Ligand-dependent genomic function of glucocorticoid receptor in triple-negative breast cancer
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ABSTRACT: Glucocorticoids (GC) have been widely used as coadjuvants in the treatment of solid tumors, but GC treatment may be associated with poor pharmacotherapeutic response and/or prognosis. The genomic action of GC in these tumors is largely unknown. Here we find that dexamethasone (Dex, a synthetic GC) regulated genes in triple-negative breast cancer (TNBC) cells are associated with drug resistance. Importantly, these GC-regulated genes are aberrantly expressed in TNBC patients and associated with unfavorable clinical outcomes. Interestingly, in TNBC cells, Compound A (CpdA, a selective GR modulator) only regulates a small number of genes not involved in carcinogenesis and therapy resistance. Mechanistic studies using a ChIP-exo approach reveal that Dex- but not CpdA-liganded glucocorticoid receptor (GR) binds to a single glucocorticoid response element (GRE), which drives the expression of pro-tumorigenic genes. Our data suggest that development of safe coadjuvant therapy should consider the distinct genomic function between Dex- and CpdA-liganded GR.
Project description:Glucocorticoids (GC) have been widely used as coadjuvants in the treatment of solid tumors, but GC treatment may be associated with poor pharmacotherapeutic response and/or prognosis. The genomic action of GC in these tumors is largely unknown. Here we find that dexamethasone (Dex, a synthetic GC) regulated genes in triple-negative breast cancer (TNBC) cells are associated with drug resistance. Importantly, these GC-regulated genes are aberrantly expressed in TNBC patients and associated with unfavorable clinical outcomes. Interestingly, in TNBC cells, Compound A (CpdA, a selective GR modulator) only regulates a small number of genes not involved in carcinogenesis and therapy resistance. Mechanistic studies using a ChIP-exo approach reveal that Dex- but not CpdA-liganded glucocorticoid receptor (GR) binds to a single glucocorticoid response element (GRE), which drives the expression of pro-tumorigenic genes. Our data suggest that development of safe coadjuvant therapy should consider the distinct genomic function between Dex- and CpdA-liganded GR. To study GR-regulated genes and define GRE in human genome, RNA-seq and GR ChIP-exo are performed in MDA-MB-231 cells before/after dex and CpdA stimulation. Each experiment includes two replicates.
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
Project description:The project is directed to the development of selective glucocorticoid receptor agonists for anticancer therapy. Glucocorticoids (GC) are widely used in treatment of many types of cancer due to its ability to induce apoptosis in malignant cells (in blood cancer therapy) and to prevent nausea and emesis (in the chemotherapy of solid tumors). However, severe dose-limiting side effects occur, including osteoporosis, muscle wasting, diabetes and other metabolic complications. Both beneficial and harmful effects of glucocorticoids are due to selective activation or repression of particular genes by glucocorticoid receptor (GR). GR regulates gene expression via transactivation that requires GR homodimer binding to gene promoters and transrepression mediated via negative interaction between GR and other transcription factors as well as binding with negative glucocorticoid response elements (nGRE) in genes. GR transactivation is linked to metabolic side effects, while GR transrepression underlies glucocorticoid therapeutic action. Novel selective GR agonist Compound A (CpdA) prevents GR dimerization and transactivation, specifically activates GR transrepression, and has fewer side effects compared to glucocorticoids. Here we compare the gene expression profiles in lymphoma cells treated with glucocorticoid Dexamethasone (Dex) or CpdA
Project description:The project is directed to the development of selective glucocorticoid receptor agonists for anticancer therapy. Glucocorticoids (GC) are widely used in treatment of many types of cancer due to its ability to induce apoptosis in malignant cells (in blood cancer therapy) and to prevent nausea and emesis (in the chemotherapy of solid tumors). However, severe dose-limiting side effects occur, including osteoporosis, muscle wasting, diabetes and other metabolic complications. Both beneficial and harmful effects of glucocorticoids are due to selective activation or repression of particular genes by glucocorticoid receptor (GR). GR regulates gene expression via transactivation that requires GR homodimer binding to gene promoters and transrepression mediated via negative interaction between GR and other transcription factors as well as binding with negative glucocorticoid response elements (nGRE) in genes. GR transactivation is linked to metabolic side effects, while GR transrepression underlies glucocorticoid therapeutic action. Novel selective GR agonist Compound A (CpdA) prevents GR dimerization and transactivation, specifically activates GR transrepression, and has fewer side effects compared to glucocorticoids. Here we compare the gene expression profiles in prostate cancer cells treated with glucocorticoid Dexamethasone (Dex) or CpdA
