Glucocorticoids (GC) are pivotal in the treatment of childhood acute lymphoblastic leukaemia (ALL) but resistance is a continuing clinical problem with the underlying mechanisms still unclear. An isobaric tag proteomic approach was used to compare protein profiles of the B lineage ALL GC-sensitive cell line, PreB 697, and its GC-resistant sub-line, R3F9, before and after dexamethasone exposure. Two transcription factors involved in B- cell differentiation, PAX5 and IRF4, were differentially regulated in the PreB 697 compared to the R3F9 cell line in response to GC. PAX5 basal protein expression was less in R3F9 compared to its GC-sensitive parent and was confirmed to be lower in other GC-resistant sub-lines of Pre B697 and was associated with a decreased expression of the PAX5 transcriptional target, CD19. Gene set enrichment analysis of microarray data from the cell lines showed that increasing GC-resistance was associated with differentiation from preB-II to an immature B-lymphocytes stage. GC resistant sub lines were shown to have a higher levels of p-JNK compared to the parent line and JNK inhibition caused re-sensitisation to GC. Reduced CD19 levels accompanying GC resistance was also apparent in some clinical samples, with high levels of MRD persisting after GC containing induction chemotherapy. Thus, quantitative proteomic analysis reveals a role for PAX5 and maturation as a recurrent mechanism underlying glucocorticoid resistance in ALL and identifies JNK inhibitors as a possible re-sensitising therapy.
Quantitative proteomic analysis reveals maturation as a mechanism underlying glucocorticoid resistance in B lineage ALL and re-sensitization by JNK inhibition.
No sample metadata fields
View SamplesMice that develop benign cartilage lesions due to overexpression of Gli2 in chondrocytes developed lesions similar to chondrosarcomas when also deficient in p53. Gli2 overexpression and p53 deficiency had opposing effects on chondrocyte differentiation, but had additive effects negatively regulating apoptosis. Regulation of Igfbp3 expression and IGF signaling by Gli and p53 integrated their effect on apoptosis. Treatment of human chondrosarcomas or fetal mouse limbs explants with IGFBP3 or by blocking IGF increased the apoptosis rate, and mice expressing Gli2 developed substantially fewer tumors when also deficient for Igf2. IGF signaling meditated apoptosis regulates the progression to malignant chondrosarcoma.
Gli2 and p53 cooperate to regulate IGFBP-3- mediated chondrocyte apoptosis in the progression from benign to malignant cartilage tumors.
Cell line
View SamplesOsteoarthritis (OA) is a common degenerative disease of the joint. Data from our lab indicates that Hedgehog (Hh) signaling is activated in human OA and murine models of OA (Lin et al., 2009, Nature Medicine). To identify Hh target genes, microarray analyses were performed to detect changes in gene expression when the Hh pathway was inhibited in human OA cartilage samples.
Regulation of Cholesterol Homeostasis by Hedgehog Signaling in Osteoarthritic Cartilage.
Sex, Specimen part, Treatment
View SamplesThe transcriptional regulator EVI1 has an essential role in early hematopoiesis and development. However, aberrantly high expression of EVI1 has potent oncogenic properties and confers poor prognosis and chemo-resistance in leukemia and solid tumors. To investigate to what extent EVI1 function might be regulated by posttranslational modifications, we carried out mass spectrometry- and antibody-based analyses and uncovered an ATM-mediated double phosphorylation of EVI1 at the carboxy-terminal S858/S860 SQS motif. In the presence of genotoxic stress, EVI1-WT (SQS), but not site mutated EVI1-AQA was able to maintain transcriptional patterns and transformation potency, while under standard conditions carboxy-terminal mutation had no effect. Maintenance of hematopoietic progenitor cell clonogenic potential was profoundly impaired with EVI1-AQA compared with EVI1-WT, in particular in the presence of genotoxic stress. Exploring mechanistic events underlying these observations, we showed that after genotoxic stress EVI1-WT, but not EVI1-AQA increased its level of association with its functionally essential interaction partner CtBP1, implying a role for ATM in regulating EVI1 protein interactions via phosphorylation. This aspect of EVI1 regulation is therapeutically relevant, as chemotherapy-induced genotoxicity might detrimentally sustain EVI1 function via stress response mediated phosphorylation, and ATM-inhibition might be of specific targeted benefit in EVI1-overexpressing malignancies. Overall design: Poly-A RNA sequencing (RNAseq) analysis of EVI1-mediated modulation of gene expression RNA was extracted from HEK293 cells, which were subjected to transient transfection using half confluent cultures with pCMV-flag, pCMV-EVI1-WT-flag or pCMV-EVI1-AQA-flag, exposed to 150 µM H2O2 or left untreated for 8 h.
