Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Whole-genome GR binding sites and histone acetylation status in pediatric acute lymphoblastic leukemia patient-derived xenografts following dexamethasone treatment in vivo

ABSTRACT: Glucocorticoids are critical components of combination chemotherapy regimens in pediatric acute lymphoblastic leukemia (ALL). However, the signaling pathways regulating apoptosis in glucocorticoid-treated lymphoid cells remain unclear. In this study, pediatric ALL patient-derived xenograft inherently sensitive to glucocorticoids were exposed to dexamethasone in vivo. Whole-genome GR binding sites and histone acetylation status were detected using chromatin immunoprecipitation sequencing analyses. This provided a global understanding of dexamethasone-induced DNA modulations in ALL cells in vivo, which is likely to be important in the understanding of mechanisms of glucocorticoid response in lymphoid malignancies. One xenograft (ALL-54) was derived from a patient of dexamethasone-good responder. The xenograft was innoculated into 2 NOD/SCID mice, and treated with dexamethasone (15 mg/kg) or vehicle control. Binding of glucocorticoid receptor (GR), histone acetylation and IgG control in spleen-harvest xenograft samples were detected using ChIP-seq.

ORGANISM(S): Homo sapiens

SUBMITTER: Dominik Beck

PROVIDER: E-GEOD-58266 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Opposing regulation of BIM and BCL2 controls glucocorticoid-induced apoptosis of pediatric acute lymphoblastic leukemia cells.

Jing Duohui D Bhadri Vivek A VA Beck Dominik D Thoms Julie A I JA Yakob Nurul A NA Wong Jason W H JW Knezevic Kathy K Pimanda John E JE Lock Richard B RB

Blood 20141021 2

Glucocorticoids are critical components of combination chemotherapy regimens in pediatric acute lymphoblastic leukemia (ALL). The proapoptotic BIM protein is an important mediator of glucocorticoid-induced apoptosis in normal and malignant lymphocytes, whereas the antiapoptotic BCL2 confers resistance. The signaling pathways regulating BIM and BCL2 expression in glucocorticoid-treated lymphoid cells remain unclear. In this study, pediatric ALL patient-derived xenografts (PDXs) inherently sensiti ...[more]

PMID: 25336632

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Project description:Glucocorticoids are critical components of combination chemotherapy regimens in pediatric acute lymphoblastic leukemia (ALL). The pro-apoptotic BIM protein is an important mediator of glucocorticoid-induced apoptosis in normal and malignant lymphocytes, while the anti-apoptotic BCL2 confers resistance. The signaling pathways regulating BIM and BCL2 expression in glucocorticoid-treated lymphoid cells remain unclear. In this study, pediatric ALL patient-derived xenografts (PDXs) inherently sensitive or resistant to glucocorticoids were exposed to dexamethasone in vivo. In order to understand the basis for differential in vivo glucocorticoid sensitivity of PDXs, microarray analysis of gene expression was carried out on 5 each of dexamethasone-sensitive and resistant PDXs . This provided a global understanding of dexamethasone-induced signaling cascades in ALL cells in vivo, and especialy identified the genes that are involved in transducing the apoptotic signal, upstream of BIM/BCL2 dynamic interactions. ALL xenograft cells were inoculated by tail-vein injection into NOD/SCID mice, and engraftment was monitored weekly. When >70% %huCD45+ engraftment in the peripheral blood was apparent, which occurred 8-10 weeks post-transplantation, mice were treated with either dexamethasone (15 mg/kg) or vehicle control by intra-peritoneal (IP) injection, and culled at 8 hours following the treatment. Cell suspensions of spleens were prepared and mononuclear cells enriched to >97% human by density gradient centrifugation. RNA was extracted using the RNeasy Mini Kit (QIAGEN, Valencia, CA, USA), and RNA samples with integrity number (RIN) > 8.0 were amplified and hybridized onto Illumina HumanWG-6 v3 Expression BeadChips (6 samples/chip). All chips (with associated reagents) were purchased from Illumina, and scanned on the Illumina BeadArray Reader according to the manufacturer’s instructions. Microarray data were analyzed using the online modules in GenePattern. 10 xenografts were derived from patients of 5 dexamethasone-good responder and 5 dexamethasone-poor responder. Each xenograft was innoculated into 5-6 mice, and treated with dexamethasone (15 mg/kg) or vehicle control. In total spleen-harvest xenograft samples from 58 mice were analyzed using microarray.

Project description:The glucocorticoid receptor (GR) regulates gene expression throughout the human genome in a cell-type-specific manner, governing various aspects of homeostasis. The influence of this transcriptional regulator is seen in multiple pathologies, including cancer. Pharmacological activation of the GR is frequently used to alleviate side-effects caused by therapy for patients with various non-lymphoid solid (i.e. non-hematologic) cancers; however, prior studies have shown that this treatment might also have anti-proliferative action on cancer cells. Nonetheless, the molecular underpinnings of glucocorticoid action and its direct effectors in non-lymphoid solid cancers remain elusive. Here, we study the molecular mechanisms of glucocorticoid response in non-lymphoid solid cancers models, focusing on lung cancer. Activation of the GR induces reversible cancer cell dormancy in which cells are tolerant to large array of anti-cancer drugs. This state transition is accompanied by induction of growth factor survival signalling (IGF-1R) and acquired vulnerability to inhibitors of this pathway, both in vitro and in vivo. The observed phenotype is dependent on a single GR target gene - CDKN1C, which encodes for a cell cycle inhibitor protein p57. We have discovered an upstream distal enhancer of CDKN1C, which through GR-induced chromatin looping regulates the expression of this key gene, as confirmed in human tumour specimens. Furthermore, we demonstrate that the SWI/SNF complex composition fine-tunes the GR transcriptional activity at the CDKN1C locus, allowing for precise regulation of cell dormancy induction. Collectively, we show that SWI/SNF-facilitated regulation of CDKN1C underlines GR-induced reversible drug-tolerant state in cancer cells. These insights illustrate the importance of GR signalling in non-lymphoid solid cancer biology, particularly in lung cancer, and warrant caution for use of glucocorticoids in treatment of anti-cancer therapy related side-effects.

Dataset Information

Whole-genome GR binding sites and histone acetylation status in pediatric acute lymphoblastic leukemia patient-derived xenografts following dexamethasone treatment in vivo

Publications

Opposing regulation of BIM and BCL2 controls glucocorticoid-induced apoptosis of pediatric acute lymphoblastic leukemia cells.

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