JAK2V617F mutant megakaryocytes contribute to hematopoietic aging in a murine model of myeloproliferative neoplasm

Megakaryocytes (MKs) is an important component of the hematopoietic niche. Abnormal MK hyperplasia is a hallmark feature of myeloproliferative neoplasms (MPNs). The JAK2V617F mutation is present in hematopoietic cells in a majority of patients with MPNs. Using a murine model of MPN in which the human JAK2V617F gene is expressed specifically in the MK lineage, we show that the JAK2V617F-bearing MKs promote hematopoietic stem cell (HSC) aging, manifesting as myeloid-skewed hematopoiesis with an expansion of CD41+ HSCs, a reduced engraftment and self-renewal capacity, and a reduced differentiation capacity. HSCs from 2yr old mice with JAK2V617F-bearing MKs were more proliferative and less quiescent than HSCs from age-matched control mice. Examination of the marrow hematopoietic niche reveals that the JAK2V617F-bearing MKs not only have decreased direct interactions with hematopoietic stem/progenitor cells during aging, but also suppress the vascular niche function during aging. Unbiased RNA expression profiling reveals that HSC aging has a profound effect on MK transcriptomic profiles, while targeted cytokine array shows that the JAK2V617F-bearing MKs can alter the hematopoietic niche through increased levels of pro-inflammatory and anti-angiogenic factors. Therefore, as a hematopoietic niche cell, MKs represent an important connection between the extrinsic and intrinsic mechanisms for HSC aging.

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Calreticulin haploinsufficiency augments stem cell activity and is required for onset of myeloproliferative neoplasms

Blood ◽

10.1182/blood.2019003358 ◽

2020 ◽

Author(s):

Kotaro Shide ◽

Takuro Kameda ◽

Ayako Kamiunten ◽

Yoshinori Ozono ◽

Yuki Tahira ◽

...

Keyword(s):

Stem Cells ◽

Hematopoietic Stem Cells ◽

Myeloproliferative Neoplasms ◽

Myeloproliferative Neoplasm ◽

Cell Activity ◽

Extramedullary Hematopoiesis ◽

The Self ◽

Self Renewal ◽

Hematopoietic Stem ◽

Deficient Mice

Mutations in JAK2, MPL, or CALR are detected in more than 80% of myeloproliferative neoplasm (MPN) patients and are thought to play a driver role in MPN pathogenesis via autosomal activation of the JAK-STAT signaling cascade. Mutant CALR binds to MPL, activates downstream MPL signaling cascades, and induces essential thrombocythemia in mice. However, embryonic lethality of Calr-deficient mice precludes determination of a role for CALR in hematopoiesis. To clarify the role of CALR in normal hematopoiesis and MPN pathogenesis, we generated hematopoietic cell-specific Calr-deficient mice. CALR deficiency had little effect on the leukocyte count, hemoglobin levels, or platelet count in peripheral blood. However, Calr-deficient mice showed some hematopoietic properties of MPN, including decreased erythropoiesis and increased myeloid progenitor cells in the bone marrow, and extramedullary hematopoiesis in the spleen. Transplantation experiments revealed that Calr haploinsufficiency promoted the self-renewal capacity of hematopoietic stem cells. We generated CALRdel52 mutant transgenic mice with Calr haploinsufficiency as a model that mimics human MPN patients and found that Calr haploinsufficiency restored the self-renewal capacity of hematopoietic stem cells damaged by CALR mutations. Only recipient mice transplanted with Lineage－Sca1+c-kit+ cells harboring both CALR mutation and Calr haploinsufficiency developed MPN in competitive conditions, showing that CALR haploinsufficiency was required for the onset of CALR-mutated MPNs.

