cytochrome-c-t and Glioma

Glioma is the foremost recurrent type of brain tumor in humans; in particular, glioblastoma (GBM) is the main form of brain tumor (GBM) that is highly proliferative and impervious to apoptosis. Triphlorethol-A (TA), a phlorotannin isolated from Ecklonia cava, exhibited cytoprotective, antioxidant, and anticancer properties. However, the exact molecular action of TA in the U251 human GBM cells remains unknown. This may be the first report on the antiproliferative and apoptotic mechanisms of TA on GBM. The cytotoxicity, intracellular reactive oxygen species (ROS), matrix metalloproteinase (MMP), and cell apoptosis activity of TA have been evaluated by the MTT assay and by DCFH-DA, Rh-123, AO/EB, and western blot analysis. The results obtained showed that TA abridged the viability of U251 cells, while MMP increased apoptosis by increasing the ROS levels in a time-dependent manner. The results showed that a reduction in U251 cell proliferation was associated with the regulation of JAK2/STAT3 and p38 MAPK/ERK signaling pathways. TA was found to suppress pJAK, pSTAT3, p38 MAPK, and pERK phosphorylation, thereby causing Bax/Bcl-2 imbalance, activating the caspase cascade and cytochrome c, and inducing apoptosis. Our findings showed that the suppression of JAK2/STAT3 and p38 MAPK/ERK signaling by TA results in cell growth arrest and stimulation of apoptosis in GBM cells. These studies justify the protective remedy of TA against GBM.

Topics: Antioxidants; Apoptosis; bcl-2-Associated X Protein; Brain Neoplasms; Caspases; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Glioblastoma; Glioma; Humans; Janus Kinase 2; MAP Kinase Signaling System; p38 Mitogen-Activated Protein Kinases; Phloroglucinol; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; STAT3 Transcription Factor

Recent studies revealed an antioxidant activity and anticancer efficiency of betanin. In this study, we investigated the cytotoxic effects and the possible mechanisms of betanin-induced apoptosis against U87MG human glioma cells and compared the results to those of human normal lymphocytes. MTT assay, caspase-3 activation assays in cells and succinate dehydrogenases (SDH), mitochondrial swelling, reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP), and cytochrome C release assays in isolated mitochondria were obtained from U87MG human glioma cells and noncancerous human lymphocytes The results illustrated the significant cytotoxic effect of betanin on U87MG human glioma cells, with a concentration value that inhibits 50% of the cell growth of 7 µg/ml after 12 h of treatment. MTT assay demonstrated that the betanin is selectively toxic to U87MG human glioma cells, and betanin induced cell apoptosis via activation of caspase-3 along with modulation of apoptosis-related mitochondria. Meanwhile, betanin selectively increased ROS formation, mitochondria swelling, MMP decrease, and cytochrome c release in cancerous mitochondria but in normal mitochondria. Based on the evidence obtained from this study, it is concluded that the betanin is a promising natural compound to fight U87MG human glioma cells via induction of apoptosis through activation of intrinsic pathways.

Topics: Apoptosis; Betacyanins; Cell Line, Tumor; Cytochromes c; Glioma; Humans; Lymphocytes; Membrane Potential, Mitochondrial; Mitochondria; Reactive Oxygen Species

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Calcium-Binding Proteins; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cytochromes c; Glioma; Humans; Mitochondria; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Reactive Oxygen Species; Saponins; Signal Transduction; Sincalide; Starfish

Malignant gliomas are the most lethal form of primary brain tumors. Despite advances in cancer therapy, the prognosis of glioma patients has remained poor. Cytochrome c (Cytc), an endogenous heme-based protein, holds tremendous potential to treat gliomas because of its innate capacity to trigger apoptosis. To this end, a hybrid cytochrome c-chlorotoxin (Cytc-CTX) protein was biosynthesized to enable cellular uptake of the cell impenetrable Cytc using CTX transporters. A nucleotide sequence containing 1 : 1 Cytc and CTX was constructed and separated by a hexahistidine-tag and an enterokinase cleavage site. The sequence was cloned into a pBTR1 plasmid, expressed in Escherichia coli, purified via 2-dimensional chromatography. The identity and size of the protein were determined by Western blot and mass spectrometry. Cytc in this soluble hybrid protein has similar structure and stability as human Cytc and the hybrid protein is endocytosed into a glioma cell line, while displaying potent cytotoxicity and a favorable therapeutic index. Its facile, low-cost, and high yield synthesis, biocompatibility, and robustness suggest that the hybrid protein is a promising candidate for antiglioma drug evaluation.

Topics: Antineoplastic Agents; Brain Neoplasms; Cell Survival; Cells, Cultured; Cytochromes c; Dose-Response Relationship, Drug; Glioma; Humans; Scorpion Venoms; Structure-Activity Relationship

Glioma is one of the most aggressive primary brain tumors and is incurable. Surgical resection, radiation, and chemotherapies have been the standard treatments for brain tumors, however, they damage healthy tissue. Therefore, there is a need for safe anticancer drug delivery systems. This is particularly true for natural prodrugs such as thymoquinone (TQ), which has a high therapeutic potential for cancers but has poor water solubility and insufficient targeting capacity. We have tailored novel core-shell nanoformulations for TQ delivery against glioma cells using mesoporous silica nanoparticles (MSNs) as a carrier.. The core-shell nanoformulations were prepared with a core of MSNs loaded with TQ (MSNTQ), and the shell consisted of whey protein and gum Arabic (MSNTQ-WA), or chitosan and stearic acid (MSNTQ-CS). Nanoformulations were characterized, studied for release kinetics and evaluated for anticancer activity on brain cancer cells (SW1088 and A172) and cortical neuronal cells-2 (HCN2) as normal cells. Furthermore, they were evaluated for caspase-3, cytochrome c, cell cycle arrest, and apoptosis to understand the possible anticancer mechanism.. TQ release was pH-dependent and different for core and core-shell nanoformulations. A high TQ release from MSNTQ was detected at neutral pH 7.4, while a high TQ release from MSNTQ-WA and MSNTQ-CS was obtained at acidic pH 5.5 and 6.8, respectively; thus, TQ release in acidic tumor environment was enhanced. The release kinetics fitted with the Korsmeyer-Peppas kinetic model corresponding to diffusion-controlled release. Comparative in vitro tests with cancer and normal cells indicated a high anticancer efficiency for MSNTQ-WA compared to free TQ, and low cytotoxicity in the case of normal cells. The core-shell nanoformulations significantly improved caspase-3 activation, cytochrome c triggers, cell cycle arrest at G2/M, and apoptosis induction compared to TQ.. Use of MSNs loaded with TQ permit improved cancer targeting and opens the door to translating TQ into clinical application. Particularly good results were obtained for MSNTQ-WA.

Topics: Antineoplastic Agents; Apoptosis; Benzoquinones; Biocompatible Materials; Brain; Calorimetry, Differential Scanning; Caspase 3; Cell Cycle Checkpoints; Cell Line, Tumor; Chitosan; Cytochromes c; Diffusion; Drug Compounding; Drug Delivery Systems; Drug Liberation; Enzyme Activation; Glioma; Humans; Hydrogen-Ion Concentration; Inhibitory Concentration 50; Kinetics; Nanoparticles; Porosity; Silicon Dioxide; Spectroscopy, Fourier Transform Infrared; Thermogravimetry

In this study, we identified the proton-coupled folate transporter (PCFT) as a route for targeted delivery of drugs to some gliomas. Using the techniques of confocal imaging, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and small interfering (siRNA) knockdown against the PCFT, we demonstrated that Gl261 and A172 glioma cells, but not U87 and primary cultured astrocytes, express the PCFT, which provides selective internalization of folic acid (FA)-conjugated cytochrome c-containing nanoparticles (FA-Cyt c NPs), followed by cell death. The FA-Cyt c NPs (100 µg/mL), had no cytotoxic effects in astrocytes but caused death in glioma cells, according to their level of expression of PCFT. Whole-cell patch clamp recording revealed FA-induced membrane currents in FA-Cyt c NPs-sensitive gliomas, that were reduced by siRNA PCFT knockdown in a similar manner as by application of FA-Cyt c NPs, indicating that the PCFT is a route for internalization of FA-conjugated NPs in these glioma cells. Analysis of human glioblastoma specimens revealed that at least 25% of glioblastomas express elevated level of either PCFT or folate receptor (FOLR1). We conclude that the PCFT provides a mechanism for targeted delivery of drugs to some gliomas as a starting point for the development of efficient methods for treating gliomas with high expression of PCFT and/or FOLR1.

Topics: Animals; Astrocytes; Brain Neoplasms; Cell Line, Tumor; Cells, Cultured; Cytochromes c; Folic Acid; Glioma; Humans; Mice; Mice, Inbred C57BL; Nanoconjugates; Proton-Coupled Folate Transporter

Pseurotin A was isolated from a culture of marine Bacillus sp. FS8D and showed to be active against the proliferation of four different glioma cells with IC

Topics: Animals; Antineoplastic Agents; Bacillus; Carrier Proteins; Cell Proliferation; Cytochromes c; Down-Regulation; Enzymes; Glioma; Glycolysis; Humans; Inhibitory Concentration 50; Isoenzymes; L-Lactate Dehydrogenase; Lactate Dehydrogenase 5; Membrane Proteins; Mitochondrial Proton-Translocating ATPases; Pyrrolidinones; Thyroid Hormone-Binding Proteins; Thyroid Hormones

Malignant glioma is one of the most challenging central nervous system diseases to treat and has high rates of recurrence and mortality. Current therapies often fail to control tumor progression or improve patient survival. Marinobufagenin (MBG) is an endogenous mammalian cardiotonic steroid involved in sodium pump inhibition. Currently, various studies have indicated the potential of MBG in cancer treatments; however, the precise mechanisms are poorly understood. The functions of MBG were examined using colony formation, migration, cell cycle, and apoptosis assays in glioma cells. A mitochondrial membrane potential assay was performed to determine the mitochondrial transmembrane potential change, and cytochrome c release from mitochondria was assayed by fluorescence microscopy. An immunofluorescence assay was performed, and the nuclear translocation of NF-κB in glioma cells was confirmed by confocal microscopy. Western blotting and RT-qPCR were used to detect the protein and gene expression levels, respectively. In addition, transfection experiment of ATP1A1-siRNA was further carried out to confirm the role of sodium pump α1 subunit in the anticancer effect of MBG in human glioma. The apoptosis-promoting and anti-inflammatory effects of MBG were further investigated, and the sodium pump α1 subunit and the ERK signaling pathway were found to be involved in the anticancer effect of MBG. The in vivo anticancer efficacy of MBG was also tested in xenografts in nude mice. Thus, therapies targeting the ERK signaling-mediated mitochondrial apoptotic pathways regulated by MBG might represent potential treatments for human glioma, and this study could accelerate the finding of newer therapeutic approaches for malignant glioma treatment.

Topics: Animals; Antineoplastic Agents; Apoptosis; Bufanolides; Cell Cycle; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Cytochromes c; Extracellular Signal-Regulated MAP Kinases; Glioma; Humans; Membrane Potential, Mitochondrial; Mice; Mice, Inbred BALB C; Mice, Nude; Mitochondria; RNA Interference; RNA, Small Interfering; Signal Transduction; Sodium-Potassium-Exchanging ATPase; Transcription Factor RelA; Xenograft Model Antitumor Assays

Malignant glioma are linked to a high mortality rate. Therefore, it is necessary to explore and develop effective therapeutic strategy. Oroxyloside is a metabolite of oroxylin A. However, its inhibitory effects on cancer are little to be known. In the present study, we investigated the effects of oroxyloside on cell proliferation, migration, and apoptosis in vitro and in vivo in human glioma. The results indicated that oroxyloside significantly suppressed the proliferation of human glioma cells through inducing cell cycle arrest at G0/G1 phase through reducing Cyclin D1 and cyclin-dependent kinase 2 (CDK2) while enhancing p53 and p21 expressions. In addition, the migration of glioma cells was dramatically inhibited by oroxyloside in a dose-dependent manner, which was related to its modulation on extracellular matrix (ECM), as evidenced by up-regulated E-cadherin, and metastasis-associated protein 3 (MTA3), whereas down-regulated N-cadherin, Vimentin, Twist, alpha-smooth muscle actin (α-SMA) and Syndecan-2. Furthermore, oroxyloside treatment markedly induced apoptosis in glioma cells through improving Caspase-9, Caspase-3 and PARP cleavage, accompanied with high release of cytochrome c (Cyto-c) into cytoplasm and subsequently increase of apoptotic protease-activating factor 1 (Apaf-1). In vivo, oroxyloside administration significantly inhibited the glioma cell xenograft tumorigenesis through various signaling pathways, including suppression of Cyclin D1/CDK2 and ECM pathways, as well as potentiation of p53/p21 and Caspases pathways. Together, the findings above illustrated that oroxyloside, for the first time, was used as a promising candidate against human glioma.

Topics: Animals; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cytochromes c; Disease Progression; Flavones; Glioma; Glucuronides; Humans; Male; Mice, Inbred BALB C; Mice, Nude; Neoplasm Metastasis; Signal Transduction; Xenograft Model Antitumor Assays

Temozolomide (TMZ) is a first-line chemotherapeutic drug for malignant gliomas. Nonetheless, TMZ-induced side effects and drug resistance remain challenges. Our previous study showed the suppressive effects of honokiol on growth of gliomas.. This study was further aimed to evaluate if honokiol could enhance TMZ-induced insults toward malignant glioma cells and its possible mechanisms.. Human U87 MG glioma cells were exposed to TMZ, honokiol, and a combination of TMZ and honokiol. Cell survival, apoptosis, necrosis, and proliferation were successively assayed. Fluorometric substrate assays were conducted to determine activities of caspase-3, -6, -8, and -9. Levels of Fas ligand, Bax, and cytochrome c were immunodetected. Translocation of Bax to mitochondria were examined using confocal microscopy. Mitochondrial function was evaluated by assaying the mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and complex I enzyme activity. Caspase-6 activity was suppressed using specific peptide inhibitors. The honokiol-induced effects were further confirmed using human U373 MG and murine GL261 cells.. Exposure of human U87 MG glioma cells to honokiol significantly increased TMZ-induced DNA fragmentation and cell apoptosis. Interestingly, honokiol enhanced intrinsic caspase-9 activity without affecting extrinsic Fas ligand levels and caspase-8 activity. Sequentially, TMZ-induced changes in Bax translocation, the MMP, mitochondrial complex I enzyme activity, intracellular ROS levels, and cytochrome c release were enhanced by honokiol. Consequently, honokiol amplified TMZ-induced activation of caspases-3 and -6 in human U87 MG cells. Fascinatingly, suppressing caspase-6 activity concurrently decreased honokiol-induced DNA fragmentation and cell apoptosis. The honokiol-involved improvement in TMZ-induced intrinsic apoptosis was also confirmed in human U373 MG and murine GL261 glioma cells.. This study showed that honokiol can enhance TMZ-induced apoptotic insults to glioma cells via an intrinsic mitochondrion-dependent mechanism. Our results suggest the therapeutic potential of honokiol to attenuate TMZ-induced side effects.

