bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduced Expression of CXCR4 on Circulating CD34+ Cells Is Associated with Hematopoietic Progenitor Cells (HPC) Mobilization in Patients with Myelofibrosis with Myeloid Metaplasia (MMM).
Authors: Massa Margherita , Rosti Vittorio , Vannuccchi Alessandro M. , Campanelli Rita , Pecci Alessandro , Viarengo Gianluca , Meli Valentina , Marchetti Monia , Guglielmelli Paola , Bruno Edward , Xu Ming , Hoffman Ronald , Barosi Giovanni 
Published: April 2020

Abstract
Spontaneous mobilization of HPC is a key feature of MMM. We investigated the CXCR4/SDF-1 (stromal derived factor-1) axis in 52 consecutive MMM patients. The percentage of circulating CD34+ cells co-expressing CXCR4 at the cytofluorimetric analysis was significantly lower (P=0.02) in MMM patients (median, 37%, range, 0 to 92%) than in the normal controls (n=12; median, 75%; range, 39 to 91%). CXCR4 mean fluorescence intensity was also highly significantly lower in MMM patients (median 0.73; range, 0.06 to 7.05) than in normal controls (median, 1.84; range, 0.41 to 6.69; P=0.004). By analyzing the association between CXCR4 expression and the mobilization of progenitor cells, an inverse correlation was found between CXCR4 expression and the number of circulating CD45+/CD34+ HPC (R=−0.40; P=0.005). By restricting the relation analysis of CXCR4 expression and clinical features to those patients who were not receiving cytoreductive treatment (n=41), there was no correlation between CXCR4 expression and patients’ sex, hemoglobin concentration, WBC, prefibrotic stage. By contrast, CXCR4 expression was inversely correlated with clinical characteristics that portrayed an advanced disease, such as older age (R=−0.31; P=0.026), longer disease duration (R=−0.37; P=0.008), larger splenomegaly (r=−0.33; P=0.015) and lower platelet count (r=0.42; P=0.007). The levels of CXCR4 mRNA, measured in peripheral blood CD34+ cells of patients with MMM were lower as compared with those of cells purified from normal peripheral blood (ΔCT by real time RT-PCR using GAPDH as housekeeping reference gene: 5.33 ± 0.49 vs. 1.53 ± 0.79, mean ± SD; P=0.003). SDF-1 plasma levels were significantly increased in patients with MMM but no correlation was documented with CXCR4 expression. We conclude that reduced expression of CXCR4 on CD34+ cells is a mechanism for the constitutive mobilization of HPC in MMM.
Detection of JAK2 V617F in the Diagnosis of Erythrocytosis: Feasibility and Diagnostic Value in Clinical Practice.
Authors: James Chloé , Delhommeau François , Marzac Christophe , Teyssandier Irène , Le Couédic Jean-Pierre , Giraudier Stéphane , Roy Lydia , Saulnier Patrick , Tulliez Michel , Vainchenker William , Casadevall Nicole , Ugo Valérie 
Published: April 2020

Abstract
Polycythemia Vera (PV) is a myeloproliferative disorder (MPD), whose diagnosis is currently based on an association of clinical and biological criteria following the WHO or the PVSG classification. It is characterized by a primitive absolute erythrocytosis, and formation of endogenous erythroid colonies (EEC). Recently, we described a point mutation in JAK2 (JAK2 V617F) and showed that this activating mutation was the cause of the disease (James et al, Nature, 2005). This molecular abnormality was therefore likely to be a diagnostic marker of PV, as bcr-abl for chronic myeloid leukemia (CML). Nevertheless, JAK2 V617F is also found in other MPDs, sharing some common features with PV, as essential thrombocythemia, idiopathic myelofibrosis, and other rare MPDs. One major criterion for the diagnosis of PV requires the demonstration of increased red cell mass as measured by isotopic methods. We assessed the value of detection of JAK2 V617F as a first intention diagnostic test in 88 patients with hematocrit values above 51% (=erythrocytosis) and showed that the mutation correlated with the diagnosis of PV according to the WHO (R=0.879) and the PVSG (R=0.717) criteria, with a positive predictive value of 100% in the context of erythrocytosis. Besides, the presence of the mutation strongly correlated with EEC formation in 81/87 patients (R=0.824) and only weakly with the serum erythropoietin level (R=0,416). PCR-based