Publications by authors named "Britta Will"

47 Publications

Chaperone-mediated autophagy sustains haematopoietic stem-cell function.

Nature 2021 03 13;591(7848):117-123. Epub 2021 Jan 13.

Department of Development and Molecular Biology, Albert Einstein College of Medicine, New York, NY, USA.

The activation of mostly quiescent haematopoietic stem cells (HSCs) is a prerequisite for life-long production of blood cells. This process requires major molecular adaptations to allow HSCs to meet the regulatory and metabolic requirements for cell division. The mechanisms that govern cellular reprograming upon stem-cell activation, and the subsequent return of stem cells to quiescence, have not been fully characterized. Here we show that chaperone-mediated autophagy (CMA), a selective form of lysosomal protein degradation, is involved in sustaining HSC function in adult mice. CMA is required for protein quality control in stem cells and for the upregulation of fatty acid metabolism upon HSC activation. We find that CMA activity in HSCs decreases with age and show that genetic or pharmacological activation of CMA can restore the functionality of old mouse and human HSCs. Together, our findings provide mechanistic insights into a role for CMA in sustaining quality control, appropriate energetics and overall long-term HSC function. Our work suggests that CMA may be a promising therapeutic target for enhancing HSC function in conditions such as ageing or stem-cell transplantation.
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http://dx.doi.org/10.1038/s41586-020-03129-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8428053PMC
March 2021

No keto for AML stem cells!

Authors:
Britta Will

Blood 2020 09;136(11):1219-1221

Albert Einstein College of Medicine.

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http://dx.doi.org/10.1182/blood.2020006733DOI Listing
September 2020

The thrombopoietin mimetic JNJ-26366821 increases megakaryopoiesis without affecting malignant myeloid proliferation.

Leuk Lymphoma 2020 10 24;61(10):2453-2465. Epub 2020 Jun 24.

Department of Oncology, Albert Einstein College of Medicine - Montefiore Medical Center, Bronx, NY, USA.

Thrombocytopenia remains a challenge in myeloid malignancies, needing safer and more effective therapies. JNJ-26366821, a pegylated synthetic peptide thrombopoietin (TPO) mimetic not homologous to endogenous TPO, has an in-vitro EC50 of 0.2 ng/mL for the TPO receptor and dose dependently elevates platelets in volunteers. We demonstrate that JNJ-26366821 increases megakaryocytic differentiation and megakaryocytic colony formation in healthy controls and samples from myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). JNJ-26366821 had no effect on proliferation of malignant myeloid cell lines at doses up to 1000 ng/mL and malignant patient-derived mononuclear cells showed no increased cell growth or leukemic colony formation capacity at concentrations between 0.2 ng/mL and 10 ng/mL. Furthermore, JNJ-26366821 did not enhance in-vivo engraftment of leukemic cells in an AML xenotransplantation murine model. Our results show that JNJ-26366821 stimulates megakaryopoiesis without causing proliferation of the malignant myeloid clones in MDS/AML and provides the rationale for clinical testing of JNJ-26366821 in myeloid malignancies.
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http://dx.doi.org/10.1080/10428194.2020.1775213DOI Listing
October 2020

Mechanisms and therapeutic prospects of thrombopoietin receptor agonists.

Semin Hematol 2019 10 19;56(4):262-278. Epub 2019 Oct 19.

Albert Einstein College of Medicine, New York, NY. Electronic address:

The second-generation thrombopoietin (TPO) receptor agonists eltrombopag and romiplostim are potent activators of megakaryopoiesis and represent a growing treatment option for patients with thrombocytopenic hematological disorders. Both TPO receptor agonists have been approved worldwide for the treatment of children and adults with chronic immune thrombocytopenia. In the EU and USA, eltrombopag is approved for the treatment of patients with severe aplastic anemia who have had an insufficient response to immunosuppressive therapy and in the USA for the first-line treatment of severe aplastic anemia in combination with immunosuppressive therapy. Eltrombopag has also shown efficacy in several other disease settings, for example, chemotherapy-induced thrombocytopenia, selected inherited thrombocytopenias, and myelodysplastic syndromes. While both TPO receptor agonists stimulate TPO receptor signaling and enhance megakaryopoiesis, their vastly different biochemical structures bestow upon them markedly different molecular and functional properties. Here, we review and discuss results from preclinical and clinical studies on the functional and molecular mechanisms of action of this new class of drug.
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http://dx.doi.org/10.1053/j.seminhematol.2019.09.001DOI Listing
October 2019

Stem cell mutations can be detected in myeloma patients years before onset of secondary leukemias.

Blood Adv 2019 12;3(23):3962-3967

Department of Oncology, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY.

