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Project description:Impact of mTOR inhibition on RNA expression in AT/RT
| PRJNA815668 | ENA
Project description:Gliomas are highly aggressive brain tumors characterized by poor prognosis and composed of diffusely infiltrating tumor cells that intermingle with non-neoplastic cells in the tumor microenvironment, including neurons. Neurons are increasingly appreciated as important reactive components of the glioma microenvironment, due to their role in causing hallmark glioma symptoms, cognitive deficits, and seizures, as well as potentially driving glioma progression. Separately, mTOR signaling has been shown to have pleiotropic effects in the brain tumor microenvironment, including regulation of neuronal hyperexcitability. However, the local cellular level effects of mTOR inhibition on glioma-induced neuronal alterations are not well understood. Here we employed neuron-specific profiling of ribosome-bound mRNA via ‘Ribotag’, morphometric analysis, and intravital imaging, along with pharmacological mTOR inhibition to investigate the impact of glioma burden on excitatory neuronal pathophysiology as well as the impact of mTOR inhibition on these neuronal alterations. The Ribotag analysis of peritumoral excitatory neurons showed an upregulation in transcripts encoding for F-actin binding and other dendritic spine-enriched proteins. Light and electron microscopy analyses revealed marked decreases in dendritic spine density in peritumoral neurons. Intravital two-photon imaging in peritumoral excitatory neurons revealed progressive alterations in neuronal activity, both at the population and single neuron level, throughout tumor growth. Intravital two-photon imaging also revealed altered stimulus-evoked somatic calcium activity, both in rate and temporal alignment, which was most pronounced in neurons with high-tumor burden. A single acute dose of AZD8055, a mTORC1 and mTORC2 inhibitor reversed the translational effect of glioma on neurons, increased dendritic spine density, and functional neuronal alterations. These results point to mTOR-driven pathological plasticity in neurons at the infiltrative margin of glioma – manifested by alterations in ribosome-bound mRNA, dendritic spine morphology, and stimulus-evoked neuronal activity. Collectively, our work identifies the pathological changes that peritumoral neurons experience as both hyperlocal and reversible under the influence of mTOR inhibition, providing foundational knowledge for developing therapies targeting neuronal signaling in glioma.
2024-01-30 | GSE254007 | GEO
Project description:The PI3K/mammalian target of rapamycin (mTOR) pathway is dysregulated in over 50% of human GBM but remains a challenging clinical target. Inhibitors against PI3K/mTOR mediators have limited clinical efficacy as single agents. Gene expression profiling after PI3K/mTOR inhibition treatment was analyzed by Affymetrix microarrays.
2016-05-20 | GSE79316 | GEO
Project description:Pancreatic ductal adenocarcinoma (PDAC), like many KRAS-driven tumors, preferentially loses CDKN2A to bypass the RB tumor suppressive pathway. This finding and a gene expression profile indicative of a CDK4/6-driven cell cycle suggests that PDAC could be particularly sensitive to CDK4/6 inhibition. Analysis of a panel of patient-derived cell lines and xenografts indicates that many pancreatic cancers have an intrinsic resistance to CDK4/6 inhibition that is not due to known molecular mechanisms. Rather, there is a rapid and potent adaptive response that led to the upregulation of Cyclin D1 and Cyclin E proteins and compromised the suppression of a DNA replication gene expression program. These adaptive responses are dependent on MTOR signaling both in cell and animal studies. Strikingly, combination treatments with MTOR and CDK4/6 inhibitor had potent activity across a large number of patient derived models of PDAC underscoring the potential clinical efficacy.