genotyping techniques are less time-consuming, less expensive, than DNA sequencing and are easier to perform in hematology diagnostic laboratories. Therefore, we studied the feasibility of the detection of JAK2 V617F with widespread instruments commonly used in routine. We analyzed 119 samples from patients with a suspicion of myeloproliferative disease and showed that JAK2 V617F was efficiently detected by LightCycler® and TaqMan® genotyping technologies, these latter being a little more sensitive than sequencing. For 50 patients, peripheral blood and bone marrow samples were both available. In all cases (34 mutated, 16 non-mutated) the mutation was identically detected. Based on these results, we propose that the detection of JAK2 V617F in granulocytes has a first place in the diagnostic chart of an erythrocytosis, as bcr-abl in CML, avoiding, if positive, an isotopic red cell mass measurement and bone marrow EEC assays. The presence of JAK2 V617F in a patient with erythrocytosis would then lead to the diagnosis of MPD of PV type. Further prospective studies will be necessary to assess if all the MPDs patients bearing JAK2 V617F can be grouped in a new subset within the MPD entity, especially in term of thrombotic and neoplasic risk.
Clonality Assay (X-CIP) and JAK 2 V617P Mutation: Clustering Patients with Essential Thrombocythemia at High Risk for Thrombosis.
Authors: Fiorini Alessia , Reddiconto Giovanni , Farina Giuliana , Chiusolo Patrizia , Teofili Luciana , Bonomo Pierluigi , Rossi Elena , Za Tommaso , Palladino Mariangela , De Stefano Valerio , Leone Giuseppe , Sica Simona 
Published: April 2020

Abstract
We have previously demonstrated that clonal hemopoiesis in female ET patients was significantly associated to the risk of thrombosis. When data on JAK2 V617P mutation became available we aimed to evaluate the incidence of this mutation according to clonality status. Ninety-two female patients, median age 32 (19–65) with a diagnosis of ET according to PVSG criteria were studied for clonality with X-CIP, 83 patients were evaluable for endogenous erythroid colonies (EECs) growth and 44 patients were evaluable for JAK2 V617P mutation. Twenty episodes of thromboses (21.7%) were detected and they include splanchnic (11), CNS (5), limb (3) thromboses and pulmonary embolism (1). Thromboses were mainly detected at diagnosis. Thirthy-seven patients showed clonal hemopoiesis (40%), 27 had polyclonal hemopoiesis (29.5%) and 28 were considered uninterpretable due to constitutional skewing (30.5%). Thromboses were overrepresented in the monoclonal group in respect to the polyclonal one (15/37 vs 2/27, p=0.003). DNA for analysis of JAK2 V617P by allele-specific PCR was available for 44 of these patients. Thirty-two patients of 44 (73%) showed JAK2 V617P mutation; JAK2 V617P was found in 16/21 patients with monoclonal hemopoiesis (76%), in 9/13 in the polyclonal group (69%) and in 7/10 (70%) in patients with constitutional skewing. Thirteen of the 32 patients with JAK2 V617P mutation (41%) had thromboses while no thrombotic event was recorded in wild type patients (p=0.008); among the 13 patients with thrombosis and JAK2 V617P mutation, 9 (69%) had monoclonal hemopoiesis, 2 (15%) had polyclonal hemopoiesis, and 2 had constitutive skewing. Thus there was a significant increase in thrombotic events in patients with JAK2 V617P mutation and monoclonal hemopoiesis (p=0.04). JAK2 V617P mutation was also significantly associated to the presence of EECs (p=0.02); in fact 22/26 patients with EECs growth showed JAK2 mutation (85%). Finally when patients with splanchnic thromboses were analyzed 9/11 had a monoclonal X-CIP (81.8%) and 7 of them who were evaluable for JAK2 V617P mutation were invariably carriers of the mutation. Thus we confirm that X-CIP in young female ET is correlated to the risk of thrombosis. JAK2 V617P mutation is significantly associated to the development of thrombosis and is present in the vast majority of patients with monoclonal hemopoiesis. The mechanisms underlying monoclonal hemopoiesis in the absence of JAK2 V617P mutation are unclear, notwithstanding these patients are clinically characterized by both absence of EECs and thrombosis.
