Clinical Significance Of Circulating Microparticles In Ph- Myeloproliferative Neoplasms (MPN)

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2368-2368 ◽  
Author(s):  
Yue Han ◽  
Shixiang Zhao ◽  
Wenjuan Zhang ◽  
Jiannong Cen ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Plasma Levels ◽  
Mononuclear Cells ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Philadelphia Chromosome ◽  
Jak2v617f Mutation ◽  
Polycythaemia Vera ◽  
Healthy Donors ◽  
Significant Difference ◽  
Thrombotic Complications

Abstract Background Microparticles (MPs) are small membrane vesicles that are classified as red blood cell MPs (RMPs), platelet-derived MPs (PMPs), tissue factor MPs (TF+MPs) and endothelial MPs (EMPs) based on their origins. Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-MPN) are disorders characterized by abnormal hematopoiesis, thrombosis, JAK2V617F mutation. Although MPs are considered as biomarkers reflecting procoagulant state in cancer patients, their involvement in the patients with Ph-MPN remains unclear. Our objective in this study was to measure the alterations of the four MPs types in the patients with MPN and to evaluate their correlations with JAK2V617F mutation and some clinical complications, especially for thrombosis and splenomegaly. Methods Sixty-seven patients with MPN were enrolled in this study, including 12 polycythaemia vera (PV), 49 essential thrombocythemia (ET) and 6 primary myelofibrosis (PMF). 30 healthy donors were selected as normal controls. Venous blood was anticoagulated with sodium citrate (1:9). Using flow cytometry, plasma samples were measured for RMPs, PMPs, TF+MPs and EMPs with phycoerythrin (PE)-conjugated monoclonal antibodies CD235a, CD61, CD142, and CD62E, respectively. Forward scatter was set in scale using fluorescent microspheres of 0.8μm and standard fluorescent microbeads (0-0.8μm) in diameter were used to set the microparticle gate. Data were expressed as median (M) and interquartile range (IQR). Meanwhile, genomic DNA was extracted from mononuclear cells and amplified by allele specific polymerase chain reaction (PCR). Results (1) Patients with MPN showed significantly higher plasma levels for all four MPs compared with healthy donors (P<0.05), namely 49.0/μl (15.8-109.5/μl) vs 21.0/μl (13.8-32.6/μl) for RMPs, 181.2/μl(75.8-1111.6/μl) vs 74.9/μl (55.5-115.4/μl) for PMPs, 48.1/μl (13.1-72.4/μl) vs 31.0/μl (14.9-47.6/μl) for TF+MPs and 310.2/μl (128.6-1130.5/μl) vs 155.9/μl (100.3-227.6/μl) for EMPs. (2) Among different subtypes of MPN, PMPs were higher in patients with PMF than patients with PV and ET (P<0.05), but there was no significant difference between PV and ET group. No obvious difference was found in RMPs, TF+MPs and EMPs among different subtypes of MPN patients. (3) MPN patients with JAK2V617F mutation (n=34) were found to have higher plasma levels of TF+MPs and RMPs than those without mutation (P<0.05) and this difference was not found for PMPs and EMPs. (4) MPN patients with various thrombotic complications (n=10) showed higher levels of all four types of MPs than those without thrombotic complications (n=31) (P<0.05). Elevated MP levels were also found in patients with splenomegaly (n=19) compared to those without splenomegaly (n=14) (P<0.05). Conclusion Higher levels of MPs were observed in MPN patients compared with healthy controls, especially in patients complicated with thrombosis and splenomegaly, which reflects a prothrombotic state. Moreover, significantly increased TF+MPs and RMPs were found in MPN patients with JAK2V617F mutatioin. Disclosures: No relevant conflicts of interest to declare.

scholarly journals TLR, RAGE, and HMGB1 in the Inflammatory Response in Ph(-) Myeloproliferative Neoplasm

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 31-32
Author(s):  
Guanfang Shi ◽  
Kiron Nair ◽  
Preethi Ramachandran ◽  
Chi Chen ◽  
Ching Wong ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Real Time ◽  
Inflammatory Cytokines ◽  
Internal Control ◽  
Real Time Pcr ◽  
Mononuclear Cells ◽  
Conflicts Of Interest ◽  
Philadelphia Chromosome ◽  
Myeloproliferative Neoplasm ◽  
Significant Difference

