BCL6 enforces human glioblastoma growth and serves as a novel therapeutic target (expression)
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE77053 | GEO | 2016/08/01
SECONDARY ACCESSION(S): PRJNA309336
REPOSITORIES: GEO
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Project description:ZBTB transcription factors extensively orchestrate gene transcription during tissue development. However, their roles in glioblastoma multiforme (GBM) remain largely unexplored. Here, through integrated functional screening and expression analyses of 49 human ZBTB genes, we identify that BCL6 is required for GBM cell proliferation and is overexpressed in GBM samples. High expression of BCL6 is associated with poor overall survival of GBM patients. Genome-wide occupancy analysis and transcriptome analysis demonstrates that BCL6 is recruited to the loci of various tumor-promoting genes (e.g. MYC, FOSL1, MALAT1 and NEAT1) and maintains their expression. Pathway enrichment analysis reveals that BCL6 regulates several important cancer related pathways (e.g. TP53, ErbB and MAPK signaling pathways). BCL6 represses the expression of TP53 and its target genes, CDKN1A and CDKN1B, thereby promoting GBM cell resistance to ionizing radiation. Moreover, antibody array profiling uncovers AXL and MET are selectively activated by BCL6 in GBM. Moreover, BCL6 enhances both MEKERK and S6K-RPS6 axes as well as cap-dependent translation through the induction of AXL expression. Importantly, depletion of BCL6 or pharmacological inhibition of BCL6/NCoR complex effectively blocks GBM growth both in vitro and in vivo, and sensitizes GBM cells to EGFR inhibitors. Together, these findings uncover a novel growth-promoting role of BCL6 in GBM, and provide the rationale of targeting BCL6 as a potential therapeutic approach for this deadly malignancy. cDNA microarray analysis was performed in U87 cells transfected with either non-targeting siRNAs or BCL6 siRNAs. All experiments were carried out in duplicates.
2016-08-01 | E-GEOD-77053 | biostudies-arrayexpress
Project description:Most small-molecule protein degraders act as interface stabilizers ‘molecular glues’ between E3 ubiquitin ligases and target proteins to induce ternary complex formation and ubiquitin-dependent target protein degradation. Here we report polymerization as a novel mechanism for small molecule-induced degradation. Using functional screens in combination with molecular and biochemical assays, we found that BI-3802, which binds to the BTB domain of the oncogenic transcription factor BCL6, induces polymerization of BCL6 into regular helical structures in vitro and foci in vivo. Polymerization precedes degradation by the SIAH1 E3 ubiquitin ligase. Hereby, a VxP amino acid motif on BCL6, distal from the drug-binding BTB domain, is required for SIAH1 binding, ubiquitination and BI-3802-induced degradation. Our findings propose that small molecule-induced polymerization is not only a new modality for targeted protein degradation, but also provides synthetic biology with a tool for tunable protein polymerization and opens new avenues for future drug design.
2020-11-20 | PXD016185 | Pride
Project description:<p>Glioblastoma (GBM) is a common and deadly form of brain tumor in adults. Dysregulated metabolism in GBM offers an opportunity to deploy metabolic interventions as precise therapeutic strategies. To identify the molecular drivers and the modalities by which different molecular subgroups of GBM exploit metabolic rewiring to sustain tumor progression, we interrogated the transcriptome, the metabolome, and the glycoproteome of human subgroup-specific GBM sphere-forming cells (GSC). L-fucose abundance and core fucosylation activation were elevated in mesenchymal (MES) compared with proneural GSCs; this pattern was retained in subgroup-specific xenografts and in subgroup-affiliated human patient samples. Genetic and pharmacological inhibition of core fucosylation significantly reduced tumor growth in MES GBM preclinical models. Liquid chromatography-mass spectrometry (LC-MS)-based glycoproteomic screening indicated that most MES-restricted core-fucosylated proteins are involved in therapeutically relevant GBM pathological processes, such as extracellular matrix interaction, cell adhesion, and integrin-mediated signaling. Selective L-fucose accumulation in MES GBMs was observed using preclinical minimally invasive PET, implicating this metabolite as a potential subgroup-restricted biomarker.Overall, these findings indicate that L-fucose pathway activation in MES GBM is a subgroup-specific dependency that could provide diagnostic markers and actionable therapeutic targets.</p><h4><strong>SIGNIFICANCE: </strong>Metabolic characterization of subgroup-specific glioblastoma (GBM) sphere-forming cells identifies the L-fucose pathway as a vulnerability restricted to mesenchymal GBM, disclosing a potential precision medicine strategy for targeting cancer metabolism.</h4>
2022-11-08 | MTBLS730 | MetaboLights
Project description:Rationale: The BCL6 oncogene is constitutively activated by chromosomal translocations and amplification in ABC-DLBCLs, a class of DLBCLs that respond poorly to current therapies. Yet the role of BCL6 in maintaining these lymphomas has not been investigated. BCL6 mediates its effects by recruiting corepressors to an extended groove motif. Development of effective BCL6 inhibitors requires compounds exceeding the binding affinity of these corepressors. Objectives: To design small molecule inhibitors with superior potency vs. endogenous BCL6 ligands for unmet putative therapeutic needs such as targeting ABC-DLBCL. Findings: We used an in silico drug design functional-group mapping approach called SILCS to create a specific BCL6 inhibitor with 10-fold greater potency than endogenous corepressors. The compound, called FX1, binds in such a way as to occupy an essential region of the BCL6 lateral groove. FX1 disrupts BCL6 repression complex formation, reactivates BCL6 target genes, and mimics the phenotype of mice engineered to express BCL6 with lateral groove mutations. This compound eradicated established DLBCLs xenografts at low doses. Most strikingly, FX1 suppressed ABC-DLBCL cells as well as primary human ABC-DLBCL specimens ex vivo. Conclusions: ABC-DLBCL is a BCL6 dependent disease that can be targeted by novel inhibitors able to exceed the binding affinity of natural BCL6 ligands.
