Mus musculus
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA106885 | ENA |
REPOSITORIES: ENA
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Project description:Glucocorticoids are an essential component of the treatment of lymphoid malignancies and resistance to glucocorticoid therapy constitutes a prominent clinical problem in relapsed and refractory lymphoblastic leukemias. Constitutively active NOTCH signaling is involved in the pathogenesis of over 50% of T-cell lymphoblastic leukemia (T-ALL) which harbor activating mutations in the NOTCH1 gene. Aberrant NOTCH1 signaling has been shown to protect normal thymocytes from glucocorticoid induced cell death. Here we analyzed the interaction of glucocorticoid therapy with inhibition of NOTCH signaling in the treatment of T-ALL. Gamma-secretase inhibitors (GSI), which block the activation of NOTCH receptors, amplified the transcriptional changes induced by glucocorticoid treatment, including glucocorticoid receptor autoinduction and restored sensitivity to dexamethasone in glucocorticoid-resistant T-ALL cells. Apoptosis induction upon inhibition of NOTCH signaling and activation of the glucocorticoid receptor was dependent on transcriptional upregulation of BIM and subsequent activation of the mitochondrial/intrinsic cell death pathway. Finally, we used a mouse xenograft model of T-ALL to demonstrate that combined treatment with dexamethasone and a GSI results in improved antileukemic effects in vivo. These studies provide insight in the mechanisms of glucocorticoid resistance and serve as rationale for the use of glucocorticoid and GSIs in combination in the treatment of T-ALL. Experiment Overall Design: Duplicate samples (biologic replicas) from CUTLL1 cells were treated for 24 hours with vehicle only (DMSO), dexamethasone (1microM), a gamma-secretase inhibitor (CompE 100nM) and a combination of dexamethasome plus gamma secretase inhibitor at the same concentrations indicated before. Gene expression profiling was analyzed to identify gene expression signatures assocuated with glucocorticoid treatment (dexamethasone), inhibition of NOTCH1 by gamma secretase inhibitor (CompE) or the combination of both treatments.
2009-01-13 | E-GEOD-7067 | biostudies-arrayexpress
Project description:T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic cancer frequently associated with activating mutations in NOTCH1. Early studies identified NOTCH1 as an attractive therapeutic target for the treatment of T-ALL through the use of gamma-secretase inhibitors (GSIs). Here, we characterized the interaction between PF-03084014, a clinically-relevant GSI, and dexamethasone in preclinical models of glucocorticoid-resistant T-ALL. Combination treatment of the GSI PF-03084014 with glucocorticoids induced a synergistic antileukemic effect in human T-ALL cell lines and primary human T-ALL patient samples. Molecular characterization of the response to PF-03084014 plus glucocorticoids through gene expression profiling revealed transcriptional upregulation of the glucocorticoid receptor as the mechanism mediating the enhanced glucocorticoid response. Moreover, treatment with PF-03084014 and glucocorticoids in combination was highly efficacious in vivo, with enhanced reduction of tumor burden in a xenograft model of T-ALL. Finally, glucocorticoid treatment was highly effective at reversing PF-03084014-induced gastrointestinal toxicity via inhibition of goblet cell metaplasia. These results suggest that combination of PF-03084014 treatment with glucocorticoids may be well-tolerated and highly active for the treatment of glucorticoid-resistant T-ALL. Duplicate samples of the CUTLL1 T-ALL cell line were treated with vehicle only (DMSO), the gamma-secretase inhibitor PF-03084014 (1 microM), dexamethasone (1 microM), or PF-03084014 (1 microM). plus dexamethasone (1 microM) for 48 hours. Gene expression profiling was analyzed to identify gene expression signatures assocuated with glucocorticoid treatment (dexamethasone), inhibition of NOTCH1 by gamma secretase inhibitor (PF-03084014) or the combination of both treatments.
