Project description:Glioblastoma multiforme is one of the most devastating cancers and presents unique challenges to therapy due to its aggressive behaviour. Cancer stem cells have been described to be the only cell population with tumorogenic capacity in glioblastoma. Therefore, effective therapeutic strategies targeting these cells may be beneficial. We have established different cultures of glioblastoma stem cells (GSCs) derived from surgical specimens and found that, after induction of differentiation, NFκB was activated, which allows intermediate tumor precursor cells to remain cycling. We also showed that blockade of NFκB signaling in differentiating GSCs by different genetic strategies or treatment with small molecule inhibitors, promoted replication arrest, progression to a mature phenotype, mainly neuronal cells, and senescence. This effect was partly mediated by downregulation of the NFκB target gene cyclin D1. Furthermore, intravenous treatment of immunodeficient mice bearing human GSC-derived tumors with a novel small-molecule inhibitor of the NFκB pathway induced senescence of tumor cells but no ultraestructural alterations of the brain parenchymal cells were detected. These findings reveal that activation of NFκB may keep differentiating GSCs from acquiring a mature postmitotic phenotype, thus allowing cell proliferation, and support the rationale for therapeutic strategies aimed at promoting premature senescence in GSCs undergoing differentiation. Gene expression in differentiated cells relative to stem cells in three different glioblastoma cultures
Project description:Although fetal bovine serum (FBS) induces the differentiation of cancer stem cells, the underlying mechanism by which this is accomplished has not been clarified. Whether reactive oxygen species affect the differentiation of cancer stem cells in solid tumors as they do in normal stem cells is not known. This study aimed to determine the role of reactive oxygen species in the FBS-induced differentiation of glioblastoma stem cells. We found that FBS activated the oxidative stress response system in glioblastoma stem cells (GSCs). The resulting differentiated cells showed tremendous increases in mitochondrial superoxide and oxygen consumption, accompanied by a loss in stem cell markers and a gain in differentiation markers. The antioxidant N-Acetyl-Cysteine (NAC) inhibited the mitochondrial superoxide increase and prevented the glioblastoma stem cells from differentiating. It appears that FBS-induced cancer stem cell differentiation is caused by mitochondrial activation, which depends on increases in levels of mitochondrial superoxide. GSC11 cells were cultured in stem cell medium or differentiated medium for 1, 3, or 7 days in triplicate. Total RNA was extracted from 12 samples. Microarray experiment and data analysis were done at Dept. of Systems Biology, MDACC (Houston, USA)
Project description:Glioblastoma (GBM) is a lethal brain cancer composed of heterogeneous cellular populations including glioma stem cells (GSCs) and their progeny differentiated non-stem glioma cells (NSGCs). Although accumulating evidence points out the significance of GSCs for tumour initiation and propagation, the roles of NSGCs remain elusive. Here we demonstrate that, when patient-derived GSCs in GBM tumours undergo differentiation with diminished telomerase activity and shortened telomeres, they subsequently become senescent phenotype, thereby secreting angiogenesis-related proteins, including vascular endothelial growth factors. Interestingly, these secreted factors from senescent NSGCs promote proliferation of human umbilical vein endothelial cells and tumorigenic potentials of GSCs in immunocompromised mice. These experimental data are likely clinically-relevant, since immunohistochemistry of both patient tumours of GBM and the patient GSC-derived mouse xenografted tumours detected tumour cells that express a set of markers for the senescence phenotype. Collectively, our data suggest that the inter-cellular signals from senescent NSGCs promote GBM tumour angiogenesis thereby increasing malignant progression of GBM. We monitored gene expression profiling in GSC, differentiated NSGC (GSC at day7 after serum exposure), and senescent NSGC (GSC at day30 after serum exposure) of GBM146 and GBM157.