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A Case of Myeloproliferative Neoplasm with BCR-FGFR1 Rearrangement: Favorable Outcome after Haploidentical Allogeneic Transplantation

Case Reports in Hematology ◽

10.1155/2018/5724960 ◽

2018 ◽

Vol 2018 ◽

pp. 1-4 ◽

Cited By ~ 1

Author(s):

Paola Villafuerte-Gutiérrez ◽

Montserrat López Rubio ◽

Pilar Herrera ◽

Eva Arranz

Keyword(s):

Kinase Inhibitors ◽

Fusion Gene ◽

Myeloproliferative Neoplasms ◽

Therapeutic Option ◽

Myeloproliferative Neoplasm ◽

Allogeneic Transplantation ◽

Term Survival ◽

Hematopoietic Stem ◽

Health Organization

Hematopoietic myeloproliferative neoplasms with FGFR1 rearrangement result in the 8p11 myeloproliferative syndrome that in the current Word Health Organization classification is designated as “myeloid and lymphoid neoplasm with FGFR1 abnormalities.” We report the case of a 66-year-old man who had clinical features that resembled chronic myeloid leukaemia (CML), but bone marrow cytogenetic and fluorescent in situ hybridization (FISH) studies showed t(8;22)(p11;q11) and BCR-FGFR1 fusion gene. He was initially managed with hydroxyurea, and given the aggressive nature of this disease, four months later, the patient underwent an allogeneic hematopoietic stem-cell transplantation (HSCT) from an HLA-haploidentical relative. Currently, HSCT may be the only therapeutic option for long-term survival at least until more efficacious tyrosine kinase inhibitors (TKIs) become available.

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Synergic Crosstalk between Inflammation, Oxidative Stress, and Genomic Alterations in BCR–ABL-Negative Myeloproliferative Neoplasm

Antioxidants ◽

10.3390/antiox9111037 ◽

2020 ◽

Vol 9 (11) ◽

pp. 1037

Author(s):

Alessandro Allegra ◽

Giovanni Pioggia ◽

Alessandro Tonacci ◽

Marco Casciaro ◽

Caterina Musolino ◽

...

Keyword(s):

Oxidative Stress ◽

Stem Cell ◽

Chronic Inflammation ◽

Myeloproliferative Neoplasms ◽

Myeloproliferative Neoplasm ◽

Tumor Stage ◽

Driver Mutations ◽

Hematopoietic Stem ◽

Chronic Myeloproliferative Neoplasms ◽

Inflammatory State

Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) have recently been revealed to be related to chronic inflammation, oxidative stress, and the accumulation of reactive oxygen species. It has been proposed that MPNs represent a human inflammation model for tumor advancement, in which long-lasting inflammation serves as the driving element from early tumor stage (over polycythemia vera) to the later myelofibrotic cancer stage. It has been theorized that the starting event for acquired stem cell alteration may occur after a chronic inflammation stimulus with consequent myelopoietic drive, producing a genetic stem cell insult. When this occurs, the clone itself constantly produces inflammatory components in the bone marrow; these elements further cause clonal expansion. In BCR–ABL1-negative MPNs, the driver mutations include JAK 2, MPL, and CALR. Transcriptomic studies of hematopoietic stem cells from subjects with driver mutations have demonstrated the upregulation of inflammation-related genes capable of provoking the development of an inflammatory state. The possibility of acting on the inflammatory state as a therapeutic approach in MPNs appears promising, in which an intervention operating on the pathways that control the synthesis of cytokines and oxidative stress could be effective in reducing the possibility of leukemic progression and onset of complications.

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Impact of Host, Lifestyle and Environmental Factors in the Pathogenesis of MPN

Cancers ◽

10.3390/cancers12082038 ◽

2020 ◽

Vol 12 (8) ◽

pp. 2038

Author(s):

Gajalakshmi Ramanathan ◽

Brianna M Hoover ◽

Angela G Fleischman

Keyword(s):