Analysis of JAK2 Mutation in Essential Thrombocythemia (ET) Patients with Monoclonal and Polyclonal X-Chromosome Inactivation Patterns (XCIPs).
Authors: Kiladjian Jean-Jacques , Elkassar Nahed , Hetet Gilles , Balitrand Nicole , Conejero Carole , Giraudier Stephane , Cassinat Bruno , Gardin Claude , Fenaux Pierre , Chomienne Christine , Grandchamp Bernard 
Published: April 2020

Abstract
Background: ET is considered as a hematopoietic stem cell disorder, closely related to polycythemia vera (PV). Several studies in female ET patients, using XCIPs analysis, have shown the persistence of polyclonal patterns in a subset of patients, the significance of this finding being unclear (Blood: 1997;89:128 and 1999;93:417). Patients with polyclonal patterns were suggested to be at lower risk of thrombosis. The mechanism of sustained megakaryocytic proliferation, in the absence of a reactive cause, is still to be found in this disease. The recent description of an activating V617F JAK2 mutation in PV prompted us to study its relevance in ET, especially with respect to XCIPs analysis results.
Methods: We looked for V617F JAK2 mutation in whole blood DNA in a series of 43 ET female patients for whom XCIPs had previously been reported by our group (Blood: 1997;89:128). Monoclonal pattern was defined by greater than 75% expression of one allele of an X-chromosome polymorphic gene. ET diagnosis was made according to PVSG criteria, after careful exclusion of PV by red cell mass measurement, CML by karyotype and/or BCR-ABL RT-PCR, and idiopathic myelofibrosis by bone marrow biopsy. V617F JAK2 mutation was screened by direct DNA sequencing (sensitivity of the assay: about 5%).
Results: V617F JAK2 mutation was found in 12 of the 43 samples (28%), in agreement with recent reports. No significant differences were found between JAK2 mutated and non-mutated patients for age (43 vs 57 years), clinical symptoms at presentation (33% vs 35%), platelet count (866 vs 907 G/l), or cytoreductive therapy (41% vs 61%), respectively. Of the 35 patients with a monoclonal pattern in granulocytes (and polyclonal T lymphocytes), 8 (23%) had JAK2 mutation, as compared to 4 of the 8 patients (50%) with polyclonal pattern in granulocytes (p=0.185, Fisher’s exact test).
Conclusion: The 50% incidence of JAK2 mutation we found in ET patients with a polyclonal pattern of hematopoiesis may be due to a better sensitivity of the JAK2 mutation assay by comparison to XCIPs clonality assays. It shows that many ET with a XCIPs polyclonal pattern are in fact clonal disorders. On the other hand, the absence of JAK2 mutation in about 75% of patients with a monoclonal pattern suggests that other molecular events can lead to clonal megakaryocytic proliferation in a large proportion of ET patients.
Activating Notch1 Mutations in Mouse Models of T-ALL.
