115 research outputs found
A Dexamethasone-regulated Gene Signature Is Prognostic for Poor Survival in Glioblastoma Patients.
No full textBACKGROUND
Dexamethasone is reported to induce both tumor-suppressive and tumor-promoting effects. The purpose of this study was to identify the genomic impact of dexamethasone in glioblastoma stem cell (GSC) lines and its prognostic value; furthermore, to identify drugs that can counter these side effects of dexamethasone exposure.
METHODS
We utilized 3 independent GSC lines with tumorigenic potential for this study. Whole-genome expression profiling and pathway analyses were done with dexamethasone-exposed and control cells. GSCs were also co-exposed to dexamethasone and temozolomide. Risk scores were calculated for most affected genes, and their associations with survival in The Cancer Genome Atlas and Repository of Molecular Brain Neoplasia Data databases. In silico Connectivity Map analysis identified camptothecin as antagonist to dexamethasone-induced negative effects.
RESULTS
Pathway analyses predicted an activation of dexamethasone network (z-score: 2.908). Top activated canonical pathways included "role of breast cancer 1 in DNA damage response" (P=1.07E-04). GSCs were protected against temozolomide-induced apoptosis when coincubated with dexamethasone. Altered cellular functions included cell movement, cell survival, and apoptosis with z-scores of 2.815, 5.137, and -3.122, respectively. CCAAT/enhancer binding protein beta (CEBPB) was activated in a dose dependent manner specifically in slow-dividing "stem-like" cells. CEBPB was activated in dexamethasone-treated orthotopic tumors. Patients with high risk scores had significantly shorter survival. Camptothecin was validated as potential partial neutralizer of dexamethasone-induced oncogenic effects.
CONCLUSIONS
Dexamethasone exposure induces a genetic program and CEBPB expression in GSCs that adversely affects key cellular functions and response to therapeutics. High risk scores associated with these genes have negative prognostic value in patients. Our findings further suggest camptothecin as a potential neutralizer of adverse dexamethasone-mediated effects
Dexamethasone-mediated oncogenicity in vitro and in an animal model of glioblastoma.
No full textOBJECTIVE Dexamethasone, a known regulator of mesenchymal programming in glioblastoma (GBM), is routinely used to manage edema in GBM patients. Dexamethasone also activates the expression of genes, such as CEBPB, in GBM stem cells (GSCs). However, the drug's impact on invasion, proliferation, and angiogenesis in GBM remains unclear. To determine whether dexamethasone induces invasion, proliferation, and angiogenesis in GBM, the authors investigated the drug's impact in vitro, in vivo, and in clinical information derived from The Cancer Genome Atlas (TCGA) cohort. METHODS Expression profiles of patients from the TCGA cohort with mesenchymal GBM (n = 155) were compared with patients with proneural GBM by comparative marker selection. To obtain robust data, GSCs with IDH1 wild-type (GSC3) and with IDH1 mutant (GSC6) status were exposed to dexamethasone in vitro and in vivo and analyzed for invasion (Boyden chamber, human-specific nucleolin), proliferation (Ki-67), and angiogenesis (CD31). Ex vivo tumor cells from dexamethasone-treated and control mice were isolated by fluorescence activated cell sorting and profiled using Affymetrix chips for mRNA (HTA 2.0) and microRNAs (miRNA 4.0). A pathway analysis was performed to identify a dexamethasone-regulated gene signature, and its relationship with overall survival (OS) was assessed using Kaplan-Meier analysis in the entire GBM TCGA cohort (n = 520). RESULTS The mesenchymal subgroup, when compared with the proneural subgroup, had significant upregulation of a dexamethasone-regulated gene network, as well as canonical pathways of proliferation, invasion, and angiogenesis. Dexamethasone-treated GSC3 demonstrated a significant increase in invasion, both in vitro and in vivo, whereas GSC6 demonstrated a modest increase. Furthermore, dexamethasone treatment of both GSC3 and GSC6 lines resulted in significantly elevated cell proliferation and angiogenesis in vivo. Patients with mesenchymal GBM had significant upregulation of dexamethasone-regulated pathways when compared with patients with proneural GBM. A prognostic (p = 0.0007) 33-gene signature was derived from the ex vivo expression profile analyses and used to dichotomize the entire TCGA cohort by high (median OS 12.65 months) or low (median OS 14.91 months) dexamethasone signature. CONCLUSIONS The authors present evidence that furthers the understanding of the complex effects of dexamethasone on biological characteristics of GBM. The results suggest that the drug increases invasion, proliferation, and angiogenesis in human GSC-derived orthotopic tumors, potentially worsening GBM patients' prognoses. The authors believe that careful investigation is needed to determine how to minimize these deleterious dexamethasone-associated side effects in GBM
The transcriptional coactivator TAZ regulates mesenchymal differentiation in malignant glioma