Recent evidence of increased constitutional symptoms and inflammatory cytokines in Philadelphia chromosome negative (Ph (-)) MPN suggests that an inflammatory response is important in the pathogenesis of Ph (-) MPN. Toll-like receptors (TLR), Receptor for Advanced Glycation End products (RAGE) and High mobility group protein B1 (HMGB1) are the important pathways for the inflammatory response. All these three important pathway proteins were studied in MPN diseases in the current studies. Materials and Methods: TLR assay. TLR 2,3, 4, 7, 9 quantification was performed by immuno-staining of 1×106 mononuclear cells (peripheral blood) which were incubated with fluorescence-conjugated anti-TLR-2,3, 4, 7, 9 antibodies and assayed by flow cytometry. HMGB1assay:HMGB1 ELISA kit from Immuno-Biological Laboratories, Inc. (IBL-America) were used. The plasma samples were diluted four times with the provided sample dilution buffer, and assayed in duplicate according to the manufacturer's suggestion. RAGE (RT-PCR) Assay: Total RNA was extracted from normal control or patient mononuclear cells. Predesigned primers for RAGE, and internal control genes were ordered from Qiagen (Germantown, MD). Real-time PCR was performed using SsoAdvanced™ Universal SYBR® Green Supermix (Bio-Rad, Hercules, CA) on Bio-Rad iQ5 Multicolor Real-Time PCR Detection System. At least three house-keeping genes (ribosomal protein L4, TATA box binding protein, and tubulin-α 1b) were used as normalization controls. The expression of RAGE were compared with each internal control. Average of three was used to calculate the ratio of final patient to normal Results: Total of 97 patients with MPN were studied 1) TLR: TLR 3,7,9 was not significantly different from controls. But TLR 2 was significantly increased in both PV, as well as in the MPN group when PV, ET and MF were grouped together as MPN (Fig A). TLR 4 was not significantly increased in PV, ET, MF individually but was found to be significantly increased than the controls, when they are grouped together as MPN (Fig B). 2) RAGE: No significant difference was found between ET, PV, MF individually or when they were grouped together as MPN than the controls (Fig C). 3) HMGB1: No significant difference was seen between ET, PV, MF or when they were grouped as MPN (Fig D). Conclusion: Current study suggests that TLR pathway especially TLR2, and to a lesser extent TLR4 are the important pathways for inflammatory response with increased inflammatory cytokines in MPN, while HMGB1 and RAGE pathways were not different from controls. Figure Disclosures No relevant conflicts of interest to declare.

Loss of Wild-Type Jak2 Allele Enhances Myeloid Cell Expansion and Accelerates Myelofibrosis in Jak2V617F Knock-in Mice

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 809-809
Author(s):  
Hajime Akada ◽  
Saeko Akada ◽  
Dongqing Yan ◽  
Robert Hutchison ◽  
Golam Mohi
Keyword(s):  
Polycythemia Vera ◽  
Cell Expansion ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Philadelphia Chromosome ◽  
Myeloid Cell ◽  
Negative Regulator ◽  
Jak2v617f Mutation ◽  
Common Mutation ◽  
Wild Type

Abstract Abstract 809 The activating JAK2V617F mutation is the most common mutation found in Philadelphia chromosome (Ph)-negative myeloproliferative neoplasms (MPNs), which include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). Although a majority of MPN patients carry heterozygous JAK2V617F mutation, loss of heterozygosity (LOH) on chromosome 9p involving JAK2 has been observed in ∼30% of patients with MPNs particularly in PV and PMF. JAK2V617F homozygosity through 9pLOH has been linked to more severe MPN phenotype. However, the contribution of 9pLOH in the pathogenesis of MPNs remains unclear. To investigate the role of wild-type JAK2 in MPNs induced by JAK2V617F, we have utilized conditional Jak2 knock-out and Jak2V617F knock-in alleles and generated heterozygous, hemizygous and homozygous Jak2V617F mice. Whereas heterozygous Jak2V617F expression results in a polycythemia vera-like disease in mice, loss of wild-type Jak2 allele in hemizygous or homozygous Jak2V617F mice results in a significantly greater increase in reticulocytes, white blood cells, neutrophils and platelets in the peripheral blood and larger spleen size. We also have found that hemizygous or homozygous Jak2V617F expression significantly increased megakaryocyte-erythroid progenitors in the bone marrow and spleens and marked infiltration of neutrophils in the liver compared with heterozygous Jak2V617F. More importantly, hemizygous or homozygous Jak2V617F mice show accelerated myelofibrosis compared with heterozygous Jak2V617F-expressing mice. Thus, loss of wild type Jak2 allele increases myeloid cell expansion and enhances the severity of the MPN. Together, these results suggest that wild-type Jak2 serves as a negative regulator of MPN induced by Jak2V617F. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Expression of CD47 and Calr in Myeloproliferative Neoplasms: Potential New Therapeutical Targets