Environmental Factors ◽

Myeloproliferative Neoplasms ◽

Driver Mutation ◽

Lifestyle Modifications ◽

Hematopoietic Stem ◽

Inflammatory Stimuli ◽

Progression Of Disease ◽

Development Support ◽

Traditional Risk Factors ◽

Hallmark Feature

Philadelphia-negative myeloproliferative neoplasms (MPNs) occur when there is over-production of myeloid cells stemming from hematopoietic stem cells with constitutive activation of JAK/STAT signaling, with JAK2V617F being the most commonly occurring somatic driver mutation. Chronic inflammation is a hallmark feature of MPNs and it is now evident that inflammation is not only a symptom of MPN but can also provoke development and precipitate progression of disease. Herein we have considered major MPN driver mutation independent host, lifestyle, and environmental factors in the pathogenesis of MPN based upon epidemiological and experimental data. In addition to the traditional risk factors such as advanced age, there is evidence to indicate that inflammatory stimuli such as smoking can promote and drive MPN clone emergence and expansion. Diet induced inflammation could also play a role in MPN clonal expansion. Recognition of factors associated with MPN development support lifestyle modifications as an emerging therapeutic tool to restrain inflammation and diminish MPN progression.

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JAK2 V617F impairs hematopoietic stem cell function in a conditional knock-in mouse model of JAK2 V617F–positive essential thrombocythemia

Blood ◽

10.1182/blood-2009-12-259747 ◽

2010 ◽

Vol 116 (9) ◽

pp. 1528-1538 ◽

Cited By ~ 136

Author(s):

Juan Li ◽

Dominik Spensberger ◽

Jong Sook Ahn ◽

Shubha Anand ◽

Philip A. Beer ◽

...

Keyword(s):

Stem Cell ◽

Hematopoietic Stem Cell ◽

Essential Thrombocythemia ◽

Cell Function ◽

Myeloproliferative Neoplasms ◽

Myeloproliferative Neoplasm ◽

Jak2 V617f ◽

Transgenic Models ◽

Disease Phenotype ◽

Hematopoietic Stem

The JAK2 V617F mutation is found in most patients with a myeloproliferative neoplasm and is sufficient to produce a myeloproliferative phenotype in murine retroviral transplantation or transgenic models. However, several lines of evidence suggest that disease phenotype is influenced by the level of mutant JAK2 signaling, and we have therefore generated a conditional knock-in mouse in which a human JAK2 V617F is expressed under the control of the mouse Jak2 locus. Human and murine Jak2 transcripts are expressed at similar levels, and mice develop modest increases in hemoglobin and platelet levels reminiscent of human JAK2 V617F–positive essential thrombocythemia. The phenotype is transplantable and accompanied by increased terminal erythroid and megakaryocyte differentiation together with increased numbers of clonogenic progenitors, including erythropoietin-independent erythroid colonies. Unexpectedly, JAK2V617F mice develop reduced numbers of lineage−Sca-1+c-Kit+ cells, which exhibit increased DNA damage, reduced apoptosis, and reduced cell cycling. Moreover, competitive bone marrow transplantation studies demonstrated impaired hematopoietic stem cell function in JAK2V617F mice. These results suggest that the chronicity of human myeloproliferative neoplasms may reflect a balance between impaired hematopoietic stem cell function and the accumulation of additional mutations.

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Oncogenic Nras Increases Hematopoietic Stem Cell Proliferation and Self-Renewal Through a Bimodal Effect

Blood ◽

10.1182/blood.v120.21.119.119 ◽

2012 ◽

Vol 120 (21) ◽

pp. 119-119

Author(s):

Qing Li ◽

Natacha Bohin ◽

Tiffany Wen ◽

Kevin M. Shannon ◽

Sean J. Morrison

Keyword(s):

