug that decomposes spontaneously, independent of an enzymatic activation step. DNA methylation induces futile mismatch repair cycles and depletion of the DNA repair enzyme O(6)-methylguanine-DNA methyltransferase should then initiate programmed cell death. We show drug-dependent inhibition of tumour growth in a three-dimensional cell culture model of the glioma cell lines U87MG and GaMG. Migrational behaviour of the glioblastoma cells remained unaltered. However, coincubation of tumour spheroids with primary brain aggregates showed reduced tumour cell invasion into brain tissue in the presence of temozolomide. This was not achieved by slowing cellular migration, as temozolomide-treated cells displayed no reduced motility. By transferase-mediated dUTP nick-end labelling (TUNEL) of apoptotic nuclei, we found that the drug was able to induce apoptosis throughout the tumour cell spheroids. Apoptosis was highest in the core region of the spheroids. Repetitive application of sublethal doses of temozolomide to multicellular spheroids resulted in the development of drug resistance in GaMG cells. We suggest that temozolomide is a strong initiator of apoptosis in glioblastoma tumour cells in a spheroid cell culture system, when cells are already in a stressful environment.
 ...
PMID:Temozolomide induces apoptosis and senescence in glioma cells cultured as multicellular spheroids. 1256 92

We reported that 50% of cisplatin-induced apoptosis in primary cultures of rabbit renal proximal tubule cells (RPTC) proceeded via caspase-independent mechanisms. This study determined whether caspase-independent apoptosis, using multiple and diverse endpoints, could be produced by toxicants other than cisplatin and in cell models other than RPTC. Cisplatin, staurosporine, vincristine, and A23187 induced RPTC apoptosis after 24 h as indicated by 2- to 2.5-fold increases in annexin V and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) staining, and 2- to 10-fold increases in cell shrinkage. All toxicants induced 8- to 50-fold increases in caspase-3 activities, which were completely inhibited by the pan caspase inhibitor ZVAD-fmk. However, ZVAD-fmk only decreased cisplatin- and staurosporine-induced annexin V staining and cell shrinkage 30 to 50%, staurosporine-induced TUNEL staining 30%, and did not affect vincristine- or A23187-induced RPTC apoptosis. All toxicants tested induced apoptotic RPTC nuclear morphology. However, similar to its effect on annexin V and TUNEL staining, ZVAD-fmk only partially inhibited toxicant-induced apoptotic nuclear morphology. Cisplatin and staurosporine also induced annexin V staining in the human epithelial cancer cell lines Caki-1 (kidney carcinoma), A549 (lung carcinoma), A172 (glioblastoma), and murine lymphocytic leukemia L1210 cells. Pretreatment with ZVAD-fmk inhibited cisplatin-induced annexin V staining in Caki-1, A172, and A549 cells but had no affect in L1210 cells. Pretreatment with ZVAD-fmk did not decrease staurosporine-induced annexin V staining in Caki-1, A549, L1210, and A172 cells. These results suggest that a significant fraction of apoptosis induced by diverse toxicants in renal epithelial cells and in four different cancer cell lines is caspase-independent.
 ...
PMID:Identification of caspase-independent apoptosis in epithelial and cancer cells. 1502 82

Human glioblastoma is a deadly brain tumor that is often treated with a combination of drugs. A new alkylating agent, temozolomide (TMZ), has recently been found efficacious in the clinical trials for glioblastoma. Steroids, such as dexamethasone (DXM), are often used concomitantly as a supportive therapy to treat cerebral edema. However, any possible modulatory effect of the steroids on the efficacy of TMZ has not yet been evaluated experimentally. In this study, we have examined whether DXM provides synergistic or antagonistic effect on TMZ-induced apoptosis in human glioblastoma T98G cells. T98G cells were pretreated with various doses of DXM followed by TMZ. The cell viability was assessed by the trypan blue dye exclusion test. Wright staining and the TdT-mediated dUTP nick-end labeling (TUNEL) assay were used to evaluate apoptotic cell death based on the morphological and biochemical (DNA fragmentation) features, respectively. More biochemical features of apoptotic death, such as upregulation of Bax:Bcl-2 ratio, calpain activity, and caspase-3 activity, were assessed by Western blot analysis. A significant number of T98G cells committed apoptosis after treatment with 200 microM TMZ. However, a pretreatment with 100 microM or 200 microM DXM protected T98G cells against TMZ-induced apoptosis, concomitantly decreasing Bax:Bcl-2 ratio, calpain activity, and caspase-3 activity. These experimental results indicate that DXM works as an antagonistic agent in combination with TMZ. Therefore, our investigation strongly implies that the combination of DXM and TMZ may be counteractive in treating human glioblastoma.
 ...
PMID:Dexamethasone decreases temozolomide-induced apoptosis in human gliobastoma T98G cells. 1568 5

