scholarly journals EPCR Signaling Controls the Activity of Hematopoietic Stem Cells Independent of Coagulation Regulation

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3263-3263
Author(s):  
Son Nguyen ◽  
Divij Verma ◽  
Claudine Graf ◽  
Shiri Gur-Cohen ◽  
Jennifer Royce ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Steady State ◽  
Hematopoietic Stem Cells ◽  
Peripheral Blood ◽  
Myeloid Leukemia ◽  
Hematopoietic Stem ◽  
Anticoagulant Function ◽  
Acute Myeloid

Abstract Background All mature blood cells are derived from multipotent hematopoietic stem cells (HSCs) which are activated to meet the demand of the host during inflammation and injury. The endothelial cell protein C receptor (EPCR) is a marker for primitivity and quiescence of HSCs but the relative contributions of EPCR signaling versus anticoagulant functions in HSC maintenance are incompletely defined. Aims We aimed to dissect functions of EPCR by studying anticoagulant and signaling function in HSC of EPCR C/S mice carrying a single intracellular point mutation abolishing normal trafficking of EPCR through endo-lysosomal compartments. We assessed the contributions of EPCR signaling to stem cell maintenance by analyzing HSC mobilization and leukemia progression. Methods We studied the frequency and cell cycle activity of bone marrow (BM) hematopoietic stem and progenitor cells (HSPC) by multicolor flow cytometry. Furthermore, we analyzed changes in hematopoiesis in steady state, after granulocyte colony stimulating factor (G-CSF)-induced mobilization, in the context of aging and in the context of leukemia, using the MLL-AF9-induced acute myeloid leukemia (AML) model. Results HSCs, lungs and isolated lung-derived smooth muscle cells of EPCR C/S mice showed protein expression levels and anticoagulant function indistinguishable from wildtype (WT). We found an increase of circulating HSCs in the peripheral blood of EPCR C/S mice compared to control under steady state conditions. Isolated HSC displayed diminished polarization of CDC42 and VLA-4 (α 4β 1 integrin) affinity to VCAM-1 in EPCR C/S versus strain-matched EPCR wt mice, indicating that EPCR signaling directly controls HSC retention via integrin affinity to the BM niche. In addition, we noticed a higher cell cycle activity in myeloid-restricted progenitors of EPCR C/S mice compared to control. G-CSF treatment led to increased mobilization of both BM neutrophils and HSCs into the peripheral blood of EPCR C/S mice compared to EPCR wt mice. A myeloid bias was also seen in serially transplanted aged mice, resulting in increased frequencies of myeloid-biased progenitors in the BM of EPCR C/S mice compared to control mice, accompanied by an increase of circulating neutrophils in the blood. Consistent with higher cell cycle activity of myeloid progenitors and an overall increase of myeloid-biased output in EPCR C/S mice, induction of AML by retroviral transduction of EPCR C/S BM cells with MLL-AF9-expressing retrovirus resulted in an increase of cell cycle activity of Lin - MLL-AF9 + leukemic BM blasts and a higher leukemic load in the peripheral blood of mice transplanted with MLL-AF9 + EPCR C/S BM compared to control. As a result, MLL-AF9 + EPCR C/S leukemia showed a more aggressive disease with shortened survival times compared to control. In contrast, chemotherapy of MLL-AF9 + EPCR C/S leukemia reduced leukemic load in the peripheral blood and decelerated disease progression. These data demonstrate that increased leukemia cell cycle activity conferred chemosensitivity. Conclusion With a site-specific EPCR mutant knock-in mouse, we here demonstrate that EPCR signaling and anticoagulant function can be separated. We provide direct evidence that EPCR signaling plays a crucial role in maintaining HSC retention via VLA-4 affinity to VCAM-1, controls cell cycle activity and myeloid output in normal, stress-induced, and malignant hematopoiesis with implications for therapeutic approaches in acute myeloid leukemia. Disclosures Ruf: MeruVasimmune: Other: Ownership Interest; ARCA bioscience: Consultancy, Patents & Royalties; ICONIC Therapeutics: Consultancy.