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4598-4598
Author(s):  
Kristian Boasman ◽  
Matthew J Simmonds ◽  
Ciro R Rinaldi
Keyword(s):  
Cell Membrane ◽  
Protein Expression ◽  
Cell Membranes ◽  
Mononuclear Cells ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Membrane Expression ◽  
Myeloid Malignancies ◽  
Response To Chemotherapy ◽  
Significant Difference

Abstract Myeloproliferative neoplasms (MPN) are myeloid malignancies characterized by overproduction of mature blood cells, hyperplastic bone marrow and tendency to evolve into acute myeloid leukaemia. In solid tumours, calreticulin (CALR) overexpression produces a pro-phagocytic signal and is counteracted by concomitant expression of anti-phagocytic CD47, reflecting an apoptosis vs survival mechanism. Increases of both CALR and CD47 on the cell membrane have been observed in response to chemotherapy, however their role in myeloid malignancies is poorly understood. Aims: Investigate the expression and cellular localisation of CALR and CD47 in untreated and treated patients with essential thrombocythemia (ET), polycythemia vera (PV) myelofibrosis (MF), in comparison with healthy controls. Methods: Mononuclear cells were collected by Ficoll separation, from peripheral blood of 30 MPN (8 PV, 16 ET, 6 MF); 18 MPN patients received cyto-reductive therapies (Hydroxyurea, Anagrelide or Ruxolitinib); and 4 controls. Cells were fractionised into 4 compartments: membrane, cytoplasm, cytosol and nucleus. Proteins were extracted using TRIzol, with CALR and CD47 protein expression analysed by western blotting. Results: Total CALR and CD47 protein expression increased in MPN samples compared with controls (CALR- 7.9 vs 5.1; CD47- 2.7 vs 2.2 fold, respectively). CD47 showed higher expression of its overall protein on MPN cell membranes when compared with CALR (22% vs 13.9%). We observed a significant reduction of CALR expression in all MPN subtypes when patients were treated with cyto-reductive agents (ET- untreated 43.3% vs treated 2%, PV- 3.6% vs 2.2%, ET- 21% vs 11%). Interestingly we have observed a significant increase in CD47 cell membrane expression after treatment in MF and PV (CD47 in MF- untreated 11.8% vs treated 34.3%, PV-11.4% vs 35.9%), suggesting an anti-phagocytic effect induced by cytotoxic drugs. In ET cell membranes however, CD47 expression is reduced after cyto-reductive treatment (22% vs 16.6%), suggesting instead a prophagocytic effect. Summary/Conclusion: CD47, but not CALR, is overexpressed on the membrane of patients with MPN, suggesting a role for CD47 as a strong antiphagocytic signal responsible for immune survival in MPN. We observed a significant difference in CD47 expression across different MPN subtypes with a significant increase in CD47 expression in PV and MF but not ET when patients were exposed to cytoreduction. The use of anti-CD47 antibodies could represent a new strategy to enhance the treatment response in particular in PV and MF. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals CD47 but Not Calreticulin Is over Expressed in Patients with Myeloproliferative Neoplasms

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 5492-5492
Author(s):  
Kristian Boasman ◽  
Matthew J Simmonds ◽  
Ciro R Rinaldi
Keyword(s):  
Cell Surface ◽  
Protein Expression ◽  
Mononuclear Cells ◽  
Immune Escape ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Response To Therapy ◽  
Solid Tumours ◽  
Polycythaemia Vera ◽  
Gene And Protein Expression