Inhibition of tumor angiogenesis through modulation of vascular endothelial growth factor (VEGF) and its signaling pathway has been clinically validated as a viable therapeutic modality in the treatment of cancer. The use of artificial transcription factors based on Cys2-His2 zinc-finger proteins (ZFPs) targeting the VEGF promoter offers a novel strategy for modulating VEGF levels in tumors. In order to demonstrate the utility of VEGF-targeted ZFPs as therapeutic agents, we generated adenoviruses (Ads) expressing VEGF promoter-targeted transcriptional repressor ZFP, F435-KOX. A replication-incompetent Ad expressing F435-KO X, namely, Ad-DeltaE1-KOX, significantly reduced VEGF expression and functionally led to inhibition of angiogenesis. In vivo, an oncolytic Ad expressing F435-KOX, namely, Ad-DeltaB7-KOX, elicited a pronounced antitumor effect against a human glioblastoma xenograft model, U87MG. Further, consistent with its expected mechanism of action, Ad-DeltaB7-KOX was shown to greatly reduce the level of VEGF and vessel density in tumor tissue and increase terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL)-positive apoptotic cells in tumors. Survival rates were also significantly increased in Ad-DeltaB7-KOX-treated mice. Taken together, the findings from this study identify F435-KOX as a novel and potent ZFP transcription factor that can inhibit VEGF-A-mediated angiogenesis and offer a novel therapeutic modality in the treatment of cancer.
 ...
PMID:Novel cancer antiangiotherapy using the VEGF promoter-targeted artificial zinc-finger protein and oncolytic adenovirus. 1839 29

Development of antineoplastic gene therapies is impaired by a paucity of transcription control elements with efficient, cancer cell-specific activity. We investigated the utility of promoter (AChP) and 5'-distal enhancer (ACE66) elements from the platelet-derived growth factor-A (PDGF-A) gene, which are hyperactive in many human cancers. Efficacy of these elements was tested in multiple tumor cell lines, both in cell culture and as tumor explants in athymic nude mice. Plasmid and viral vectors were constructed with the AChP promoter alone or in fusion with three copies of the ACE66 enhancer for expression of the prototype suicide gene, thymidine kinase (TK). ACE/AChP and AChP cassettes elicited ganciclovir (GCV)-induced cytotoxicity in multiple tumor cell lines. The ACE enhancer element also exhibited synergism with placental and liver-specific promoter elements. An adenovirus containing the AChP-TK cassette produced striking increases in GCV sensitivity in cultured tumor cell lines, as well as GCV-induced regression of U87 MG glioblastoma explants in vivo. TK expression was distributed throughout tumors receiving the therapeutic virus, whereas TdT-mediated dUTP nick end labeling (TUNEL) analysis revealed numerous regions undergoing apoptosis. Vascularization and reticulin fiber networks were less pronounced in virus-GCV-treated tumors, suggesting that both primary and stromal cell types may have been targeted. These studies provide proof-of-principle for utility of the PDGF-A promoter and ACE66 enhancer in antineoplastic gene therapy for a diverse group of human cancers.
 ...
PMID:PDGF-A promoter and enhancer elements provide efficient and selective antineoplastic gene therapy in multiple cancer types. 1898 53

Here we describe the substitution of fluorescently labeled ddUTP for dUTP in the TUNEL assay to allow quantification of generated fluorescence signals by epifluorescence microscopy. The capping of DNase type I 3'OH DNA ends using ddTUNEL was further combined with phosphatase treatment for detection of DNase type II 3'PO4 ends in the same sample using a second round of ddTUNEL. Levels of modified DNA bases in tissues and fixed cultured cells could be interrogated in the ddTUNEL assay with the base modification repair enzyme formamidopyrimidine DNA glycosylase. Using rat mammary gland, from days 1 and 7 of involution, we validate the methodology's ability to label apoptotic nuclei and apoptotic inclusion bodies. In addition, we examined the types of DNA damage and modification that occur in human glioblastoma, U87 cells, following exposure to reactive oxygen stressing agents, chemotherapeutic alkylating agents, and a topoisomerase I inhibitor, irinotecan.
 ...
PMID:Quantification of DNase type I ends, DNase type II ends, and modified bases using fluorescently labeled ddUTP, terminal deoxynucleotidyl transferase, and formamidopyrimidine-DNA glycosylase. 2061 3


1 2 3 Next >>