2019-05-14 | GSE113922 | GEO
Project description:The mechanistic target of rapamycin (mTOR) is a central regulator of cell growth and an attractive anti-cancer target that integrates diverse signals to control cell proliferation. Previous studies using mTOR inhibitors have shown that mTOR targeting suppresses gene expression and cell proliferation. To date, however, mTOR targeted therapies in cancer have seen very limited efficacy, and one key issue is related to the development of evasive resistance. In this manuscript, through the use of a gene targeting mouse model, we have found that inducible deletion of mTOR in hematopoietic stem cells (HSCs) results in a loss of quiescence and increased proliferation. Adaptive to the mTOR loss, mTOR-/- HSCs increase chromatin accessibility and activate global gene expression, contrary to the effects of short-term inhibition by mTOR inhibitors. Mechanistically, such genomic changes are due to a rewiring and adaptive activation of the ERK/MNK/eIF4E signaling pathway that enhances the protein translation of RNA polymerase II (RNAP II), which in turn leads to increased c-Myc gene expression, allowing the HSCs to thrive despite loss of a functional mTOR pathway. This adaptive mechanism can also be utilized by leukemia cells undergoing long-term mTOR inhibitor treatment to confer resistance to mTOR drug targeting. The resistance can then be counteracted by MNK, CDK9, or c-Myc inhibition. These results provide new insights into the physiological role of mTOR in mammalian stem cell regulation and implicate a novel mechanism of evasive resistance in the context of mTOR targeting.
2020-12-24 | GSE134316 | GEO
Project description:Human Naive Pluripotency Attained by Transient Inhibition of Mtor
| PRJNA517616 | ENA
Project description:The mTOR (mammalian Target of Rapamycin) pathway is constitutively activated in Diffuse Large B-Cell Lymphoma (DLBCL). mTOR inhibition has been shown to have clinical activity in patients with DLBCL, although overall response rates remain low. We therefore evaluated differences in the transcriptome between DLBCL cell lines with differential sensitivity to the mTOR inhibitor Rapamycin, to (A) identify gene-expression patterns(GEP) capable of identifying sensitivity to Rapamycin, (B) understand the underlying mechanisms of resistance to Rapamycin in DLBCL and (C) identify bioactive molecules likely to synergize with mTOR inhibitors. Using Affymetrix HuGene ST 1.0 microarrays, we were able to identify a gene expression signature capable of accurately predicting sensitivity and resistance to Rapamycin in DLBCL cell lines. Pathway analysis identified the serine/threonine kinase Akt as central to the differentially-expressed gene network. Connectivity mapping of our datasets identified compounds targeting the AKT pathway with a high likelihood of reversing the GEP associated with resistance to Rapamycin. Specifically, we evaluated the HIV protease inhibitor (PI) Nelfinavir, which is known to have anti-cancer and Akt-inhibitory properties, as well as the small molecule Akt inhibitor MK-2206, for their potential to synergize with to Rapamycin in DLBCL. Nelfinavir and MK-2206 caused profound inhibition of cell viability in combination with Rapamycin in DLBCL cell lines. Low nanomolar concentrations of Rapamycin inhibited phosphorylation of Akt and also downstream targets of activated mTOR when used in combination with these Akt inhibitors. These findings have the potential to significantly improve patient selection for mTOR inhibitor therapy, and to improve rates and depths of response. More broadly, they support the use of global RNA expression and connectivity mapping to improve patient selection and identify synergistic drug combinations for cancer therapy. DLBCL cell lines were tested for Rapamycin sensitivity and classified as "sensitive" or "resistant." Genome-wide analysis of all cell lines were performed using the Affymetrix HuGene ST 1.0 Array Platform. Genes with differential expression between sensitive and resistant cell lines were analyzed using Statistical Analysis of Microarrays (SAM) software, and a signature of genes determnined. This signature was found to accurately predict sensitivity or resistance of other DLBCL cell lines, and to identify the protein kinase Akt as central to resistance.
2012-04-29 | E-GEOD-27255 | biostudies-arrayexpress
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:To further develop our gene expression approach to treatment of autoimmunity, we have employed whole genome microarray expression profiling as a discovery platform to identify genes differentially expressed upon immunosuppressor treatment responsible for inhibition of T cell effector functions. Human CD4+CD25- cells from healthy donors were pretreated or not with rapamycin and stimulated with anti-CD3 and anti-CD28 for 12h. mTOR (Mammalian Target of Rapamycin) inhibition-induced gene expression was evaluated in human effector T cells after 1 hour rapamycin pretreatment and compared to vehicle-pretreated cells. Three independent experiments were performed for each of the two different experimental conditions using different donors for each experiment.
2012-09-05 | E-GEOD-29606 | biostudies-arrayexpress