MicroRNA-29a Is An Oncogene in Acute Myeloid Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 683-683
Author(s):  
Christopher Y. Park ◽  
Yoon-Chi Han ◽  
Govind Bhagat ◽  
Jian-Bing Fan ◽  
Irving L Weissman ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Mirna Expression ◽  
Myeloid Leukemia ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Abstract microRNAs (miRNAs) are short, non-protein encoding RNAs that bind to the 3′UTR’s of target mRNAs and negatively regulate gene expression by facilitating mRNA degradation or translational inhibition. Aberrant miRNA expression is well-documented in both solid and hematopoietic malignancies, and a number of recent miRNA profiling studies have identified miRNAs associated with specific human acute myeloid leukemia (AML) cytogenetic groups as well as miRNAs that may prognosticate clinical outcomes in AML patients. Unfortunately, these studies do not directly address the functional role of miRNAs in AML. In fact, there is no direct functional evidence that miRNAs are required for AML development or maintenance. Herein, we report on our recent efforts to elucidate the role of miRNAs in AML stem cells. miRNA expression profiling of AML stem cells and their normal counterparts, hematopoietic stem cells (HSC) and committed progenitors, reveals that miR-29a is highly expressed in human hematopoietic stem cells (HSC) and human AML relative to normal committed progenitors. Ectopic expression of miR-29a in mouse HSC/progenitors is sufficient to induce a myeloproliferative disorder (MPD) that progresses to AML. During the MPD phase of the disease, miR-29a alters the composition of committed myeloid progenitors, significantly expedites cell cycle progression, and promotes proliferation of hematopoietic progenitors at the level of the multipotent progenitor (MPP). These changes are manifested pathologically by marked granulocytic and megakaryocytic hyperplasia with hepatosplenomegaly. Mice with miR-29a-induced MPD uniformly progress to an AML that contains a leukemia stem cell (LSC) population that can serially transplant disease with as few as 20 purified LSC. Gene expression analysis reveals multiple tumor suppressors and cell cycle regulators downregulated in miR-29a expressing cells compared to wild type. We have demonstrated that one of these genes, Hbp1, is a bona fide miR-29a target, but knockdown of Hbp1 in vivo does not recapitulate the miR-29a phenotype. These data indicate that additional genes are required for miR-29a’s leukemogenic activity. In summary, our data demonstrate that miR-29a regulates early events in normal hematopoiesis and promotes myeloid differentiation and expansion. Moreover, they establish that misexpression of a single miRNA is sufficient to drive leukemogenesis, suggesting that therapeutic targeting of miRNAs may be an effective means of treating myeloid leukemias.

scholarly journals Evidence for malignant transformation in acute myeloid leukemia at the level of early hematopoietic stem cells by cytogenetic analysis of CD34+ subpopulations

Blood ◽  
1995 ◽  
Vol 86 (8) ◽  
pp. 2906-2912 ◽  
Author(s):  
D Haase ◽  
M Feuring-Buske ◽  
S Konemann ◽  
C Fonatsch ◽  
C Troff ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Malignant Transformation ◽  
Cell Sorting ◽  
Myeloid Leukemia ◽  
De Novo ◽  
Leukemic Cells ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Acute myeloid leukemia (AML) is a heterogenous disease according to morphology, immunophenotype, and genetics. The retained capacity of differentiation is the basis for the phenotypic classification of the bulk population of leukemic blasts and the identification of distinct subpopulations. Within the hierarchy of hematopoietic development and differentiation it is still unknown at which stage the malignant transformation occurs. It was our aim to analyze the potential involvement of cells with the immunophenotype of pluripotent stem cells in the leukemic process by the use of cytogenetic and cell sorting techniques. Cytogenetic analyses of bone marrow aspirates were performed in 13 patients with AML (11 de novo and 2 secondary) and showed karyotype abnormalities in 10 cases [2q+, +4, 6p, t(6:9), 7, +8 in 1 patient each and inv(16) in 4 patients each]. Aliquots of the samples were fractionated by fluorescence-activated cell sorting of CD34+ cells. Two subpopulations, CD34+/CD38-(early hematopoietic stem cells) and CD34+/CD38+ (more mature progenitor cells), were screened for karyotype aberations as a marker for leukemic cells. Clonal abnormalities and evaluable metaphases were found in 8 highly purified CD34+/CD38-populations and in 9 of the CD34+/CD38-specimens, respectively. In the majority of cases (CD34+/CD38-, 6 of 8 informative samples; CD34+/CD38+, 5 of 9 informative samples), the highly purified CD34+ specimens also contained cytogenetically normal cells. Secondary, progression-associated chromosomal changes (+8, 12) were identified in the CD34+/CD38-cells of 2 patients. We conclude that clonal karyotypic abnormalities are frequently found in the stem cell-like (CD34+/CD38-) and more mature (CD34+/CD38+) populations of patients with AML, irrespective of the phenotype of the bulk population of leukemic blasts and of the primary or secondary character of the leukemia. Our data suggest that, in AML, malignant transformation as well as disease progression may occur at the level of CD34+/CD38-cells with multilineage potential.