Abstract Myeloproliferative neoplasms (MPN) are chronic myeloid cancers characterized by the overproduction of mature blood cells, and the tendency to evolve into acute leukaemia. In solid tumours, calreticulin (CALR) overexpression on the cell surface, produces a pro-phagocytic signal and is counteracted by concomitant expression of anti- phagocytic CD47, reflecting an apoptosis vs survival mechanism. In this study, we investigated the expression of CALR and CD47 in patients with MPN and potential changes induced by treatment. CALR and CD47 gene and protein expression were measured by Real Time PCR and western blotting, in K562 and in mononuclear cells obtained by FICOLL separation, from peripheral blood of 13 MPN patients [4 Polycythaemia Vera, 8 Essential Thrombocythemia, and 1 myelofibrosis; 7 treated (IFN or Hydroxyurea) and 6 untreated] and compared with 4 healthy controls. Cells were also fractionised into 4 compartments: membrane, cytoplasm, cytosol and nucleus and protein fractions analysed. We found a significant increase in CD47 protein expression into the membrane of MPN patients comparing with controls (91.9 % vs 19.7%). Interestingly in treated MPN the CD47 expression increases even further in comparison with untreated (92.6% vs 91.9%). No significant differences were found in total CALR expression comparing with controls (3.23, vs 2.95-fold), however in treated patients we observed a reduction in the expression in the membrane comparing with untreated (26.4 % vs 39.5 %) and an increase into cytoplasm (69.4 % vs 54.6 %). These findings suggest CD47 exposure as a mechanism of defence in MPN cells during treatment. To better understand the potential effects of therapy on CALR and CD47 expression, we incubated K562 with 0.05μM/ml of Ruxolitinib (RUXO), re-dosed at 24 hours and harvested at 48 hours. RUXO induced CALR internalization, reducing its expression into the membrane (RUXO 8.2% vs Untreated: 13.3%), but increasing its expression in cytosol (RUXO 51% vs Untreated 48.4%) and in the cytoplasm (RUXO 13.5% vs Untreated 2.9%). In contrast, CD47 expression remains relatively unmodified, with only slight increases on the membrane (RUXO 43.1% vs Untreated 40.4%) and in the cytoplasm (RUXO 34.5% vs UT 32.5%). In this study we demonstrated that CD47 but not CALR, is overexpressed on the membrane of patients with MPN. This opposes previous studies in solid tumours, which show significant increases of both CALR and CD47. This suggests a role for CD47 as a strong anti-phagocytic signal responsible for immune survival in MPN. We have also shown a potential mechanism adopted by MPN cells in response to therapy, with the internalization of CALR and the enhanced membrane expression of CD47 which remains strongly expressed on cell surface. The addition of Anti-CD47 compounds in combination with conventional therapies might represent a future therapeutically strategy to counteract MPN cells immune-escape mechanism. Disclosures No relevant conflicts of interest to declare.

Derangements of Toll-like Receptors, Inflammatory Cytokines, and Reactive Oxygen Species in Philadelphia Chromosome-Negative Myeloproliferative Neoplasm: Implicate Roles of Inflammation in the Pathogenesis

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1945-1945 ◽  
Author(s):  
Guanfang Shi ◽  
Hui Chen ◽  
Cherif Abdelmalek ◽  
Andrei Bandarchuk ◽  
Abdullah Khawer Mahmood ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Dendritic Cells ◽  
Inflammatory Cytokines ◽  
Mononuclear Cells ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Philadelphia Chromosome ◽  
Toll Like Receptors ◽  
Clonal Proliferation ◽  
Inflammatory Processes