Stem Cells ◽

Conflicts Of Interest ◽

Myeloproliferative Neoplasm ◽

Mek Inhibitor ◽

Ras Signaling ◽

Self Renewal ◽

Hematopoietic Stem ◽

Activating Mutations ◽

Cycle Regulation

Abstract Abstract 119 Accumulating evidence suggests that most leukemias are initiated by rare leukemic stem cells (LSC) that are transformed from the normal hematopoietic stem cells and progenitors (HSC/P) by genetic lesions that lead to activation of oncogenes and inactivation of tumor suppressor genes. However, the signaling mechanisms by which these genes transform HSC/P into LSC are poorly understood. Activating mutations of NRAS and KRAS are highly prevalent in acute myeloid leukemia (AML), some myeloproliferative neoplasm (MPN) and myelodysplastic syndromes (MDS). In addition other leukemia associated genetic lesions, such as the BCR-ABL fusion, PTPN11 mutations, FLT3 internal tandem duplications, and NF1 inactivation all deregulate Ras signaling. We previously developed a mouse strain that conditionally expresses an oncogenic NrasG12D allele from the endogenous locus. This consistently resulted in an indolent MPD with delayed onset and prolonged survival in Mx1-cre, NrasG12D/+ mice (referred to as NrasG12D). Oncogenic NrasG12D, however, cooperated with the MOL4070LTR retrovirus to induce AMLs that share molecular and morphologic features with human M4/M5 AML. Here we report that NrasG12D directly affects HSC/P functions. While normal HSCs must remain quiescent to maintain the long term self-renewal capacity and mutations that drive HSC into cycle often lead to HSC depletion, NrasG12D increased HSC proliferation but at the same time increased the self-renewal and competitiveness of HSCs. Serial transplantations revealed that NrasG12D HSCs were able to give higher level of reconstitution than wild-type (WT) HSCs and gave rise to long term multi-lineage reconstitution in lethally irradiated mice after up to four rounds of transplantation while WT HSCs failed to reconstitute beyond two rounds. These effects were not associated with the development of leukemia suggesting oncogenic Nras dys-regulates HSC at a pre-leukemic stage and therefore plays an important role in leukemia initiation. Using histone-2B-GFP (H2B-GFP) label-retaining assays, we further detected a “bimodal” effect of NrasG12D on HSCs: NrasG12D induced a subpopulation of rapid “cycling” HSCs that lost GFP labeling and reconstitution activity faster than WT HSC but another HSC subpopulation that remained more “quiescent” than WT HSCs and retained higher reconstitution when transplanted to irradiated mice. The canonical Ras effector, ERK, was not activated in NrasG12D HSC/Ps and inhibition of ERK with a MEK inhibitor, PD325901, did not have any effect on the Nras induced increase of HSC proliferation. Stat5, on the other hand, was significantly activated in NrasG12D HSC/Ps and heterozygous knockout of Stat5ab abolished the increased proliferation in NrasG12D HSCs, suggesting that Stat5 signaling mediates at least part of the Nras induced increase in HSC proliferation. Nras is thus the first signaling pathway that simultaneously increases HSC proliferation, self-renewal and competitiveness without inducing frank leukemogenesis. This is likely through a “bimodal” effect of Nras signaling on HSC cell cycle regulation. Our studies also identified Stat5 as a novel therapeutic target to inhibit early events in Ras mediated leukemic transformation. Disclosures: No relevant conflicts of interest to declare.

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Embryonic Regulation of the Mouse Hematopoietic Niche

The Scientific World JOURNAL ◽

10.1100/2011/598097 ◽

2011 ◽

Vol 11 ◽

pp. 1770-1780 ◽

Cited By ~ 19

Author(s):

Daisuke Sugiyama ◽

Tomoko Inoue-Yokoo ◽

Stuart T. Fraser ◽

Kasem Kulkeaw ◽

Chiyo Mizuochi ◽

...

Keyword(s):

Regenerative Medicine ◽

Extrinsic Factors ◽

Self Renewal ◽

Hematopoietic Stem ◽

Graft Versus Host ◽

Healthy Donors ◽

Intrinsic Regulation ◽

Embryonic Regulation ◽

Hematopoietic Niche ◽

Transplantation Therapy

Hematopoietic stem cells (HSCs) can differentiate into several types of hematopoietic cells (HCs) (such as erythrocytes, megakaryocytes, lymphocytes, neutrophils, or macrophages) and also undergo self-renewal to sustain hematopoiesis throughout an organism's lifetime. HSCs are currently used clinically as transplantation therapy in regenerative medicine and are typically obtained from healthy donors or cord blood. However, problems remain in HSC transplantation, such as shortage of cells, donor risks, rejection, and graft-versus-host disease (GVHD). Thus, increased understanding of HSC regulation should enable us to improve HSC therapy and develop novel regenerative medicine techniques. HSC regulation is governed by two types of activity: intrinsic regulation, programmed primarily by cell autonomous gene expression, and extrinsic factors, which originate from so-called “niche cells” surrounding HSCs. Here, we focus on the latter and discuss HSC regulation with special emphasis on the role played by niche cells.