TIM-3 Is a Promising Target to Eradicate Acute Myeloid Leukemia Stem Cells Sparing Normal Hematopoietic Stem Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 559-559
Author(s):  
Toshihiro Miyamoto ◽  
Yoshikane Kikushige ◽  
Takahiro Shima ◽  
Koichi Akashi
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Myeloid Leukemia ◽  
Leukemia Cell ◽  
Cytotoxic Activities ◽  
Antibody Treatment ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Abstract Abstract 559 Acute myeloid leukemia (AML) originates from self-renewing leukemic stem cells (LSCs), an ultimate therapeutic target for permanent cure. To selectively kill AML LSCs sparing normal hematopoietic stem cells (HSCs), one of the most practical approaches is to target the AML LSCs-specific surface or functionally indispensable molecules. Based on differential transcriptome analysis of prospectively-purified CD34+CD38− LSCs from AML patient samples and normal HSCs, we found that T-cell immunoglobulin mucin-3 (TIM-3) was highly expressed in AML LSCs but not in normal HSCs (Kikushige et al., Cell Stem Cell, 2010). In normal hematopoiesis, TIM-3 is mainly expressed in mature monocytes and a fraction of NK cells, but not in granulocytes, T cells or B cells. In the bone marrow, TIM-3 is expressed only in a fraction of granulocyte/macrophage progenitors (GMPs) at a low level, but not in HSCs, common myeloid progenitors, or megakaryocyte/erythrocyte progenitors. In contrast, in human AML, TIM-3 was expressed on cell surface of the vast majority of CD34+CD38− LSCs and CD34+CD38+ leukemic progenitors in AML of most FAB types, except for acute promyelocytic leukemia (M3). FACS-sorted TIM-3+ but not TIM-3− AML cells reconstituted human AML in the immunodeficient mice, indicating that the TIM-3+ population contains most of functional LSCs. To selectively eradicate TIM-3-expressing AML LSCs, we established an anti-human TIM-3 mouse IgG2a antibody, ATIK2a, possessing antibody-dependent cellular cytotoxic and complement-dependent cytotoxic activities in leukemia cell lines transfected with TIM-3. We first tested the effect of ATIK2a treatment on reconstitution of normal HSCs in a xenograft model. ATIK2a was intraperitoneally injected to the mice once a week after 12 hours of transplantation of human CD34+ cells. Injection of ATIK2a did not affect reconstitution of normal human hematopoiesis except removing TIM-3-expressing mature monocytes. In contrast, injection of TIM-3 to the mice transplanted with human AML samples markedly reduced leukemic repopulation. In some mice transplanted with AML bone marrow, only normal hematopoiesis was reconstituted after anti-TIM-3 antibody treatment, suggesting that the antibody selectively killed AML cells, sparing residual normal HSCs. To further test the inhibitory effect of ATIK2a on established human AML, eight weeks after transplantation of human AML cells, engraftment of human AML cells was confirmed by blood sampling and thereafter ATIK2a was injected to these mice. In all cases tested, ATIK2a treatment significantly reduced human TIM-3+ AML fraction as well as the CD34+CD38− LSCs fraction. In addition, to verify the anti-AML LSCs effect of ATIK2a treatment, human CD45+AML cells from the primary recipients were re-transplanted into secondary recipients. All mice transplanted from primary recipients treated with control IgG developed AML, whereas none of mice transplanted with cells from ATIK2a-treated primary recipients developed AML, suggesting that functional LSCs were effectively eliminated by ATIK2a treatment in primary recipients. Thus, TIM-3 is a promising surface molecule to target AML LSCs. Our experiments strongly suggest that targeting this molecule by monoclonal antibody treatment is a practical approach to eradicate human AML. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Clonal Evolution of Preleukemic Hematopoietic Stem Cells Precedes Human Acute Myeloid Leukemia

