PTEN DEFICIENCY LEADS TO PROTEASOME ADDICTION, A NOVEL VULNERABILITY IN GLIOBLASTOMA
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE163906 | GEO | 2020/12/29
REPOSITORIES: GEO
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Project description:Glioblastoma (GBM) is the most common primary brain tumor in adults with a median survival of approximately 15 months, therefore, more effective treatment options for GBM are required. To identify new drugs targeting glioblastomas, we performed a high throughput drug screen using patient-derived neurospheres cultured to preferentially retain their glioblastoma stem cell (GSC) phenotype.
High throughput drug screening was performed on GSCs followed by a second dose response assay of the 5 identified original hits. A PI3K/mTOR dependency to a proteasome inhibitor (carfilzomib), was confirmed by gain of function and loss of function experiments. Proteasome inhibition response signatures were derived from proteomic and bioinformatic analysis. Molecular mechanism of action was determined using in vitro 3-dimensional (3D) GBM organoid models and in vivo preclinical orthotopic GBM models.
We found that GSCs were highly sensitive to proteasome inhibition due to an underlying dependency on an increased protein synthesis rate, and loss of autophagy, associated with PTEN loss and activation of the PI3K/mTOR pathway. In contrast, combinatory inhibition of autophagy and the proteasome, resulted in enhanced cytotoxicity specifically in GSCs that did express PTEN. Finally, proteasome inhibition specifically increased cell death markers in 3D glioblastoma organoids, suppressed tumor growth, and increased survival of mice orthotopically engrafted with GSCs. As perturbations of the PTEN/ PI3K axis occur in nearly 50% of GBMs, these findings suggest that a significant fraction of these tumors could be vulnerable to proteasome inhibition.
2020-12-04 | MSV000086560 | MassIVE
Project description:The PI3K-PKB/c-akt-FOXO signalling network provides a major intracellular hub for regulation of cell proliferation, survival and stress resistance1. Here we report a novel function for FOXO transcription factors in regulating autophagy through modulation of intracellular glutamine levels. To identify novel transcriptional targets of this module we performed an unbiased microarray analysis after conditional activation of the key components PI3K, PKB, FOXO3 and FOXO4. Utilising this global pathway approach we identified glutamine synthetase (GS) as being transcriptionally regulated by PI3K-PKB-FOXO signalling. FOXO-mediated increase in GS expression specifically induced glutamine production independently of cell type, and this was evolutionary conserved. FOXO activation resulted in mTOR inhibition by preventing the translocation of mTOR to lysosomal membranes, which was dependent on GS activity. Increased GS activity resulted in increased autophagosome turnover as measured by LC3 lipidation, p62 degradation, and confocal imaging of LC3, p62, WIPI-1, ULK2 and Atg12. Inhibition of FOXO3-mediated autophagy resulted in increased apoptosis, suggesting that the induction of autophagy by FOXO3-mediated upregulation of GS is important for cellular survival. These findings reveal a novel signalling network that can directly modulate autophagy through regulation of glutamine metabolism. conditional activation of pkb and pi3k were followed in a timeseries. Each timepoint consists of 4 independent replicates, labeled with either cy3 or cy5 and put on array against time0.
2012-07-21 | E-GEOD-35701 | biostudies-arrayexpress
Project description:The PI3K-PKB/c-akt-FOXO signalling network provides a major intracellular hub for regulation of cell proliferation, survival and stress resistance1. Here we report a novel function for FOXO transcription factors in regulating autophagy through modulation of intracellular glutamine levels. To identify novel transcriptional targets of this module we performed an unbiased microarray analysis after conditional activation of the key components PI3K, PKB, FOXO3 and FOXO4. Utilising this global pathway approach we identified glutamine synthetase (GS) as being transcriptionally regulated by PI3K-PKB-FOXO signalling. FOXO-mediated increase in GS expression specifically induced glutamine production independently of cell type, and this was evolutionary conserved. FOXO activation resulted in mTOR inhibition by preventing the translocation of mTOR to lysosomal membranes, which was dependent on GS activity. Increased GS activity resulted in increased autophagosome turnover as measured by LC3 lipidation, p62 degradation, and confocal imaging of LC3, p62, WIPI-1, ULK2 and Atg12. Inhibition of FOXO3-mediated autophagy resulted in increased apoptosis, suggesting that the induction of autophagy by FOXO3-mediated upregulation of GS is important for cellular survival. These findings reveal a novel signalling network that can directly modulate autophagy through regulation of glutamine metabolism. conditional activation of foxo3 and foxo4 were followed in a timeseries. Each timepoint consists of 4 independent replicates, labeled with either cy3 or cy5 and put on array against time0 as reference.