2011-11-09 | E-GEOD-33562 | biostudies-arrayexpress
Project description: Not available
| S-EPMC8784167 | biostudies-literature
Project description:Glucocorticoids are an essential component of the treatment of lymphoid malignancies and resistance to glucocorticoid therapy constitutes a prominent clinical problem in relapsed and refractory lymphoblastic leukemias. Constitutively active NOTCH signaling is involved in the pathogenesis of over 50% of T-cell lymphoblastic leukemia (T-ALL) which harbor activating mutations in the NOTCH1 gene. Aberrant NOTCH1 signaling has been shown to protect normal thymocytes from glucocorticoid induced cell death. Here we analyzed the interaction of glucocorticoid therapy with inhibition of NOTCH signaling in the treatment of T-ALL. Gamma-secretase inhibitors (GSI), which block the activation of NOTCH receptors, amplified the transcriptional changes induced by glucocorticoid treatment, including glucocorticoid receptor autoinduction and restored sensitivity to dexamethasone in glucocorticoid-resistant T-ALL cells. Apoptosis induction upon inhibition of NOTCH signaling and activation of the glucocorticoid receptor was dependent on transcriptional upregulation of BIM and subsequent activation of the mitochondrial/intrinsic cell death pathway. Finally, we used a mouse xenograft model of T-ALL to demonstrate that combined treatment with dexamethasone and a GSI results in improved antileukemic effects in vivo. These studies provide insight in the mechanisms of glucocorticoid resistance and serve as rationale for the use of glucocorticoid and GSIs in combination in the treatment of T-ALL. Keywords: Drug response
2008-12-01 | GSE7067 | GEO
Project description:Gamma-secretase inhibitors (GSIs), which block the activation of NOTCH receptors, are being tested in the treatment of T-cell acute lymphoblastic leukemia (T-ALL). Thus far, limited antileukemic cytotoxicity and severe gastrointestinal toxicity have restricted the clinical application of these targeted drugs. Here we show that combination therapy with GSIs plus glucocorticoids can improve the antileukemic effects of GSIs and reduce their gut toxicity in vivo. Inhibition of NOTCH1 signaling in glucocorticoid-resistant T-ALL restored glucocorticoid receptor auto-up-regulation and induced apoptotic cell death through induction of BIM expression. Additionally, cotreatment with glucocorticoids induced Ccnd2 upregulation in the gut which protected mice from the intestinal secretory metaplasia typically induced by loss of NOTCH signaling. These results support a role for glucocorticoids plus GSIs in the treatment of glucocorticoid-resistant T-ALL. Experiment Overall Design: Experiments analyzing the interacition of dexamethasone and the gamma-secretase inhibitor DBZ were carried out in 6-week-old C57/Black6 female mice (Jackson Laboratory). In these studies we treated mice with vehicle (DMSO) (n=2), dexamethasone (15 mg/kg) (n=2), DBZ (10 micromol/kg) (n=2) and dexamethasone (15 mg/kg) plus DBZ (10 micromol/kg) (n=2) daily by intraperitoneal injection for 5 days. At the end of the treatment, animals were euthanized and segments of the small intestine were collected and processed for RNA extraction, histological and immunohistochemical analysis.
2009-04-10 | E-GEOD-11184 | biostudies-arrayexpress
Project description:γ-secretase is a transmembrane protease complex responsible for processing multiple type I transmembrane proteins, including the amyloid precursor protein and NOTCH. Despite various γ-secretase inhibitors and modulators developed in the past decades to target Notch-dependent cancers, their clinical use is still limited due to the low substrate specificity and on-target gut toxicity. Using a proteomics-based screening approach, we found that the dedicator of cytokinesis protein 2 (DOCK2) interacts with the γ-secretase complex component Nicastrin, regulating Nicastrin N45-mannosidation and γ-secretase activity towards NOTCH receptors.
2026-07-31 | PXD057036 | Pride
Project description:Presenilin mutations that alter γ-secretase activity cause familial Alzheimer's disease (AD), whereas ApoE4, an apolipoprotein for cholesterol transport, predisposes to sporadic AD. Both sporadic and familial AD feature synaptic dysfunction. Whether γ-secretase is involved in cholesterol metabolism and whether such involvement impacts synaptic function remains unknown. Here, we show that in human neurons, chronic pharmacological or genetic suppression of γ-secretase increases synapse numbers but decreases synaptic transmission by lowering the presynaptic release probability without altering dendritic or axonal arborizations. In search of a mechanism underlying these synaptic impairments, we discovered that chronic γ-secretase suppression robustly decreases cholesterol levels in neurons but not in glia, which in turn stimulates neuron-specific cholesterol-synthesis gene expression. Suppression of cholesterol levels by HMG-CoA reductase inhibitors (statins) impaired synaptic function similar to γ-secretase inhibition. Thus, γ-secretase enables synaptic function by maintaining cholesterol levels, whereas the chronic suppression of γ-secretase impairs synapses by lowering cholesterol levels.
2023-08-06 | GSE206102 | GEO
Project description: Not available
| S-EPMC11335981 | biostudies-literature
Project description:Effect of a gamma secretase inhibitor on the T29 cell line
| PRJNA197252 | ENA
Project description: Not available
| S-EPMC5321798 | biostudies-literature