Topics: Animals; Apoptosis; Biphenyl Compounds; Caspases; Cell Line, Tumor; Cell Survival; Cytochromes c; Dacarbazine; DNA Fragmentation; Drugs, Chinese Herbal; Fas Ligand Protein; Glioma; Humans; Lignans; Membrane Potential, Mitochondrial; Mice; Mitochondria; Reactive Oxygen Species; Signal Transduction; Temozolomide

Dihydrotanshinone, a functional food in China, is an effective anti-cardiovascular disease substance isolated from Salvia miltiorrhiza (S. miltiorrhiza). Glioma is considered to be fatal due to its poor prognosis and few effective therapeutic options. In this study, we investigated the anticancer effects of S. miltiorrhiza extract dihydrotanshinone on human glioma SHG-44 cells, by using 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide assay, Hoechst 33258 nuclear staining, Annexin V/propidium iodide double staining, as well as western blot analysis. The results showed that dihydrotanshinone effectively suppressed SHG-44 cells proliferation and induced apoptosis in both dose- and time-dependent manner. Moreover, we demonstrated that dihydrotanshinone increased the activation of caspases (caspase-3 and caspase-9) and the release of cytochrome c in SHG-44 cells. Overall, dihydrotanshinone could induce apoptosis and inhibit proliferation of glioma cells by regulating caspases and cytochrome c. This study suggests that dihydrotanshinone may serve as a potential treatment option for patients with glioma.

Topics: Abietanes; Antineoplastic Agents, Phytogenic; Apoptosis; Brain Neoplasms; Caspases; Cell Line, Tumor; Cell Proliferation; Cytochromes c; DNA Fragmentation; Dose-Response Relationship, Drug; Glioma; Humans; Plant Extracts; Salvia miltiorrhiza

Malignant glioma continues to be a clinical challenge with an urgent need for developing curative therapeutic intervention. Apoptosis induction in tumor-associated endothelial cells represent a central mechanism that counteracts angiogenesis in glioma and other solid tumors. We previously demonstrated that intraperitoneal administration of sheep erythrocyte membrane glycopeptide T11-target structure (T11TS) in rodent glioma model inhibits PI3K/Akt pathway and Raf/MEK/ERK signaling in glioma-associated brain endothelial cells. In the present study, we investigated whether T11TS treatment influence apoptosis signaling in vivo in glioma-associated brain endothelial cells. Annexin-V/PI staining showed that T11TS treatment in glioma-induced rats increases apoptosis of glioma-associated endothelial cells within glioma milieu compared to brain endothelial cells in glioma induced and control groups. Flowcytometric JC-1 assay revealed that T11TS administration triggers loss of mitochondrial membrane potential in glioma-associated brain endothelial cells. Flowcytometry, immunoblotting, and in situ immunofluoresecnt imaging were employed to investigate the effect of T11TS on apoptotic regulatory proteins in brain endothelial cells. T11TS treatment-upmodulated expression of p53, Bax, Fas, FasL, and FADD in glioma associated endothelial cells and downregulated Bcl-2 protein. T11TS therapy induced cytochrome-c release into cytosol, activated caspase -9, 8, 3, and cleaved Bid in glioma associated brain endothelial cells. The study demonstrates that T11TS induces apoptosis in glioma-associated brain endothelial cells via p53 accumulation and activation of intrinsic as well as Fas-dependent extrinsic pathway. The pro-apoptotic action of T11TS on glioma-associated endothelial cells provides crucial insight into how T11TS exerts its anti-angiogenic function in glioma. J. Cell. Physiol. 232: 526-539, 2017. © 2016 Wiley Periodicals, Inc.

Topics: Angiogenesis Inhibitors; Animals; Apoptosis; bcl-2-Associated X Protein; BH3 Interacting Domain Death Agonist Protein; Brain Neoplasms; Caspases; Cytochromes c; Cytosol; Endothelial Cells; Enzyme Activation; Fas Ligand Protein; fas Receptor; Fas-Associated Death Domain Protein; Female; Glioma; Glycopeptides; Male; Membrane Glycoproteins; Membrane Potential, Mitochondrial; Models, Biological; Neovascularization, Pathologic; Rats; Sheep; Tumor Suppressor Protein p53

Because the anti-apoptotic protein Bcl-xL is overexpressed in glioma, one might expect that inhibiting or silencing this gene would promote tumor cell killing. However, our studies have shown that this approach has limited independent activity, but may tip the balance in favor of apoptosis induction in response to other therapeutic interventions. To address this issue, we performed a pharmacological screen using a panel of signaling inhibitors and chemotherapeutic agents in Bcl-xL silenced cells. Although limited apoptosis induction was observed with a series of inhibitors for receptor tyrosine kinases, PKC inhibitors, Src family members, JAK/STAT, histone deacetylase, the PI3K/Akt/mTOR pathway, MAP kinase, CDK, heat shock proteins, proteasomal processing, and various conventional chemotherapeutic agents, we observed a dramatic potentiation of apoptosis in Bcl-xL silenced cells with the survivin inhibitor, YM155. Treatment with YM155 increased the release of cytochrome c, smac/DIABLO and apoptosis inducing-factor, and promoted loss of mitochondrial membrane potential, activation of Bax, recruitment of LC3-II to the autophagosomes and apoptosis in Bcl-xL silenced cells. We also found an additional mechanism for the augmentation of apoptosis due to abrogation of DNA double-strand break repair mediated by Rad51 repression and enhanced accumulation of γH2AX. In summary, our observations may provide a new insight into the link between Bcl-xL and survivin inhibition for the development of novel therapies for glioma. © 2016 Wiley Periodicals, Inc.

Topics: Antineoplastic Agents; Apoptosis; Autophagy; bcl-X Protein; Cell Line, Tumor; Cytochromes c; DNA Damage; Gene Silencing; Glioma; Humans; Imidazoles; Inhibitor of Apoptosis Proteins; Membrane Potential, Mitochondrial; Naphthoquinones; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction; Survivin; TOR Serine-Threonine Kinases

Gambogic acid (GA), a natural product with a xanthone structure, has a broad range of anti-proliferative effects on cancer cell lines. We evaluated GA for its cytotoxic effects on T98G glioblastoma cells. GA exhibited potent anti-proliferative activity and induced apoptosis in T98G glioblastoma cells in a dose-dependent manner. Incubation of cells with GA revealed apoptotic features including increased Bax and AIF expression, cytochrome c release, and cleavage of caspase-3, -8, -9, and PARP, while Bcl-2 expression was downregulated. Furthermore, GA induced reactive oxygen species (ROS) generation in T98G cells. Our results indicate that GA increases Bax- and AIF-associated apoptotic signaling in glioblastoma cells.

Topics: Antineoplastic Agents; Apoptosis; Brain Neoplasms; Caspase 3; Caspase 8; Caspase 9; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Down-Regulation; Glioma; Humans; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Signal Transduction; Xanthones

Proteins often possess highly specific biological activities that make them potential therapeutics, but their physical and chemical instabilities during formulation, storage, and delivery have limited their medical use. Therefore, engineering of nanosized vehicles to stabilize protein therapeutics and to allow for targeted treatment of complex diseases, such as cancer, is of considerable interest. A micelle-like nanoparticle (NP) was designed for both, tumor targeting and stimulus-triggered release of the apoptotic protein cytochrome c (Cyt c). This system is composed of a Cyt c NP stabilized by a folate-receptor targeting amphiphilic copolymer (FA-PEG-PLGA) attached to Cyt c through a redox-sensitive bond. FA-PEG-PLGA-S-S-Cyt c NPs exhibited excellent stability under extracellular physiological conditions, whereas once in the intracellular reducing environment, Cyt c was released from the conjugate. Under the same conditions, the folate-decorated NP reduced folate receptor positive HeLa cell viability to 20%, while the same complex without FA only reduced it to 80%. Confocal microscopy showed that the FA-PEG-PLGA-S-S-Cyt c NPs were internalized by HeLa cells and were capable of endosomal escape. The specificity of the folate receptor-mediated internalization was confirmed by the lack of uptake by two folate receptor deficient cell lines: A549 and NIH-3T3. Finally, the potential as antitumor therapy of our folate-decorated Cyt c-based NPs was confirmed with an in vivo brain tumor model. In conclusion, we were able to create a stable, selective, and smart nanosized Cyt c delivery system.

Topics: A549 Cells; Animals; Apoptosis; Cytochromes c; Drug Carriers; Drug Delivery Systems; Glioma; HeLa Cells; Humans; Mice; Mice, Inbred C57BL; Micelles; Nanoparticles; NIH 3T3 Cells; Polymers

The enzyme cytochrome c oxidase (CcO) or complex IV (EC 1.9.3.1) is a large transmembrane protein complex that serves as the last enzyme in the respiratory electron transport chain of eukaryotic mitochondria. CcO promotes the switch from glycolytic to oxidative phosphorylation (OXPHOS) metabolism and has been associated with increased self-renewal characteristics in gliomas. Increased CcO activity in tumors has been associated with tumor progression after chemotherapy failure, and patients with primary glioblastoma multiforme and high tumor CcO activity have worse clinical outcomes than those with low tumor CcO activity. Therefore, CcO is an attractive target for cancer therapy. We report here the characterization of a CcO inhibitor (ADDA 5) that was identified using a high throughput screening paradigm. ADDA 5 demonstrated specificity for CcO, with no inhibition of other mitochondrial complexes or other relevant enzymes, and biochemical characterization showed that this compound is a non-competitive inhibitor of cytochrome c When tested in cellular assays, ADDA 5 dose-dependently inhibited the proliferation of chemosensitive and chemoresistant glioma cells but did not display toxicity against non-cancer cells. Furthermore, treatment with ADDA 5 led to significant inhibition of tumor growth in flank xenograft mouse models. Importantly, ADDA 5 inhibited CcO activity and blocked cell proliferation and neurosphere formation in cultures of glioma stem cells, the cells implicated in tumor recurrence and resistance to therapy in patients with glioblastoma. In summary, we have identified ADDA 5 as a lead CcO inhibitor for further optimization as a novel approach for the treatment of glioblastoma and related cancers.

Topics: Animals; Cell Line, Tumor; Cytochromes c; Drug Resistance, Neoplasm; Electron Transport Complex IV; Enzyme Inhibitors; Glioma; Humans; Mice; Neoplasm Proteins; Xenograft Model Antitumor Assays

Recent studies have demonstrated the role of indirect effect of radiation in neurodegeneration. However, the role of glial cells in neuroprotection against indirect effect of radiation is still not clear, although they are known to protect neurons under stress conditions in central nervous system. Our study showed that indirect effect of radiation increased the oxidative stress that further enhances the expression of key apoptotic proteins and leads to neuronal cell death. We also investigated the indirect effect of radiation on neuronal cells in the presence of glial cells in a transwell co-culture system, while our analysis was focused on neuronal cells. Irradiated cell-conditioned medium (ICCM) was used as source of indirect radiation and neuroprotective effect was analyzed by various endpoints. It was observed that ICCM-induced reactive oxidative species level was significantly reduced in SH-SY5Y cells co-cultured with glial U87 cells, which might help to maintain the integrity of mitochondrial membrane potential. Increased levels of antioxidant enzyme superoxide dismutase and antioxidant glutathione were observed in SH-SY5Y cells co-cultured with glial U87 cells. Moreover, it was also observed that co-culture with glial cells inhibits the expression of ICCM-induced apoptotic proteins, i.e. Bax, cytochrome c, and caspase-3 in SH-SY5Y cells. Hence, it can be speculated that in co-culture system glial cells may protect the neuronal SH-SY5Y cells by reducing the ICCM-induced oxidative stress and apoptotic death.

Topics: Apoptosis; bcl-2-Associated X Protein; Blotting, Western; Caspase 3; Cell Line, Tumor; Cell Survival; Coculture Techniques; Culture Media, Conditioned; Cytochromes c; Dose-Response Relationship, Drug; Gamma Rays; Glioma; Glutathione; Humans; In Situ Nick-End Labeling; Membrane Potential, Mitochondrial; Neuroblastoma; Oxidative Stress; Protective Agents; Reactive Oxygen Species; Superoxide Dismutase

The oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3) is overactivated in malignant glioma and plays a key role in promoting cell survival, thereby increasing the acquired apoptosis resistance of these tumors. Here we investigated the STAT3/myeloid cell leukemia 1 (MCL1) signaling pathway as a target to overcome the resistance of glioma cells to the Bcl-2-inhibiting synthetic BH3 mimetic ABT-737. Stable lentiviral knockdown of MCL1 sensitized LN229 and U87 glioma cells to apoptotic cell death induced by single-agent treatment with ABT-737 which was associated with an early activation of DEVDase activity, cytochrome c release, and nuclear apoptosis. Similar sensitizing effects were observed when ABT-737 treatment was combined with the multikinase inhibitor sorafenib which effectively suppressed levels of phosphorylated STAT3 and MCL1 in MCL1-proficient LN229 and U87 glioma cells. In analogous fashion, these synergistic effects were observed when we combined ABT-737 with the STAT3 inhibitor WP-1066. Lentiviral knockdown of the activating transcription factor 5 combined with subsequent quantitative polymerase chain reaction analysis revealed that sorafenib-dependent suppression of MCL1 occurred at the transcriptional level but did not depend on activating transcription factor 5 which previously had been proposed to be essential for MCL1-dependent glioma cell survival. In contrast, the constitutively active STAT3 mutant STAT3-C was able to significantly enhance MCL1 levels under sorafenib treatment to retain cell survival. Collectively, these data demonstrate that sorafenib targets MCL1 in a STAT3-dependent manner, thereby sensitizing glioma cells to treatment with ABT-737. They also suggest that targeting STAT3 in combination with inducers of the intrinsic pathway of apoptosis may be a promising novel strategy for the treatment of malignant glioma.

Topics: Activating Transcription Factors; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Biphenyl Compounds; Cell Line, Tumor; Cell Survival; Cytochromes c; Gene Knockdown Techniques; Glioma; Humans; Myeloid Cell Leukemia Sequence 1 Protein; Niacinamide; Nitrophenols; Peptide Hydrolases; Phenylurea Compounds; Piperazines; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-bcl-2; Pyridines; Sorafenib; STAT3 Transcription Factor; Sulfonamides; Tyrphostins

A multitude of plants have been used extensively for the treatment of cancers throughout the world. The protein, α, β momorcharin has been extracted from the plant Momordica charantia (MC), and it possesses anti-cancer and anti-HIV properties similar to the crude water and methanol soluble extract of the plant. This study investigated the anti-cancer effects and the cellular mechanisms of action of α, β momocharin (200-800 μM) on 1321N1, Gos-3, U87-MG, Sk Mel, Corl-23 and Weri Rb-1 cancer cell lines compared to normal healthy L6 muscle cell line measuring cell viability using MTT assay kit, Caspase-3 and 9 activities, cytochrome c release and intracellular free calcium concentrations [Ca(2+)]i. The results show that α, β momorcharin can evoke significant dose-dependent (P < 0.05; Student's t test) decreases in the viability (increases in cell death) of 1321N1, Gos-3, U87-MG, Sk Mel, Corl-23 and Weri Rb-1 cancer cell lines compared to healthy L6 muscle cell line and untreated glioma cells. α, β momorcharin (800 μM) also evoked significant (P < 0.05) increases in caspase-3 and 9 activities and cytochrome c release. Similarly, α, β momorcharin elicited significant (P < 0.05) time-dependent elevation in [Ca(2+)]i in all five glioma cell lines compared to untreated cells. Together, the results have demonstrated that α, β momorcharin can exert its anti-cancer effect on different cancer cell lines by intracellular processes involving an insult to the mitochondria resulting in cellular calcium over loading, apoptosis, cytochrome release and subsequently, cell death.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Calcium; Caspase 3; Caspase 9; Cell Line, Tumor; Cell Survival; Cytochromes c; Glioma; Humans; Momordica charantia; Plant Extracts; Ribosome Inactivating Proteins

In recent years there has been an increasing interest in naturally occurring substances in plant origin that may be used as potential chemopreventive and chemotherapeutic agents to prevent or slow the progression of chronic illnesses, such as cancer. In this study, we aimed at examining the antitumor activity of Atractylodes macrocephala polysaccharide (AMPs) in vitro using glioma C6 cells and the underlying mechanisms were also investigated. The results demonstrated that AMPs significantly inhibited proliferation of C6 cells in a concentration dependent manner by DNA fragmentation and apoptosis induction. Besides, AMPs treatment induced the loss of mitochondrial membrane potential and caused release of cytochrome c to cytosol. Furthermore, the activation of capase-3, caspase-9 and poly(ADP-ribose) polymerase (PARP) cleavage occurred following AMPs treatment in C6 cells. These results suggested that the induction of apoptosis via the mitochondrial pathway was involved in the anti-proliferative activity of AMPs against glioma C6 cells.