Authors: O’Neil Jennifer , Calvo Jennifer , McKenna Keith , Krishnamoorthy Veena , Aster Jon C. , Bassing Craig H. , Alt Frederick W. , Kelliher Michelle , Look A. Thomas 
Published: April 2020

Abstract
NOTCH1 was discovered through its involvement in the t(7;9) chromosomal translocation found in less than 1% of T-ALLs. Recent studies have demonstrated a broader involvement of NOTCH1 in human T-ALL. The majority of T-ALL patients have activating mutations that disrupt either the heterodimerization domain or the PEST domain of NOTCH1. We sought to determine whether these mutations are also acquired in mouse models of T-ALL. We have sequenced the heterodimerization domain and PEST domain of notch1 in our mouse model of TAL1-induced leukemia and have found that 74% of the tumors harbor activating mutations in notch1. Cell lines derived from these tumors undergo G0/G1 arrest and often apoptosis when treated with a γ-secretase inhibitor (DAPT). In addition, we found activating notch1 mutations in 38% of thymic lymphomas that occur in mice deficient for various combinations of the H2AX, p53 and Rag2 genes. Thus, notch1 mutations are often acquired as a part of the molecular pathogenesis of T-ALL occurring in mice predisposed to develop the disease because they are transgenic for overexpression of the tal1 oncogene or because they have lost key tumor suppressor genes known to promote genomic instability.
Self-Association Contributes to E2a-Pbx1-Mediated Oncogenesis.
Authors: Wang Zhong , Cleary Michael L. 
Published: April 2020

Abstract
Pbx1 is a proto-oncogene that was originally discovered at the site of t(1;19) chromosomal translocations in pediatric acute B cell precursor leukemia. It codes for a TALE (three amino acid loop extension) class homeodomain transcription factor, which is a component of hetero-oligomeric protein complexes that regulate developmental gene expression. As a result of chromosomal translocations, Pbx1 is oncogenically activated by in-frame fusions with the E2a bHLH protein, which confers strong transcriptional activator properties and constitutive nuclear localization, bypassing the need for dimerization with Meinox homeodomain proteins to stabilize and import Pbx1 into the nucleus. E2a-Pbx1 oncoproteins retain an ability to bind DNA as a complex with Hox transcription factors, and co-expressed HoxA9 accelerates leukemogenesis. Using a biochemical approach, we have recently observed that E2a-Pbx1 self-associates through the Pbx moiety of the chimeric protein to form higher-order oligomers. Structure/function studies suggest that self-association is required for oncogenic activity since mutant E2a-Pbx1 proteins unable to self-associate are transformation defective in an in vitro myeloid progenitor serial replating assay. Interestingly, their oncogenic activity in this assay is rescued using synthetic oligomerization domains of FKBP. The drug AP21998, which disrupts FKBP-mediated oligomerization, blocks the proliferation of transformed myeloid progenitors and facilitates their terminal myeloid differentiation. In addition to self-association, the DNA binding homeodomain of Pbx1 is also required for transformation, but mutagenesis studies indicate that Pbx1 domains involved in cooperative DNA binding with Hox partners are dispensable. These studies suggest an alternative mechanism for leukemogenesis in which E2a-Pbx1 deregulates subordinate gene expression as an oligomeric complex that circumvents interactions with heterologous homeodomain proteins that otherwise modulate Pbx1 nuclear localization, DNA binding, and transcriptional activity.
Identification of ID4 as a Cooperating Second Hit for T Cell Lymphoma Development in PU.1 UREΔ/Δ Mice.