Abstract Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) including essential thrombocythemia(ET), polycythemia vera(PV), and myelofibrosis (MF) have been regarded as a stem cell diseases with malignant clonal proliferation; but recently, inflammatory processes have been proposed as playing found a major role in the pathogenesis of MPN. Toll-like receptors (TLRs) are a family of pattern-recognition receptors that function as key initiators of innate immunity signaling, then induce inflammatorycytokines, and ROS formation. Therefore we measured TLRs, inflammatory cytokines, and ROS in patients with MPN to assess the role of inflammation in MPN. Methods: TLR assay.TLR-2, 4, 7, 9 quantification was performed by immuno-staining of 1×106 mononuclear cells which were incubated with fluorescence-conjugated anti-TLR-2, 4, 7, 9 antibodies and assayed by flow cytometry. Monocytes culture and dendritic cells differentiation.Human monocytes were isolated from human peripheral blood mononuclear cells (PBMNC) using Pan Monocyte Isolation Kit. Isolated monocytes were incubated with IL-4 and GM-CSF in cultures to differentiate to dendric cells . Immature dendritic cells were either left untreated or stimulated with Pam3CSK4. The maturation of dendritic cells was determined by flow cytometry using CD80, CD83, CD11c, and HLA-DR. Multiplex ELISA. Human plasma and cell culture supernatants were analyzed in duplicates by Meso Scale Discovery Multi-Spot Assay system. In total, ten cytokines were assayed: IFN-g, IL-1b, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, and TNF-a. Cell ROS measurement. Cellular ROS was determined by a dichlorofluorescein (DCF) assay. PBMNCs were incubated with 10 µM 2′,7′-dichlorodihydrofluorescein diacetate (carboxy-H2DCFDA) (Life Technology) for 30 min at 37°C. The oxidation of H2DCFDA was measured and analyzed by flowcytometery. Results. 1)TLR2 was the only TLR found to be elevated in PV or ET patients (Fig 1). 2) PlasmaIL-1b levels were elevated in TLR2 high patients than TLR-2 low patients. 3) No difference between TLR-2 high and low patients in the maturation of monocytes to dendritic cells. 4) Monocyte derived dendritic cells with high TLR-2 patientsreleased more IL-8 and TNF-a after Pam3CSK4 stimulation (Fig 2). 5) ROS were more elevated in MF patients than PV, ET patients, and controls (Fig 3). Conclusion. 1) TLR 2 is significantly elevated in PV and some ET patients and TLR-2 high patients were found to have elevated plasma IL-1b,and IL-8, and TNF-α in monocytes-derived dendric cell cultures afterPam3CSK4 stimulation than TLR-2 low patients. This confirms that TLR-2 is deranged in PV and ET. 2) ROS is elevated in MF patients compared to ET and PV patients, or controls. Thus, this study suggests that inflammatory processes likely play a role in the pathogenesis of Ph- MPN through first TLR-2 derangement in PV and ET , then through years of chronic inflammatory process , with the accumulation of more ROS seen in MF, which caused more damage to the DNA resulting more malignant clonal proliferation. A similar phenomenon was observed that in JAK2V617F mutation , allele-burden was observed gradually increased from ET , PV then to MF . Disclosures No relevant conflicts of interest to declare.

JAK2 Mutation Analysis and Function of Bone Marrow Mesenchymal Stem Cells in Myeloproliferative Neoplasms

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 5179-5179
Author(s):  
Hong Tian ◽  
Yang Xu ◽  
Guanghua Chen ◽  
Man Qiao ◽  
Wu Depei
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Mesenchymal Stem Cells ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Jak2v617f Mutation ◽  
Primary Study ◽  
Jak2 Mutation ◽  
Healthy Donors ◽  
Marrow Mesenchymal Stem Cells

Abstract Abstract 5179 Background: JAK2V617F and JAK2 exon12 mutations in haematopoietic cells were partially responsible for the pathogenesis of myeloproliferative neoplasms (MPN).But it was still unclear whether bone marrow mesenchymal stem cells (BMSCs), the significant component of hemopoiesis microenvironment, were participated in the pathogenesis of MPN. Objective: To study the physiopathology characteristics and analyze JAK2 mutation in BMSCs from MPN patients. Methods: By searched for the JAK2V617F mutation and exon 12 mutation in 135 MPN patients' blood /bone marrow samples, 20 patients with JAK2V617F mutation, 10 patients with JAK2 exon 12 mutation, 5 JAK2-mutation-negetive patients and 10 healthy donors were recruited. The phenotype, mesenchymal differentiation capacity, expression of hematopoietic and immune molecules and JAK2 mutation of isolated bone marrow BMSCs were detected. Results: BMSCs derived from the four groups were found to be similar in morphology, differentiation ability and expression of hematopoietic and immune molecules. Primary study indicated that the isolated BMSCs from patients groups were not able to harbor JAK2 mutation in spite of positive or negative JAK2 mutation in blood /bone marrow samples. Conclusion: BMSCs from MPN patients had similar biological characteristics to healthy donors, and BMSCs were not likely involved in pathogenesis of MPN. Disclosures: No relevant conflicts of interest to declare.