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Combination approach to diagnosis and treatment of an elderly patient with chronic Ph-negative myeloproliferative neoplasm and concomitant surgical pathology. Clinical observation

MD-Onco ◽

10.17650/2782-3202-2021-1-1-61-65 ◽

2021 ◽

Vol 1 (1) ◽

pp. 61-65

Author(s):

Yu. E. Ryabukhina ◽

P. A. Zeynalova ◽

O. I. Timofeeva ◽

F. M. Abbasbeyli ◽

T. V. Ponomarev ◽

...

Keyword(s):

Elderly Patient ◽

Essential Thrombocythemia ◽

Early Stage ◽

Myeloproliferative Neoplasms ◽

Myeloproliferative Neoplasm ◽

Jak2 V617f ◽

Primary Myelofibrosis ◽

Left Femur ◽

Hematopoietic Stem ◽

Chronic Myeloproliferative Neoplasms

Chronic myeloproliferative neoplasms (CMPN), Ph-negative, are of clonal nature, develop on the level of hematopoietic stem cell and are characterized by proliferation of one or more hematopoietic pathways. Currently, the group of Ph-negative CMPN includes essential thrombocythemia, primary myelofibrosis, polycythemia vera, myeloproliferative neoplasm unclassifiable.Identification of mutations in the Jak2 (V617F), CALR, and MPL genes extended understanding of biological features of Ph-negative CMPN and improved differential diagnosis of myeloid neoplasms. Nonetheless, clinical practice still encounters difficulties in clear separation between such disorders as primary myelofibrosis, early-stage and transformation of essential thrombocythemia into myelofibrosis with high thrombocytosis. Thrombocytosis is one of the main risk factors for thromboembolic complications, especially in elderly people.A clinical case of an elderly patient with fracture of the left femur developed in the context of Ph-negative CMPN (myelofibrosis) with high level of thrombocytosis is presented which in combination with enforced long-term immobilization and presence of additional risk created danger of thrombosis and hemorrhage during surgery and in the postoperative period.

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Environmental Factors, Lifestyle Risk Factors, and Host Characteristics Associated With Philadelphia Negative Myeloproliferative Neoplasm: A Systematic Review

Cancer Control ◽

10.1177/10732748211046802 ◽

2021 ◽

Vol 28 ◽

pp. 107327482110468

Author(s):

Niloofar Allahverdi ◽

Mohamed Yassin ◽

Mohamed Ibrahim

Keyword(s):

Risk Factors ◽

Environmental Factors ◽

Myeloproliferative Neoplasms ◽

Grey Literature ◽

Myeloproliferative Neoplasm ◽

Hazardous Substances ◽

Hematopoietic Stem ◽

Proinflammatory Mediators ◽

Increased Risk ◽

Host Characteristics

Myeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell disorders characterized by the overproduction of mature myeloid cells and are often associated with an acquired genetic mutation of Janus Kinase2V617F. Various epidemiological studies have indicated associations between environmental factors, lifestyle factors, and host characteristics with developing MPNs. This review aims to collect and summarize the existing information on these risk factors and establish their association with pathogenesis MPNs. Medline, Embase, PubMed, and grey literature were systematically searched using key terms for MPNs, and epidemiological study designs, that is, cross-sectional studies, case-control, and cohort, that investigated the risk factors for MPNs published were identified. Out of the 4621 articles identified, 20 met the selection criteria and were included in this review. Heterogeneity, study reliability, and bias were assessed. A significant association was found between smoking and the development of MPNs. This relationship has been explained by the substantial increase in several proinflammatory mediators and systematic oxidative stress causing hyperstimulation of myeloid compartments leading to the development of MPNs. Obesity was modestly linked with an increased risk of MPNs. The underlying mechanisms have been linked to changes in endocrine, metabolic, and inflammatory systems. No strong association was found between exposure to hazardous substances, that is, benzene and MPNs, but further investigation on the effects of increased levels and duration of exposure on hematopoietic stem cells will be beneficial. Unique individual and host variations have been determined as a modifier of disease pathogenesis and phenotype variations. There is a higher incidence rate of females developing MPNs, specifically ET, than males with higher PV incidence. Therefore, gender contributes to the heterogeneity in myeloproliferative neoplasm. Studies identified as part of this review are very diverse. Thus, further in-depth assessment to explore the role of these etiological factors associated with MPNs is warranted.