Authors: Owens Bronwyn M. , Yu Li , Steidl Ulrich , Kutok Jeffrey L. , Clayton Linda K. , Wagner Katharina , Iwasaki Hiromi , Liu Chunhui , Hackanson Björn , Akashi Koichi , Plass Christoph , Tenen Daniel G. , Rosenbauer Frank 
Published: April 2020

Abstract
The transcription factor PU.1 is a key regulator of hematopoiesis and is essential for normal hematopoietic stem cell (HSC) function and myeloid and lymphoid differentiation. Knockout mice are embryonic or neonatal lethal and exhibit an early differentiation block at the transition from HSC to CMP and CLP. Mice with a deletion of a critical upstream regulatory element (URE) at −14kb has been deleted exhibited decreased PU.1 expression in HSC, progenitors and B cells to 20% of normal levels. In contrast, an increase of PU.1 expression was detected in early thymic progenitors. UREΔ/Δ animals exhibited a block in normal thymocyte differentiation and frequently progressed to fatal T cell lymphomas between 3 and 8 months of age. Tumors were clonal and transplantable into NOD-SCID recipients. Since aberrant PU.1 expression constituted the initiating mutation, we sought to identify cooperating mutations contributing to tumor development by surveying the genome for hypermethylated promoter regions using restriction landmark global scanning. Methylation patterns revealed a characteristic epigenetic footprint leading to selective tumor suppressor gene silencing in transformation of lymphoid but not myeloid UREΔ/Δ progenitors, since DNA methylation was significantly lower in the AML samples compared with lymphomas. One of the corresponding methylated genes that was silenced in all lymphomas analyzed but none of the AMLs was identified as Idb4 (encoding ID4, inhibitor of DNA binding 4). This observation is consistent with data describing ID4 as a strong tumor suppressor gene which is frequently silenced in neoplasms. The expression of Idb4 in 6 additional lymphomas was assessed by quantitative RT-PCR and showed a strong correlation between promoter hypermethylation and Idb4 downregulation. To test whether Idb4 silencing through promoter hypermethylation can be pharmacologically reversed, a UREΔ/Δ lymphoma cell line was established and treated with 5-aza-2′deoxycytidine. We found that Idb4 expression was restored to normal levels following increasing concentrations of this demethylating agent. Finally, we analyzed the functional relevance of the Idb4 downregulation by restoring Idb4 expression in the UREΔ/Δ tumor line. UREΔ/Δ lymphoma cells reexpressing Idb4 had a marked reduction in both the in vitro growth rate and the ability to cause tumors after transplantation into NOD/SCID recipient mice, indicating that Idb4 is a potent suppressor of UREΔ/Δ thymic tumorigenicity. Taken together, we provide evidence that epigenetic DNA modifications contribute significantly and selectively to lymphoid transformation in UREΔ/Δ mice, and suggest a role for Idb4 repression as a second event in PU.1-initiated transformation of lymphoid precursors.
The BCL6 Oncoprotein Forms Distinct Transcriptional Repression Complexes on Cohorts of Target Genes Involved in Specific Cellular Functions.
Authors: Polo Jose M. , Ranuncolo Stella Maris , Parek Samir , Arcaya Jose , Melnick Ari M. 
Published: April 2020

Abstract
The BCL6 (B-Cell-Lymphoma-6) oncoprotein is required for formation of germinal centers by normal B-cells and is frequently constitutively activated in B-cell lymphomas. BCL6 is a transcriptional repressor of the BTB/POZ - zinc finger family of proteins. Transcriptional repressors are generally believed to function by binding to specific DNA sequences in target promoters and then recruiting a cohort of corepressor proteins that physically alter the chromatin structure of the locus leading to silencing. BCL6 can recruit several different corepressors. Accordingly, N-CoR, SMRT and BCoR bind to the BTB domain of BCL6, the NuRD complex binds to the second repression domain and ETO binds to the C-terminal zinc finger domain. These proteins recruit additional corepressors such as HDACS, thus forming multi-protein complexes. BCL6 is involved in both licensing germinal center B-cells for survival as well as blocking differentiation to memory or plasma cells. However, we found that blockade of the BCL6 BTB domain with a specific inhibitor causes only apoptosis but not differentiation of B-cells. In order to identify BCL6 target genes and the mechanism through which they are silenced, we performed extensive ChIP on chip analysis of BCL6, its corepressors, and their chromatin signatures using tiled oligonucleotide arrays containing 1.5 KB of 24,000 promoters. These were performed in the presence or absence of BCL6 shRNA and other BCL6 inhibitor molecules, in tandem with expression arrays as a functional readout. We also performed in depth ChIP on chip experiments using custom arrays, where sets of entire BCL6 target loci were tiled through with overlapping oligos. From these studies we i) identified a large cohort of direct BCL6 target genes involved in apoptosis, cell damage, protein degradation and differentiation that provide critical insight into the mechanism of action of BCL6 in normal and malignant B-cells; ii) discovered that cohorts of BCL6 direct target genes involved in different pathways are regulated by specific corepressors, which are mutually exclusive in their binding to BCL6 target loci, iii) that BCL6 can repress genes through a variety of different mechanisms with unique chromatin signatures. Thus, previously unrecognized mechanisms exist in transcriptional repression, that determine formation of specific corepressor complexes. Using this information, we have been able to re-activate discrete cohorts of BCL6 target genes controlled by specific corepressors, resulting in specific biological effects such as apoptosis or differentiation of lymphoma cells. These results provide fundamental insights into the transcriptional and biological mechanism of action of BCL6 in B-cells.