Topics: Animals; Apoptosis; Atractylodes; Caspase 3; Caspase 9; Cell Line, Tumor; Cell Proliferation; Cytochromes c; DNA Fragmentation; Glioma; Membrane Potential, Mitochondrial; Mitochondria; Poly(ADP-ribose) Polymerases; Polysaccharides; Rats

Shikonin is a quinone-containing natural product that induces the apoptotic death of some cancer cell lines in culture through increasing intracellular reactive oxygen species (ROS). Quinone-based drugs have shown potential in the clinic, making shikonin an interesting compound to study. Our previous study found that shikonin induces apoptosis in neuroblastoma by induction of ROS, but its mechanism of action and scope of activity are unknown. In this study, we investigated the mode of oxidative stress of shikonin in human glioma cells. ROS induction by shikonin was of mitochondrial origin, as demonstrated by detection of superoxide with MitoSOX Red. Pre-incubation of shikonin with inhibitors of different complexes of the respiratory chain suggested that shikonin-induced ROS production occurred via complex II. In addition, NADPH oxidase and lipooxygenase are two other main ROS-generated sites in shikonin treatment. ROS production by shikonin resulted in the inhibition of nuclear translocation of Nrf2. Stable overexpression of Nrf2 in glioma cells inhibited ROS generation by shikonin. ROS generation from mitochondrial complex II, NADPH oxidase and lipooxygenase is likely the primary mechanism by which shikonin induces apoptosis in glioma cells. These findings also have relevance to the development of certain ROS producers as anti-cancer agents. These, along with shikonin have potential as novel chemotherapeutic agents on human glioma.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle; Cell Line, Tumor; Cytochromes c; Cytosol; Glioma; Humans; Membrane Potential, Mitochondrial; Mitochondria; Naphthoquinones; NF-E2-Related Factor 2; Oxidative Stress; Reactive Oxygen Species; Superoxides

We previously observed that glioma cells are differentially sensitive to ABT-737 and, when used as a single-agent, this drug failed to induce apoptosis. Identification of therapeutic strategies to enhance the efficacy of the Bcl-2 inhibitor ABT-737 in human glioma is of interest. Histone deacetylation inhibitors (HDACI) are currently being assessed clinically in patients with glioma, as regulation of epigenetic abnormalities is expected to produce pro-apoptotic effects. We hypothesized that co-treatment of glioma with a BH3-mimetic and HDACI may induce cellular death. We assessed the combination of ABT-737 and HDACI SAHA in established and primary cultured glioma cells. We found combination treatment led to significant cellular death when compared to either drug as single agent and demonstrated activation of the caspase cascade. This enhanced apoptosis also appears dependent upon the loss of mitochondrial membrane potential and the release of cytochrome c and AIF into the cytosol. The upregulation of Noxa, truncation of Bid, and activation of Bax caused by this combination were important factors for cell death and the increased levels of Noxa functioned to sequester Mcl-1. This combination was less effective in PTEN-deficient glioma cells. Both genetic and pharmacologic inactivation of the PI3K/Akt signaling pathway sensitized PTEN-deleted glioma cells to the combination. This study demonstrates that antagonizing apoptosis-resistance pathways, such as targeting the Bcl-2 family in combination with epigenetic modifiers, may induce cell death. These findings extend our previous observations that targeting the PI3K/Akt pathway may be additionally necessary to promote apoptosis in cancers lacking PTEN functionality.

Topics: Antineoplastic Agents; Apoptosis; Apoptosis Inducing Factor; bcl-2-Associated X Protein; BH3 Interacting Domain Death Agonist Protein; Biphenyl Compounds; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Drug Therapy, Combination; Glioma; Histone Deacetylase Inhibitors; Humans; Membrane Potential, Mitochondrial; Mitochondria; Nitrophenols; Piperazines; Proto-Oncogene Proteins c-bcl-2; PTEN Phosphohydrolase; Sulfonamides; Up-Regulation

The objective of this study was to investigate the role of intracellular calcium overload in the in vitro apoptosis of C6 glioma cells mediated by low level ultrasound and hematoporphyrin monomethyl ether (HMME) therapy. The frequency of ultrasound was optimized by the cell viability assay using 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The apoptotic rate, reactive oxygen species (ROS) and decreased mitochondrial membrane potential (MMP) were determined by flow cytometry. Morphological changes were observed by the transmission electron microscope. Concentrations of intracellular Ca2+, [Ca2+]i were detected by a confocal microscopic laser scanning, and the release of cytochrome-c (cyt-c) was measured by western blotting.. The SDT-mediated apoptotic effect involved an overload of [Ca2+]i derived from the intra- and extracellular sources during the early progression of apoptotosis. The process was associated with an increased ROS production, a decreased MMP, and a release of cyt-c. In conclusion,the combined use of low level ultrasound and HMME improved the apoptotic rate of C6 glioma cells mediated by ultrasound alone. The [Ca2+]i overload involving activation of mitochondrial signaling played a pivotal role in the SDT-induced apoptosis.

Topics: Apoptosis; Calcium; Calcium Channels, L-Type; Cell Line, Tumor; Combined Modality Therapy; Cytochromes c; Extracellular Space; Glioma; Hematoporphyrins; Humans; Intracellular Space; Membrane Potential, Mitochondrial; Nimodipine; Reactive Oxygen Species; Ultrasonic Therapy

To study the relationship of basic fibroblast growth factor (bFGF) and signal transducer and activator of transcription 3(STAT3) in glioma apoptosis and possible mechanisms of its interaction.. Two glioblastomamultiforme (GBM) cell lines: U87 (wild-type p53) and U251 (mutant p53) were used in this study and divided into normal control group, mock group and experiment group.Small interfering RNA-carried recombinant lentivirus, LV-bFGFsiRNA and LV-STAT3siRNA, targeting bFGF and STAT3 were constructed respectively. After 48 hours of lentivirus transfection, small molecular inhibitors were used to block specific signaling pathways, AG490 20 µmol/L blocking JAK, LY294002 20 µmol/L blocking PI3K/Akt pathways for 24 hours, 48 hours and 72 hours, respectively. Then, apoptosis, changes in apoptosis-related proteins and mitochondrial membrane potential were detected through the methods of flow cytometry, protein chip and confocal microscopy, respectively.Groups were compared using single factor analysis of variance (One-way ANOVA).. Western blot results revealed the levels of Tyr705 and Ser727 phosphorylationin reduced in a time dependent manner by blocking JAK and PI3K/Akt pathway respectively. The results of flow cytometry showed that the apoptosis rate in normal control group, mock group, experiment group were 17.97% ± 0.24%, 18.26% ± 0.88%, 46.57% ± 1.63% in U87 cells and 15.94% ± 1.18%, 16.88% ± 0.17%, 39.34% ± 0.87% in U251 cells, respectively. There was no statistically significant change between the normal control group and the mock group (P > 0.05) , while when compared with the experiment group, both group showed statistically significant difference (F = 697.41, 729.58, both P < 0.05). The results of protein chip demonstrated that protein expression of Bad, Caspase3, Cytochrome C, p27 were higher and XIAP was lower in the experiment group compared with the normal control group and mock group. Also, confocal microscopy could detect apoptosis and mitochondrial membrane potential reduced significantly in the experimental group compared with the normal control group and the mock group.. bFGF mainly interacts with STAT3 tyrosine site-pSTAT3(Tyr705) to influence the level of STAT3 phosphorylation;blocking bFGF/STAT3 signaling pathway can induce glioma cell apoptosis through mitochondrial pathway.

Topics: Apoptosis; Brain Neoplasms; Cell Line, Tumor; Cytochromes c; Fibroblast Growth Factor 2; Glioma; Humans; Mitochondria; Phosphatidylinositol 3-Kinases; Phosphorylation; RNA, Small Interfering; Signal Transduction; STAT3 Transcription Factor; Transfection; Tyrphostins

Glioblastoma multiforme (GBM) is the most aggressive astrocytoma, and therapeutic options are generally limited to surgical resection, radiotherapy, and Temozolomide (TMZ) chemotherapy. TMZ is a DNA alkylating agent that causes DNA damage and induces cell death. Unfortunately, glioma cells often develop resistance to TMZ treatment, with DNA de-methylation of the MGMT promoter identified as the primary reason. However, the contributions from proteins that normally protect cells against cytotoxic stress in TMZ-induced apoptosis have not been extensively explored. Here, we showed that increasing the level of the gap junction protein, Cx43, in human LN18 and LN229 glioma cells enhances resistance to TMZ treatment while knockdown of Cx43 in these same cells sensitizes them to TMZ treatment. By expressing a channel-dead or a C-terminal truncation mutant of Cx43, we show that Cx43-mediated TMZ resistance involves both channel dependent and independent functions. Expression of Cx43 in LN229 cells decreases TMZ-induced apoptosis, as determined by Annexin V staining. Cx43-mediated chemoresistance appears to be acting via a mitochondrial apoptosis pathway as manifested by the reduction in Bax/Bcl-2 ratio and the release of cytochrome C. Our findings highlight additional mechanisms and proteins that contribute to TMZ resistance, and raise the possibility of increasing TMZ efficiency by targeting Cx43 protein. This article is part of the Special Issue Section entitled 'Current Pharmacology of Gap Junction Channels and Hemichannels'.

Topics: Analysis of Variance; Annexin A5; Antineoplastic Agents, Alkylating; Apoptosis; Brain Neoplasms; Cell Line, Tumor; Connexin 43; Cytochromes c; Dacarbazine; Dose-Response Relationship, Drug; Fluoresceins; Glioma; Humans; Mitochondria; Mutation; Phosphorylation; RNA, Small Interfering; Signal Transduction; Temozolomide; Time Factors; Transfection

Glioblastomas are invasive tumors with poor prognosis despite current therapies. Histone deacetylase inhibitors (HDACIs) represent a class of agents that can modulate gene expression to reduce tumor growth, and we and others have noted some antiglioma activity from HDACIs, such as vorinostat, although insufficient to warrant use as monotherapy. We have recently demonstrated that proteasome inhibitors, such as bortezomib, dramatically sensitized highly resistant glioma cells to apoptosis induction, suggesting that proteasomal inhibition may be a promising combination strategy for glioma therapeutics. In this study, we examined whether bortezomib could enhance response to HDAC inhibition in glioma cells. Although primary cells from glioblastoma multiforme (GBM) patients and established glioma cell lines did not show significant induction of apoptosis with vorinostat treatment alone, the combination of vorinostat plus bortezomib significantly enhanced apoptosis. The enhanced efficacy was due to proapoptotic mitochondrial injury and increased generation of reactive oxygen species. Our results also revealed that combination of bortezomib with vorinostat enhanced apoptosis by increasing Mcl-1 cleavage, Noxa upregulation, Bak and Bax activation, and cytochrome c release. Further downregulation of Mcl-1 using shRNA enhanced cell killing by the bortezomib/vorinostat combination. Vorinostat induced a rapid and sustained phosphorylation of histone H2AX in primary GBM and T98G cells, and this effect was significantly enhanced by co-administration of bortezomib. Vorinostat/bortezomib combination also induced Rad51 downregulation, which plays an important role in the synergistic enhancement of DNA damage and apoptosis. The significantly enhanced antitumor activity that results from the combination of bortezomib and HDACIs offers promise as a novel treatment for glioma patients.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; Bcl-2-Like Protein 11; Boronic Acids; Bortezomib; Cell Line, Tumor; Central Nervous System Neoplasms; Cytochromes c; DNA Damage; Glioblastoma; Glioma; Histones; Humans; Hydroxamic Acids; Membrane Potential, Mitochondrial; Membrane Proteins; Mitochondria; Myeloid Cell Leukemia Sequence 1 Protein; Phosphorylation; Proteasome Inhibitors; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Pyrazines; Reactive Oxygen Species; Tumor Cells, Cultured; Vorinostat

Photodynamic therapy (PDT) induces selective cell death of neoplastic tissue and connecting vasculature by combining photosensitizers with light. Here we clarified the types of cell death induced by PDT in combination with the photosensitizer talaporfin sodium (mono-L-aspartyl chlorine e6, NPe6) in order to evaluate the potential of this therapy as a treatment for glioma. PDT with NPe6 (NPe6-PDT) induces dose-dependent cell death in human glioblastoma T98G cells. Specifically, cell death modalities were observed in NPe6-PDT treated T98G cells, including signs of apoptosis (activation of caspase-3, expression of phosphatidylserine, and DNA fragmentation) and necrosis (stainability of propidium iodide). In addition, high doses of NPe6-PDT decreased the proportion of apoptotic cell death, while increasing necrosis. Closer examination of apoptotic characteristics revealed release of cytochrome-c from mitochondria as well as activation of both caspse-9 and caspase-3 in cells treated with low doses of NPe6-PDT. Benziloxycarbonyl-Leu-Gln(OMe)-His-Asp(OMe)-fluoromethyl-ketone (Z-LEHD-fmk), a caspase-9 specific inhibitor, and benziloxycarbonyl-Asp(OMe)-Gln-Met-Asp(OMe)-fluoromethyl-ketone (Z-DQMD-fmk), a caspase-3 specific inhibitor, showed dose-dependent prevention of cell death in NPe6-PDT treated cells, indicating that mitochondrial apoptotic pathway was a factor in the observed cell death. Further, the cell morphology was observed after PDT. Time- and NPe6-dose dependent necrotic features were increased in NPe6-PDT treated cells. These results suggest that NPe6-PDT could be an effective treatment for glioma if used in mild doses to avoid the increased necrosis that may induce undesirable obstacles.

Topics: Antineoplastic Agents; Brain Neoplasms; Caspase 3; Cell Death; Cell Line, Tumor; Cytochromes c; DNA Fragmentation; Glioma; Humans; Mitochondria; Necrosis; Photochemotherapy; Photosensitizing Agents; Porphyrins

Cathepsin B and urokinase plasminogen activator receptor (uPAR) are postulated to play key roles in glioma invasion. Calcineurin is one of the key regulators of mitochondrial-dependent apoptosis, but its mechanism is poorly understood. Hence, we studied subcellular localization of calcineurin after transcriptional downregulation of uPAR and cathepsin B in glioma. In the present study, efficient downregulation of uPAR and cathepsin B increased the translocation of calcineurin A from the mitochondria to the cytosol, decreased pBAD (S136) expression and its interaction with 14-3-3ζ and increased the interaction of BAD with Bcl-xl. Co-depletion of uPAR and cathepsin B induced mitochondrial translocation of BAD, activation of caspase 3 as well as PARP and cytochrome c and SMAC release. These effects were inhibited by FK506 (10 μM), a specific inhibitor of calcineurin. Calcineurin A was co-localized and also co-immunoprecipitated with Bcl-2. This interaction decreased with co-depletion of uPAR and cathepsin B and also with Bcl-2 inhibitor, HA 14-1 (20 μg/ml). Altered localization and interaction of calcineurin A with Bcl-2 was also observed in vivo when uPAR and cathepsin B were downregulated. In conclusion, downregulation of uPAR and cathepsin B induced apoptosis by targeting calcineurin A to BAD via Bcl-2 in glioma.