2012-07-21 | E-GEOD-35703 | biostudies-arrayexpress
Project description:Osteosarcoma is the third most common cancer in adolescence and the first common primary malignant tumor of bone. The long-term prognosis of osteosarcoma, especially for unresectable and metastatic tumors, still remains unsatisfactory in the past decades. In this study, we systematically investigated the antitumor effect of imperatorin (IMP), a small molecule extracted from Angelica dahurica, in human osteosarcoma cells. The results showed that IMP triggered time-dependent and dose-dependent inhibition of tumor growth mainly by inducing autophagy promotion and G0/G1 phase arrest in vitro and in vivo. Besides, IMP treatment elevated the expression level of PTEN and p21, down-regulated the phosphorylation of AKT and mTOR. In contrast, the inhibition of PTEN using Bpv (HOpic), a potential and selective inhibitor of PTEN, concurrently rescued IMP-induced autophagy promotion, cell cycle arrest and inactivation of PTEN-PI3K-AKT-mTOR/p21 pathway. Taken together, our data revealed that imperatorin induced autophagy and cell cycle arrest through PTEN-PI3K-AKT-mTOR/p21 signaling pathway by targeting and up-regulating PTEN in human osteosarcoma cells. Hence, imperatorin is a desirable candidate for clinical treatments of osteosarcoma.
2021-12-23 | GSE180321 | GEO
Project description:The PI3K-PKB/c-akt-FOXO signalling network provides a major intracellular hub for regulation of cell proliferation, survival and stress resistance1. Here we report a novel function for FOXO transcription factors in regulating autophagy through modulation of intracellular glutamine levels. To identify novel transcriptional targets of this module we performed an unbiased microarray analysis after conditional activation of the key components PI3K, PKB, FOXO3 and FOXO4. Utilising this global pathway approach we identified glutamine synthetase (GS) as being transcriptionally regulated by PI3K-PKB-FOXO signalling. FOXO-mediated increase in GS expression specifically induced glutamine production independently of cell type, and this was evolutionary conserved. FOXO activation resulted in mTOR inhibition by preventing the translocation of mTOR to lysosomal membranes, which was dependent on GS activity. Increased GS activity resulted in increased autophagosome turnover as measured by LC3 lipidation, p62 degradation, and confocal imaging of LC3, p62, WIPI-1, ULK2 and Atg12. Inhibition of FOXO3-mediated autophagy resulted in increased apoptosis, suggesting that the induction of autophagy by FOXO3-mediated upregulation of GS is important for cellular survival. These findings reveal a novel signalling network that can directly modulate autophagy through regulation of glutamine metabolism.
2012-07-22 | GSE35703 | GEO
Project description:The PI3K-PKB/c-akt-FOXO signalling network provides a major intracellular hub for regulation of cell proliferation, survival and stress resistance1. Here we report a novel function for FOXO transcription factors in regulating autophagy through modulation of intracellular glutamine levels. To identify novel transcriptional targets of this module we performed an unbiased microarray analysis after conditional activation of the key components PI3K, PKB, FOXO3 and FOXO4. Utilising this global pathway approach we identified glutamine synthetase (GS) as being transcriptionally regulated by PI3K-PKB-FOXO signalling. FOXO-mediated increase in GS expression specifically induced glutamine production independently of cell type, and this was evolutionary conserved. FOXO activation resulted in mTOR inhibition by preventing the translocation of mTOR to lysosomal membranes, which was dependent on GS activity. Increased GS activity resulted in increased autophagosome turnover as measured by LC3 lipidation, p62 degradation, and confocal imaging of LC3, p62, WIPI-1, ULK2 and Atg12. Inhibition of FOXO3-mediated autophagy resulted in increased apoptosis, suggesting that the induction of autophagy by FOXO3-mediated upregulation of GS is important for cellular survival. These findings reveal a novel signalling network that can directly modulate autophagy through regulation of glutamine metabolism.
2012-07-22 | GSE35701 | GEO
Project description:Introduction Basal-like (BLCs) and epidermal growth factor receptor 2 overexpressing (HER2+) carcinomas are the subgroups of breast cancers which have the more aggressive clinical behavior. In contrast to HER2+ carcinomas, no targeted therapy is currently available for the treatment of patients with BLCs. In order to discover potential therapeutic targets, we searched for deregulated signaling pathways in human BLCs. Methods In this study, we focused on the oncogenic phosphatidylinositol 3-kinase (PI3K) pathway in twelve BLCs, and compared it to a control series of eleven hormonal receptor negative- and grade III- matched HER2+ carcinomas. The two tumor populations were first characterized by immunohistochemistry and gene expression. The PI3K pathway was then investigated by gene copy-number analysis, gene expression profiling and at a proteomic level using reverse phase protein array technology and tissue microarray. The effects of PI3K inhibition pathway on proliferation and apoptosis was further analyzed in three human basal-like cell lines. Results The PI3K pathway was found to be activated in BLCs and up-regulated compared to HER2+ tumors as shown by a significantly increased activation of the downstream targets Akt and mTOR. BLCs expressed significantly lower levels of the tumor suppressor PTEN and PTEN levels correlated negatively in a significant manner with Akt activity within that population. PTEN protein expression correlated significantly with PTEN DNA copy number and more importantly, reduced PTEN DNA copy numbers were observed specifically in BLCs. Similarly to human samples, basal-like cell lines exhibited an activation of PI3K / Akt pathway and low/lack PTEN expression. Both PI3K and mTOR inhibitors led to basal-like cell growth arrest. However, apoptosis was observed specifically after PI3K inhibition.
