High-resolution structural genomics reveals new therapeutic vulnerabilities in glioblastoma
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ABSTRACT:
PROVIDER: EGAS00001003493 | EGA |
REPOSITORIES: EGA
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Project description:Glioblastomas are highly lethal cancers, containing self-renewing glioblastoma stem cells (GSCs). Here, we show that GSCs, differentiated glioblastoma cells (DGCs), and normal brain cultures all displayed robust circadian rhythms, yet GSCs alone displayed exquisite dependence on core clock transcription factors, BMAL1 and CLOCK, for optimal cell growth. Downregulation of BMAL1 or CLOCK in GSCs induced cell cycle arrest and apoptosis. Chromatin immunoprecipitation revealed BMAL1 preferentially bound at metabolic genes in GSCs, associated with differences in active chromatin regions compared to NSCs. Targeting BMAL1 or CLOCK attenuated mitochondrial metabolic function and reduced expression of the tricarboxylic acid (TCA) cycle enzymes. Small molecule agonists of two independent BMAL1::CLOCK negative regulators, the Cryptochromes and REV-ERBs, downregulated stem cell factors and reduced GSC growth. Combination of Cryptochrome and REV-ERB agonists induced synergistic anti-tumor efficacy. Collectively, GSCs coopt circadian regulators beyond canonical circadian circuitry to promote stemness maintenance and metabolism, offering novel therapeutic paradigms.
2019-10-24 | GSE134973 | GEO
Project description:Glioblastomas are highly lethal cancers, containing self-renewing glioblastoma stem cells (GSCs). Here, we show that GSCs, differentiated glioblastoma cells (DGCs), and normal brain cultures all displayed robust circadian rhythms, yet GSCs alone displayed exquisite dependence on core clock transcription factors, BMAL1 and CLOCK, for optimal cell growth. Downregulation of BMAL1 or CLOCK in GSCs induced cell cycle arrest and apoptosis. Chromatin immunoprecipitation revealed BMAL1 preferentially bound at metabolic genes in GSCs, associated with differences in active chromatin regions compared to NSCs. Targeting BMAL1 or CLOCK attenuated mitochondrial metabolic function and reduced expression of the tricarboxylic acid (TCA) cycle enzymes. Small molecule agonists of two independent BMAL1::CLOCK negative regulators, the Cryptochromes and REV-ERBs, downregulated stem cell factors and reduced GSC growth. Combination of Cryptochrome and REV-ERB agonists induced synergistic anti-tumor efficacy. Collectively, GSCs coopt circadian regulators beyond canonical circadian circuitry to promote stemness maintenance and metabolism, offering novel therapeutic paradigms.
2019-10-24 | GSE134972 | GEO
Project description:Glioma stem cells (GSCs) drive propagation and therapeutic resistance of glioblastomas, the most aggressive diffuse brain tumor. However, the molecular mechanisms that maintain the stemness and promote therapy resistance remain poorly understood. Here we study CD109 – STAT3 axis as crucial for the maintenance of stemness and tumorigenicity of GSCs and as a mediator of chemoresistance. Mechanistically, CD109 physically interacts with glycoprotein 130 (GP130) to promote activation of the IL-6/STAT3 pathway in GSCs. Genetic depletion of CD109 abolished the stemness and self-renewal of GSCs and impaired tumorigenicity. Loss of stemness was accompanied with a phenotypic shift of GSCs to more differentiated astrocytic-like cells. Importantly, genetic or pharmacologic targeting of CD109 – STAT3 axis sensitized the GSCs to chemotherapy suggesting that targeting CD109 – STAT3 axis has potential to overcome therapy resistance in glioblastoma.
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Project description:Human naïve pluripotent stem cells (hnPSCs) can generate integrated models of blastocysts termed blastoids upon switch to inductive medium. However, the underlying mechanisms remain obscure. Here we report that self-renewing hnPSCs spontaneously and efficiently give rise to blastoids upon three dimensional (3D) suspension culture. The spontaneous blastoids mimic early stage human blastocysts in terms of structure, size, and transcriptome characteristics and are capable of progressing to post-implantation stages. This property is conferred by the glycogen synthase kinase-3 (GSK3) signalling inhibitor IM-12 present in 5iLAF self-renewing medium. IM-12 upregulates oxidative phosphorylation-associated genes that underly the capacity of hnPSCs to generate blastoids spontaneously. Starting from day one of self-organization, hnPSCs at the boundary of all 3D aggregates dedifferentiate into E5 embryo-like intermediates. Intermediates co-express SOX2/OCT4 and GATA6 and by day 3 specify trophoblast fate, which coincides with cavity and blastoid formation. In summary, spontaneous blastoid formation results from 3D culture triggering dedifferentiation of hnPSCs into earlier embryo-like intermediates which are then competent to segregate blastocyst fates.