EVI1 carboxy-terminal phosphorylation is ATM-mediated and sustains transcriptional modulation and self-renewal via enhanced CtBP1 association.
Cell line, Treatment, Subject
View SamplesWe are currently studying the mechanisms that confer tumour initiating potential upon SP, and as part of this work, we undertook gene profiling studies comparing expression between SP and non-SP cells, initially focusing on the most common soft tissue sarcoma, malignant fibrous histiocytoma (or MFH)
Hedgehog and Notch signaling regulate self-renewal of undifferentiated pleomorphic sarcomas.
No sample metadata fields
View SamplesTumours contain heterogeneous cell populations. A population enriched in tumour-initiating potential has been identified in soft-tissue sarcoma (STS) by the isolation of side population (SP) cells. In this study, we compared the gene expression profiles of SP and non-SP cells in STS and identified Hedgehog (Hh) and Notch pathways as potential candidates for the targeting of SP cells. Upon verification of the activation of these pathways in SP cells, using primary tumor xenografts in NOD-SCID mice as our experimental model, we used the Hh blocker Triparanol and the Notch blocker DAPT to demonstrate that the suppression of these pathways effectively depleted the abundance of SP cells, reduced tumour growth, and inhibited the tumour-initiating potential of the treated sarcoma cells upon secondary transplantation. The data provide additional evidence that SP cells act as tumour initiating cells and points to Hh and Notch pathways as enticing targets for developing potential cancer therapies.
Hedgehog and Notch signaling regulate self-renewal of undifferentiated pleomorphic sarcomas.
Specimen part
View SamplesWe demonstrated that deletion of the p53 tumor suppressor gene in NG2 expressing cells resulted in the development of bone and soft tissue sarcomas that closely resemble human tumors. To determine gene expression differences between NG2 expressing pericytes lacking p53 and sarcomas that arose from deletion of p53 in NG2 expressing cells, RNA sequencing analysis was implemented. Overall design: We isolated total RNA from NG2 expressing pericytes (2 samples), which were sorted from skeletal muscle tissues of NG2-Cre;p53flox/flox mice using an NG2 antibody. We also isolated total RNA from osteosarcomas (2 samples) and soft tissue sarcomas (2 samples), which were developed in NG2-Cre;p53flox/flox mice. Differentially expressed genes were analyzed using Illumina HiSeq 2000.
Mesenchymal Tumors Can Derive from Ng2/Cspg4-Expressing Pericytes with β-Catenin Modulating the Neoplastic Phenotype.
No sample metadata fields
View SamplesIn a study focused on the role for CHD7 in angiogenesis we completed RNA-sequencing of D456, a glioblastoma xenograft line and neural precursor cells after CHD7 knockdown Overall design: RNA-sequencing after shRNA KD of CHD7 in two cell lines
Chromodomain Helicase DNA-Binding Protein 7 Is Suppressed in the Perinecrotic/Ischemic Microenvironment and Is a Novel Regulator of Glioblastoma Angiogenesis.
Treatment, Subject
View SamplesGlioblastomas grow in a rich neurochemical mileu, but targeting neurochemical signaling as a potential therapeutic avenue for these incurable tumors has been underexplored. Thus, we probed patient derived glioblastoma stem cells with a focused library of neurochemicals, to identify new therapeutic targets. Dopaminergic, serotonergic and cholinergic pathways were found to be active against glioblastoma. In particular, dopamine receptor D4 (DRD4) antagonists selectively inhibited glioblastoma growth in vitro and in vivo, in addition to showing synergistic effect with temozolomide. Small molecule or genetic antagonism of DRD4 suppressed ERK1/2 signaling and impaired autophagic flux causing accumulation of autophagic vacuoles and ubiquitinated proteins, associated with G0/G1 cell cycle arrest. These data suggest a new mechanism for treating glioblastoma through modulating dopamine DRD4 signaling.
Inhibition of Dopamine Receptor D4 Impedes Autophagic Flux, Proliferation, and Survival of Glioblastoma Stem Cells.
Specimen part
View SamplesPrimary glioblastoma (GBM) cultures vary with respect to differentiation competency. We sought to identify putative transcription factors necessary for the differentiation of GBM cultures. In this dataset, we include expression data obtained from 2 human-fetal neural stem cell (HF-NS) cultures and 2 GBM stem cell (GSC) cultures. We assessed changes in gene expression from 3 timepoints during an in vitro differentiation protocol.
ASCL1 Reorganizes Chromatin to Direct Neuronal Fate and Suppress Tumorigenicity of Glioblastoma Stem Cells.
Specimen part, Time
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