Targeted Cancer Exome Sequencing Discovers Novel Recurrent Mutations In MPN

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4099-4099
Author(s):  
Elena Tenedini ◽  
Isabella Bernardis ◽  
Valentina Artusi ◽  
Lucia Artuso ◽  
Enrica Roncaglia ◽  
...  
Keyword(s):  
Somatic Mutations ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Philadelphia Chromosome ◽  
Jak2v617f Mutation ◽  
Exome Capture ◽  
Multiple Control ◽  
Disease Evolution ◽  
Recurrent Mutations

Abstract The discovery of the JAK2V617F mutation in 2005 [Kralovics R, N Engl J Med 2005] represented a major breakthrough in the understanding of the molecular pathogenesis of Philadelphia chromosome negative chronic myeloproliferative neoplasms (MPN). Nevertheless several observations suggest that the JAK2V617F mutation may not be the disease funding mutation, at least in most instances. Therefore, a great deal of effort is ongoing with the aim to identifying novel genetic lesions contributing to the disease pathogenesis. The two major theoretical and technical drawbacks to the identification of new somatic mutations are represented, respectively, by the huge number of genes potentially involved in tumorigenesis of MPN and by the availability of a “pure” germline control DNA. Buccal swabs and saliva have been generally considered as readily available sources of DNA of non-hematopoietic origin, but detection of the JAK2V617F mutation in at least some of these samples indeed suggested the presence of myeloid cell contamination [Levine RL, Cancer Cell 2005]. So, in order to discover novel mutations in MPN using upfront technologies based on next-generation sequencing (NGS) we designed a “cancer exome” capture panel of 2000 unique genes and microRNAs. This panel was used to capture libraries generated from genomic DNA extracted from granulocytes and in vitro expanded CD3+ T-lymphocytes as germline control, in a cohort of 20 MPN patients. These captured libraries were than massively sequenced using the Roche 454 FLX platform. DNA samples had been collected at the diagnosis of PV in 9 subjects and PMF in 6 subjects, while the remaining 5 DNA samples were from 5 of the 9 PV patients at the time they evolved to post-PV myelofibrosis. After extensive bioinformatics analysis and multiple control adjustments, we finally produced a list of 171 novel “true” somatic mutations occurring in genes and microRNAs coding regions of those MPN samples; some of these mutations have been already described in MPN, whereas novel variants represent the vast majority. Despite patients harbored different numbers of somatic mutations, spanning from four to twenty-one variants, only 22 genes appear recurrently mutated. It is worth of notice the acquisition of additional mutations and/or the occurrence of loss of some mutations at the time of disease evolution from PV to a post-PV Myelofibrosis in the five patients for whom samples were available at both disease phases. Some of them, either acquired (NTRK1, PRDM2, BRCA2 and BARD1) or lost (APC, CARS, MLL3 and FAT2) had been found also in another PV or PMF sample. To test the recurrence of these mutations, we screened a different cohort of 189 patients composed by PMF (91 samples), PV (50 patients) and post-PV Myelofibrosis (48 samples) by Ion AmpliSeq technology on an Ion Torrent PGM platform. Deep amplicon sequencing of granulocytes DNA achieved a sample median of 1000-fold coverage. Excluding JAK2, MPL, IDH2, ASXL1 known variants, for 7 genes (SCRIB, MIR662, BARD1, TCF12, FAT4, DAP3, NRAS) we demonstrated in MPN a global mutation frequency greater than the 3%. Whereas some new variants need functional validation to prove causal mechanisms, some other mutations have a well-known pathogenic role in solid cancers but here are described for the first time in MPN. Disclosures: No relevant conflicts of interest to declare.

MSCs From Patients with Myelofibrosis Display a Fibrotic Phenotype

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 5160-5160 ◽  
Author(s):  
Rebekka K Schneider ◽  
Isabelle Leisten ◽  
Susanne Ziegler ◽  
Anne Schumacher ◽  
Tim H Brümmendorf ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Extracellular Matrix ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Primary Myelofibrosis ◽  
Collagen I ◽  
Rt Pcr ◽  
Healthy Donors ◽  
Collagenous Matrix ◽  
Significant Difference