Topics: Apoptosis; bcl-Associated Death Protein; Blotting, Western; Calcineurin; Caspase 3; Cathepsin B; Cell Line, Tumor; Cytochromes c; Down-Regulation; Fluorescent Antibody Technique; Glioma; Humans; Immunoenzyme Techniques; Immunoprecipitation; Membrane Potential, Mitochondrial; Proto-Oncogene Proteins c-bcl-2; Receptors, Urokinase Plasminogen Activator; Signal Transduction; Subcellular Fractions

Growth-inhibitory effects of mimosine, a plant amino acid, on rat C6 glioma cells were analyzed. Mimosine markedly inhibited proliferation and induced apoptosis of C6 glioma cells in a dose- and time-dependent manner. Mimosine-mediated apoptosis was accompanied by promoting reactive oxygen species (ROS) generation in mitochondria, and by decreased mitochondrial membrane potential (Δψ), and release of cytochrome c from mitochondria, followed by caspase 3 activation. Furthermore, mimosine increased the phosphorylation level of c-Jun-N-terminal protein kinase and p38, which was the downstream effect of ROS accumulation. Mimosine was confirmed to show profound effects on apoptosis of C6 glioma cells by ROS-regulated mitochondria pathway, and these results bear on the hypothesized potential for mimosine as promising agents in the treatment of malignant gliomas.

Topics: Apoptosis; Blotting, Western; Brain Neoplasms; Caspase 3; Caspase 7; Cell Line, Tumor; Comet Assay; Cytochromes c; Dose-Response Relationship, Drug; Enzyme Activation; Fluorescent Antibody Technique; Glioma; Humans; MAP Kinase Kinase 4; Membrane Potentials; Mimosine; Mitochondria; p38 Mitogen-Activated Protein Kinases; Reactive Oxygen Species

A previous study showed that miR-221/222 can regulate cell apoptosis. p53 is a well known tumor suppressor which can influence the chemosensitivity of glioma cells. However, the effect of miR-221/222 in gliomas with different p53 status is unknown. Here, we demostrate that knockdown of miR-221/222 increases apoptosis in human gliomas of different p53 types (U251 cells, p53 mutant-type; LN308 cells, p53 null-type; and U87 cells, p53 wild-type). Furthermore, the effect of miR-221/22 caused no change of p53 expression in the glioma cells studied. In addition, when a specific siRNA against p53 was employed in U87 cells, no attenuation of apoptosis was found after knockdown of miR-221/222. Importantly, we found that As-miR-221/222-treated cells increased expression of Bax, cytochrome c, Apaf-1 and cleaved-caspase-3. Our results showed that low expression of miR-221/222 sensitized glioma cells to temozolomide (TMZ); in addition, ectopic expression of PUMA by pcDNA-PUMA had a similar effect. Taken together, our study indicates that downregulated miR-221/222 can sensitize glioma cells to TMZ by regulating apoptosis independently of p53 status.

Topics: Apoptosis; Apoptosis Regulatory Proteins; Apoptotic Protease-Activating Factor 1; bcl-2-Associated X Protein; Brain Neoplasms; Caspase 3; Cytochromes c; Dacarbazine; Down-Regulation; Gene Knockdown Techniques; Glioma; Humans; MicroRNAs; Mitochondria; Proto-Oncogene Proteins; RNA, Small Interfering; Signal Transduction; Temozolomide; Tumor Cells, Cultured; Tumor Suppressor Protein p53

Quercetin has been shown to induce apoptosis in a number of cancer cell lines, but a quercetin-loaded nanoliposomal formulation with enhanced antitumor activity in C6 glioma cells and its effect on cancer cell death has not been well studied. The aim of this study was to examine if quercetin-loaded liposomes (QUE-NL) has enhanced cytotoxic effects and if such effects involve type III programmed cell death in C6 glioma cells.. C6 glioma cells were treated with QUE-NL and assayed for cell survival, apoptosis, and necrosis. Levels of reactive oxygen species production and loss of mitochondrial membrane potential (ΔΨm) were also determined by flow cytometry assay to assess the effects of QUE-NL. ATP levels and lactate dehydrogenase activity were measured, and Western blotting was used to assay cytochrome C release and caspase expression.. QUE-NL induced type III (necrotic) programmed cell death in C6 glioma cells in a dose-dependent and time-dependent manner. High concentrations of QUE-NL induced cell necrosis, which is distinct from apoptosis and autophagy, whereas liposomes administered alone induced neither significant apoptosis nor necrosis in C6 glioma cells. QUE-NL-induced ΔΨm loss and cytochrome C release had no effect on caspase activation, but decreased ATP levels and increased lactate dehydrogenase activity indicated that QUE-NL stimulated necrotic cell death.. C6 glioma cells treated with QUE-NL showed a cellular pattern associated with necrosis without apoptosis and was independent of caspase activity. Nonapoptotic cell death induced by high concentrations of QUE-NL for controlling caspase-independent type III programmed cell death may provide the basis for novel therapeutic approaches to overcome avoidance of apoptosis by malignant cells.

Topics: Adenosine Triphosphate; Animals; Antioxidants; Apoptosis; Caspase 3; Caspase 9; Cell Line, Tumor; Cell Shape; Cell Survival; Cytochromes c; Glioma; L-Lactate Dehydrogenase; Liposomes; Membrane Potential, Mitochondrial; Nanoparticles; Necrosis; Quercetin; Rats; Reactive Oxygen Species

This research focused on the induction of cytotoxic effects by danthron, a natural anthraquinone derivative on C6 rat glioma cells through exploring the means of cell death and the effects on mitochondrial function. We found that danthron decreased the percentage of viable C6 cells and induced cell morphological changes in a dose-and time-dependent manner. The morphological and nuclei changes (DAPI staining) in C6 cells were observed using a contrast-microscope and fluorescence microscopy, respectively. The results suggest that cell death of C6 cells which are induced by danthron is closely related to apoptotic death. Danthron decreased the level of mitochondrial membrane potential (ΔΨ( m )), stimulated the release of cytochrome c from mitochondria to cytosol and promoted the levels of caspase-9 and caspase-3, or induced the release of AIF and Endo G from mitochondria. Based on both observations, we suggest that the danthron-provoked apoptotic death of C6 cells is mediated through the mitochondria-dependent pathway. Furthermore, our results also indicated that danthron triggered apoptosis through reactive oxygen species (ROS) production which were increased after 1 h exposure of danthron, which was reversed by the ROS scavenger N-acetyl-L: -cysteine (NAC). As a consequence, danthron-mediated cell death of C6 cells via ROS production, mitochondrial transmembrane potential collapse and releases of cytochrome c, AIF and Endo G. Taken together, danthron was demonstrated to be effective in killing C6 rat glioma cells via the ROS-promoted and mitochondria-dependent apoptotic pathways.

Topics: Acetylcysteine; Animals; Anthraquinones; Apoptosis; Apoptosis Inducing Factor; Caspases; Cell Death; Cell Line, Tumor; Cytochromes c; Endodeoxyribonucleases; Glioma; Membrane Potential, Mitochondrial; Mitochondria; Rats; Reactive Oxygen Species; Signal Transduction

CLIC4/mtCLIC, a chloride intracellular channel protein, localizes to mitochondria, endoplasmic reticulum (ER), nucleus and cytoplasm, and participates in the apoptotic response to stress. Apoptosis and autophagy, the main types of the programmed cell death, seem interconnected under certain stress conditions. However, the role of CLIC4 in autophagy regulation has yet to be determined. In this study, we demonstrate upregulation and nuclear translocation of the CLIC4 protein following starvation in U251 cells. CLIC4 siRNA transfection enhanced autophagy with increased LC3-II protein and puncta accumulation in U251 cells under starvation conditions. In that condition, the interaction of the 14-3-3 epsilon isoform with CLIC4 was abolished and resulted in Beclin 1 overactivation, which further activated autophagy. Moreover, inhibiting the expression of CLIC4 triggered both mitochondrial apoptosis involved in Bax/Bcl-2 and cytochrome c release under starvation and endoplasmic reticulum stress-induced apoptosis with CHOP and caspase-4 upregulation. These results demonstrate that CLIC4 nuclear translocation is an integral part of the cellular response to starvation. Inhibiting the expression of CLIC4 enhances autophagy and contributes to mitochondrial and ER stress-induced apoptosis under starvation.

Topics: Apoptosis; Autophagy; Caspases, Initiator; Cell Line, Tumor; Cell Survival; Chloride Channels; Cytochromes c; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Glioma; Humans; Mitochondria; Transfection; Up-Regulation

The Ezh2 gene is an important member of the polycomb-group (PcG) family. As a newly identified oncogene, the expression of Ezh2 has been shown to be significantly increased in prostate cancer, breast cancer, renal cell carcinoma and hepatic cancer; however, a role for Ezh2 in the occurrence of glioma has not yet been reported. In this study, we found that the Ezh2 gene is highly expressed in U87 human glioma cells. Using RNA interference, we demonstrated that the downregulation of Ezh2 expression in U87 human glioma cells resulted in apoptosis and a cell cycle arrest in the G0/G1 phase. In addition, we found that silencing of the Ezh2 gene altered the mitochondrial membrane potential and promoted the release of cytochrome c from the mitochondria. Furthermore, the reduced expression of Ezh2 altered the Bax and Bcl-2 protein levels and led to the activation of caspase 9 and 3. These results indicate that the apoptosis induced in U87 human glioma cells by the silencing of the Ezh2 gene is related to the mitochondrial pathway.

Topics: Apoptosis; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; Caspase 3; Caspase 9; Cell Line, Tumor; Cytochromes c; Down-Regulation; Enhancer of Zeste Homolog 2 Protein; G1 Phase Cell Cycle Checkpoints; Glioma; Humans; Membrane Potential, Mitochondrial; Mitochondria; Polycomb Repressive Complex 2; RNA Interference; RNA, Small Interfering

Our aim was to study calcium overload-induced apoptosis and its relation to reactive oxygen species (ROS) in rat C6 glioma cells after sonodynamic treatment (SDT).. Hematoporphyrin monomethyl ether (HMME) was used as the sonosensitizer. The concentration of intracellular Ca(2+) ([Ca(2+)](i)) was measured by fluorometry. Apoptosis and necrosis rates were evaluated by a flow cytometry. Moreover, sarcoplasmic reticulum Ca(2+) -ATPase (SERCA(2)), cytochrome c (cyto-c) and cleaved caspase-3 were investigated by immunoblotting.. Our study indicated that [Ca(2 +)](i) and ROS increased in cells of SDT group, the apoptosis rate, quantity of cyto-c and cleaved caspase-3 markedly increased after SDT. Furthermore, N-Acetyl-L-cysteine (NAC) or 1,2-bisethane-N,N,N',N'-tetraacetic acid tetrakis ester (BAPTA-AM) could decrease the apoptosis rate, the release of cyto-c and cleaved caspase-3 in SDT group, SERCA(2) degradation was found in SDT group and could also be prevented by the addition of NAC.. Our results show that HMME-SDT can induce C6 cell death through both necrosis and apoptosis. ROS in C6 cells play a decisive role in HMME-SDT-induced cell death. The endoplasmic reticulum (ER) may be a major target of HMME-SDT, ROS can induce SERCA(2) degradation, causing the elevation of [Ca(2+)](i).

Topics: Acetylcysteine; Animals; Apoptosis; Calcium; Caspase 3; Cytochromes c; Egtazic Acid; Fluorometry; Glioma; Hematoporphyrins; Immunoblotting; Intracellular Membranes; Necrosis; Photosensitizing Agents; Rats; Reactive Oxygen Species; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Tumor Cells, Cultured; Ultrasonic Therapy

The proliferative and antiapoptotic actions of endothelin (ET)-1 in cancer cells have been documented and ET receptor antagonists have been exploited as potential anticancer drugs. Glioblastoma cell lines express both ETA and ETB receptors and previous works have shown that ETB receptors are involved in the proliferation of different cancer cell types. In this study we have investigated the effects of two structurally unrelated ETB receptor antagonists, BQ788 and A192621, on cell survival, proliferation and apoptosis in 1321-N1, U87 and IPDDCA2 glioma cell lines. BQ788 and A192621 reduced glioma cells viability and proliferation assessed by BrdU incorporation and cell cycle analysis by flow cytometry, while in contrast the ETA receptor antagonist BQ123 had no effect on cell survival. TUNEL assay and immunocytochemical experiments showed that BQ788 and A192621 trigger apoptotic processes mainly via activation of the intrinsic mitochondrial pathway involving caspase-9 activation, AIF release and cytochrome c translocation. Furthermore, treatment with ETB antagonists downregulates ERK- and p38MAPK-dependent pathways but does not affect VEGF mRNA levels. Our findings support the hypothesis that ETB antagonists represent a new promising therapeutic strategy for the treatment of high grade gliomas.

Topics: Apoptosis; Apoptosis Inducing Factor; Caspase 9; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cytochromes c; Down-Regulation; Drug Screening Assays, Antitumor; Endothelin B Receptor Antagonists; Glioma; Humans; Oligopeptides; Piperidines; Pyrrolidines; Signal Transduction; Vascular Endothelial Growth Factor A

Mulberry has been reported to contain wide range of polyphenols and have chemopreventive activity. However, little has been known regarding the effect of mulberry fruit extracts on cell viability in vitro in human glioma cells and the anticancer efficacy in vivo. This study was undertaken to examine the effect of mulberry fruit (Moris fructus; MF) extracts on cell viability in vitro and anticancer efficacy in vivo. Cell viability and cell death were estimated by MTT assay and trypan blue exclusion assay, respectively. Reactive oxygen species (ROS) generation was measured using the fluorescence probe DCFH-DA. The mitochondrial transmembrane potential was measured with DiOC(6)(3). Bax expression and cytochrome c release were measured by Western blot analysis. Caspase activity was estimated using colorimetric kit. Cell migration was estimated using the scratched wound model. In vivo anticancer efficacy of MF extracts was evaluated using a subcutaneously injected mouse tumor model. Changes in proliferation and apoptosis were estimated by immunohistochemistric analysis. MF extracts resulted in apoptotic cell death in a dose- and time-dependent manner. MF extracts increased ROS generation, and the MF extract-induced cell death was also prevented by antioxidants, suggesting that ROS generation plays a critical role in the MF extract-induced cell death. Western blot analysis showed that treatment of MF extracts caused an increase in Bax expression, which was inhibited by the antioxidant N-acetylcysteine (NAC). MF extracts induced depolarization of mitochondrial membrane potential, and its effect was inhibited by the antioxidants NAC and catalase. MF extracts induced cytochrome c release, which was inhibited by NAC. Caspase activity was stimulated by MF extracts, and caspase inhibitors prevented the MF extract-induced cell death. Treatment of MF extracts inhibited cell migration. Oral MF extracts administration in animals with subcutaneous U87MG glioma cells reduced tumor volume. Subsequent tumor tissue analysis showed a decrease in PCNA-positive cells, an increase in TUNEL-positive cells, and caspase activation. From these data, we concluded that MF extracts reduce glioma tumor growth through inhibition of cell proliferation resulting from induction of apoptosis. These findings suggest that MF extracts result in human glioma cell death in vitro through ROS-dependent mitochondrial pathway and glioma tumor growth in vivo via reduction of tumor cell proliferation an

Topics: Apoptosis; bcl-2-Associated X Protein; Caspases; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Cytochromes c; Glioma; Humans; Mitochondria; Morus; Phytotherapy; Plant Extracts; Reactive Oxygen Species

Guanidino compounds, as methylguanidine (MG), may play an important role in the etiology of neurological complications which occur in uremic syndrome. Dementia is a neurological complication more common in uremic patients than in general population and several types of dementia are associated to astroglial apoptosis. Here we report the effect of MG on oxidative stress-induced apoptosis in rat glioma cell line (C6) in vitro. The oxidative stress was induced by hydrogen peroxide (H(2)O(2); 1 mM) and the cellular and molecular parameters were observed after 18 h. Uremic conditions were simulated by pre-incubation of C6 cells with MG (0.1-10 mM) 1h before H(2)O(2)-induced oxidative stress. MG alone did not affect cell viability, but it significantly increased cell death induced by H(2)O(2), as assessed by MTT assay. This effect could be related to the MG capability to enhance H(2)O(2) pro-apoptotic effect on C6 cells. The fluorescent dye FURA 2-AM test showed a significant raise in [Ca(2+)](i) in MG and H(2)O(2) co-treated C6 cells, mainly for depolarizing mitochondrial membrane potential. Furthermore, MG in a concentration-dependent manner, significantly increased H(2)O(2)-induced Bax expression, activation of caspase-3 and PARP in C6 cells. This study firstly reports that the uremic catabolyte MG could contribute to neurodegeneration associated to uremia enhancing the pro-apoptotic effect of H(2)O(2) and through an alteration in mitochondrial calcium homeostasis in glial cells.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; bcl-2-Associated X Protein; Blotting, Western; Brain Neoplasms; Calcium Signaling; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Enzyme Activation; Glioma; Hydrogen Peroxide; Indicators and Reagents; Methylguanidine; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Propidium; Rats

Glioblastoma multiforme is the most frequent and aggressive primary brain tumor. A strong rationale to identify innovative approaches to treat these tumors is required since treatment failures result in local recurrences and median survivals range from 9 to 12 months. Glioma cells are reported to have less mitochondrial content compared to adjacent normal brain cells. Based on this difference, we suggest a new strategy, utilizing protection of normal brain cells by mitochondria-targeted electron scavengers and antioxidants-nitroxides-thus allowing for the escalation of the radiation doses. In this paper, we report that a conjugate of nitroxide with a hydrophobic cation, triphenyl-phosphonium (TPEY-Tempo), significantly protected brain endothelial cells from γ-irradiation-induced apoptosis while radiosensitizing brain tumor cells. Thus, TPEY-Tempo may be a promising adjunct in the treatment of glioblastoma with the potential to not only prolong survival but also to maintain quality of life and reduce treatment toxicity.