Project description:We explored the utility of oncolytic virus therapy against glioblastoma with Zika virus (ZIKV), a flavivirus that induces cell death and differentiation of neural precursor cells in the developing fetus. ZIKV preferentially infected and killed glioblastoma stem cells (GSCs) relative to differentiated tumor progeny or normal neuronal cells. The effects against GSCs were not a general property of neurotropic flaviviruses, as West Nile Virus (WNV) indiscriminately killed both tumor and normal neural cells. ZIKV potently depleted patient-derived GSCs grown in culture and in organoids. Moreover, mice with glioblastoma survived substantially longer and at greater rates when the tumor was inoculated with a murine adapted strain of ZIKV. Our results suggest that ZIKV is an oncolytic virus that can preferentially target GSCs, and thus, genetically modified strains that further optimize safety could have therapeutic efficacy for adult glioblastoma patients.
Project description:It has been previously described that in glioblastoma (GBM), BMPs deplete the tumorigenic potential of glioblastoma stem cells (GSCs), promoting their differentiation towards the astrocytic lineage. To gain more insight on how BMPs regulate differentiation in GSCs, we are interested in identifying new BMP target genes in GBM cells. To this end, the patient derived glioblastoma cell lines U3031MG and U3034MG were stimulated or not with 30ng/ml BMP7 for 2 and 24 h, total RNA was isolated from three biological replicates per condition, and a microarray screen with the Affymetrix U133plus2 platform was performed.
Project description:Glioblastoma (GBM) is a deadly disease without effective treatment. Because glioblastoma stem cells (GSCs) contribute to tumor resistance and recurrence, improved treatment of GBM can be achieved by eliminating GSCs through inducing their differentiation. Prior efforts have been focused on studying GSC differentiation towards the astroglial lineage.
Project description:Glioblastoma ranks among the most lethal of primary brain malignancies, with glioblastoma stem cells (GSCs) at the apex of tumor cellular hierarchies. Here, to discover novel therapeutic GSC targets, we interrogated gene expression profiles from GSCs, differentiated glioblastoma cells (DGCs), and neural stem cells (NSCs), revealing EYA2 as preferentially expressed by GSCs. Targeting EYA2 impaired GSC maintenance and induced cell cycle arrest, apoptosis, and loss of self-renewal. EYA2 displayed novel localization to centrosomes in GSCs, and EYA2 tyrosine (Tyr) phosphatase activity was essential for proper mitotic spindle assembly and survival of GSCs. Inhibition of the EYA2 Tyr phosphatase activity, via genetic or pharmacological means, mimicked EYA2 loss in GSCs in vitro and extended the survival of tumor-bearing mice. Supporting the clinical relevance of these findings, EYA2 portends poor patient prognosis in glioblastoma. Collectively, our data indicate that EYA2 phosphatase function plays selective critical roles in the growth and survival of GSCs, potentially offering a high therapeutic index for EYA2 inhibitors.
Project description:Glioblastoma stem cells (GSCs) fate is controlled by environmental cues, among which cytokines play a crucial role. The transforming growth factor β (TGFβ) family signaling pathways controls GSCs. On one hand, TGFβ promotes cell proliferation in GBM, it induces the expression of platelet-derived growth factor-B (PDGFB). Moreover, TGFβ, via its signaling mediators Smad2/3, induces the expression of the cytokine leukemia inhibitory factor (LIF) and Sox4, which in turn enhances the expression of the stem cell transcription factor Sox2; this increases the self-renewal capacity of the GSCs and their stemness characteristics, and enhances the GSC tumor-initiating potential. On the other hand, Bone morphogenic proteins (BMPs) are known to promote GSC differentiation towards the astrocytic phenotype. To further understand which genes are regulated by TGFβ and BMP7 in GSCs we performed a microarray in the Affymetrix HTA2 platform in three different glioblastoma cell line, U2987, and two patient-derived glioblastoma stem cells, U3031MG and U3034MG, in the presence or absence of 5 ng/ml of TGFβ or 30 ng/ml BMP7 for 24 h, three biological replicates per condition.