No full textRecent molecular classification of glioblastoma (GBM) has shown that patients with a mesenchymal (MES) gene expression signature exhibit poor overall survival and treatment resistance. Using regulatory network analysis of available expression microarray data sets of GBM, including The Cancer Genome Atlas (TCGA), we identified the transcriptional coactivator with PDZ-binding motif (TAZ), to be highly associated with the MES network. TAZ expression was lower in proneural (PN) GBMs and lower-grade gliomas, which correlated with CpG island hypermethylation of the TAZ promoter compared with MES GBMs. Silencing of TAZ in MES glioma stem cells (GSCs) decreased expression of MES markers, invasion, self-renewal, and tumor formation. Conversely, overexpression of TAZ in PN GSCs as well as murine neural stem cells (NSCs) induced MES marker expression and aberrant osteoblastic and chondrocytic differentiation in a TEAD-dependent fashion. Using chromatin immuno-precipitation (ChIP), we show that TAZ is directly recruited to a majority of MES gene promoters in a complex with TEAD2. The coexpression of TAZ, but not a mutated form of TAZ that lacks TEAD binding, with platelet-derived growth factor-B (PDGF-B) resulted in high-grade tumors with MES features in a murine model of glioma. Our studies uncover a direct role for TAZ and TEAD in driving the MES differentiation of malignant glioma
STEM-02. CHARACTERIZATION OF PATIENT-DERIVED BONE MARROW MESENCHYMAL STEM CELLS AS VIRUS CARRIERS FOR THE TREATMENT OF GLIOBLASTOMA
No full textTGF-ß Mediates the Tropism of Human Mesenchymal Stem Cells (hMSCs) for Malignant Gliomas
No full text
Mesenchymal Stem Cells Display Tumor-Specific Tropism in an RCAS/Ntv-a Glioma Model
No full textAbstractBone marrow-derived mesenchymal stem cells (MSCs) have been shown to localize to gliomas and deliver therapeutic agents. However, the clinical translation of MSCs remains poorly defined because previous studies relied on glioma models with uncertain relevance to human disease, typically xenograft models in immunocompromised mice. To address this shortcoming, we used the RCAS/Ntv-a system, in which endogenous gliomas that recapitulate the tumor and stromal features of human gliomas develop in immunocompetent mice. MSCs were harvested from bonemarrowof Ntv-a mice and injected into the carotid artery of Ntv-a mice previously inoculated with RCAS-PDGF-B and RCAS-IGFBP2 to induce malignant gliomas (n = 9). MSCs were labeled with luciferase for in vivo bioluminescence imaging (BLI). After intra-arterial injection, BLI revealed MSCs in the right frontal lobe in seven of nine mice. At necropsy, gliomas were detected within the right frontal lobe in all these mice, correlating with the location of the MSCs. In the twomice without MSCs based on BLI, no tumor was found, indicating thatMSC localization was tumor specific. In another cohort of mice (n = 9), MSCs were labeled with SP-DiI, a fluorescent vital dye. After intra-arterial injection, fluorescence microscopy revealed SP-DiI-labeled MSCs throughout tumors 1 to 7 days after injection but not in nontumoral areas of the brain. MSCs injected intravenously did not localize to tumors (n = 12). We conclude that syngeneic MSCs are capable of homing to endogenous gliomas in immunocompetent mice. These findings support the use of MSCs as tumor-specific delivery vehicles for treating gliomas
ESI–MS/MS and MALDI-IMS Localization Reveal Alterations in Phosphatidic Acid, Diacylglycerol, and DHA in Glioma Stem Cell Xenografts
No full textMagnetic resonance and photoacoustic imaging of brain tumor mediated by mesenchymal stem cell labeled with multifunctional nanoparticle introduced via carotid artery injection
No full text412 Synergistic Targeting of Lysine-specific demethylase 1 (LSD1) and MAPK Signaling: A Mechanism-Guided Therapeutic Approach for Glioblastoma (GBM)
No full textOBJECTIVES/GOALS: LSD1 is a histone demethylase important in GBM regulation. Our goal is to design a therapeutic strategy for LSD1 inhibitors to meet clinical needs in GBM. Despite the abundance of LSD1 inhibitors, resistance emerges in GBM mouse models. We aim to understand the relevance of proliferative signaling pathways, such as MAPK, in LSD1 inhibitor resistance. METHODS/STUDY POPULATION: Following LSD1 knockdown in GBM cells, we determined differentially expressed genes using RNA-seq and gene set enrichment analysis (GSEA). Kinase signaling processes enriched for LSD1 expression were identified. Utilizing western blot, we assessed LSD1’s impact on MAPK signaling in patient-derived GBM stem cells (GSCs) and pediatric high-grade glioma cell models. Pharmacological evaluation of LSD1 involved five inhibitor candidates. Additionally, we explored LSD1 inhibition in combination with brain penetrant kinase inhibitors, osimertinib and ulixertinib, directed against the epidermal growth factor receptor (EGFR) and MAPK, respectively. The treatment combinations were assessed at multiple concentrations and analyzed using SynergyFinder. RESULTS/ANTICIPATED RESULTS: Pharmacological LSD1 inhibition after 24 hours induced increased phosphorylated ERK1/2 across multiple glioma cell lines. Concurrent LSD1 and EGFR/MAPK inhibition demonstrated improvedin vitro efficacy compared to individual agents. Notably, the combination of Iadademstat (ORY-1001) and osimertinib demonstrated the highest synergy score of 37.2 using the bliss synergy model in the GSC17s. Furthermore, 11 out of the 12 combination treatments tested had a synergistic relationship, with bliss synergy scores greater than 10. DISCUSSION/SIGNIFICANCE: Our study addresses the pressing need for novel therapeutic strategies in GBM. We leveraged pharmacological tools of LSD1 inhibition to determine how they could be used most effectively, revealing kinase inhibition as a promising strategy with demonstrated in vitro efficacy. Future efforts will focus on validating these findingsin vivo
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