Topics: Apoptosis; Brain; Brain Neoplasms; Caspase 3; Cell Line, Transformed; Cyclic N-Oxides; Cytochromes c; Dose-Response Relationship, Radiation; Electron Transport Complex IV; Endothelial Cells; Gamma Rays; Glioma; Humans; Mitochondria; Neuroprotective Agents; Nitrogen Oxides; Organic Chemicals; Organoselenium Compounds

The cytotoxicity of berberine on C6 rat glioma cells indicated that berberine induced morphological changes and caused cell death through G2/M arrest and apoptosis. While undergoing apoptosis, there was a remarkable accumulation of G2/M cells with the upregulatoin of Wee1 but it also inhibited cyclin B, CDK1 and Cdc25c that led to G2/M arrest. Along with cytotoxicity in C6 cells, several apoptotic events including mitochondrial cytochrome c release, activation of caspase-9, -3 and -8 and DNA fragmentation were induced. Berberine increased the levels of GADD153 and GRP 78 in C6 cells based on the examination of Western blotting and this is a major hallmark of endoplasmic reticulum (ER) stress. We also found that berberine promoted the production of reactive oxygen species and Ca2+ in C6 cells. Western blotting assay also showed that berberine inhibited the levels of anti-apoptotic protein Bcl-2 but increased the levels of pro-apoptotic protein Bax before leading to a decrease in the levels of mitochondrial membrane potential (DeltaPsim) followed by cytochrome c release that caused the activations of capase-9 and -3 for apoptotic occurrence. The caspase-8, -9 and -3 were activated by berberine in C6 cells based on the substrate solution (PhiPhiLux-G1D1, CaspaLux 8-L1D2, CaspaLux 9-M1D2 for caspase-3, -8 and -9, respectively) and analyzed by flow cytometer and each inhibitor of caspase-8, -9 and -3 led to increase the percentage of viable C6 cells after exposure to berberine. This finding was also confirmed by Western blot assay which showed that berberine promoted the active form of caspase-8, -9 and -3. These results demonstrate that the cytotoxicity of berberine in C6 rat glioma cells is attributable to apoptosis mainly through induced G2/M-arrested cells, in an ER-dependent manner, via a mitochondria-dependent caspase pathway regulated by Bax and Bcl-2.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Berberine; Blotting, Western; Calcium; Caspase Inhibitors; Caspases; Cell Division; Cell Line, Tumor; Cytochromes c; DNA Damage; Endoplasmic Reticulum; Enzyme Inhibitors; Flow Cytometry; G2 Phase; Glioma; Membrane Potential, Mitochondrial; Mitochondria; Proto-Oncogene Proteins c-bcl-2; Rats; Reactive Oxygen Species

Glioblastoma represent the most common primary brain tumor in adults and are currently considered incurable. We investigated antiproliferative and anti-invasive mechanisms of 6-OH-11-O-hydroxyfenantrene (IIF), a retinoid X receptor ligand, and pioglitazone (PGZ), a peroxisome proliferator-activated receptor gamma activator, in three different glioblastoma cell lines. A dose-dependent reduction of tumor invasion and strong decrease of matrix metalloproteinases 2 and 9 expression was observed, especially when a combination therapy of IIF and PGZ was administered. Combined treatment also markedly reduced proliferation and induced apoptosis in all glioma cell lines tested. This was in particular accompanied by decrease of antiapoptotic proteins Bcl2 and p53, while simultaneously pro-apoptotic cytochrome c, cleaved caspase 3, Bax and Bad levels increased. These in vitro findings were further substantiated in a murine glioma model in vivo, where oral administration of PGZ and IIF resulted in significantly reduced tumor volume and proliferation. Of note, treatment with nuclear receptor ligands was not only effective when the treatment was initiated shortly after the intraparenchymal seeding of the glioma cells, but even when initiated in the last third of the observation period. Collectively, our results demonstrate the effectiveness of a combined treatment of ligands of proliferator-activated receptor and retinoid X receptor against glioblastoma.

Topics: Analysis of Variance; Animals; Annexin A5; Antineoplastic Agents; bcl-2-Associated X Protein; Brain Neoplasms; Bromodeoxyuridine; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Synergism; Gene Expression Regulation, Neoplastic; Glioma; Humans; Ligands; Matrix Metalloproteinases; Mice; Mice, Inbred C57BL; Neoplasm Invasiveness; Pioglitazone; PPAR gamma; Proto-Oncogene Proteins c-bcl-2; Rats; Retinoid X Receptor gamma; Tetrazolium Salts; Thiazoles; Thiazolidinediones; Transfection; Tretinoin; Tumor Stem Cell Assay

Gliomas, particularly glioblastomas, are among the deadliest of human tumors. Gliomas emerge through the accumulation of recurrent chromosomal alterations, some of which target yet-to-be-discovered cancer genes. A persistent question concerns the biological basis for the coselection of these alterations during gliomagenesis.. To describe a network model of a cooperative genetic landscape in gliomas and to evaluate its clinical relevance.. Multidimensional genomic profiles and clinical profiles of 501 patients with gliomas (45 tumors in an initial discovery set collected between 2001 and 2004 and 456 tumors in validation sets made public between 2006 and 2008) from multiple academic centers in the United States and The Cancer Genome Atlas Pilot Project (TCGA).. Identification of genes with coincident genetic alterations, correlated gene dosage and gene expression, and multiple functional interactions; association between those genes and patient survival.. Gliomas select for a nonrandom genetic landscape-a consistent pattern of chromosomal alterations-that involves altered regions ("territories") on chromosomes 1p, 7, 8q, 9p, 10, 12q, 13q, 19q, 20, and 22q (false-discovery rate-corrected P<.05). A network model shows that these territories harbor genes with putative synergistic, tumor-promoting relationships. The coalteration of the most interactive of these genes in glioblastoma is associated with unfavorable patient survival. A multigene risk scoring model based on 7 landscape genes (POLD2, CYCS, MYC, AKR1C3, YME1L1, ANXA7, and PDCD4) is associated with the duration of overall survival in 189 glioblastoma samples from TCGA (global log-rank P = .02 comparing 3 survival curves for patients with 0-2, 3-4, and 5-7 dosage-altered genes). Groups of patients with 0 to 2 (low-risk group) and 5 to 7 (high-risk group) dosage-altered genes experienced 49.24 and 79.56 deaths per 100 person-years (hazard ratio [HR], 1.63; 95% confidence interval [CI], 1.10-2.40; Cox regression model P = .02), respectively. These associations with survival are validated using gene expression data in 3 independent glioma studies, comprising 76 (global log-rank P = .003; 47.89 vs 15.13 deaths per 100 person-years for high risk vs low risk; Cox model HR, 3.04; 95% CI, 1.49-6.20; P = .002) and 70 (global log-rank P = .008; 83.43 vs 16.14 deaths per 100 person-years for high risk vs low risk; HR, 3.86; 95% CI, 1.59-9.35; P = .003) high-grade gliomas and 191 glioblastomas (global log-rank P = .002; 83.23 vs 34.16 deaths per 100 person-years for high risk vs low risk; HR, 2.27; 95% CI, 1.44-3.58; P<.001).. The alteration of multiple networking genes by recurrent chromosomal aberrations in gliomas deregulates critical signaling pathways through multiple, cooperative mechanisms. These mutations, which are likely due to nonrandom selection of a distinct genetic landscape during gliomagenesis, are associated with patient prognosis.

Topics: 3-Hydroxysteroid Dehydrogenases; Aldo-Keto Reductase Family 1 Member C3; Annexin A7; Apoptosis Regulatory Proteins; ATPases Associated with Diverse Cellular Activities; Brain Neoplasms; Chromosome Aberrations; Cytochromes c; Dosage Compensation, Genetic; Epistasis, Genetic; Female; Gene Dosage; Gene Expression Regulation, Neoplastic; Genes, myc; Genes, Neoplasm; Genome-Wide Association Study; Glioma; Humans; Hydroxyprostaglandin Dehydrogenases; Male; Metalloendopeptidases; Middle Aged; Mitochondrial Proteins; Models, Genetic; Mutation; Nuclear Proteins; Prognosis; Proportional Hazards Models; Risk; RNA-Binding Proteins; Signal Transduction; Survival Analysis

Previously, we identified noscapine as a small molecule inhibitor of the hypoxia-inducible factor-1 pathway in hypoxic human glioma cells and human umbilical vein endothelial cells. Noscapine is a nontoxic ingredient in cough medicine currently used in clinical trials for patients with non-Hodgkin's lymphoma or chronic lymphocytic leukemia to assess antitumor efficacy. Here, we have evaluated the sensitivity of four human glioma cell lines to noscapine-induced apoptosis. Noscapine was a potent inhibitor of proliferation and inducer of apoptosis. Induction of apoptosis was associated with activation of the c-jun N-terminal kinase signaling pathway concomitant with inactivation of the extracellular signal regulated kinase signaling pathway and phosphorylation of the antiapoptotic protein Bcl-2. Noscapine-induced apoptosis was associated with the release of mitochondrial proteins apoptosis-inducing factor (AIF) and/or cytochrome c. In some glioma cell lines, only AIF release occurred without cytochrome c release or poly (ADP-ribose) polymerase cleavage. Knock-down of AIF decreased noscapine-induced apoptosis. Our results suggest the potential importance of noscapine as a novel agent for use in patients with glioblastoma owing to its low toxicity profile and its potent anticancer activity.

Topics: Apoptosis; Apoptosis Inducing Factor; Cell Division; Cell Line, Tumor; Cell Proliferation; Cyclin B; Cyclin B1; Cytochromes c; Glioma; Humans; MAP Kinase Signaling System; Noscapine; Proto-Oncogene Proteins c-bcl-2

The novel protein kinase C-beta inhibitor enzastaurin (ENZA) induced apoptosis in LNT-229 and T98G cells whereas A172 cells were resistant. Further, ENZA reduced proliferation in glioblastoma-initiating cells T 269 and T 323 but did not induce apoptosis. ENZA-induced apoptosis involved cleavage of caspases 3, 8, and 9 and led to mitochondrial cytochrome c release and was strongly suppressed by the broad spectrum caspase inhibitor zVAD-fmk but only slightly by the expression of the viral caspase 1/8 inhibitor cytokine response modifier-A. ENZA did not reduce the phosphorylation of protein kinase B (Akt), but of p70 S6 kinase and of its substrate S6 protein in T98G cells. Inhibition of the phosphatidylinositol 3 kinase signaling pathway did not restore sensitivity of A172 cells towards ENZA, and constitutively active Akt did not protect LNT-229 and T98G cells from ENZA-induced apoptosis. Dephosphorylation of glycogen synthase kinase 3beta, a biomarker of ENZA action, and cell death induction by ENZA were separately regulated. Inhibition or activation of Akt only weakly modulated ENZA-induced dephosphorylation of glycogen synthase kinase 3beta. In ENZA-resistant A172 cells, apoptosis ligand 2 (Apo2L.0)-induced cleavage of caspases 3, 8, and 9 was increased by ENZA, resulting in synergistic activity of ENZA and Apo2L.0.

Topics: Adult; Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; bcl-X Protein; Brain Neoplasms; Caspases; Cell Line, Tumor; Cytochromes c; Drug Resistance, Neoplasm; Enzyme Inhibitors; Glioma; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Indoles; Mitochondria; Protein Kinase C; Proto-Oncogene Proteins c-akt; Receptors, TNF-Related Apoptosis-Inducing Ligand

The specific apoptotic role of T11TS has been well established in glioma animal models. T11TS specifically induces the glioma cells to die an apoptotic death via immune cross-talk with the two intracranial immune competent cells-microglia and the brain-infiltrating lymphocytes. To unearth the molecular cascades operative within the glioma cells and to some extent in the two interacting immunocytes, we had initiated studies where preliminary findings not only had indicated the involvement of death receptors but had also hinted to the involvement of other apoptotic regulators. Hence, to identify the molecular pathway of apoptosis involving other apoptotic regulators in the three cell types, the cells were studied for the intrinsic apoptotic death regulators that were engaged to maintain the mitochondrial membrane integrity. The proteins that were selected could be divided into three broad classes-the Bcl-2 family of proteins-Bid, Bax and Bcl-2; the guardian of the genome p53 and the proteins downstream of mitochondria-Apaf-1, cytochrome c, caspase-9 and caspase-3. Activated Bid as well as maximal p53 expression was observed in the first dose of T11TS thus dually activating the pro-apoptotic Bax in the first and second dose in the glioma cells. Concurrently, the pro-survival protein Bcl-2's expression level was very much down-regulated in the same two doses favoring the internal microenvironment to proceed for apoptosis. High expression of cytochrome c and Apaf-1 and the presence of active caspase-9 and active caspase-3 in all the T11TS-treated tumor-bearing groups further adjudicated apoptosis of the glioma cells with clear involvement of mitochondrial death pathway in the T11TS-treated animals. Even though expression of the apoptotic regulators remained more or less the same indicating the involvement of mitochondria in the two interacting immunocytes, the intensity of expression of these proteins was much lower than the tumor cells. The present work focuses on the mechanistic approach of how T11TS mediates apoptosis and hence is the first approach of its kind in the field of immunology where the immunotherapeutic molecule's mode of action has been worked out.