Therapy-related acute myeloid leukemia and myelodysplastic syndromes (t-AML/t-MDS) are secondary hematologic malignancies associated with poor prognosis, warranting insights into their predisposing conditions and cells of origin. We identified patients with myeloma who developed t-AML/t-MDS and analyzed their stem and progenitor cells collected years before the onset of secondary disease. We demonstrate that aberrant stem cells with high CD123 expression can be detected long before the onset of overt leukemia. Rigorous sorting, followed by targeted sequencing, resulted in ultradeep functional depth of sequencing and revealed preexisting mutant hematopoietic stem cell (HSC) clones, mainly harboring TP53 mutations, that became the dominant population at the time of leukemic presentation. Taken together, these data show that HSCs can act as reservoirs for leukemia-initiating cells many years before the onset of myeloid leukemia.
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http://dx.doi.org/10.1182/bloodadvances.2019000731DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6963234PMC
December 2019

Phase II Study of the ALK5 Inhibitor Galunisertib in Very Low-, Low-, and Intermediate-Risk Myelodysplastic Syndromes.

Clin Cancer Res 2019 12 3;25(23):6976-6985. Epub 2019 Sep 3.

Department of Medicine, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York.

Purpose: Overactivation of TGF-β signaling is observed in myelodysplastic syndromes (MDS) and is associated with dysplastic hematopoietic differentiation. Galunisertib, a first-in-class oral inhibitor of the TGF-β receptor type 1 kinase (ALK5) has shown effectiveness in preclinical models of MDS and acceptable toxicity in phase I studies of solid malignancies.

Patients And Methods: A phase II multicenter study of galunisertib was conducted in patients with very low-, low-, or intermediate-risk MDS by the Revised International Prognostic Scoring System criteria with hemoglobin ≤ 10.0 g/dL. Patients received oral galunisertib 150 mg twice daily for 14 days on/14 days off.

Results: Ten of 41 evaluable patients (24.4%; 95% confidence interval, 12.4-40.3) achieved hematologic improvement erythroid response by International Working Group (IWG) 2006 criteria. A total of 18 of 41 patients (43.9%) achieved erythroid response as per IWG 2000 criteria. Nine of 28 (32.1%) of transfusion-dependent patients had hematologic improvement. A total of 18 of 41 (44%) patients had a significant reduction in fatigue. Overall median duration of response was 90 days in all patients. Rigorous stem and progenitor flow cytometry showed that patients with an early stem cell differentiation block were more likely to respond to galunisertib. The most common treatment-emergent adverse events were grade 1 or 2 in 20 (49%) of 41 patients, including any-grade fatigue (8/41, 20%), diarrhea (7/41, 17%), pyrexia (5/41, 12%), and vomiting (5/41, 12%).

Conclusions: In summary, galunisertib treatment has an acceptable safety profile and was associated with hematologic improvements in lower- and intermediate-risk MDS, with responses in heavily transfusion-dependent patients and in those with signs of an early stem cell differentiation block.
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http://dx.doi.org/10.1158/1078-0432.CCR-19-1338DOI Listing
December 2019

HIV portends a poor prognosis in myelodysplastic syndromes.

Leuk Lymphoma 2019 12 8;60(14):3529-3535. Epub 2019 Jul 8.

Department of Medicine, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY, USA.

Even though HIV is associated with worse prognosis in many malignancies, the clinical course of myelodysplastic syndrome (MDS) in HIV + patients has not been well studied. Determining the clinical presentation and outcomes of MDS in these patients would be important for future diagnostic strategies, as anemia and other cytopenias are commonly seen in HIV + patients. Unique data mining software was used to identify cases of MDS or AML in adult patients who were also HIV + at Albert Einstein/Montefiore Medical Center between 1 January 2003 and 1 January 2017. Using Chi-Square and Fisher's exact test, characteristics of the HIV + MDS patients were compared to 135 HIV - MDS patients from the same institution diagnosed between 1997 and 2011. Fourteen biopsy proven MDS patients were identified with concomitant HIV. HIV + MDS patients presented at a younger age (59 vs. 71 yrs,  = .001) had higher risk disease, faster progression to acute leukemia, and worse overall survival (median survival 11.2 vs. 69.1 mo,  < .001) compared to HIV - MDS controls. Additionally, there was a higher prevalence of clonal-hematopoiesis related mutations (ASXL1, DNMT3A) and a higher proportion of patients with high risk cytogenetics. Analysis of the largest single center cohort of HIV + MDS patients demonstrated that these individuals present at a significantly younger age and with higher risk disease than their HIV - counterparts.
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http://dx.doi.org/10.1080/10428194.2019.1633631DOI Listing
December 2019

Proteome-wide analysis of chaperone-mediated autophagy targeting motifs.

PLoS Biol 2019 05 31;17(5):e3000301. Epub 2019 May 31.

Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America.

