T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic cancer frequently associated with activating mutations in NOTCH1. Early studies identified NOTCH1 as an attractive therapeutic target for the treatment of T-ALL through the use of gamma-secretase inhibitors (GSIs). Here, we characterized the interaction between PF-03084014, a clinically-relevant GSI, and dexamethasone in preclinical models of glucocorticoid-resistant T-ALL. Combination treatment of the GSI PF-03084014 with glucocorticoids induced a synergistic antileukemic effect in human T-ALL cell lines and primary human T-ALL patient samples. Molecular characterization of the response to PF-03084014 plus glucocorticoids through gene expression profiling revealed transcriptional upregulation of the glucocorticoid receptor as the mechanism mediating the enhanced glucocorticoid response. Moreover, treatment with PF-03084014 and glucocorticoids in combination was highly efficacious in vivo, with enhanced reduction of tumor burden in a xenograft model of T-ALL. Finally, glucocorticoid treatment was highly effective at reversing PF-03084014-induced gastrointestinal toxicity via inhibition of goblet cell metaplasia. These results suggest that combination of PF-03084014 treatment with glucocorticoids may be well-tolerated and highly active for the treatment of glucorticoid-resistant T-ALL.
Preclinical analysis of the γ-secretase inhibitor PF-03084014 in combination with glucocorticoids in T-cell acute lymphoblastic leukemia.
Cell line, Treatment
View SamplesDefining the role of epigenetic regulators in normal hematopoiesis has become critically important, as recurrent mutations or aberrant expression of these genes has been identified in both myeloid and lymphoid hematological malignancies. We have found that PRMT4, a type I arginine methyltransferase, whose function in normal and malignant hematopoiesis is unknown, is overexpressed in AML patient samples. In support of an oncogenic role for PRMT4, we find that its overexpression blocks the myeloid differentiation of human stem/progenitor cells (HSPCs) while its knockdown (KD) is sufficient to induce myeloid differentiation of HSPCs and multiple AML cell lines. Although classically thought of as a co-activator, we found that PRMT4 functions to repress the expression of miR-223 in HSPCs via the methylation of RUNX1, which triggers the assembly of a multi-protein repressor complex that includes DPF2. As part of a feedback loop, PRMT4 expression is repressed post-transcriptionally by miR-223 during the normal differentiation process. These data reveal an unidentified role of PRMT4 in myeloid differentiation and its unexpected repressive role in transcriptional regulation. Furthermore, depletion of PRMT4 results in the differentiation of myeloid leukemia cells in vitro and their decrease proliferation in vivo. Thus, targeting PRMT4 holds potential as a novel therapy for acute myelogenous leukemia. Overall design: Purified human primary CD34+ cells were transduced with lentiviruses carrying PRMT4KD or scramble control shRNAs. Total RNA was extrated. RNAseq was performed to identify target genes that are regulated by PRMT4. Experiments were performed in triplicate.
PRMT4 blocks myeloid differentiation by assembling a methyl-RUNX1-dependent repressor complex.
Specimen part, Subject
View SamplesIn order to investigate the function of Bach2 in pre-B ALL, we isolated bone marrow cells from wildtype and Bach2 knockout mice of C57Bl6 background and transformed them with BCR-ABL1.
Mechanistic rationale for targeting the unfolded protein response in pre-B acute lymphoblastic leukemia.
Age, Specimen part, Disease, Disease stage, Treatment
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Mechanistic rationale for targeting the unfolded protein response in pre-B acute lymphoblastic leukemia.
Specimen part
View SamplesThe plasma cell transcription factor XBP1 is critical for terminal differentiation of B cells into plasma cells but has no known role at earlier stages of B-cell development. Here we show that XBP1 is not only important during early B-cell development and for survival of pre-B cells but also protects pre-B ALL cells. Among pre-B ALL subset, XBP1 was hypomethylated and highest expressed in the Ph+ ALL subset. Cre-mediated deletion of XBP1 in a mouse model of Ph+ ALL compromised proliferation and viability and prolonged survival of leukemia-bearing mice. Interestingly, XBP1 expression levels were positively transcriptionally regulated by STAT5 and negatively by BACH2 and BCL6. High XBP1 expression in high risk ALL patients at the time of diagnosis predicted poor outcome in two clinical trials. Clinically, small-molecule inhibition of IRE1-dependent XBP1-activation caused cell death of patient-derived pre-B ALL cells and affected leukemia-initiation in transplant recipient mice. Collectively, these studies identify XBP1 as an important survival factor and as a potential therapeutic target to overcome drug-resistance in pre-B ALL. Overall design: Genome-wide profiling of mRNA levels in p210 transduced murine Xbp1 fl/+ pre-B cells with ERT2 (XE.1,2,3) and Cre- ERT2 Â (XC.1,2,3).
Mechanistic rationale for targeting the unfolded protein response in pre-B acute lymphoblastic leukemia.