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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.
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Project description:It is becoming better understood that radiation resistance in glioblastomas (GBMs) may be secondary to a self-renewing subpopulation of cells in the bulk tumor that form neurospheres in culture. This population has been referred to as Glioma stem cells (GSCs). One of the limitations regarding the use of GSCs is that these studies require fresh tumor biopsy samples obtained from patients, and can be extremely difficult to culture, propagate, and perform treatment-response assays. This report describes the generation of a self-renewing population of GSCs derived from commercially available U87 cells using NOD-SCID mice as carrier. The tumors were dissociated to obtain GSCs that demonstrate stem-like properties and high degree of chemo and radiation resistance. Pathological analysis of tumors obtained using GSCs exhibit all the histological hallmarks of human GBMs which is quite uncommon in GBM rodent models and hence could serve as a better model for pre-clinical study. We have shown that MGH87GSCs have an enhanced tumorogenicity than parental U87 and about 500 cells are sufficient to form tumors. To understand the transcriptome and accompanied proteome better, we explored the gene expression profiles of MGH87GSC and U87. We have shown that these GSCs are plastic like stem cells and can be directed towards a particular progeny within neural lineage by providing suitable growth factor. Our objective was to understand the genetic and biochemical mechanisms that control the self-renewal phenotype, asymmetric subdivision, chemo and radiation resistance and the role of the GSC niche in regulating the biological properties of GSC. Through this model we anticipate to devise therapeutic strategies to target this sub population of GSCs within GBMs to eradicate treatment resistance and tumor recurrence.
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Project description:Glioblastomas show heterogeneous histological features. These distinct phenotypic states are thought to be associated with the presence of glioma stem cells (GSCs), which are highly tumorigenic and self-renewing sub-population of tumor cells that have different functional characteristics. To investigate Glioblastomas (GBMs) show heterogeneous histological features. These distinct phenotypic states are thought to be originated by the glioma stem cells (GSCs), which are highly tumorigenic and self-renewing sub-population of tumor cells. Notch signaling has been shown to be important for maintenance of GSC population both in vitro and in vivo. A recent study showed that NOTCH -triggered oncogenic activity can be due to not only its ability to regulate coding genes but also long non-coding RNAs (lncRNAs). Here, we investigated the molecular effects of lncRNA in GSC, whose expression is induced by Notch signaling. We searched for downregulated lncRNAs in GSCs by treatment of small interfering RNA (siRNA) targeting Notch1 and JAG1 (si-Notch1 and si-JAG1).
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Project description:Glioblastomas show heterogeneous histological features. These distinct phenotypic states are thought to be associated with the presence of glioma stem cells (GSCs), which are highly tumorigenic and self-renewing sub-population of tumor cells that have different functional characteristics. To investigate gene expression profiling in GSC, we have performed microarray experiment using Agilent Whole Human Genome Oligo Microarrays (G4112F).
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Project description:Our observation suggest that ADAR may play important role to maintain GSC stemness. In order to address this hypothesis, we abrogated the expression of ADAR in GSCs using two distinct short and non-overlapping shot hairpin RNAs (shRNAs). A non-targeting control shRNA (shCONT) is used as control in these experiments. Both shRNAs significantly reduced ADAR protein expression. Depletion of ADAR impaired GSCs proliferation but did not affect matched DGCs. Similarly, lack of ADAR reduces GSC self-renewal capacity as assessed by in vitro limiting dilution assay . In order to identify the antitumor mechanisms triggered by ADAR depletion, we performed global transcriptional profiling through RNA-sequencing in GSCs upon ADAR knockdown. These analyses show that ADAR downregulation impairs the impairs the expression of genes involved in cancer proliferation, particularly those involved in cell cycle regulation
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