Project description:This SuperSeries is composed of the following subset Series: GSE39335: Expression data from glucocorticoid-treated ALL (BCR-ABL patients) GSE39338: Expression data from glucocorticoid-treated ALL (CCRF-CEM-C7-14 cells) Refer to individual Series
Project description:One of the main objective of this study is to characterize Imatinib induced MSCs-mediated resistance evolution in BCR-ABL+ ALL. Tyrosine kinase inhibitor (TKI) Imatinib (IM) is used as a frontline therapy for BCR-ABL–positive (BCR-ABL+) acute lymphoblastic leukemia (ALL). However, resistance to IM therapy develops rapidly in a substantial proportion of treated patients, and the molecular mechanisms underlying the resistance are poorly understood. In this study, we identified a novel cascade of consequential events that are initiated by IM, which traverse through mesenchymal stem/stromal cells (MSCs) to leukemic cells, and lead to IM resistance. Our data showed that MSCs exposed to IM were decreased in their stemness and acquired a new functional status that enabled the formation of leukemic cell niches. These MSCs had increased expression of genes encoding chemo-attractants, adhesion molecules, and pro-survival stimulant growth factors. We found that BCR-ABL+ leukemic cells persistently exposed to IM were able to switch from BCR-ABL–driven signaling to growth factor–driven signaling for survival, and this switch was reversible. Blocking both the BCR-ABL–driven pathway and the growth factor–driven JAK pathway effectively eradicated the leukemic cell niches. Our findings illustrate TKI-induced, MSC-mediated drug resistance, suggesting an effective way to eliminate this type of drug resistance in patients with BCR-ABL+ ALL. Gene expression signatures were compared from triplicate samples of MSCs that were either treated with vehicle or imatinib for 32, 64 and 96 hours.
Project description:One of the main objective of this study is to characterize Imatinib induced MSCs-mediated resistance evolution in BCR-ABL+ ALL. Tyrosine kinase inhibitor (TKI) Imatinib (IM) is used as a frontline therapy for BCR-ABL–positive (BCR-ABL+) acute lymphoblastic leukemia (ALL). However, resistance to IM therapy develops rapidly in a substantial proportion of treated patients, and the molecular mechanisms underlying the resistance are poorly understood. In this study, we identified a novel cascade of consequential events that are initiated by IM, which traverse through mesenchymal stem/stromal cells (MSCs) to leukemic cells, and lead to IM resistance. Our data showed that MSCs exposed to IM were decreased in their stemness and acquired a new functional status that enabled the formation of leukemic cell niches. These MSCs had increased expression of genes encoding chemo-attractants, adhesion molecules, and pro-survival stimulant growth factors. We found that BCR-ABL+ leukemic cells persistently exposed to IM were able to switch from BCR-ABL–driven signaling to growth factor–driven signaling for survival, and this switch was reversible. Blocking both the BCR-ABL–driven pathway and the growth factor–driven JAK pathway effectively eradicated the leukemic cell niches. Our findings illustrate TKI-induced, MSC-mediated drug resistance, suggesting an effective way to eliminate this type of drug resistance in patients with BCR-ABL+ ALL.
Project description:MiR-142 is dynamically expressed and plays a regulatory role in hematopoiesis. Based on the simple observation that miR-142 levels are significantly lower in CD34+CD38- cells from blast crisis (BC) chronic myeloid leukemia (CML). CML patients compared with chronic phase (CP) CML patients (p=0.002), we hypothesized that miR-142 deficit plays a role in BC transformation. To test this hypothesis, we generated a miR-142 KO BCR-ABL (i.e., miR-142−/−BCR-ABL) mouse by crossing a miR-142−/− mouse with a miR-142+/+BCR-ABL mouse. While the miR-142+/+BCR-ABL mice developed and died of CP CML, the miR-142−/−BCR-ABL mice developed a BC-like phenotype in the absence of any other acquired gene mutations and died significantly sooner than miR-142+/+BCR-ABL CP controls (p=0.001). Leukemic stem cell (LSC)-enriched Lineage-Sca-1+c-Kit+ cells (LSKs) from diseased miR-142−/−BCR-ABL mice transplanted into congenic recipients, recapitulated the BC features thereby suggesting stable transformation of CP-LSCs into BC-LSCs in the miR-142 KO CML mouse. Single cell (sc) RNA-seq profiling showed that miR-142 deficit changed the cellular landscape of the miR-142−/−BCR-ABL LSKs compared with miR-142+/+BCR-ABL LSKs with expansion of myeloid-primed and loss of lymphoid-primed factions. Bulk RNA-seq analyses along with