2008-12-03 | GSE13787 | GEO
Project description:Roquin proteins are required to preclude spontaneous T cell activation and aberrant T follicular helper (Tfh) or T helper 17 (Th17) differentiation. Here, we show that deletion of Roquin encoding alleles in regulatory T cells (Tregs) also caused the activation of conventional T cells. These Tregs exhibited a follicular Treg phenotype, CD25 downregulation and could not protect from colitis. Mechanistically, Roquin was required for full expression and activity of Pten and Foxo1, two essential signaling molecules in Tregs and effector T cells. Roquin upregulated Pten by interfering with miR-17~92 binding to an overlapping cis-element in the Pten 3' UTR and downregulated the Foxo1-specific E3 ubiquitin ligase Itch. Loss of Roquin enhanced mTOR signaling and global protein synthesis, while inhibition of PI3K or mTOR in Roquin-deficient CD4+ T cells corrected increased Tfh and Th17 differentiation. Thereby, the control of PI3K-mTOR signaling by Roquin prevents autoimmunity through T cell-intrinsic and Treg-mediated regulation.
2018-01-08 | GSE86110 | GEO
Project description:Phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway activation contributes to mantle cell lymphoma (MCL) pathogenesis and drug resistance. However, the use of mTOR inhibitors as single agents have shown limited clinical efficacy in relation with drug activation of feedback loops. Selective PI3K inhibition or dual PI3K/mTOR catalytic inhibition are different therapeutic approaches developed to achieve effective pathway blockage. Here, we evaluated the antitumor activity of a mTOR inhibitor, a pan-PI3K inhibitor and a dual PI3K/mTOR inhibitor in primary MCL cells. We found that dual PI3K/mTOR inhibitor modulated angiogenesis, tumor invasiveness and cytokine signaling compared to a mTOR inhibitor and a pan-PI3K inhibitor in MCL. We used microarrays to compare the effect of these three compounds in MCL and identified distinct classes of down-regulated genes modulated by each compound. Global RNA expression in primary cells from two MCL patients treated with a mTOR inhibitor, a pan-PI3K inhibitor and a dual PI3K/mTOR inhibitor for 8 hours
2013-12-14 | E-GEOD-53309 | biostudies-arrayexpress
Project description:Purpose: The phosphoinositide 3-kinase (PI3K) pathway is fundamental for cell proliferation and survival and is frequently altered and activated in neoplasia, including carcinomas of the lung. In this study we investigated the potential of targeting the catalytic class IA PI3K isoforms in small cell lung cancer (SCLC), which is the most aggressive of all lung cancer types. Experimental Design: The expression of PI3K isoforms in patient specimens was analyzed. The effects on SCLC cell survival and downstream signaling were determined following PI3K isoform inhibition by selective inhibitors or down-regulation by small interfering RNA. Results: Over-expression of the PI3K isoforms p110 -alpha and p110-alpha was shown by immunohistochemistry in primary SCLC tissue samples. Targeting the PI3K p110 -alpha with RNA interference (RNAi) or selective pharmacological inhibitors resulted in strongly affected cell proliferation of SCLC cells in vitro and in vivo, while targeting p110-alph was less effective. Inhibition of p110 -alpha also resulted in increased apoptosis and autophagy, which was accompanied by decreased phosphorylation of Akt and components of the mammalian target of rapamycin (mTOR) pathway, such as the ribosomal S6 protein, and the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1). A DNA microarray analysis revealed that p110-alpha inhibition profoundly affected the balance of pro- and anti-apoptotic Bcl-2 family proteins. Finally, p110 -alpha inhibition led to impaired SCLC tumor formation and vascularization in vivo. Conclusion: Together our data demonstrate the key involvement of the PI3K isoform p110 -alpha in multiple tumor-promoting processes in SCLC. 3 control samples, 3 samples for two treaments
2012-12-01 | E-GEOD-40564 | biostudies-arrayexpress