Topics: Animals; Apoptosis; Apoptosomes; Apoptotic Protease-Activating Factor 1; bcl-2-Associated X Protein; BH3 Interacting Domain Death Agonist Protein; Caspases; Cytochromes c; Enzyme Activation; Erythrocytes; Glioma; Lymphocytes, Tumor-Infiltrating; Membrane Glycoproteins; Microglia; Mitochondria; Nitrosourea Compounds; Rats; Sheep; Signal Transduction

Recent studies have suggested that the proliferation of malignant gliomas may result from activation of protein kinase C (PKC)-mediated pathways. Enzastaurin (LY317615), an acyclic bisindolylmaleimide, is an oral inhibitor of PKCbeta as well as other isoforms. The initial objective of this study was to assess the efficacy of enzastaurin in a series of malignant human glioma cell lines with diverse genomic alterations. Although enzastaurin independently produced a dose-dependent inhibition of cellular proliferation and decreased cell viability in each of the glioma cell lines examined, and partially down-regulated Akt and GSK3beta phosphorylation, median effective concentrations were at the upper limits of, or above, the clinically achievable range in all cell lines tested. We therefore examined whether the efficacy of enzastaurin could be enhanced by combination with the HSP90 antagonist, 17-AAG, which inhibits Akt and other signaling intermediates by a distinct mechanism. In comparison to the effect of enzastaurin alone, combination of enzastaurin with 17-AAG led to marked enhancement of antiproliferative and cytotoxic effects. Simultaneous exposure to both agents significantly increased the release of cytochrome c, as well as caspase 3 activation, Bax cleavage, and inhibition of Akt phosphorylation. Cells exposed to enzastaurin and 17-AAG also displayed a significant reduction in cell cycle regulatory proteins, such as CDK4 and CDK6. Taken together, these findings suggest that the efficacy of enzastaurin can be potentiated by the addition of 17-AAG, and indicate that combining molecularly targeted therapies may provide a more effective strategy than single-agent therapy to treat patients with malignant gliomas.

Topics: Apoptosis; Benzoquinones; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cytochromes c; Down-Regulation; Drug Synergism; Glioma; HSP90 Heat-Shock Proteins; Humans; Indoles; Lactams, Macrocyclic; Oncogene Protein v-akt; Phosphorylation

Glioblastoma (GBM) is an astrocytic brain tumor characterized by an aggressive clinical course and intense resistance to all therapeutic modalities. Here, we report the identification and functional characterization of Bcl2L12 (Bcl2-like-12) that is robustly expressed in nearly all human primary GBMs examined. Enforced Bcl2L12 expression confers marked apoptosis resistance in primary cortical astrocytes, and, conversely, its RNA interference (RNAi)-mediated knockdown sensitizes human glioma cell lines toward apoptosis in vitro and impairs tumor growth with increased intratumoral apoptosis in vivo. Mechanistically, Bcl2L12 expression does not affect cytochrome c release or apoptosome-driven caspase-9 activation, but instead inhibits post-mitochondrial apoptosis signaling at the level of effector caspase activation. One of Bcl2L12's mechanisms of action stems from its ability to interact with and neutralize caspase-7. Notably, while enforced Bcl2L12 expression inhibits apoptosis, it also engenders a pronecrotic state, which mirrors the cellular phenotype elicited by genetic or pharmacologic inhibition of post-mitochondrial apoptosis molecules. Thus, Bcl2L12 contributes to the classical tumor biological features of GBM such as intense apoptosis resistance and florid necrosis, and may provide a target for enhanced therapeutic responsiveness of this lethal cancer.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Apoptosomes; Astrocytes; Brain Neoplasms; Caspase 7; Caspase 9; Cytochromes c; Enzyme Activation; Glioblastoma; Glioma; Humans; Immunoglobulin G; Mice; Mice, SCID; Mitochondria; Muscle Proteins; Necrosis; Proteins; Proto-Oncogene Proteins c-bcl-2; Rabbits; RNA, Small Interfering; Signal Transduction

The basic mechanism of cell death induced by 5-aminolevulinic acid (5-ALA)-mediated photodynamic therapy (PDT) (ALA-PDT) in glioma cells has not been fully elucidated. In this study, the details of the cell death mechanism induced by ALA-PDT were investigated in three human glioma cell lines (U251MG, U87MG, and U118MG) in vitro. To evaluate the manner of accumulation of protoporphyrin IX (PpIX), intracellular PpIX contents were measured by flow cytometry after incubation with 5-ALA. To analyze the mechanism of cell death, U251MG cells were assayed by the terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick end-labeling (TUNEL) method, and the caspase activity was measured after ALA-PDT. Furthermore, the mitochondrial membrane potential (MMP) and the release of mitochondrial cytochrome c were determined. PpIX fluorescence reached a plateau 4 h after exposure to 5-ALA. The proportion of dead cells increased with increases in the dosage of light. These cells were confirmed by TUNEL staining to be apoptotic. Increases in the activity of both caspase-3 and -9, a decrease in MMP, and a marked increase in cytochrome c in the cytosolic fraction were found after cells were subjected to PDT. These results indicate that a dysfunction of MMP is followed by mitochondrial cytochrome c release, which triggers apoptosis through a mitochondrial pathway. ALA-PDT induces massive apoptosis due to the direct activation of a mitochondrial pathway, which is resistant to many anti-apoptotic processes, in human glioma cells. This finding implies that ALA-PDT is a promising therapy for the treatment of apoptosis-reluctant tumors such as malignant gliomas.

Topics: Aminolevulinic Acid; Apoptosis; Brain Neoplasms; Caspase 3; Caspase 9; Cell Line, Tumor; Cytochromes c; Flow Cytometry; Glioma; Humans; In Situ Nick-End Labeling; Membrane Potential, Mitochondrial; Photochemotherapy; Photosensitizing Agents; Protoporphyrins; Signal Transduction

To study the cytotoxic effects of doxorubicin on apoptosis in glioma cell lines U343, U138, U373 induced by anti-human DR4/DR5 monoclonal antibodies (FMU1.4/FMU1.5) and the underlying mechanism.. Expression of DR4/DR5 was quantitated by flow cytometry. Cytotoxicity exerted by FMU1.4/FMU1.5 on three cell lines was measured by MTT colorimetry and the induced apoptosis was determined by agarose gel electrophoresis. The expression of cytochrome C, FLIP and Ca2+ concentration were also measured.. Following the treatment of doxorubicin DR4 and DR5 were highly expressed on the cell surface; The apoptosis of U138 and U373 induced by FMU1.4 and FMU1.5 was stronger. expression of cytochrome C and Ca2+ concentration were enhanced, whereas the expression of FLIP was downregulated.. Subtoxic doxorubicin applied with antibodies caused higher cell death rate of glioma cells, which may be relevant to DR4/DR5, the release of cytochrome C and FLIP and Ca2+ concentration.

Topics: Antibiotics, Antineoplastic; Antibodies, Monoclonal; Apoptosis; Calcium; CASP8 and FADD-Like Apoptosis Regulating Protein; Cell Line, Tumor; Cytochromes c; Doxorubicin; Electrophoresis, Agar Gel; Flow Cytometry; Gene Expression; Glioma; Humans; Microscopy, Electron, Transmission; Receptors, TNF-Related Apoptosis-Inducing Ligand

West Nile virus (WNV) infection can cause severe meningitis and encephalitis in humans. Apoptosis was recently shown to contribute to the pathogenesis of WNV encephalitis. Here, we used WNV-infected glioma cells to study WNV-replication and WNV-induced apoptosis in human brain-derived cells.. T98G cells are highly permissive for lytic WNV-infection as demonstrated by the production of infectious virus titre and the development of a characteristic cytopathic effect. WNV replication decreased cell viability and induced apoptosis as indicated by the activation of the effector caspase-3, the initiator caspases-8 and -9, poly(ADP-ribose)polymerase (PARP) cleavage and the release of cytochrome c from the mitochondria. Truncation of BID indicated cross-talk between the extrinsic and intrinsic apoptotic pathways. Inhibition of the caspases-8 or -9 inhibited PARP cleavage, demonstrating that both caspases are involved in WNV-induced apoptosis. Pan-caspase inhibition prevented WNV-induced apoptosis without affecting virus replication.. We found that WNV infection induces cell death in the brain-derived tumour cell line T98G by apoptosis under involvement of constituents of the extrinsic as well as the intrinsic apoptotic pathways. Our results illuminate the molecular mechanism of WNV-induced neural cell death.

Topics: Animals; Apoptosis; Caspase Inhibitors; Cell Line, Tumor; Cell Survival; Chlorocebus aethiops; Cytochromes c; Cytopathogenic Effect, Viral; Enzyme Activation; Enzyme Inhibitors; Glioma; Humans; Vero Cells; Virus Replication; West Nile virus

Cannabinoids have been associated with tumor regression and apoptosis of cancer cells. Recently, we have shown that R(+)-methanandamide (R(+)-MA) induces apoptosis of H4 human neuroglioma cells via a mechanism involving de novo expression of the cyclooxygenase-2 (COX-2) enzyme. The present study investigated a possible involvement of a mitochondrial-driven pathway in this process.. Cell death was determined by the WST-1 cell viability test, and changes in apoptotic parameters [i.e., release of mitochondrial cytochrome c, activation of caspases, cleavage of poly(ADP-ribose) polymerase (PARP)] were detected by Western blotting.. H4 cells treated with R(+)-MA showed typical signs of mitochondrial apoptosis, i.e., release of mitochondrial cytochrome c into the cytosol and activation of initiator caspase-9. Moreover, activation of the executor caspase-3 was observed following cannabinoid treatment. Cells were fully protected from apoptotic cell death by the caspase-3 inhibitor Ac-DEVD-CHO, indicating a crucial role for caspase-3 activation in R(+)-MA-elicited apoptosis. Furthermore, cleavage of the caspase-3 target protein PARP was registered. All of the aforementioned effects were substantially reduced by the selective COX-2 inhibitor celecoxib (1 muM) at a pharmacologically relevant, nonapoptotic concentration.. R(+)-MA-induced apoptosis is mediated via a mitochondrial-dependent pathway that becomes activated, at least in part, through up-regulation of the COX-2 enzyme.

Topics: Animals; Apoptosis; Arachidonic Acids; Blotting, Western; Brain Neoplasms; Caspase 3; Caspase 9; Caspases; Celecoxib; Cell Survival; CHO Cells; Cricetinae; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cytochromes c; Glioma; Humans; Mitochondria; Poly(ADP-ribose) Polymerases; Pyrazoles; Signal Transduction; Sulfonamides

N-(4-hydroxyphenyl)retinamide (4-HPR), a synthetic retinoid is under clinical evaluation as a therapeutic agent in a variety of cancers. Its mechanism(s) of action involves multiple overlapping pathways that still remain unclear. In glioma cells its mechanism of action is not well elucidated. Here, we show that 4-HPR and not all-trans retinoic acid and 9-cis retinoic acid effectively induce apoptosis in glioma cells. 4-HPR-induced apoptosis is associated with hydroperoxide production and loss of mitochondrial membrane potential (Delta Psi(m)). Ultrastructural changes further indicate 4-HPR-induced mitochondrial swelling, endoplasmic reticulum (ER) dilation as well as close proximity of mitochondria and ER. As suggested by dilated ER, 4-HPR treatment increased the free cytosolic Ca(2+) as well as mitochondrial Ca(2+). Chelation of extracellular Ca(2+) by EGTA did not prevent Ca(2+) elevation, thus suggesting involvement of intracellular calcium stores in the release. Buffering of intracellular calcium by BAPTA-AM did not prevent 4-HPR-induced apoptosis; however, blocking the release of Ca(2+) from ER by heparin inhibited apoptosis, indicating the role of depletion of Ca(2+) from ER stores in apoptosis. 4-HPR treatment also resulted in an increase in Bax levels along with its translocation to mitochondria that promote mitochondrial membrane permeabilization. 4-HPR-induced apoptosis was further associated with the release of cytochrome c and apoptosis-inducing factor (AIF) from mitochondria to cytosol and nucleus, respectively, along with caspase-3 and caspase-7 activation. However, AIF nuclear translocation, peripheral chromatin condensation and apoptosis were not completely prevented by general caspase inhibitors, thus suggesting involvement of a caspase-dependent and caspase-independent pathway in 4-HPR-induced apoptosis. Taken together, these results suggest the role of mitochondrial-mediated pathway and ER stress as a key event in 4-HPR-induced apoptosis in glioma cells.

Topics: Alitretinoin; Animals; Antineoplastic Agents; Apoptosis; Apoptosis Inducing Factor; Calcium; Cell Line, Tumor; Cytochromes c; Endoplasmic Reticulum; Fenretinide; Glioma; Humans; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Rats; Reactive Oxygen Species; Receptors, Retinoic Acid; Retinoic Acid Receptor gamma; Retinoid X Receptor alpha; Tretinoin

Despite much evidence that lithium and valproate, two commonly used mood stabilizers, exhibit neuroprotective properties against an array of insults, the pharmacological relevance of such effects is not clear because most of these studies examined the acute effect of these drugs in supratherapeutic doses against insults which were of limited disease relevance to bipolar disorder. In the present study, we investigated whether lithium and valproate, at clinically relevant doses, protects human neuroblastoma (SH-SY5Y) and glioma (SVG and U87) cells against oxidative stress and endoplasmic reticulum stress in a time-dependent manner. Pretreatment of SH-SY5Y cells for 7 days, but not 1 day, with 1 mM of lithium or 0.6 mM of valproate significantly reduced rotenone and H2O2-induced cytotoxicity, cytochrome c release and caspase-3 activation, and increased Bcl-2 levels. Conversely, neither acute nor chronic treatment of SH-SY5Y cells with lithium or valproate elicited cytoprotective responses against thapsigargin-evoked cell death and caspase-3 activation. Moreover, inhibitors of glycogen synthase kinase-3 (GSK-3), kenpaullone and SB216763, abrogated rotenone-induced, but not H2O2-induced, cytotoxicity. Thus the cytoprotective effects of lithium and valproate against H2O2-induced cell death is likely independent of GSK-3 inhibition. On the other hand, chronic lithium or valproate treatment did not ameliorate cytotoxicity induced by rotenone, H2O2, and thapsigargin in SVG astroglial and U87 MG glioma cell lines. Our results suggest that lithium and valproate may decrease vulnerability of human neural, but not glial, cells to cellular injury evoked by oxidative stress possibly arising from putative mitochondrial disturbances implicated in bipolar disorder.