unbiased metabolomic profiling and functional metabolic assays demonstrated enhanced fatty acid β-oxidation (FAO) and oxidative phosphorylation (OxPhos) in miR-142−/−BCR-ABL LSKs vs miR-142+/+BCR-ABL LSKs. MiR-142 deficit enhanced FAO in miR-142−/−BCR-ABL LSKs by increasing the expression of CPT1A and CPT1B, that controls the cytosol-to-mitochondrial acyl-carnitine transport, a critical step in FAO. MiR-142 deficit also enhanced OxPhos in miR-142−/−BCR-ABL LSKs by increasing mitochondrial fusion and activity. As the homeostasis and activity of LSCs depend on higher levels of these oxidative metabolism processes, we then postulate that miR-142 deficit is a potentially druggable target for BC-LSCs. To this end, we developed a novel CpG-miR-142 mimic oligonucleotide (ODN; i.e., CpG-M-miR-142) that corrected the miR-142 deficit and alone or in combination with a tyrosine kinase inhibitor (TKI) significantly reduced LSC burden and prolonged survival of miR-142−/−BCR-ABL mice. The results from murine models were validated in BC CD34+CD38- primary blasts and patient-derived xenografts (PDXs). In conclusion, an acquired miR-142 deficit sufficed in transforming CP-LSCs into BC-LSCs, via enhancement of bioenergetic oxidative metabolism in absence of any additional gene mutations, and likely represent a novel therapeutic target in BC CML.
Project description:To investigate the mechanism of telomerase regulation in BCR-ABL positive cells due to its clinical value, we studied the catalytic component of telomerase, TERT. Our results suggest that BCR-ABL plays an important role in regulating hTERT in K562 (BCR-ABL positive human leukemia) cells. When Gleevec inhibited the tyrosine kinase activity of BCR-ABL, phosphorylation of hTERT was downregulated, therefore suggesting a positive correlation between BCR-ABL and hTERT. Gleevec treatment inhibited hTERT at the mRNA level and significantly reduced telomerase activity (TA) in K562 cells, but not in HL60 or Jurkat cells. TRAP assay also revealed that Gleevec treatment significantly reduced TA specifically in K562 cells. Furthermore, translocation of hTERT from nucleoli to nucleoplasm was observed in K562 cells induced by Gleevec. Although Gleevec down-regulated hTERT mRNA level, the protein level of hTERT remained unchanged. Therefore, Gleevec-induced-TA decrease is not due to the alteration in telomerase subunits expression. It could be presumably due to posttranslational modification of hTERT, possibly through multiple signaling pathways. We have found that Gleevec reduced the tyrosine phosphorylation of hTERT by BCR-ABL, which is associated with the nucleoplasm localization of hTERT from nucleoli sequesters. These findings reveal unknown functions and regulations of telomerase by BCR-ABL. Using cRNA microarray, gene expression of Gleevec-treated and non-treated K562 (BCR-ABL positive) cells were compared against Gleevec-treated and non-treated HL60 (BCR-ABL deficient) cells.
Project description:Although Bcr-Abl kinase inhibitors have proven effective in the treatment of chronic myeloid leukemia (CML), they generally fail to completely eradicate Bcr-Abl+ leukemia cells. To identify genes whose inhibition sensitizes Bcr-Abl+ leukemias to killing by Bcr-Abl inhibitors, we performed an RNAi-based synthetic lethal screen with imatinib in CML cells. This screen identified numerous components of a Wnt/Ca2+/NFAT signaling pathway. Antagonism of this pathway led to impaired NFAT activity, decreased cytokine production and enhanced sensitivity to Bcr-Abl inhibition. Furthermore, NFAT inhibition with cyclosporin A facilitated leukemia cell elimination by the Bcr-Abl inhibitor dasatinib and markedly improved survival in a mouse model of Bcr-Abl+ acute lymphoblastic leukemia (ALL). Targeting this pathway in combination with Bcr-Abl inhibition could improve treatment of Bcr-Abl+ leukemias.
Project description:K562 cells were treated with the BCR-ABL kinase inhibitor dasatinib over an extended period of time to determine how BCR-ABL inhibition affects BCR-ABL-dependent negative feedback and erythropoietin receptor (EPO-R) signaling. Specifically, what types of changes (upregulation versus downregulation) occur in both the negative and positive regulators of growth-factor receptor signaling.
Project description:We screened TKI-treated-CML-samples in different-phases based on < or >10% copies of BCR-ABL, undetected and control-samples for generating transcriptomics-profile. Transcriptionally, three clusters were identified which showed correlation with BCR-ABL transcript-levels i.e. <10% copies (I-cluster) , undetectable (II-cluster) and >10% copies (III-cluster).