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PI3Kδ inhibition potentiates glucocorticoids in B-ALL by decreased receptor phosphorylation and enhanced gene regulation

ABSTRACT: Glucocorticoids, including dexamethasone and prednisone, are key components of therapy for B-lymphoblastic leukemia (B-ALL) that work through the glucocorticoid receptor (GR). However, glucocorticoids are not effective for all patients, leading to poor outcomes, and the high doses used in chemotherapy cause many toxicities. We have shown that inhibition of the leukocyte restricted PIK3δ is a promising way to specifically enhance glucocorticoids in B-ALL, with the potential to improve outcomes without increasing toxicities. Here, we show that the PI3Kδ inhibitor idelalisib potentiates both prednisolone and dexamethasone in both B-ALL cell lines and primary patient specimens, particularly at sub-saturating doses. Potentiation is partially explained by a widespread enhancement of glucocorticoid gene regulation, including effector genes that drive B-ALL cell death. Idelalisib causes a reduction in direct phosphorylation of GR at S203 and S226. Ablation of these phospho-acceptor sites enhances glucocorticoid potency. Phosphorylation of S226 inhibits GR DNA binding, indicating that PI3Kδ mediated phosphorylation directly inhibits GR function in part though reduction of DNA binding affinity. Thus, PI3Kδ inhibition improves glucocorticoid efficacy in B-ALL in part by decreasing GR phosphorylation and enhancing DNA binding and downstream gene regulation. Identification of this and other contributing mechanisms will help identify patients who can most benefit clinically from this combination therapy.

ORGANISM(S): Homo sapiens

PROVIDER: GSE215385 | GEO | 2022/10/18

REPOSITORIES: GEO

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Glycogen Synthase Kinase-3-beta Regulates Glucocorticoid Signaling by Phosphorylating the Glucocorticoid Receptor

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2008-11-24 | GSE11205 | GEO

MDFIC alteration of the GR transcriptome in COS-1 cells depends on S211 phosphorylation of GR

Project description:Glucocorticoids are primary stress hormones that regulate many physiological processes, and synthetic derivatives of these molecules and are widely used in the clinic. The cellular response to glucocorticoids is remarkably diverse; however, the molecular factors that govern tissue specificity are poorly understood. The actions of glucocorticoids are mediated by the glucocorticoid receptor (GR). To discover new proteins that interact with GR and modulate its function, we performed a yeast 2 hybrid assay using as bait the hinge region of GR. The MyoD family inhibitor domain-containing (MDFIC) protein was identified as a binding partner for GR. Knockdown of MDFIC in A549 cells alters the GR transcriptome. Overexpression of MDFIC with GR in COS-1 cells also modulates the GR transcriptome by expanding the number of genes regulated in response to glucocorticoid treatment. Our findings in A549 cells suggest that MDFIC alters the gene regulatory profile of GR by modulating receptor phosphorylation at several residues, including S211. To further investigate the molecular link between MDFIC-mediated effects on GR phosphorylation at S211 and alterations in the GR transcriptome, we performed a genome-wide microarray in COS-1 cells that were transfected with the GR phosphorylation mutant S211A or S211A and MDFIC. The transfected cells were treated with vehicle or the synthetic glucocorticoid Dexamethasone (Dex) for 6 hours. The ability of MDFIC to expand the GR transcriptome was attenuated in cells expressing S211A mutant.

2017-04-07 | GSE93900 | GEO

Potentiation of glucocorticoid signaling by chloroquine via inhibition of lysosomes

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2012-01-18 | E-GEOD-24579 | biostudies-arrayexpress

Whole-genome GR binding sites and histone acetylation status in pediatric acute lymphoblastic leukemia patient-derived xenografts following dexamethasone treatment in vivo

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2014-12-18 | E-GEOD-58266 | biostudies-arrayexpress

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2010-07-30 | E-GEOD-22647 | biostudies-arrayexpress

Comparative analysis of gene expression profiles in lymphoma cells after treatment by Dexamethasone or CpdA

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2015-07-21 | GSE71102 | GEO

Comparative analysis of gene expression profiles in prostate cancer cells after treatment by Dexamethasone or CpdA

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2015-07-21 | GSE71099 | GEO

Glucocorticoid Regulated Transcriptome in Wild-type and GR-C3 Knockin Mouse Embryonic Fibroblasts

Project description:Glucocorticoids are primary stress hormones and their synthetic derivatives are widely used clinically. The therapeutic efficacy of these steroids is limited by severe side effects and glucocorticoid resistance. Multiple glucocorticoid receptor (GR) isoforms are produced by alternative translation initiation; however, the role individual isoforms play in controlling tissue-specific responses to glucocorticoids in vivo is unknown. We have generated knockin mice that exclusively express the most active receptor isoform, GR-C3. The GR-C3 knockin mice die at birth due to respiratory distress but can be completely rescued by antenatal glucocorticoid administration. To evaluate the GR-C3 transcriptome, we prepared mouse embryonic fibroblasts (MEFs) from E12.5 wild-type (WT) and GR-C3 knockin embryos and treated the cells with vehicle or the synthetic glucocorticoid Dexamethasone (Dex) for 6 hours. The GR-C3 isoform was found to have a markedly different gene-regulatory profile than GR in WT MEFs.

2018-04-23 | GSE103675 | GEO

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Project description:Glucocorticoids are widely used to treat inflammatory disorders. Prolonged use results in side effects including osteoporosis, diabetes and obesity. The selective glucocorticoid receptor (GR) modulator Compound A (CpdA) exhibits an inflammation-suppressive effect, largely in absence of detrimental side effects. To understand the mechanistic differences between the classic glucocorticoid dexamethasone (DEX) and CpdA, we looked for proteins oppositely regulated using an unbiased proteomics approach. We found that the autophagy receptor p62 but not GR mediates the anti-inflammatory action of CpdA in macrophages. CpdA drives the upregulation of p62 by recruiting the NRF2 transcription factor to its promoter. Contrarily, the classic GR ligand dexamethasone recruits GR to p62 and other NRF2 controlled gene promoters, resulting in gene downregulation. Both DEX and CpdA are able to induce autophagy, albeit in a cell-type and time-dependent manner. Suppression of LPS-induced IL-6 and MCP1 genes in bone marrow-derived macrophages by CpdA is hampered upon p62 silencing, confirming that p62 is essential for the anti-inflammatory capacity of CpdA. Together, these results demonstrate how off-target mechanisms of selective GR ligands may establish a more efficient anti-inflammatory therapy

2022-06-03 | PXD007793 | Pride

Intestinal epithelial GR in response to DEX treatment

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