Topics: Antimanic Agents; Caspase 3; Caspases; Cell Death; Cell Line, Tumor; Cytochromes c; Cytoprotection; Electron Transport Complex I; Endoplasmic Reticulum; Enzyme Activation; Enzyme Inhibitors; Glioma; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Hydrogen Peroxide; Lithium Compounds; Neuroblastoma; Neuroprotective Agents; Oxidative Stress; Proto-Oncogene Proteins c-bcl-2; Rotenone; Thapsigargin; Up-Regulation; Valproic Acid

In vitro studies using monolayer cultures of human tumor cell lines have shown that 2-DG selectively inhibits energy-dependent DNA repair and cellular recovery processes in cancer cells. However, monolayer cultures differ greatly from the complex environmental conditions generated in solid tumors that develop inhomogeneous hypoxic and necrotic regions. In contrast, multicellular spheroids mimic heterogeneous cellular behavior and the consequent functional characteristics of in vivo solid tumors, and serve as important in vitro model to investigate tumor biology and responses to potential therapeutic agents. The present study compares the radiomodification by 2-DG in monolayer cultures and spheroids of a human glioma cell line (BMG-1) to gain insight into the effects in solid tumors. In spheroids, the glucose consumption (2.1 p mole/cell/h) and lactate production (3.67 p mole/cell/h) was nearly 2-3 fold higher than in monolayer cells (0.83 and 1.43 p mole/cell/h respectively). Presence of 2-DG (5 mM) for 2-4 h inhibited the glucose usage and lactate production by 70% in spheroids, while a 35% reduction was observed in monolayer cells. Under these conditions, 2-DG drastically enhanced the radiation-induced cell death of spheroids (by 2-3 folds); while a 40% increase was observed in monolayer cells. Radiosensitization by 2-DG in monolayer cells was primarily due to an increase in mitotic death (23%) linked to cytogenetic damage (micronuclei), whereas a profound induction of apoptosis (40%) accounted for the sensitization in spheroids. Although the Bcl-2 and Bax levels were significantly higher in spheroids, Bcl-2/Bax ratio was similar in monolayers and spheroids. Comet assay revealed a late onset of DNA breaks in the presence of 2- DG following irradiation only in spheroids, which corroborated well with the late onset of oxidative stress. 2-DG did not induce a significant cell cycle delay in monolayers, while a transient G(2) delay was apparent in spheroids.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Chromosome Aberrations; Cytochromes c; Deoxyglucose; DNA Repair; Glioma; Glucose; Humans; Lactic Acid; Mice; Proto-Oncogene Proteins c-bcl-2; Radiation-Sensitizing Agents; Reactive Oxygen Species; Spheroids, Cellular

Resveratrol (trans-3,4',5-trihydroxystilbene) is a naturally occurring polyphenolic compound highly enriched in grapes, peanuts, red wine, and a variety of food sources. Resveratrol has antiinflammatory and antioxidant properties, and also has potent anticancer properties. Human glioma U251 cells were used to understand the molecular mechanisms by which resveratrol acts as an anticancer agent, since glioma is a particularly difficult cancer to treat and eradicate. Our data show that resveratrol induces dose- and time-dependent death of U251 cells, as measured by lactate dehydrogenase release and internucleosomal DNA fragmentation assays. Resveratrol induces activation of caspase-3 and increases the cleavage of the downstream caspase substrate, poly(ADP-ribose) polymerase. Resveratrol-induced DNA fragmentation can be completely blocked by either a general caspase inhibitor (Z-VAD-FMK) or a selective caspase-3 inhibitor (Z-DEVD-FMK), but not by a selective caspase-1 inhibitor. Resveratrol induces cytochrome c release from mitochondria to the cytoplasm and activation of caspase-9. Resveratrol also increases expression of proapoptotic Bax and its translocation to the mitochondria. Resveratrol inhibits U251 proliferation, as measured by MTS assay [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt], and induces G0/G1 growth arrest, as determined by flow cytometry. The cyclin-dependent kinase inhibitor, olomoucine, prevents cell cycle progression and resveratrol-induced apoptosis. These results suggest that multiple signaling pathways may underlie the apoptotic death of U251 glioma induced by resveratrol, which warrants further exploration as an anticancer agent in human glioma.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents, Phytogenic; Apoptosis; bcl-2-Associated X Protein; Blotting, Western; Caspase 3; Caspase 9; Caspase Inhibitors; Caspases; Cell Cycle; Cell Line, Tumor; Cytochromes c; Cytoplasm; DNA Fragmentation; Dose-Response Relationship, Drug; Enzyme Activation; Enzyme Inhibitors; Flavonoids; Glioma; Humans; Kinetin; L-Lactate Dehydrogenase; Phenols; Poly(ADP-ribose) Polymerases; Polyphenols; Proto-Oncogene Proteins c-bcl-2; Purines; Resveratrol; Signal Transduction; Stilbenes; Subcellular Fractions; Time Factors; Up-Regulation

Mitochondrial benzodiazepine-receptor (mBzR) ligands constitute a heterogeneous class of compounds that show a pleiotropic spectrum of effects within the cells, including the modulation of apoptosis. In this paper, a novel synthetic 2-phenylindol-3-ylglyoxylamide derivative, N,N-di-n-butyl-5-chloro-2-(4-chlorophenyl)indol-3-ylglyoxylamide (PIGA), which shows high affinity and selectivity for the mBzR, is demonstrated to induce apoptosis in rat C6 glioma cells. PIGA was able to dissipate mitochondrial transmembrane potential (DeltaPsim) and to cause a significant cytosolic accumulation of cytochrome c. Moreover, typical features of apoptotic cell death, such as caspase-3 activation and DNA fragmentation, were also detected in PIGA-treated cells. Our data expand the knowledge on mBzR ligand-mediated apoptosis and suggest PIGA as a novel proapoptotic compound with therapeutic potential against glial tumours, in which apoptosis resistance has been reported to be involved in carcinogenesis.

Topics: Animals; Antineoplastic Agents; Apoptosis; Caspase 3; Caspases; Cells, Cultured; Cytochromes c; Cytosol; DNA Damage; Glioma; Indoles; Ligands; Membrane Potentials; Mitochondria; Rats; Receptors, GABA-A; Time Factors

Several antidepressants, mainly selective serotonin-reuptake inhibitors (SSRIs) and some tricyclic antidepressants (TCAs), have been shown to possess potent apoptotic activity in different cell lines. Our aim was to screen and select those agents with significant activity and elucidate the molecular pathway underlying this process in rat glioma and human neuroblastoma cell lines. We studied the effect of different antidepressants on apoptotic markers, including: cell viability, DNA fragmentation, cytochrome c (Cyt c) release from mitochondria, and caspase-3- like activity. In addition, the involvement of MAPK genes, c-Jun, and ERK was determined. Paroxetine and fluoxetine, SSRIs, clomipramine, a TCA, but not imipramine or mianserin (an atypical antidepressant), caused apoptosis in both cell lines, as assessed by flow cytometry of propidium iodide-stained C6 cells and typical fluorescence microscopy in glioma cells. These apoptotic changes were preceded by rapid increase in p-c-Jun levels, Cyt c release from mitochondria, and increased caspase-3-like activity. Assessment of paroxetine cytotoxicity in primary mouse brain and neuronal cultures showed significantly lower sensitivity to the drug's proapoptotic activity. These results strongly suggest that selected antidepressants induce apoptosis in neuronal and glial cell lines. Activation of p-c-Jun and subsequent increased Cyt c mitochondrial release participate in the apoptotic mechanism of the antidepressant. The high sensitivity to these drugs of the cancer cell, compared with primary brain tissue, suggests the potential use of these agents in the treatment of brain-derived tumors.

Topics: Animals; Antidepressive Agents; Apoptosis; Caspase 3; Caspases; Cell Line, Tumor; Cell Survival; Cytochromes c; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Glioma; Humans; JNK Mitogen-Activated Protein Kinases; Mianserin; Mice; Neuroblastoma; Neurons; Paroxetine; Rats

Malignant glioma cells are generally resistant or only weakly sensitive to tumor necrosis factor family of cell death-inducing ligands, including TNF-related apoptosis-inducing ligand (TRAIL)/Apo2L. The chemopreventive activity of polyphenolic compounds present in plant-derived food products has been well recognized in epidemiological studies; however, the mechanism of chemoprevention by these dietary constituents largely remains unknown. Curcumin, the yellow pigment in the spice turmeric, has profound anti-inflammatory activity and exhibits chemopreventive and tumor growth inhibitory activity. In the present study, we investigated whether curcumin sensitizes malignant glioma cell lines U251MG and U87MG to TRAIL-induced apoptosis. Treatment with low concentrations (5-20 microM) of curcumin alone had no effect on the viability of either cell line. At low concentration (5 ng/ml) TRAIL induced cytotoxicity in U251MG cells but not in U87MG cells. Whereas curcumin at subtoxic concentration sensitized U87MG cells to TRAIL-induced cytotoxicity, it had no effect on TRAIL-mediated cytotoxicity in U251MG cells. The combined curcumin and TRAIL treatment enhanced accumulation of hypo-diploid U87MG cells in sub G1 cell cycle phase and induced the cleavage of procaspases-3, -8, -9 and release of cytochrome c from mitochondria. These data indicate that curcumin differentially sensitizes glioma cells to TRAIL-induced apoptosis through the activation of both extrinsic (receptor-mediated) and intrinsic (chemical-induced) pathways of apoptosis. These results define a potential use of curcumin to sensitize glioma cells for TRAIL-mediated immunotherapy.

Topics: Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Blotting, Western; Brain Neoplasms; Caspase 3; Caspase 8; Caspase 9; Caspases; Cell Line, Tumor; Cell Survival; Curcumin; Cytochromes c; Enzyme Activation; Glioma; Humans; Indicators and Reagents; L-Lactate Dehydrogenase; Membrane Glycoproteins; Mitochondria; TNF-Related Apoptosis-Inducing Ligand; Tumor Necrosis Factor-alpha

Glioblastoma multiforme, the most common brain tumor, typically exhibits markedly increased angiogenesis, which is crucial for tumor growth and invasion. Antiangiogenic strategies based on disruption of the tumor microvasculature have proven effective for the treatment of experimental brain tumors. Here, we have overexpressed human caspase-9 by stable transfection in the SNB19 glioblastoma cell line, which normally expresses low levels of caspase-9. Our studies revealed that overexpression of caspase-9 coupled with radiation has a synergistic effect on the inhibition of glioma invasion as demonstrated by Matrigel assay (> 65%). Furthermore, sense caspase stable clones cocultured with fetal rat brain aggregates along with radiation showed complete inhibition as compared to the parental and vector controls. During in vitro angiogenesis, SNB19 cells cocultured with human microvascular endothelial cells (HMEC) showed vascular network formation after 48-72 h. In contrast, these capillary-like structures were inhibited when HMEC cells were cocultured with sense caspase stable SNB19 cells. This effect was further enhanced by radiation (5 Gy). Signaling mechanisms revealed that apoptosis is induced by cleavage of caspase-9 by radiation, loss of mitochondrial membrane potential and activation of caspase-3. These results demonstrate that activation of caspase-9 disrupts glioma cell invasion and angiogenesis in vitro. Hence, overexpression of proapoptotic molecules such as caspase-9 may be an important determinant of the therapeutic effect of radiation in cancer therapy.

Topics: Animals; Apoptosis; Capillaries; Caspase 9; Caspases; Cytochromes c; Glioma; Humans; Membrane Potentials; Mice; Mitochondria; Neoplasm Invasiveness; Neovascularization, Pathologic; Proto-Oncogene Proteins c-bcl-2

In this study, alpha-bisabolol, a sesquiterpene alcohol present in natural essential oil, was found to have a strong time- and dose-dependent cytotoxic effect on human and rat glioma cells. After 24 h of treatment with 2.5-3.5 microM alpha-bisabolol, the viability of these cells was reduced by 50% with respect to untreated cells. Furthermore, the viability of normal rat glial cells was not affected by treatment with alpha-bisabolol at the same concentrations as above. Glioma cells treated with high concentration of alpha-bisabolol (10 microM) resulted in a 100% cell death. Judging from hypo-G1 accumulation, poly(ADP-ribose) polymerase cleavage, and DNA ladder formation, the cytotoxicity triggered by alpha-bisabolol resulted from apoptosis induction. Moreover, the dissipation of mitochondrial-inner transmembrane potential and the release of cytochrome c from mitochondria indicated that, in these glioma cells, apoptosis occurred through an intrinsic pathway. As pointed out by the experimental results, alpha-bisabolol may be considered a novel compound able to inhibit glioma cell growth and survival.

Topics: Animals; Antineoplastic Agents; Apoptosis; Astrocytes; Cell Line, Tumor; Cell Membrane Permeability; Cell Survival; Cytochromes c; Cytoplasm; Cytosol; DNA Fragmentation; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Flow Cytometry; Glioma; Humans; Intracellular Membranes; Mitochondria; Monocyclic Sesquiterpenes; Poly(ADP-ribose) Polymerases; Rats; Sesquiterpenes

Fifty percent of high-grade glioma patients die within a year of diagnosis and less than two percent survive five years postdiagnosis. Elucidating apoptosis signaling pathways may assist in designing better adjuvant therapies. Preliminary characterizations suggested that glioma cells may either employ mitochondrial-independent or -dependent death receptor-induced apoptotic pathways, characteristic of cells termed type I and type II, respectively. In the present study, we generated panels of clonal transfectants overexpressing various levels of Bcl-2, in two parental glioma cell lines. These cells were used to explore molecular factors determining the necessity for mitochondrial amplification of death receptor signaling. Moderate Bcl-2 expression was sufficient to render one glioma cell line (D270) resistant to apoptosis induced by Fas ligand or TRAIL, consistent with these cells being type II. However, expression of even very high levels of Bcl-2 in a second line (D645) did not affect death ligand sensitivity, indicative of a type I phenotype. D270 cells expressed much less caspase-8 protein than D645 cells. Enforced overexpression of caspase-8 (or cytoplasmic Diablo/Smac) in D270 cells overcame Bcl-2 inhibition of death ligand-induced apoptosis, converting them from type II to type I. This indicates that caspase-8 levels can influence the requirement for mitochondrial involvement in death receptor apoptotic signaling in glioma cells.

Topics: Apoptosis; Base Sequence; Brain Neoplasms; Caspase 8; Caspases; Cell Line, Tumor; Cytochromes c; DNA Primers; Glioma; Humans; Mitochondria; Substrate Specificity

Previously, we evaluated the therapeutic efficacy of the adenovirus-mediated transduction of the cytosine deaminase (CD) gene and 5-fluorocytosine (5-FC) for malignant gliomas. However, the molecular pathways that mediate the 5-FC/CD gene therapy-induced cell death remains to be elucidated. In this study, we examined the induction of apoptosis and the role of caspases in 5-FC/CD gene therapy using human malignant glioma cells [Gli36delta5 (mutated p53) and U87MG (wild p53)]. The treatment with 5-FC/CD gene-therapy-induced apoptosis both in Gli36delta5 cells and in U87MG cells according to flow cytometric analysis. Immunoblot analysis revealed that caspases 3 and 9 were processed in response to 5-FC/CD in a concentration- and time-dependent manner, but caspase 8 was not. Each caspase 3 and 9 inhibitor significantly reduced apoptosis triggered by 5-FC/CD, but the caspase 8 inhibitor did not affect apoptosis induction. 5-FC/CD significantly promoted the release of cytochorme c from mitochondria in a concentration-dependent manner. These results indicate that 5-FC/CD gene therapy induces apoptosis in human malignant glioma cells and that the apoptotic cell death is mediated by the activation of mitochondrial caspase cascades involving caspases 3 and 9. This is the first report concerning the apoptotic mechanism of 5-FC/CD gene therapy, and these findings could be used to increase the efficacy of suicide gene therapy systems for the treatment of malignant glioma.

Topics: Adenoviridae; Antimetabolites; Apoptosis; Caspase 3; Caspase 9; Caspase Inhibitors; Caspases; Cytochromes c; Cytosine Deaminase; Drug Screening Assays, Antitumor; Enzyme Activation; Enzyme Inhibitors; Flucytosine; Genetic Therapy; Genetic Vectors; Glioma; Humans

The present study was designed to examine the roles of p53, reactive oxygen species (ROS), and ceramide, and to determine their mutual relationships during tumor necrosis factor (TNF)-alpha-induced apoptosis of human glioma cells. In cells possessing wild-type p53, TNF-alpha stimulated ceramide formation via the activation of both neutral and acid sphingomyelinases (SMases), accompanied by superoxide anion (O2-*) production, and induced mitochondrial depolarization and cytochrome c release, whereas p53-deficient cells were partially resistant to TNF-alpha and lacked O2-* generation and neutral SMase activation. Restoration of functional p53 sensitized glioma cells expressing mutant p53 to TNF-alpha by accumulation of O2-*. z-IETD-fmk (benzyloxycarbonyl-Ile-Glu-Thr-Asp fluoromethyl ketone), but not z-DEVD-fmk (benzyloxycarbonyl-Asp-Glu-Val-Asp fluoromethyl ketone), blocked TNF-alpha-induced ceramide formation through both SMases as well as O2-* generation. Caspase-8 was processed by TNF-alpha regardless of p53 status of cells or the presence of antioxidants. Two separate signaling cascades, p53-mediated ROS-dependent and -independent pathways, both of which are initiated by caspase-8 activation, thus contribute to ceramide formation in TNF-alpha-induced apoptosis of human glioma cells.