Chaperone-mediated autophagy (CMA) contributes to the lysosomal degradation of a selective subset of proteins. Selectivity lies in the chaperone heat shock cognate 71 kDa protein (HSC70) recognizing a pentapeptide motif (KFERQ-like motif) in the protein sequence essential for subsequent targeting and degradation of CMA substrates in lysosomes. Interest in CMA is growing due to its recently identified regulatory roles in metabolism, differentiation, cell cycle, and its malfunctioning in aging and conditions such as cancer, neurodegeneration, or diabetes. Identification of the subset of the proteome amenable to CMA degradation could further expand our understanding of the pathophysiological relevance of this form of autophagy. To that effect, we have performed an in silico screen for KFERQ-like motifs across proteomes of several species. We have found that KFERQ-like motifs are more frequently located in solvent-exposed regions of proteins, and that the position of acidic and hydrophobic residues in the motif plays the most important role in motif construction. Cross-species comparison of proteomes revealed higher motif conservation in CMA-proficient species. The tools developed in this work have also allowed us to analyze the enrichment of motif-containing proteins in biological processes on an unprecedented scale and discover a previously unknown association between the type and combination of KFERQ-like motifs in proteins and their participation in specific biological processes. To facilitate further analysis by the scientific community, we have developed a free web-based resource (KFERQ finder) for direct identification of KFERQ-like motifs in any protein sequence. This resource will contribute to accelerating understanding of the physiological relevance of CMA.
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http://dx.doi.org/10.1371/journal.pbio.3000301DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6561683PMC
May 2019

Publisher Correction: Myelodysplastic syndrome progression to acute myeloid leukemia at the stem cell level.

Nat Med 2019 Mar;25(3):529

Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, USA.

In the version of this article originally published, Ulrich Steidl's name was listed as "and Ulrich Steidl." His name has been updated to "Ulrich Steidl." The error has been fixed in the print, PDF and HTML versions of this article.
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http://dx.doi.org/10.1038/s41591-018-0333-yDOI Listing
March 2019

Myelodysplastic syndrome progression to acute myeloid leukemia at the stem cell level.

Nat Med 2019 01 3;25(1):103-110. Epub 2018 Dec 3.

Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY, USA.

Myelodysplastic syndromes (MDS) frequently progress to acute myeloid leukemia (AML); however, the cells leading to malignant transformation have not been directly elucidated. As progression of MDS to AML in humans provides a biological system to determine the cellular origins and mechanisms of neoplastic transformation, we studied highly fractionated stem cell populations in longitudinal samples of patients with MDS who progressed to AML. Targeted deep sequencing combined with single-cell sequencing of sorted cell populations revealed that stem cells at the MDS stage, including immunophenotypically and functionally defined pre-MDS stem cells (pre-MDS-SC), had a significantly higher subclonal complexity compared to blast cells and contained a large number of aging-related variants. Single-cell targeted resequencing of highly fractionated stem cells revealed a pattern of nonlinear, parallel clonal evolution, with distinct subclones within pre-MDS-SC and MDS-SC contributing to generation of MDS blasts or progression to AML, respectively. Furthermore, phenotypically aberrant stem cell clones expanded during transformation and stem cell subclones that were not detectable in MDS blasts became dominant upon AML progression. These results reveal a crucial role of diverse stem cell compartments during MDS progression to AML and have implications for current bulk cell-focused precision oncology approaches, both in MDS and possibly other cancers that evolve from premalignant conditions, that may miss pre-existing rare aberrant stem cells that drive disease progression and leukemic transformation.
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http://dx.doi.org/10.1038/s41591-018-0267-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6436966PMC
January 2019

Antisense STAT3 inhibitor decreases viability of myelodysplastic and leukemic stem cells.

J Clin Invest 2018 12 5;128(12):5479-5488. Epub 2018 Nov 5.

AstraZeneca Pharmaceuticals, Waltham, Massachusetts, USA.

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are associated with disease-initiating stem cells that are not eliminated by conventional therapies. Transcriptomic analysis of stem and progenitor populations in MDS and AML demonstrated overexpression of STAT3 that was validated in an independent cohort. STAT3 overexpression was predictive of a shorter survival and worse clinical features in a large MDS cohort. High STAT3 expression signature in MDS CD34+ cells was similar to known preleukemic gene signatures. Functionally, STAT3 inhibition by a clinical, antisense oligonucleotide, AZD9150, led to reduced viability and increased apoptosis in leukemic cell lines. AZD9150 was rapidly incorporated by primary MDS/AML stem and progenitor cells and led to increased hematopoietic differentiation. STAT3 knockdown also impaired leukemic growth in vivo and led to decreased expression of MCL1 and other oncogenic genes in malignant cells. These studies demonstrate that STAT3 is an adverse prognostic factor in MDS/AML and provide a preclinical rationale for studies using AZD9150 in these diseases.
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http://dx.doi.org/10.1172/JCI120156DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6264739PMC
December 2018

Thrombopoietin receptor-independent stimulation of hematopoietic stem cells by eltrombopag.