Project description:The glucocorticoid receptor (GR) is a crucial drug target in multiple myeloma as its activation with glucocorticoids effectively triggers myeloma cell death. However, as high-dose glucocorticoids are also associated with deleterious side effects, novel approaches are urgently needed to improve GR’s action in myeloma. Here we reveal a functional crosstalk between GR and the mineralocorticoid receptor (MR) that culminates in improved myeloma cell killing. We show that the GR agonist Dexamethasone (Dex) downregulates MR levels in a GR-dependent way in myeloma cells. Co-treatment of Dex with the MR antagonist Spironolactone (Spi) enhances Dex-induced cell killing in primary, newly diagnosed GC-sensitive myeloma cells, while in a relapsed GC-resistant setting, Spi alone induces distinct myeloma cell killing. On a mechanistic level, we find that a GR-MR crosstalk is arising from an endogenous interaction between GR and MR in myeloma cells. Quantitative dimerization assays show that Spi reduces Dex-induced GR-MR heterodimerization and completely abolishes Dex-induced MR MR homodimerization but leaves GR-GR homodimerization intact. Unbiased transcriptomics further reveals that c-myc and many of its target genes are downregulated most by Dex and Spi combined, while proteomics analyses identify that several metabolic hallmarks are modulated most by this combination treatment. Finally, we identified a subset of Dex+Spi downregulated genes and proteins that may predict prognosis in the CoMMpass patient cohort. Our study demonstrates that GR-MR crosstalk is therapeutically relevant in myeloma as it provides novel strategies towards glucocorticoid-based dose-reduction.
Project description:Glucocorticoid plays an essential role in various stress responses and metabolism, which is mediated by the glucocorticoid receptor (GR) in cells. This hormonal action is integrated to transcriptional control of the GR target genes in cell type-specific and condition-dependent manners. In this study, we report that GR regulates the angiopoietin-like 4 (ANGPTL4) gene in a CCCTC-binding factor (CTCF)-mediated chromatin context in human hepatic HepG2 cells. There were at least four CTCF-enriched sites and two GR-binding sites in the ANGPTL4 locus. Among them, major CTCF-enriched site was positioned nearly GR-bound enhancer of this gene. Using treatment with the synthetic glucocorticoid dexamethasone (Dex), our data showed that CTCF is required for proper induction and subsequent silencing of ANGPTL4 gene. Interestingly, this gene induction was diminished under the long-term Dex pretreatment. Although ANGPTL4 locus maintains stable higher-order chromatin conformation at the basal and the Dex-treated states, liganded GR activated the ANGPTL4 gene, but not the neighboring three genes, via the interactions between enhancer, promoter and CTCF sites. These results reveal that liganded GR spatiotemporally controls ANGPTL4 gene in the chromosomal context.
Project description:Obesity, a worldwide epidemic, leads to various metabolic disorders threatening human health. In response to stress or fasting, glucocorticoid (GC) levels are elevated to promote food intake. This involves GC-induced expression of the orexigenic neuropeptides in agouti-related protein (AgRP) neurons of the hypothalamic arcuate nucleus (ARC) via the GC receptor (GR). Here, we report a selective GR modulator (SGRM) that suppresses GR-induced transcription of genes with non-classical glucocorticoid response elements (GREs) such as Agrp-GRE, but not with classical GREs, and via this way may serve as a novel anti-obesity agent. We have identified a novel SGRM, 2-O-trans-p-coumaroylalphitolic acid (Zj7), a triterpenoid extracted from the Ziziphus jujube plant, that selectively suppresses GR transcriptional activity in Agrp-GRE without affecting classical GREs. Zj7 reduces the expression of orexigenic genes in the ARC and exerts a significant anorexigenic effect with weight loss and increased energy expenditure in both high-fat diet-induced obese and genetically obese db/db mouse models. Transcriptome analysis showed that Zj7 represses the expression of a group of orexigenic genes including Agrp and Npy induced by the synthetic GR ligand dexamethasone (Dex) in the hypothalamus. Overall, our studies demonstrate that selectively targeting the orexigenic action of GR in AgRP neurons is a promising approach for the treatment of metabolic disorders with fewer side effects.