Abstract Abstract 5160 Myeloproliferative neoplasms (MPNs) are characterized by the excessive production of terminally differentiated nonlymphoid cells or platelets in the bone marrow. They represent a heterogenous group of clonal hematologic malignancies and are classified into chronic myeloid leukemia (CML), essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (PMF) and other rarer diseases. MPNs are often associated with extramedullary hematopoiesis and progressive hepatosplenomegaly due to displacement of hematopoietic progenitor cells from the BM to spleen and liver. Progenitor mobilization follows the enhanced deposition of extracellular matrix proteins, which can be found in the bone marrow of MPN patients. Nonhematopoietic bone marrow stromal cells (BMSCs) and their precursors (mesenchymal stem cells) are believed to be conditioned by abundantly released growth factors from the pathological hematopoietic clone in MPNs and in turn contribute to a modified niche environment which participates in the maintenance of the malignant clone and in disease progression. We therefore aimed at the comparative analysis of BMSCs from MPN patients (displaying myelofibrosis 0–1) and healthy donors as well as at their matrix remodelling capacity. BMSCs from PMF patients were obtained by trephine biopsies and isolated by plastic adherence in IMDM, 20% FCS and cortisone. BMSCs from PMF patients fulfilled MSC criteria according to common consensus (Dominici et al., 2007). To compare their potential to support hemato-lymphopoiesis, we analyzed their hemato-lymphotropic cytokine transcription by RT-PCR. MSCs from MPN patients and healthy donors expressed gene transcripts for M-CSF, SDF-1, LIF, FLT3L, Oct-4, SCF, IL-6 and IL-7, suggesting no significant difference in cytokine production. However, when activated through contact with collagen I/III and embedded in three-dimensional scaffolds, MSCs from MPN-patients extensively remodelled the collagenous matrix compared to healthy donors. Under osteogenic and undifferentiated culture conditions, the extracellular matrix (ECM) production by MPN-MSC was strongly enhanced compared to MSCs from healthy controls as shown by RT-PCR and immunohistochemistry for collagen I, IV, fibronectin, laminin and osteopontin. Furthermore, MSCs from MPN patients significantly contracted and densified the collagenous matrix and the ECM deposition by MSCs from MPN patients was highly comparable to the ECM changes observed in corresponding bone punches. We therefore hypothesize that MSCs from MPN patients are primed to produce enhanced ECM proteins, whereas their capacity to support hematopoiesis seems to be unchanged. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Endothelial JAK2V617F Expression Drives Inflammation and Cellular Senescence; New Evidence for the Roles of Endothelial Cells in MPN-Related Clotting Abnormalities?

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3134-3134
Author(s):  
Megan E Cosgrove ◽  
Rakesh Suman ◽  
Helen J Harrison ◽  
Gillian E Jackson ◽  
Martin R Howard ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cellular Senescence ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Umbilical Vein ◽  
Critical Role ◽  
Philadelphia Chromosome ◽  
Polycythaemia Vera ◽  
Label Free ◽  
Allelic Burden

Abstract JAK2V617F is the primary pathogenic mutation in patients with Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs), a heterogeneous group of haematological malignancies characterised by increases in one or more myeloid lineages. The most common cause of morbidity and mortality in patients with MPNs are thrombohemorrhagic incidents, although the events leading to these clotting abnormalities remain unclear. It is now known that a subset of MPN patients express JAK2V617F in endothelial cells (ECs) which has been linked with a poorer prognosis and an increase in the incidence of thrombosis. Furthermore, using transgenic mouse models we have recently shown that expression of JAK2V617F in ECs plays a critical role in aberrant thrombosis in vivo (PNAS, 2014. 111(6): p. 2295-300). Here, we describe the transcriptomic and phenotypic profiles of JAK2V617F-positive ECs. Lentivirally transduced human umbilical vein ECs (HUVECs) showed a sustained increase in levels of activated JAK2, STAT3 and STAT1 in JAK2V617F-expressing cells compared to WT JAK2. In addition, JAK2V617F also caused a significant increase in expression of total STAT1 protein. Subsequent RNAseq analysis revealed an upregulation of several mRNAs related to inflammation and permeability in JAK2V617F-expressing cells. Expression of interferon-related genes, including serine protease inhibitor B2 (SERPINB2) and early growth response protein 1 (EGR1), and chemokine ligand 2 (CCL2) were also increased in JAK2V617F cells. SERPINB2 and EGR1 have roles in initiating cellular senescence and CCL2 was previously reported to induce permeability. These data, combined with increased expression of total STAT1, suggest that JAK2V617F expression in ECs induces an inflammatory response in this cell type. Moreover, in vitro permeability assays show increased permeability in HUVECs transduced with JAK2V617Fcompared to WT JAK2, which was significantly amplified following stimulation with thrombin. We then determined whether any functional differences existed between patient-derived normal and JAK2V617F-expressing ECs. For this we obtained blood from JAK2V617F-positive polycythaemia vera patients undergoing therapeutic phlebotomy and isolated blood outgrowth endothelial cells (BOECs) by repeated culture of PBMCs. Allelic burden of JAK2V617F, determined by quantitative allele-specific amplification (QuASA) was shown to vary between patient samples, (0% to 59.8% (n=9)) and increased expression of JAK2V617F appeared to correlate with decreased proliferation and significant changes in cellular morphology. In order to quantify these differences, ptychography, a novel label-free imaging technology was used to generate quantitative phase images of BOECs in time-lapse, to measure phenotypic changes in cell morphology, motility and proliferation. These results confirmed that JAK2V617F allelic burden was inversely related to BOEC proliferation. Cells which expressed only WT JAK2 or low levels of JAK2V617F exhibited exponential growth. However, an increase in JAK2V617F resulted in a decrease in BOEC proliferation. Indeed, cells which expressed high JAK2V617F levels (30-60%) failed to proliferate over the 48 hour imaging period. Furthermore, JAK2V617F-high BOECs were also shown to be larger in size, multi-nucleated and less motile compared to JAK2V617F-low. The increase in cell size and decreases in cell motility and proliferation suggest that increased JAK2V617F expression induces senescence in BOECs. These data describe features of ECs which are commonly associated with dysfunctional endothelium: sustained inflammation/permeability, limited cell growth and senescence. The critical role of ECs in maintaining hemostasis and the observed features of EC dysfunction in cells which express JAK2V617F, implicate mutation burden in ECs as a contributing factor towards the thrombotic abnormalities observed in patients with MPNs. Disclosures No relevant conflicts of interest to declare.