Sci Transl Med 2018 09;10(458)

Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

Eltrombopag (EP), a small-molecule thrombopoietin receptor (TPO-R) agonist and potent intracellular iron chelator, has shown remarkable efficacy in stimulating sustained multilineage hematopoiesis in patients with bone marrow failure syndromes, suggesting an effect at the most immature hematopoietic stem and multipotent progenitor level. Although the functional and molecular effects of EP on megakaryopoiesis have been studied in the past, mechanistic insights into its effects on the earliest stages of hematopoiesis have been limited. We investigated the effects of EP treatment on hematopoietic stem cell (HSC) function using purified primary HSCs in separation-of-function mouse models, including a TPO-R-deficient strain, and stem cells isolated from patients undergoing TPO-R agonist treatment. Our mechanistic studies showed a stimulatory effect on stem cell self-renewal independently of TPO-R. Human and mouse HSCs responded to acute EP treatment with metabolic and gene expression alterations consistent with a reduction of intracellular labile iron pools that are essential for stem cell maintenance. Iron preloading prevented the stem cell stimulatory effects of EP. Moreover, comparative analysis of stem cells in the bone marrow of patients receiving EP showed a marked increase in the number of functional stem cells compared to patients undergoing therapy with romiplostim, another TPO-R agonist lacking an iron-chelating ability. Together, our study demonstrates that EP stimulates hematopoiesis at the stem cell level through iron chelation-mediated molecular reprogramming and indicates that labile iron pool-regulated pathways can modulate HSC function.
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http://dx.doi.org/10.1126/scitranslmed.aas9563DOI Listing
September 2018

Dual inhibition of MDMX and MDM2 as a therapeutic strategy in leukemia.

Sci Transl Med 2018 04;10(436)

Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.

The tumor suppressor p53 is often inactivated via its interaction with endogenous inhibitors mouse double minute 4 homolog (MDM4 or MDMX) or mouse double minute 2 homolog (MDM2), which are frequently overexpressed in patients with acute myeloid leukemia (AML) and other cancers. Pharmacological disruption of both of these interactions has long been sought after as an attractive strategy to fully restore p53-dependent tumor suppressor activity in cancers with wild-type p53. Selective targeting of this pathway has thus far been limited to MDM2-only small-molecule inhibitors, which lack affinity for MDMX. We demonstrate that dual MDMX/MDM2 inhibition with a stapled α-helical peptide (ALRN-6924), which has recently entered phase I clinical testing, produces marked antileukemic effects. ALRN-6924 robustly activates p53-dependent transcription at the single-cell and single-molecule levels and exhibits biochemical and molecular biological on-target activity in leukemia cells in vitro and in vivo. Dual MDMX/MDM2 inhibition by ALRN-6924 inhibits cellular proliferation by inducing cell cycle arrest and apoptosis in cell lines and primary AML patient cells, including leukemic stem cell-enriched populations, and disrupts functional clonogenic and serial replating capacity. Furthermore, ALRN-6924 markedly improves survival in AML xenograft models. Our study provides mechanistic insight to support further testing of ALRN-6924 as a therapeutic approach in AML and other cancers with wild-type p53.
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http://dx.doi.org/10.1126/scitranslmed.aao3003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6130841PMC
April 2018

LSD1 inhibition exerts its antileukemic effect by recommissioning PU.1- and C/EBPα-dependent enhancers in AML.

Blood 2018 04 16;131(15):1730-1742. Epub 2018 Feb 16.

Center for Epigenetics Research, Memorial Sloan Kettering Cancer Center, New York, NY.

Epigenetic regulators are recurrently mutated and aberrantly expressed in acute myeloid leukemia (AML). Targeted therapies designed to inhibit these chromatin-modifying enzymes, such as the histone demethylase lysine-specific demethylase 1 (LSD1) and the histone methyltransferase DOT1L, have been developed as novel treatment modalities for these often refractory diseases. A common feature of many of these targeted agents is their ability to induce myeloid differentiation, suggesting that multiple paths toward a myeloid gene expression program can be engaged to relieve the differentiation blockade that is uniformly seen in AML. We performed a comparative assessment of chromatin dynamics during the treatment of mixed lineage leukemia (MLL)-AF9-driven murine leukemias and MLL-rearranged patient-derived xenografts using 2 distinct but effective differentiation-inducing targeted epigenetic therapies, the LSD1 inhibitor GSK-LSD1 and the DOT1L inhibitor EPZ4777. Intriguingly, GSK-LSD1 treatment caused global gains in chromatin accessibility, whereas treatment with EPZ4777 caused global losses in accessibility. We captured PU.1 and C/EBPα motif signatures at LSD1 inhibitor-induced dynamic sites and chromatin immunoprecipitation coupled with high-throughput sequencing revealed co-occupancy of these myeloid transcription factors at these sites. Functionally, we confirmed that diminished expression of PU.1 or genetic deletion of C/EBPα in MLL-AF9 cells generates resistance of these leukemias to LSD1 inhibition. These findings reveal that pharmacologic inhibition of LSD1 represents a unique path to overcome the differentiation block in AML for therapeutic benefit.
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http://dx.doi.org/10.1182/blood-2017-09-807024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5897868PMC
April 2018

Pharmacological inhibition of the transcription factor PU.1 in leukemia.

J Clin Invest 2017 12 30;127(12):4297-4313. Epub 2017 Oct 30.

Department of Cell Biology, Albert Einstein College of Medicine, New York, New York, USA.