Project description:The glucocorticoid receptor (GR) binds the human genome at >10,000 sites, but only regulates the expression of hundreds of genes. To determine the functional effect of each site, we measured the glucocorticoid (GC) responsive activity of nearly all GR binding sites (GBSs) captured using chromatin immunoprecipitation (ChIP) in A549 cells. 13% of GBSs assayed had GC-induced activity. The responsive sites were defined by direct GR binding via a GC response element (GRE) and exclusively increased reporter- gene expression. Meanwhile, most GBSs lacked GC-induced reporter activity. The non-responsive sites had epigenetic features of steady state enhancers and clustered around direct GBSs. Together, our data support a model in which clusters of GBSs observed with ChIP-seq reflect interactions between direct and tethered GBSs over tens of kilobases. We further show that those interactions can synergistically modulate the activity of direct GBSs, and may therefore play a major role in driving gene activation in response to GCs. Glucoroticoid receptor binding site chip-seq libraries were cloned into STARR-seq for massively parallel functioal analysis. The results were confirmed by ChIP-Exo performed on the GR in A549 cells treated with 100 nM dexamethasone for one hour. This dataset [6] contains the ChIP exo data from cells treated with 100 nM DEX.
Project description:The glucocorticoid receptor (GR) binds the human genome at >10,000 sites, but only regulates the expression of hundreds of genes. To determine the functional effect of each site, we measured the glucocorticoid (GC) responsive activity of nearly all GR binding sites (GBSs) captured using chromatin immunoprecipitation (ChIP) in A549 cells. 13% of GBSs assayed had GC-induced activity. The responsive sites were defined by direct GR binding via a GC response element (GRE) and exclusively increased reporter- gene expression. Meanwhile, most GBSs lacked GC-induced reporter activity. The non-responsive sites had epigenetic features of steady state enhancers and clustered around direct GBSs. Together, our data support a model in which clusters of GBSs observed with ChIP-seq reflect interactions between direct and tethered GBSs over tens of kilobases. We further show that those interactions can synergistically modulate the activity of direct GBSs, and may therefore play a major role in driving gene activation in response to GCs. Glucoroticoid receptor binding site chip-seq libraries were cloned into STARR-seq for massively parallel functional analysis. The results were confirmed by ChIP-Exo performed on the GR in A549 cells treated with 100 nM dexamethasone for one hour. This dataset [8] contains ChIP-seq data for A549 cells treated with DEX or EtOH for 3 hours.
Project description:The glucocorticoid receptor (GR) binds the human genome at >10,000 sites, but only regulates the expression of hundreds of genes. To determine the functional effect of each site, we measured the glucocorticoid (GC) responsive activity of nearly all GR binding sites (GBSs) captured using chromatin immunoprecipitation (ChIP) in A549 cells. 13% of GBSs assayed had GC-induced activity. The responsive sites were defined by direct GR binding via a GC response element (GRE) and exclusively increased reporter- gene expression. Meanwhile, most GBSs lacked GC-induced reporter activity. The non-responsive sites had epigenetic features of steady state enhancers and clustered around direct GBSs. Together, our data support a model in which clusters of GBSs observed with ChIP-seq reflect interactions between direct and tethered GBSs over tens of kilobases. We further show that those interactions can synergistically modulate the activity of direct GBSs, and may therefore play a major role in driving gene activation in response to GCs. Glucoroticoid receptor binding site chip-seq libraries were cloned into STARR-seq for massively parallel functional analysis. The results were confirmed by ChIP-Exo performed on the GR in A549 cells treated with 100 nM dexamethasone for one hour. This dataset [3] contains the results of RNA-seq performed on A549 cells treated with DEX or EtOH for 3 hours.