No sample metadata fields
View SamplesThe plasma cell transcription factor XBP1 is critical for terminal differentiation of B cells into plasma cells but has no known role at earlier stages of B-cell development. Here we show that XBP1 is not only important during early B-cell development and for survival of pre-B cells but also protects pre-B ALL cells. Among pre-B ALL subset, XBP1 was hypomethylated and highest expressed in the Ph+ ALL subset. Cre-mediated deletion of XBP1 in a mouse model of Ph+ ALL compromised proliferation and viability and prolonged survival of leukemia-bearing mice. Interestingly, XBP1 expression levels were positively transcriptionally regulated by STAT5 and negatively by BACH2 and BCL6. High XBP1 expression in high risk ALL patients at the time of diagnosis predicted poor outcome in two clinical trials. Clinically, small-molecule inhibition of IRE1-dependent XBP1-activation caused cell death of patient-derived pre-B ALL cells and affected leukemia-initiation in transplant recipient mice. Collectively, these studies identify XBP1 as an important survival factor and as a potential therapeutic target to overcome drug-resistance in pre-B ALL.
Mechanistic rationale for targeting the unfolded protein response in pre-B acute lymphoblastic leukemia.
Specimen part
View SamplesTo formally address the tumor suppressor activity of Sh2b3 in vivo, we tested the interaction between oncogenic NOTCH1 and Sh2b3 loss in a retroviral- transduction bone marrow transplantation model of NOTCH-induced T-ALL
Genetic loss of SH2B3 in acute lymphoblastic leukemia.
Specimen part
View SamplesEarly immature T-cell acute lymphoblastic leukemias (T-ALLs) account for about 5-10% of pediatric T-ALLs and are associated with poor prognosis. However, the genetic defects that drive the biology of these tumors remain largely unknown. Analysis of microarray gene expression signatures in adult T-ALL demonstrated a high prevalence of early immature leukemias and revealed a close relationship between these tumors and myeloid leukemias. Consistently, adult immature T- ALLs showed characteristic mutations in myeloid specific oncogenes and tumor suppressors including IDH1, IDH2, DNMT3A, FLT3 and NRAS. Moreover, we identified ETV6 mutations as a novel genetic lesion uniquely present in immature adult T-ALL. All together, our results demonstrate that early immature adult T- ALL represents a heterogeneous category of leukemias characterized by the presence of overlapping myeloid and T-ALL characteristics and highlight the role of ETV6 mutations in these tumors.
ETV6 mutations in early immature human T cell leukemias.
Specimen part
View SamplesLeukemia stem cells (LSCs) are found in most aggressive myeloid diseases and contribute to therapeutic resistance. Genetic and epigenetic alterations cause a dysregulated developmental program in leukemia. The MSI2 RNA binding protein has been previously shown to predict poor survival in leukemia. We demonstrate that the conditional deletion of Msi2 results in delayed leukemogenesis, reduced disease burden and a loss of LSC function. Gene expression profiling of the Msi2 ablated LSCs demonstrates a loss of the HSC/LSC and an increase in the differentiation program. The gene signature from the Msi2 deleted LSCs correlates with survival in AML patients. MSI2’s maintains the MLL self-renewal program by interacting with and retaining efficient translation of Hoxa9, Myc and Ikzf2. We further demonstrate that shRNA depletion of the MLL target gene Ikzf2 also contributes to MLL leukemia cell survival. Our data provides evidence that MSI2 controls efficient translation of the oncogenic LSC self-renewal program and a rationale for clinically targeting MSI2 in myeloid leukemia. Overall design: RNA-Seq was performed on sorted c-Kit high leukemic cells from 2 Msi2 -/- and 2 Msi2 f/f mice.
Musashi2 sustains the mixed-lineage leukemia-driven stem cell regulatory program.
No sample metadata fields
View SamplesCytogenetically normal acute myeloid leukemia (CN-AML) represents nearly 50% of human acute myeloid leukemia (AML) cases with a 5-year overall survival of approximately 30%. In CN-AML with poorer prognosis, mutations in the de novo DNA methyltransferase (DNMT3A) and the FMS-like tyrosine kinase 3 (Flt3) commonly co-occur (1-3). We demonstrate that mice with Flt3-internal-tandem duplication (Flt3ITD) and inducible deletion of Dnmt3a spontaneously develop a rapidly-lethal, completely-penetrant, and transplantable AML of normal karyotype. These murine AML retain a single Dnmt3a floxed allele, revealing the oncogenic potential of Dnmt3a haploinsufficiency. FLT3-ITD/DNMT3A-mutant primary human and murine AML demonstrate a similar pattern of global DNA methylation. In the murine model, rescuing DNMT3A expression was accompanied by DNA re-methylation and loss of clonogenic potential, suggesting that Dnmt3a-mutant oncogenic effects are reversible. Differentially methylated genomic regions were associated with changes in the expression of nearby genes. Moreover, dissection of the cellular architecture of the AML model using single-cell RNA-Seq, flow cytometry and colony assays identified clonogenic subpopulations that differentially express genes that are sensitive to the methylation of nearby genomic loci and varied in response to Dnmt3a levels. Thus, Dnmt3a haploinsufficiency transforms Flt3ITD myeloproliferative disease by modulating methylation-sensitive gene expression within a clonogenic AML subpopulation. Overall design: To identify the gene expression changes associated with Dnmt3a loss of function in human and murine Flt3-ITD and Dnmt3a-mutant AML (Single Cell RNA-Seq).
DNMT3A Haploinsufficiency Transforms FLT3ITD Myeloproliferative Disease into a Rapid, Spontaneous, and Fully Penetrant Acute Myeloid Leukemia.
Specimen part, Disease, Subject
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