The transcription factor PU.1 is often impaired in patients with acute myeloid leukemia (AML). Here, we used AML cells that already had low PU.1 levels and further inhibited PU.1 using either RNA interference or, to our knowledge, first-in-class small-molecule inhibitors of PU.1 that we developed specifically to allosterically interfere with PU.1-chromatin binding through interaction with the DNA minor groove that flanks PU.1-binding motifs. These small molecules of the heterocyclic diamidine family disrupted the interaction of PU.1 with target gene promoters and led to downregulation of canonical PU.1 transcriptional targets. shRNA or small-molecule inhibition of PU.1 in AML cells from either PU.1lo mutant mice or human patients with AML-inhibited cell growth and clonogenicity and induced apoptosis. In murine and human AML (xeno)transplantation models, treatment with our PU.1 inhibitors decreased tumor burden and resulted in increased survival. Thus, our study provides proof of concept that PU.1 inhibition has potential as a therapeutic strategy for the treatment of AML and for the development of small-molecule inhibitors of PU.1.
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http://dx.doi.org/10.1172/JCI92504DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5707147PMC
December 2017

Epigenetically Aberrant Stroma in MDS Propagates Disease via Wnt/β-Catenin Activation.

Cancer Res 2017 09 6;77(18):4846-4857. Epub 2017 Jul 6.

Columbia University, New York, New York.

The bone marrow microenvironment influences malignant hematopoiesis, but how it promotes leukemogenesis has not been elucidated. In addition, the role of the bone marrow stroma in regulating clinical responses to DNA methyltransferase inhibitors (DNMTi) is also poorly understood. In this study, we conducted a DNA methylome analysis of bone marrow-derived stromal cells from myelodysplastic syndrome (MDS) patients and observed widespread aberrant cytosine hypermethylation occurring preferentially outside CpG islands. Stroma derived from 5-azacytidine-treated patients lacked aberrant methylation and DNMTi treatment of primary MDS stroma enhanced its ability to support erythroid differentiation. An integrative expression analysis revealed that the WNT pathway antagonist FRZB was aberrantly hypermethylated and underexpressed in MDS stroma. This result was confirmed in an independent set of sorted, primary MDS-derived mesenchymal cells. We documented a WNT/β-catenin activation signature in CD34 cells from advanced cases of MDS, where it associated with adverse prognosis. Constitutive activation of β-catenin in hematopoietic cells yielded lethal myeloid disease in a NUP98-HOXD13 mouse model of MDS, confirming its role in disease progression. Our results define novel epigenetic changes in the bone marrow microenvironment, which lead to β-catenin activation and disease progression of MDS. .
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http://dx.doi.org/10.1158/0008-5472.CAN-17-0282DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5600853PMC
September 2017

A myeloid tumor suppressor role for .

J Exp Med 2017 03 23;214(3):753-771. Epub 2017 Feb 23.

Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461

Despite the identification of several oncogenic driver mutations leading to constitutive JAK-STAT activation, the cellular and molecular biology of myeloproliferative neoplasms (MPN) remains incompletely understood. Recent discoveries have identified underlying disease-modifying molecular aberrations contributing to disease initiation and progression. Here, we report that deletion of () in mice leads to an MPN resembling primary myelofibrosis (PMF). MPN mice harbor an expanded Thy1LSK stem cell population exhibiting increased cell cycling and a myelomonocytic differentiation bias. Molecularly, this phenotype is mediated by -induced JAK-STAT activation and downstream activation of () and MPN Thy1LSK cells share significant molecular similarities with primary CD34 cells from PMF patients. levels are decreased in CD34 cells from PMF patients, and the locus is deleted in a subset of patients with myeloid malignancies. Our results reveal a novel genetic PMF-like mouse model and identify a tumor suppressor role for in the pathogenesis of myeloid malignancies.
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http://dx.doi.org/10.1084/jem.20162089DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5339683PMC
March 2017

Stem and progenitor cell alterations in myelodysplastic syndromes.

Blood 2017 03 3;129(12):1586-1594. Epub 2017 Feb 3.

Division of Hemato-Oncology, Department of Oncology, Albert Einstein College of Medicine, Bronx, NY; and.

Recent studies have demonstrated that myelodysplastic syndromes (MDSs) arise from a small population of disease-initiating hematopoietic stem cells (HSCs) that persist and expand through conventional therapies and are major contributors to disease progression and relapse. MDS stem and progenitor cells are characterized by key founder and driver mutations and are enriched for cytogenetic alterations. Quantitative alterations in hematopoietic stem and progenitor cell (HSPC) numbers are also seen in a stage-specific manner in human MDS samples as well as in murine models of the disease. Overexpression of several markers such as interleukin-1 (IL-1) receptor accessory protein (IL1RAP), CD99, T-cell immunoglobulin mucin-3, and CD123 have begun to differentiate MDS HSPCs from healthy counterparts. Overactivation of innate immune components such as Toll-like receptors, IL-1 receptor-associated kinase/tumor necrosis factor receptor-associated factor-6, IL8/CXCR2, and IL1RAP signaling pathways has been demonstrated in MDS HSPCs and is being targeted therapeutically in preclinical and early clinical studies. Other dysregulated pathways such as signal transducer and activator of transcription 3, tyrosine kinase with immunoglobulinlike and EGF-like domains 1/angiopoietin-1, p21-activated kinase, microRNA 21, and transforming growth factor β are also being explored as therapeutic targets against MDS HSPCs. Taken together, these studies have demonstrated that MDS stem cells are functionally critical for the initiation, transformation, and relapse of disease and need to be targeted therapeutically for future curative strategies in MDSs.
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http://dx.doi.org/10.1182/blood-2016-10-696062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5364336PMC
March 2017

Leukemic Stem Cells S(p)liced Off.