scholarly journals The Zygosity of JAK2V617F Determines the Disease Entities of Myeloproliferative Neoplasms By Modulating Erythropoiesis but Not Megakaryopoiesis

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3068-3068
Author(s):  
Hiraku Takei ◽  
Yoko Edahiro ◽  
Lihua Li ◽  
Yoshihisa Mizukami ◽  
Misa Imai ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Clinical Features ◽  
Copy Number ◽  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasms ◽  
Philadelphia Chromosome ◽  
Hematopoietic Cell ◽  
Jak2v617f Mutation ◽  
Hematopoietic Stem ◽  
The Impact

Abstract Philadelphia-chromosome negative myeloproliferative neoplasms (MPNs) consists of different clinical entities that include polycythemia vera (PV) and essential thrombocythemia (ET). Despite of differential clinical features, JAK2V617F mutation is found in both PV and ET, leaving the cause of differential biological phenotypes by an oncogene obscure. Previously, studies have shown that higher allele frequencies or expression of JAK2V617F are associated with PV symptom/features in patients or model animals, respectively, suggesting that the copy number of JAK2V617F modulates hematopoietic cell differentiation and thus exhibits differential clinical features. However, this remained elusive in human hematopoiesis. To examine the impact of the zygosity of JAK2V617F allele on hematopoietic differentiation in human cells, we established induced pluripotent stem cells (iPSCs) harboring heterozygous- and homozygous-JAK2V617F mutation using genome-editing techniques from normal iPSCs. The introduction of JAK2V617F mutation with one or two copies did not alter the pluripotency of iPSCs and their capacity to differentiate into hematopoietic stem/progenitor cells (HSPCs) in vitro. When we induced hematopoietic cell differentiation from HSPCs, factor-independent erythropoiesis and megakaryopoiesis were induced in both heterozygous and homozygous JAK2V617F-HSPCs. Furthermore, homozygous JAK2V617F-HSPCs showed higher potential for erythropoiesis compared to the ones with heterozygous JAK2V617F, while the zygosity of JAK2V617F showed less effect on megakaryopoiesis. To further understand the molecular mechanism of hematopoietic cell differentiation modulated by differential copy number of JAK2V617F, we analyzed the activation of JAK-STAT signal by immunoblot analysis. The activation of JAK-STAT signals was more prominent in HSPCs harboring homozygous JAK2V617F, than those with heterozygous JAK2V617F. This suggested that the level of JAK2 phosphorylation was positively correlated with the copy number of JAK2V617F. These observations implied followings: 1) heterozygous JAK2V617F was sufficient to promote the development of MPN by inducing the factor-independent erythropoiesis and megakaryopoiesis; 2) the zygosity of JAK2V617F determined the disease phenotypes of MPNs by modulating erythropoiesis but not megakaryopoiesis; and 3) the homozygous JAK2V617F increased JAK-STAT signaling in HSPCs, promoting an increased erythropoiesis. Disclosures No relevant conflicts of interest to declare.

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