Topics: Apoptosis; Blotting, Western; Brain Neoplasms; Caspase 8; Caspases; Cathepsin B; Cell Line, Tumor; Cell Nucleus; Ceramides; Chromatography, High Pressure Liquid; Cycloheximide; Cysteine Proteinase Inhibitors; Cytochromes c; Cytosol; Electrophoresis, Polyacrylamide Gel; Enzyme Activation; Enzyme Inhibitors; Glioma; Glutathione; Humans; Macrolides; Microscopy, Fluorescence; Mitochondria; Mitosis; Oligopeptides; Oncogene Proteins, Viral; Oxidation-Reduction; Oxidative Stress; Oxygen; Protein Synthesis Inhibitors; Reactive Oxygen Species; Recombinant Proteins; Repressor Proteins; Retroviridae; RNA, Small Interfering; Signal Transduction; Temperature; Time Factors; Transfection; Tumor Necrosis Factor-alpha; Tumor Suppressor Protein p53

Geldanamycin (GA) binds to heat shock protein 90 (Hsp90) and interferes with its function which is to protect various cellular proteins involved in signaling, growth control, and survival from ubiquitination and subsequent degradation by the proteasome. Recently, we demonstrated that GA inhibited migration of glioma cells in vitro associated with downregulation of hypoxia-inducible factor (HIF-1 alpha) and phosphorylation of focal adhesion kinase (FAK) (Zagzag et al., 2003, J Cell Physiol 196:394-402). Here, we have investigated the mechanisms through which GA treatment of the T98G glioma cell line induces apoptosis. We found that GA treatment induced cell death in a caspase-dependent manner through activation of caspase-3 and PARP cleavage together with release of cytochrome c and apoptosis inducing factor (AIF) from the mitochondria. Use of synchronized T98G cells showed that GA treatment of glioma cells during S-phase enhanced cytotoxicity followed by M-phase arrest, resulting in mitotic catastrophe. In addition, apoptosis was associated with the downregulation of the survival protein, phosphorylated Akt (pAkt), an important signaling protein in the PI3K pathway, that is overexpressed in many cancers including gliomas. Given that many glioma tumors show deregulation of the PI3K signaling pathway, either through loss of the tumor suppressor protein PTEN or overexpression of the growth factor EGFR, the ability to identify different subsets of patients using simple immunohistochemistry for the presence of absence of pAkt could enable selection of the appropriate kinase inhibitor, such as GA, for drug therapy. Based on our data presented here, GA or its analogs may have potential in the treatment of glioma.

Topics: Apoptosis; Apoptosis Inducing Factor; Benzoquinones; Cell Line, Tumor; Cell Proliferation; Cell Survival; Cytochromes c; Flavoproteins; Glioma; Humans; Lactams, Macrocyclic; Membrane Proteins; Mitochondria; Mitosis; Quinones

In the hyperthermal treatment, the wild type (wt) p53 plays an important role in apoptosis induction in the tumor cells. In human gliomas, p53 frequently has some form of mutation. The mutant type (mt) p53 does not work properly as a tumor suppressor and this may result in poor responses during treatment. We investigated the relationship between apoptosis-inducing factor (AIF) and apoptosis under various thermal conditions (43, 45, and 47 degrees C for 1 h) using four p53-wild or -mutant human glioma cell lines (A172, T98G, U251MG, and YKG-1). AIF translocation from the mitochondria to the nucleus under hyperthermal conditions was demonstrated by confocal laser microscopy. The percentage of AIF-positive nuclei increased significantly in comparison with the control in all cell lines and in all temperature groups except for YKG-1 at 47 degrees C. Immunoblot analyses of the nuclear fraction of each cell line revealed temperature-dependent increases in AIF. A simultaneous release of cytochrome c from the mitochondria to the cytosol was noted. A flow cytometric analysis showed that apoptosis induction occurred more often in a temperature-dependent manner in the 45 and 47 degrees C groups than in the control group. These findings indicate that the hyperthermal conditions can lead to AIF translocation and apoptotic cell death in the p53-mutant human glioma cells. The present report is the first description of AIF-induced apoptosis in hyperthermia.

Topics: Apoptosis; Apoptosis Inducing Factor; Brain Neoplasms; Cell Line, Tumor; Cell Proliferation; Cytochromes c; Flavoproteins; Flow Cytometry; Genes, p53; Glioma; Humans; Hyperthermia, Induced; Immunoblotting; Immunohistochemistry; Membrane Proteins; Microscopy, Confocal; Mutation; Protein Transport

Hypoxia induces apoptosis in primary and transformed cells and in various tumor cell lines in vitro. In contrast, there is little apoptosis and predominant necrosis despite extensive hypoxia in human glioblastomas in vivo. We here characterize ultrastructural and biochemical features of cell death in LN-229, LN-18 and U87MG malignant glioma cells in a paradigm of hypoxia with partial glucose deprivation in vitro. Electron microscopic analysis of hypoxia-challenged glioma cells demonstrated early stages of apoptosis but predominant necrosis. ATP levels declined during hypoxia, but recovered with re-exposure to normoxic conditions unless hypoxia exceeded 8 h. Longer hypoxic exposure resulted in irreversible ATP depletion and delayed cell death. Hypoxia induced mitochondrial release of cytochrome c, but there was no cleavage of caspases 3, 7, 8 or 9, and no DNA fragmentation. Ectopic expression of BCL-XL conferred protection from hypoxia-induced cell death, whereas the overexpression of the antiapoptotic proteins X-linked-inhibitor-of-apoptosis-protein and cytokine response modifier-A had no effect. These findings suggest that glioma cells resist adverse effects of hypoxia until energy stores are depleted and then undergo necrosis rather than apoptosis because of energy deprivation.

Topics: Adenosine Triphosphate; bcl-X Protein; Brain Neoplasms; Caspases; Cell Death; Cell Hypoxia; Cell Nucleus; Cytochromes c; Cytoplasm; Energy Metabolism; Glioma; Glucose; Humans; Immunologic Factors; Microscopy, Electron; Mitochondria; Necrosis; Proteins; Proto-Oncogene Proteins c-bcl-2; Starvation; Tumor Cells, Cultured; X-Linked Inhibitor of Apoptosis Protein

Polyunsaturated fatty acids (PUFAs) can influence tumor growth and migration, both in vitro and in vivo. The PUFA gamma-linolenic acid (GLA) has been reported to improve the poor prognosis associated with human gliomas, although its effects at sublethal concentrations on residual cells postsurgery are poorly understood. The study investigated the effects sublethal PUFA doses (90 or 150 microM) may have on rat C6 glioma cell energy metabolism, since an adequate energy supply is essential for cell proliferation, migration, and apoptosis. Of note was the identification of mitochondrial heterogeneity in relation to the mitochondrial membrane potential (MMP), which has been suggested but unproven in previous studies. GLA and eicosapentaenoic acid (EPA) caused significant changes in cellular fatty acid composition and increased the percentage of cells with a low MMP after a 96-h exposure period. The presence of PUFAs inhibited C6 cell proliferation and migration, although apoptosis was not induced. The protein expression and activity of glucose-6-phosphate dehydrogenase was increased after 96-h incubation with 90 microM GLA and EPA and would allow redox regulation through increased NADPH production, permitting the maintenance of adequate intracellular reduced glutathione concentrations and limiting rates of lipid peroxidation and reactive oxygen species generation. Neither NADP(+)-isocitrate dehydrogenase nor NADP(+)-malate dehydrogenase activity responded to PUFAs, suggesting it is glucose-6-phosphate dehydrogenase that is the principal source of NADPH in C6 cells. These data compliment studies showing that higher concentrations of GLA induced glioma cell death and tumor regression and suggest that GLA treatment could be useful for the inhibition of residual cell proliferation and migration after surgical removal of the tumor mass.

Topics: Animals; Annexin A5; Benzimidazoles; Blotting, Western; Carbocyanines; Cell Movement; Cells, Cultured; Cytochromes c; DNA Fragmentation; Ethidium; Fatty Acids, Unsaturated; Fluorescent Antibody Technique; Fluorescent Dyes; Gas Chromatography-Mass Spectrometry; Glioma; Glucosephosphate Dehydrogenase; Membrane Potentials; Microscopy, Confocal; Mitochondria; Mitosis; Rats; Time Factors

Death receptor-mediated apoptosis of human malignant glioma cells triggered by CD95 ligand (CD95L) or Apo2 ligand/tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) share several features, including processing of multiple caspases and mitochondrial cytochrome c release. We here report that CD95L-induced cell death is inhibited by sulfasalazine (SS) in all of four human glioma cell lines, both in the absence and presence of cycloheximide (CHX). Coexposure to CD95L and SS prevents the CD95L-evoked processing of caspases 2, 3, 8 and 9, the release of cytochrome c from mitochondria, and the loss of BCL-x(L) protein. This places the protective effect of SS proximal to most known events triggered by the CD95-dependent signaling pathway in glioma cells. CD95L promotes the accumulation of nuclear factor kappa B (NF-kappaB) in the nucleus and induces the DNA-binding activity of NF-kappaB assessed by electrophoretic mobility shift assay. The total levels of p50, p65 and IkappaBalpha remain unchanged, but the levels of phosphorylated IkappaBalpha and of nuclear p65 increase, in response to CD95L. IkappaBalpha phosphorylation as well as nuclear NF-kappaB translocation and DNA binding are blocked by SS. However, unlike SS, dominant-negative IkappaBalpha (IkappaBdn) does not block apoptosis, suggesting that SS inhibits CD95L-mediated apoptosis in an NF-kappaB-independent manner. In contrast to CD95L, the cytotoxic effects of Apo2L/TRAIL are enhanced by SS, and SS facilitates Apo2L/TRAIL-evoked caspase processing, cytochrome c release, and nuclear translocation of p65. These effects of SS are nullified in the presence of CHX, suggesting that the effects of SS and CHX are redundant or that enhanced apoptosis mediated by SS requires protein synthesis. IkappaBdn fails to modulate Apo2L/TRAIL-induced apoptosis. Similar effects of SS on CD95L- and Apo2L/TRAIL-induced apoptosis are observed in MCF-7 breast and HCT116 colon carcinoma cells. Interestingly, HCT cells lacking p21 (80S14(p21-/-)) are only slightly protected by SS from CD95L-induced apoptosis, but sensitized to Apo2L/TRAIL-induced apoptosis, indicating a link between the actions of SS and p21. Thus, SS modulates the death cascades triggered by CD95L and Apo2L/TRAIL in opposite directions in an NF-kappaB-independent manner, and SS may be a promising agent for the augmentation of Apo2L/TRAIL-based cancer therapies.

Topics: Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Caspases; Cell Line, Tumor; Cell Nucleus; Cycloheximide; Cytochromes c; Fas Ligand Protein; Glioma; Humans; I-kappa B Proteins; Membrane Glycoproteins; NF-kappa B; Signal Transduction; Sulfasalazine; TNF-Related Apoptosis-Inducing Ligand; Transcription Factor RelA; Tumor Necrosis Factor-alpha

We had earlier shown that higher concentration of hydrogen peroxide (H(2)O(2)) induced p53-dependent apoptosis in glioma cell line with wild type p53 but had minimal effect on cells with mutated p53. Here we show a potentiating effect of hydroxylamine (HA), an inhibitor of catalase, on a nontoxic dose of H(2)O(2) in glioma cells. HA sensitized both p53 wild type and mutated glioma cells to 0.25 mM H(2)O(2). Potentiating effect of HA was independent of p53. Higher levels of reactive oxygen species (ROS) generation were observed in cells treated with HA+H(2)O(2) as compared to cells treated with each component alone in both the cell lines. Dimethyl sulfoxide (DMSO) protected cells. Cytosolic cytochrome c and activated caspase 3 were detected at 4h. The results suggest that higher levels of intracellular ROS, generated by HA+H(2)O(2) act as a molecular switch in activating a rapidly acting p53-independent mitochondrial apoptotic pathway.

Topics: Caspase 3; Caspases; Cell Death; Cell Line, Tumor; Cytochromes c; Dimethyl Sulfoxide; Enzyme Activation; Glioma; Humans; Hydrogen Peroxide; Hydroxylamine; Oxidants; Oxidation-Reduction; Reactive Oxygen Species; Survival Rate; Tumor Suppressor Protein p53

Caffeic acid phenethyl ester (CAPE), an active component of propolis, has many biological and pharmacological activities including antioxidant, anti-inflammation, antiviral action, and anticancer effect. Our previous studies showed that CAPE exhibited significant cytotoxicity in oral cancer cells. Herein we further investigated the cytotoxicity potential of CAPE and the mechanism of its action in C6 glioma cells. The data exhibited that C6 glioma cells underwent internucleosomal DNA fragmentation 24 hr after the treatment of CAPE (50 microM). The proportion of C6 glioma cells with hypodiploid nuclei was increased to 24% at 36 hr after the exposure. Further results showed that CAPE induced the release of cytochrome c from mitochondria into cytosol, and the activation of CPP32. CAPE application also enhanced the expression of p53, Bax, and Bak. Finally, the potential signaling components underlying CAPE induction of apoptosis were elucidated. We found that CAPE activated extracellular signal-regulated kinase (ERKs) and p38 mitogen-activated protein kinase (p38 MAPK) in C6 glioma cells. More importantly, p38 kinase formed a complex with p53 after the treatment of CAPE for 0.5 hr. The expression of p53, phospho-serine 15 of p53, and Bax, and inactivate form of CPP32 was suppressed by a pretreatment of a specific p38 MAPK inhibitor, SB203580. The resultant data suggest that p38 MAPK mediated the CAPE-induced p53-dependent apoptosis in C6 glioma cells.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Caffeic Acids; Caspase 3; Caspases; Cytochromes c; Glioma; Imidazoles; Mitogen-Activated Protein Kinases; p38 Mitogen-Activated Protein Kinases; Phenylethyl Alcohol; Phosphorylation; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Proteins; Proto-Oncogene Proteins c-bcl-2; Pyridines; Rats; Serine; Tumor Cells, Cultured; Tumor Suppressor Protein p53

Many malignant glioma cells express death receptors for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), yet some of these cells are resistant to TRAIL. Here, we examined signaling events in TRAIL-induced apoptosis and searched for therapeutic agents that could overcome TRAIL resistance in glioma cells. TRAIL induced apoptosis through death receptor 5 (DR5) and was mediated by caspase-8-initiated extrinsic and intrinsic mitochondrial pathways in sensitive glioma cell lines. TRAIL also triggered apoptosis in resistant glioma cell lines through the same pathways, but only if the cells were pretreated with chemotherapeutic agents, cisplatin, camptothecin and etoposide. Previous studies suggested that this was due to an increase in DR5 expression in wild-type TP53 cells, but this mechanism did not account for cells with mutant TP53. Here, we show that a more general effect of these agents is to downregulate caspase-8 inhibitor c-FLIP(S) (the short form of cellular Fas-associated death domain-fike interleukin-1-converting enzyme-inhibitory protein) and up-regulate Bak, a pro-apoptotic Bcl-2 family member, independently of cell's TP53 status. Furthermore, we showed that TRAIL alone or in combination with chemotherapeutic agents, induced apoptosis in primary tumor cultures from patients with malignant gliomas, reinforcing the potential of TRAIL as an effective therapeutic agent for malignant gliomas.

Topics: Antineoplastic Agents; Apoptosis; Apoptosis Inducing Factor; Apoptosis Regulatory Proteins; bcl-2 Homologous Antagonist-Killer Protein; Blotting, Northern; Blotting, Western; Brain Neoplasms; Carrier Proteins; CASP8 and FADD-Like Apoptosis Regulating Protein; Caspases; Cytochromes c; Dose-Response Relationship, Drug; Drug Interactions; Enzyme Inhibitors; Flavoproteins; Flow Cytometry; Glioma; Humans; Intracellular Signaling Peptides and Proteins; Membrane Glycoproteins; Membrane Proteins; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases; Mutation; Proteins; Receptors, Tumor Necrosis Factor; rho GTP-Binding Proteins; Signal Transduction; Subcellular Fractions; Temperature; Time Factors; TNF-Related Apoptosis-Inducing Ligand; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha; Tumor Suppressor Protein p53; X-Linked Inhibitor of Apoptosis Protein