Cell Stem Cell 2016 11;19(5):561-563

Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA; Department of Medicine (Oncology), Albert Einstein College of Medicine-Montefiore Medical Center, Bronx, NY 10467, USA; Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA; Institute for Stem Cell Research and Regenerative Medicine, Albert Einstein College of Medicine, Bronx, NY 10461, USA. Electronic address:

Myeloid malignancies often arise from an aging hematopoietic system and are currently incurable due to therapy-resistant, disease-reinitiating leukemic stem cells. In this issue of Cell Stem Cell, Crews et al. (2016) report RNA splice isoform signatures unique to patient-derived leukemic stem cells that constitute a therapeutic Achilles' heel of myeloid leukemia.
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http://dx.doi.org/10.1016/j.stem.2016.10.016DOI Listing
November 2016

Chronic interleukin-1 exposure drives haematopoietic stem cells towards precocious myeloid differentiation at the expense of self-renewal.

Nat Cell Biol 2016 06 25;18(6):607-18. Epub 2016 Apr 25.

The Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, Department of Medicine, Division of Hematology/Oncology, University of California San Francisco, San Francisco, California 94143, USA.

Haematopoietic stem cells (HSCs) maintain lifelong blood production and increase blood cell numbers in response to chronic and acute injury. However, the mechanism(s) by which inflammatory insults are communicated to HSCs and their consequences for HSC activity remain largely unknown. Here, we demonstrate that interleukin-1 (IL-1), which functions as a key pro-inflammatory 'emergency' signal, directly accelerates cell division and myeloid differentiation of HSCs through precocious activation of a PU.1-dependent gene program. Although this effect is essential for rapid myeloid recovery following acute injury to the bone marrow, chronic IL-1 exposure restricts HSC lineage output, severely erodes HSC self-renewal capacity, and primes IL-1-exposed HSCs to fail massive replicative challenges such as transplantation. Importantly, these damaging effects are transient and fully reversible on IL-1 withdrawal. Our results identify a critical regulatory circuit that tailors HSC responses to acute needs, and is likely to underlie deregulated blood homeostasis in chronic inflammation conditions.
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http://dx.doi.org/10.1038/ncb3346DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4884136PMC
June 2016

New IDH1 mutant inhibitors for treatment of acute myeloid leukemia.

Nat Chem Biol 2015 Nov 5;11(11):878-86. Epub 2015 Oct 5.

Division of Hemato-Oncology, Department of Medicine (Oncology), Albert Einstein College of Medicine / Montefiore Medical Center, Bronx, New York, USA.

Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are driver mutations in acute myeloid leukemia (AML) and other cancers. We report the development of new allosteric inhibitors of mutant IDH1. Crystallographic and biochemical results demonstrated that compounds of this chemical series bind to an allosteric site and lock the enzyme in a catalytically inactive conformation, thereby enabling inhibition of different clinically relevant IDH1 mutants. Treatment of IDH1 mutant primary AML cells uniformly led to a decrease in intracellular 2-HG, abrogation of the myeloid differentiation block and induction of granulocytic differentiation at the level of leukemic blasts and more immature stem-like cells, in vitro and in vivo. Molecularly, treatment with the inhibitors led to a reversal of the DNA cytosine hypermethylation patterns caused by mutant IDH1 in the cells of individuals with AML. Our study provides proof of concept for the molecular and biological activity of novel allosteric inhibitors for targeting different mutant forms of IDH1 in leukemia.
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http://dx.doi.org/10.1038/nchembio.1930DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5155016PMC
November 2015

Minimal PU.1 reduction induces a preleukemic state and promotes development of acute myeloid leukemia.

Nat Med 2015 Oct 7;21(10):1172-81. Epub 2015 Sep 7.

Department of Cell Biology, Albert Einstein College of Medicine, Bronx, USA.

Modest transcriptional changes caused by genetic or epigenetic mechanisms are frequent in human cancer. Although loss or near-complete loss of the hematopoietic transcription factor PU.1 induces acute myeloid leukemia (AML) in mice, a similar degree of PU.1 impairment is exceedingly rare in human AML; yet, moderate PU.1 inhibition is common in AML patients. We assessed functional consequences of modest reductions in PU.1 expression on leukemia development in mice harboring DNA lesions resembling those acquired during human stem cell aging. Heterozygous deletion of an enhancer of PU.1, which resulted in a 35% reduction of PU.1 expression, was sufficient to induce myeloid-biased preleukemic stem cells and their subsequent transformation to AML in a DNA mismatch repair-deficient background. AML progression was mediated by inhibition of expression of a PU.1-cooperating transcription factor, Irf8. Notably, we found marked molecular similarities between the disease in these mice and human myelodysplastic syndrome and AML. This study demonstrates that minimal reduction of a key lineage-specific transcription factor, which commonly occurs in human disease, is sufficient to initiate cancer development, and it provides mechanistic insight into the formation and progression of preleukemic stem cells in AML.
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http://dx.doi.org/10.1038/nm.3936DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5144917PMC
October 2015

IL8-CXCR2 pathway inhibition as a therapeutic strategy against MDS and AML stem cells.