2016-10-12 | GSE80351 | GEO
Project description:<p>Glioblastoma (GBM) is a common and deadly form of brain tumor in adults. Dysregulated metabolism in GBM offers an opportunity to deploy metabolic interventions as precise therapeutic strategies. To identify the molecular drivers and the modalities by which different molecular subgroups of GBM exploit metabolic rewiring to sustain tumor progression, we interrogated the transcriptome, the metabolome, and the glycoproteome of human subgroup-specific GBM sphere-forming cells (GSC). L-fucose abundance and core fucosylation activation were elevated in mesenchymal (MES) compared with proneural GSCs; this pattern was retained in subgroup-specific xenografts and in subgroup-affiliated human patient samples. Genetic and pharmacological inhibition of core fucosylation significantly reduced tumor growth in MES GBM preclinical models. Liquid chromatography-mass spectrometry (LC-MS)-based glycoproteomic screening indicated that most MES-restricted core-fucosylated proteins are involved in therapeutically relevant GBM pathological processes, such as extracellular matrix interaction, cell adhesion, and integrin-mediated signaling. Selective L-fucose accumulation in MES GBMs was observed using preclinical minimally invasive PET, implicating this metabolite as a potential subgroup-restricted biomarker.Overall, these findings indicate that L-fucose pathway activation in MES GBM is a subgroup-specific dependency that could provide diagnostic markers and actionable therapeutic targets.</p><h4><strong>SIGNIFICANCE: </strong>Metabolic characterization of subgroup-specific glioblastoma (GBM) sphere-forming cells identifies the L-fucose pathway as a vulnerability restricted to mesenchymal GBM, disclosing a potential precision medicine strategy for targeting cancer metabolism.</h4>
2022-11-08 | MTBLS4708 | MetaboLights
Project description:Rapid immunoprecipitation mass spectrometry of endogenous proteins (RIME) for BCL6 in untreated and irradiated glioblastoma cell lines and a positive control lymphoma cell line.
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Project description:Glioblastoma (GBM) is a deadly cancer in which cancer stem cells (CSCs) sustain tumor growth and contribute to therapeutic resistance. Protein Arginine Methyltransferase 5 (PRMT5) has recently emerged as a promising target in GBM. Using two orthogonal-acting inhibitors of PRMT5 (GSK591 or LLY-283), we show that pharmacological inhibition of PRMT5 suppresses the growth of a cohort of 46 patient-derived GBM stem cell cultures, with the proneural subtype showing greater sensitivity. We show that PRMT5 inhibition caused widespread disruption of splicing across the transcriptome, particularly affecting cell cycle gene products. We identify a GBM splicing signature that correlates with the degree of response to PRMT5 inhibition. Importantly, we demonstrate that LLY-283 is brain-penetrant and significantly prolongs the survival of mice with orthotopic patient-derived xenografts. Collectively, our findings provide a rationale for the clinical development of brain penetrant PRMT5 inhibitors as treatment for GBM.
2020-11-03 | PXD021635 | Pride
Project description:We aimed to identify the response mechanism to EGFR tyrosine kinase inhibition. A431 cells were transfected with mock siRNA or BCL6 siRNA. Cells were then treated with gefitinib. Harvesting was done at 0h, at 24h and at 48h. Two TMT10plex sets were organized as follows: TMT set1: mock 0h (3x, channels 126, 127N and 127C), mock 24h (3x, 128N, 128C and 129N), mock 48h (3x, 129C, 130N, 130C) and internal pooled standard (131) composed from equal aliquots of all samples (mock siRNA and BCL6 siRNA). TMT set2: siBCL6 0h (3x, channels 126, 127N and 127C), siBCL6 24h (3x, 128N, 128C and 129N), siBCL6 48h (3x, 129C, 130N, 130C) and the same internal pooled standard (131) as for set 1.
2020-12-09 | PXD016605 | Pride
Project description:The purpose of this study is to determine whether the combination of two agents, INC280 and bevacizumab, is safe and effective when administered to patients with Glioblastoma Multiforme (GBM) who have progressed after receiving prior therapy or who have unresectable GBM.
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Project description:Whole proteome analysis of LN18 cell treated with one of five DNA-damaging treatments (fractionated irradiation (IRM), temozolomide (TMZ), acute irradiation 24 hours (IRS 24h), acute irradiation 48 hours (IRS 48h) or doxorubicin (Dox)) +/- the BCL6 inhibitor FX1.
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