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Depletion of Jak2V617F MPN Stem Cells by IFNα in a Murine Model of Polycythemia Vera

Blood ◽

10.1182/blood.v120.21.806.806 ◽

2012 ◽

Vol 120 (21) ◽

pp. 806-806

Author(s):

Ann Mullally ◽

Claudia Bruedigam ◽

Dirk Heckl ◽

Luke Poveromo ◽

Florian H. Heidel ◽

...

Keyword(s):

Cell Cycle ◽

Stem Cells ◽

Murine Model ◽

Myeloproliferative Neoplasms ◽

Spleen Weight ◽

Erythroid Progenitors ◽

Hematopoietic Stem ◽

Type 1 Interferon

Abstract Abstract 806 Interferon alpha (IFNα) is an effective treatment for patients with myeloproliferative neoplasms (MPN). In addition to inducing hematological responses in most MPN patients, IFNα reduces the JAK2V617F allelic burden and can render the JAK2V617F mutant clone undetectable in some patients. The mechanism underlying these responses is incompletely understood and whether the molecular responses that are seen occur due to the effects of IFNα on JAK2V617F mutant stem cells is debated. Using a murine model of Jak2V617F MPN, we investigated the effects of IFNα on Jak2V617F MPN stem cells in vivo. Chimeric transplant recipients were generated with purified stem cell enriched populations (lin−Kit+Sca1+) and these were treated for 4 weeks with either IFNα or vehicle control. IFNα treatment caused a reduction in extramedullary hematopoiesis (spleen weight, vehicle 262mg vs IFNα 192mg, p<0.01), hematocrit (vehicle 76.0% vs IFNα 65.5%, p<0.05) and white blood cell count (vehicle 13.9×109/L vs IFNα 7.5×109/L, p<0.01) in this disease model. IFNα treatment caused a reduction in early (CD71+Ter119+) erythroid progenitors that had accumulated in the spleen of Jak2V617F mice. IFNα treatment caused selective depletion of Jak2V617F MPN hematopoietic stem cells (HSC, lin−kit+Sca1+CD150+CD48−) over time and this was associated with reduced Jak2V617F chimerism in the long-term HSC compartment (Jak2V617F chimerism Vehicle 41.4% vs. IFNα 23.9%, p<0.05). IFNα treatment impaired the transmission of Jak2V617F-MPN and reduced Jak2V617F chimerism in transplanted recipient mice, demonstrating functional depletion of disease-specific stem cells. Mechanistically, IFNα treatment preferentially induced cell-cycle activation of Jak2V617F mutant long-term HSCs. Gene expression profiling revealed relative enrichment of cell cycle genes and depletion of quiescence related genes in IFNα treated Jak2V617F HSC compared to IFNα treated WT HSC. IFNα treatment promoted a predetermined terminal erythroid-lineage differentiation program within myeloid progenitor cells. The effects on Jak2V617F long-term HSC were absent in Jak2V617F+/−IFNAR1−/− (lacking the type 1 interferon receptor) chimeric mice demonstrating that the effects of IFNα treatment were cell autonomous and specific for type 1 interferon signalling. These findings provide insights into the differential effects of IFNα on Jak2V617F mutant and normal hematopoiesis and suggest that IFNα achieves molecular remissions in MPN patients through its effects on MPN stem cells. Furthermore, these results support combinatorial therapeutic approaches in MPN, by concurrently depleting dormant JAK2V617F MPN-propagating stem cells with IFNα and targeting the proliferating downstream progeny with JAK2-inhibitors or cytotoxic chemotherapy. Disclosures: Heidel: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees. Ebert:Celgene: Consultancy; Genoptix: Consultancy.

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