Blood 2015 May 25;125(20):3144-52. Epub 2015 Mar 25.

Division of Hemato-Oncology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY;

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are associated with disease-initiating stem cells that are not eliminated by conventional therapies. Novel therapeutic targets against preleukemic stem cells need to be identified for potentially curative strategies. We conducted parallel transcriptional analysis of highly fractionated stem and progenitor populations in MDS, AML, and control samples and found interleukin 8 (IL8) to be consistently overexpressed in patient samples. The receptor for IL8, CXCR2, was also significantly increased in MDS CD34(+) cells from a large clinical cohort and was predictive of increased transfusion dependence. High CXCR2 expression was also an adverse prognostic factor in The Cancer Genome Atlas AML cohort, further pointing to the critical role of the IL8-CXCR2 axis in AML/MDS. Functionally, CXCR2 inhibition by knockdown and pharmacologic approaches led to a significant reduction in proliferation in several leukemic cell lines and primary MDS/AML samples via induction of G0/G1 cell cycle arrest. Importantly, inhibition of CXCR2 selectively inhibited immature hematopoietic stem cells from MDS/AML samples without an effect on healthy controls. CXCR2 knockdown also impaired leukemic growth in vivo. Together, these studies demonstrate that the IL8 receptor CXCR2 is an adverse prognostic factor in MDS/AML and is a potential therapeutic target against immature leukemic stem cell-enriched cell fractions in MDS and AML.
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http://dx.doi.org/10.1182/blood-2015-01-621631DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4432009PMC
May 2015

Combinatorial haplo-deficient tumor suppression in 7q-deficient myelodysplastic syndrome and acute myeloid leukemia.

Cancer Cell 2014 May;25(5):555-7

Department of Cell Biology, Albert Einstein College of Medicine/Montefiore Medical Center, New York, NY 10461, USA; Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, Albert Einstein College of Medicine/Montefiore Medical Center, New York, NY 10461, USA; Division of Hematologic Malignancies, Department of Medicine (Oncology), Albert Einstein College of Medicine/Montefiore Medical Center, New York, NY 10461, USA; Albert Einstein Cancer Center, Albert Einstein College of Medicine/Montefiore Medical Center, New York, NY 10461, USA. Electronic address:

Heterozygous deletions of chromosome 7 are frequent in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). In this issue of Cancer Cell, Chen and colleagues identify MLL3 as a novel haplo-insufficient tumor suppressor on 7q that, in combination with NF1 suppression and TP53 deficiency, mediates MDS and AML phenotypes in mouse and human systems.
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http://dx.doi.org/10.1016/j.ccr.2014.04.018DOI Listing
May 2014

Eltrombopag can overcome the anti-megakaryopoietic effects of lenalidomide without increasing proliferation of the malignant myelodysplastic syndrome/acute myelogenous leukemia clone.

Leuk Lymphoma 2014 Dec 20;55(12):2901-6. Epub 2014 Mar 20.

Division of Hematologic Malignancies, Albert Einstein College of Medicine, Montefiore Medical Center , Bronx, NY , USA.

Lenalidomide (Len) is clinically indicated in myelodysplastic syndrome (MDS) but its use is limited by significant thrombocytopenia. Eltrombopag (EP) is a thrombopoietin receptor agonist that can stimulate platelet production and has shown preclinical efficacy in inhibiting leukemic cell proliferation. Thus, we determined the preclinical efficacy and safety of combining Len and EP in acute myelogenous leukemia (AML) and MDS. We found that single agent treatment of leukemia and lymphoma cell lines with EP and Len showed differential sensitivities to either agent. Combination therapy did not result in reversal of anti-malignant effects on these cells. Furthermore, the combination of Len and EP resulted in significant inhibitory effects on growth of leukemic colonies in the majority of primary MDS and AML samples. Most importantly, EP was able to reverse the anti-megakaryopoietic effects of Len in primary MDS patient samples. These results provide a preclinical rationale for the use of this combination in MDS and AML.
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http://dx.doi.org/10.3109/10428194.2014.894186DOI Listing
December 2014

Stem cell fate regulation by dynein motor protein Lis1.

Nat Genet 2014 Mar;46(3):217-8

Department of Cell Biology, the Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research, the Department of Medicine (Oncology) and the Albert Einstein Cancer Center, Albert Einstein College of Medicine/Montefiore Medical Center, New York, New York, USA.