2012 ◽  
Vol 4 (149) ◽  
pp. 149ra118-149ra118 ◽  
Author(s):  
M. Jan ◽  
T. M. Snyder ◽  
M. R. Corces-Zimmerman ◽  
P. Vyas ◽  
I. L. Weissman ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Myeloid Leukemia ◽  
Clonal Evolution ◽  
Hematopoietic Stem ◽  
Human Acute Myeloid Leukemia ◽  
Acute Myeloid

scholarly journals Self-Renewal Pathways in Acute Myeloid Leukemia Stem Cells

2020 ◽  
Author(s):  
Jonason Yang ◽  
Nunki Hassan ◽  
Sheng Xiang Franklin Chen ◽  
Jayvee Datuin ◽  
Jenny Y. Wang
Keyword(s):  
Stem Cells ◽  
Monoclonal Antibody ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Myeloid Leukemia ◽  
Leukemia Stem Cells ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Clinical Potential ◽  
Acute Myeloid

Acute myeloid leukemia (AML) is a difficult-to-treat blood cancer. A major challenge in treating patients with AML is relapse, which is caused by the persistence of leukemia stem cells (LSCs). Self-renewal is a defining property of LSCs and its deregulation is crucial for re-initiating a new leukemia after chemotherapy. Emerging therapeutic agents inhibiting aberrant self-renewal pathways, such as anti-RSPO3 monoclonal antibody discovered in our recent study, present significant clinical potential that may extend beyond the scope of leukemogenesis. In this chapter, we provide an overview of normal and malignant hematopoietic stem cells, discuss current treatments and limitations, and review key self-renewal pathways and potential therapeutic opportunities in AML.

scholarly journals Acute myeloid leukemia cells secrete microRNA-4532-containing exosomes to mediate normal hematopoiesis in hematopoietic stem cells by activating the LDOC1-dependent STAT3 signaling pathway

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Chen Zhao ◽  
Feng Du ◽  
Yang Zhao ◽  
Shanshan Wang ◽  
Ling Qi
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Signaling Pathway ◽  
Myeloid Leukemia ◽  
Hematopoietic Stem ◽  
Stat3 Signaling ◽  
Stat3 Signaling Pathway ◽  
Stat3 Phosphorylation ◽  
Acute Myeloid

Abstract Background MicroRNA (miR)-containing exosomes released by acute myeloid leukemia (AML) cells can be delivered into hematopoietic progenitor cells to suppress normal hematopoiesis. Herein, our study was performed to evaluate the effect of exosomal miR-4532 secreted by AML cells on hematopoiesis of hematopoietic stem cells. Methods Firstly, differentially expressed miRs related to AML were identified using microarray analysis. Subsequently, AML cell lines were collected, and CD34+ HSCs were isolated from healthy pregnant women. Then, miR-4532 expression was measured in AML cells and AML cell-derived exosomes and CD34+ HSCs, together with evaluation of the targeting relationship between miR-4532 and LDOC1. Then, AML cells were treated with miR-4532 inhibitor, and exosomes were separated from AML cells and co-cultured with CD34+ HSCs. Gain- and loss-function approaches were employed in CD34+ HSCs. Colony-forming units (CFU) and expression of dickkopf-1 (DKK1), a hematopoietic inhibiting factor associated with pathogenesis of AML, were determined in CD34+ HSCs, as well as the extents of JAK2 and STAT3 phosphorylation and LDOC1 expression. Results miR-4532 was found to be upregulated in AML cells and AML cell-derived exosomes, while being downregulated in CD34+ HSCs. In addition, exosomes released by AML cells targeted CD34+ HSCs to decrease the expression of CFU and increase the expression of DKK1. miR-4532 was delivered into CD34+ HSCs to target LDOC1 via AML cell-released exosomes. AML cell-derived exosomes containing miR-4532 inhibitor increased CFU but reduced DKK1 in CD34+ HSCs. Inhibition of miR-4532 or JAK2, or ectopic expression of LDOC1 upregulated CFU and downregulated DKK1 expression as well as the extents of JAK2 and STAT3 phosphorylation in CD34+ HSCs. Conclusion In conclusion, AML cell-derived exosomes carrying miR-4532 repress normal HSC hematopoiesis via activation of the LDOC1-dependent STAT3 signaling pathway.

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