cJun Is Phosphorylated at Ser73 and Contributes to Cell Cycle Progression in Anaplastic Large Cell Lymphoma.
Authors: Leventaki Vassiliki , Drakos Elias , Claret Francois-Xavier , Medeiros L. Jeffrey , Rassidakis George Z. 
Published: April 2020

Abstract
Anaplastic Large Cell Lymphoma (ALCL) frequently carries the t(2;5)(p23;q35) or variant translocations resulting in overexpression of anaplastic lymphoma kinase (ALK). cJun is a member of the activator protein-1 (AP-1) family, which is a group of transcription factors that control cell proliferation, differentiation, growth and apoptosis. The activity of cJun can be regulated by phosphorylation at serine 73 (Ser73) and serine 63 (Ser63) residues of the N-terminal domain. It is believed that cJun promotes cell cycle progression, in part, through downregulation of the cyclin-dependent kinase inhibitor p21. Previous studies have shown high AP-1 activity and cJun overexpression in Hodgkin lymphoma and ALCL (Mathas et al, EMBO J2002; 21:4104). In this study, we assessed for expression of cJun and its Ser73- and Ser63-phosphorylated forms in two ALK+ (Karpas 299 and SU-DHL-1) and one ALK- (Mac2A) ALCL cell lines by western blot analysis, and in 31 ALCL tumors (15 ALK+, 16 ALK-) by immunohistochemistry using tissue microarrays and specific antibodies. To examine the role of cJun in cell survival and proliferation in our in vitro system, ALCL cells were transiently transfected with small interfering RNA (siRNA) specific for cJun. Cell viability, proliferation of viable cells and cell cycle progression from G1 to S-phase were assessed by trypan blue exclusion, MTS and BrdU assays, respectively. All three ALCL cell lines expressed total cJun and Ser73-phosphorylated cJun (Ser73p-cJun) at a high level, whereas Ser63-phosphorylated cJun was expressed at a low level. In addition, all 31 ALCL tumors expressed total cJun in most neoplastic cells. Ser73p-cJun was also detected in all ALCL tumors at a variable level with the percentage of Ser73p-cJun-positive tumor cells ranging from 5% to 95%. By contrast, Ser63p-cJun was detected rarely in tumor cells. Transient transfection of ALCL cells with specific siRNA resulted in almost complete silencing of total cJun expression and absence of Ser73p-cJun expression, which was associated with decreased cell viability and a substantial (40%) decrease of cell growth. cJun silencing also resulted in cell cycle arrest as shown by decreased S-phase fraction. These cell cycle changes were associated with a marked increase of p21 levels and downregulation of cyclin D2 and D3. In conclusion, cJun is highly phosphorylated at serine 73 in ALCL cell lines and tumors and may contribute to cell cycle progression. Targeting cJun expression or phosphorylation using gene therapy approaches may represent a novel therapeutic strategy for patients with ALCL.