Cell fate regulation is a central component of maintaining tissue homeostasis, yet the mechanisms instructing cell division diversity in tissue-specific stem cells have not been well understood. A new study uncovers a central role for microtubule motor-regulating protein Lis1 in hematopoietic stem cell fate determination and in leukemogenesis.
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http://dx.doi.org/10.1038/ng.2902DOI Listing
March 2014

HSC commitment-associated epigenetic signature is prognostic in acute myeloid leukemia.

J Clin Invest 2014 Mar;124(3):1158-67

Acute myeloid leukemia (AML) is characterized by disruption of HSC and progenitor cell differentiation. Frequently, AML is associated with mutations in genes encoding epigenetic modifiers. We hypothesized that analysis of alterations in DNA methylation patterns during healthy HSC commitment and differentiation would yield epigenetic signatures that could be used to identify stage-specific prognostic subgroups of AML. We performed a nano HpaII-tiny-fragment-enrichment-by-ligation-mediated-PCR (nanoHELP) assay to compare genome-wide cytosine methylation profiles between highly purified human long-term HSC, short-term HSC, common myeloid progenitors, and megakaryocyte-erythrocyte progenitors. We observed that the most striking epigenetic changes occurred during the commitment of short-term HSC to common myeloid progenitors and these alterations were predominantly characterized by loss of methylation. We developed a metric of the HSC commitment–associated methylation pattern that proved to be highly prognostic of overall survival in 3 independent large AML patient cohorts, regardless of patient treatment and epigenetic mutations. Application of the epigenetic signature metric for AML prognosis was superior to evaluation of commitment-based gene expression signatures. Together, our data define a stem cell commitment–associated methylome that is independently prognostic of poorer overall survival in AML.
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http://dx.doi.org/10.1172/JCI71264DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3934187PMC
March 2014

Satb1 regulates the self-renewal of hematopoietic stem cells by promoting quiescence and repressing differentiation commitment.

Nat Immunol 2013 May 7;14(5):437-45. Epub 2013 Apr 7.

Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, USA.

How hematopoietic stem cells (HSCs) coordinate the regulation of opposing cellular mechanisms such as self-renewal and differentiation commitment remains unclear. Here we identified the transcription factor and chromatin remodeler Satb1 as a critical regulator of HSC fate. HSCs lacking Satb1 had defective self-renewal, were less quiescent and showed accelerated lineage commitment, which resulted in progressive depletion of functional HSCs. The enhanced commitment was caused by less symmetric self-renewal and more symmetric differentiation divisions of Satb1-deficient HSCs. Satb1 simultaneously repressed sets of genes encoding molecules involved in HSC activation and cellular polarity, including Numb and Myc, which encode two key factors for the specification of stem-cell fate. Thus, Satb1 is a regulator that promotes HSC quiescence and represses lineage commitment.
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http://dx.doi.org/10.1038/ni.2572DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3633104PMC
May 2013

Methylome profiling reveals distinct alterations in phenotypic and mutational subgroups of myeloproliferative neoplasms.

Cancer Res 2013 Feb 11;73(3):1076-85. Epub 2012 Oct 11.

Albert Einstein College of Medicine, Bronx, New York; Mayo Clinic, Rochester, MN, USA.

Even though mutations in epigenetic regulators frequently occur in myeloproliferative neoplasms, their effects on the epigenome have not been well studied. Furthermore, even though primary myelofibrosis (PMF) has a markedly worse prognosis than essential thrombocytosis or polycythemia vera, the molecular distinctions between these subgroups are not well elucidated. We conducted the HELP (HpaII tiny fragment enriched by LM-PCR) assay to study genome-wide methylation in polycythemia vera, essential thrombocytosis, and PMF samples compared with healthy controls. We determined that polycythemia vera and essential thrombocytosis are characterized by aberrant promoter hypermethylation, whereas PMF is an epigenetically distinct subgroup characterized by both aberrant hyper- and hypomethylation. Aberrant hypomethylation in PMF was seen to occur in non-CpG island loci, showing further qualitative differences between the disease subgroups. The differentially methylated genes in polycythemia vera and essential thrombocytosis were involved predominantly in cell signaling pathways and were enriched for binding sites of GATA1 and other transcription factors. In contrast, aberrantly methylated genes in PMF were involved in inflammatory pathways and were enriched for NF1, LEF1, and other transcription factors. Within the PMF subgroup, cases with ASXL1 disruptions formed an epigenetically distinct subgroup with relatively increased methylation. Cases of myeloproliferative neoplasms (MPN) with TET2 mutations showed decreased levels of hydroxymethylation and distinct set of hypermethylated genes. In contrast, the JAK2V617F mutation did not drive epigenetic clustering within MPNs. Finally, the significance of aberrant methylation was shown by sensitivity of MPN-derived cell lines to decitabine. These results show epigenetic differences between PMF and polycythemia vera/essential thrombocytosis and reveal methylomic signatures of ASXL1 and TET2 mutations.
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http://dx.doi.org/10.1158/0008-5472.CAN-12-0735DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5500294PMC
February 2013
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