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Sample records for jak2 v617f constitutive

  1. JAK2V617F-negative ET Patients do not display constitutively active JAK/STAT signaling

    PubMed Central

    Schwemmers, Sven; Will, Britta; Waller, Cornelius F.; Abdulkarim, Khadija; Johansson, Peter; Andreasson, Björn; Pahl, Heike L.

    2008-01-01

    Objective Presence of the JAK2V617F mutation in only 40-60% of patients with Essential Thrombocythemia (ET) underscores the heterogeneity of this myeloproliferative disorder (MPD). Several distinct mutations, either in JAK2 (exon 12) or in c-Mpl (W515L) have been described in subsets of other MPDs, Polycythemia vera (PV) and Idiopathic Myelofibrosis (IMF). Analogous to JAK2V617F, these mutations cause constitutive JAK2 and STAT activation. It has therefore been proposed that constitutive activation of the JAK/STAT pathway underlies the molecular etiology of all MPDs. We investigated the alternative hypothesis that distinct alterations, separate from the JAK/STAT signal transduction pathway, underlie a subset of JAK2V617F-negative ET. Methods cDNA microarrays and qRT-PCR were used to compare gene expression in 40 ET patients with and without the JAK2V617F mutation. Results Unsupervised clustering of gene expression patterns in ET patients revealed two distinct subclasses of patients. These subclasses differed in presence or absence of the JAK2V617F mutation. Patients lacking the JAK2V617F mutation displayed significantly lower expression of the JAK/STAT target genes Pim-1 and SOCS2. In addition, JAK2V617F-negative patients showed lower levels of STAT3 phosphorylation. Conclusions These data demonstrate that a large proportion of JAK2V617F–negative ET patients do not display constitutive JAK/STAT signaling. Hence, we propose that alterations in different signal transduction pathways can lead to the clinical phenotype of ET. Elucidation of novel ET-inducing changes will facilitate both a molecular classification of ET and the development of rationally designed therapies. PMID:17764814

  2. Critical role of FANCC in JAK2 V617F mutant-induced resistance to DNA cross-linking drugs.

    PubMed

    Ueda, Fumihito; Sumi, Kazuya; Tago, Kenji; Kasahara, Tadashi; Funakoshi-Tago, Megumi

    2013-11-01

    A point mutation (V617F) of tyrosine kinase Janus kinase 2 (JAK2) is found in the majority of patients with myeloproliferative neoplasms (MPNs) and an aberrant signaling pathway induced by constitutively active JAK2 V617F mutant is a hallmark of MPNs. Cells transformed by JAK2 V617F mutant exhibited resistance to anti-cancer drugs such as cisplatin (CDDP), mitomycin C (MMC) and bleomycin (BLM). We first found that the expression of FANCC, a member of the Fanconi anemia (FA) proteins, was significantly induced by JAK2 V617F mutant through activation of signal transducers and activators of transcription 5 (STAT5). In addition, monoubiqitination and foci formation of FANCD2, which are critical for activation of the FA pathway, were increased in cells transformed by JAK2 V617F mutant, compared to cells expressing wild-type JAK2. Interestingly, knockdown of FANCC in cells expressing JAK2 V617F mutant induced not only the reduction of monoubiqitination and foci formation of FANCD2 but also the enhancement of sensitivity to DNA damage induced by CDDP and MMC but not BLM. Taken together, FANCC is most likely to be critical for resistance to DNA cross-linking drug-induced DNA damage in cells transformed by JAK2 V617F mutant. PMID:23838005

  3. JAK-2 V617F mutation increases heparanase procoagulant activity.

    PubMed

    Kogan, Inna; Chap, Dafna; Hoffman, Ron; Axelman, Elena; Brenner, Benjamin; Nadir, Yona

    2016-01-01

    Patients with polycythaemia vera (PV), essential thrombocythaemia (ET) and primary myelofibrosis (PMF) are at increased risk of arterial and venous thrombosis. In patients with ET a positive correlation was observed between JAK-2 V617F mutation, that facilitates erythropoietin receptor signalling, and thrombotic events, although the mechanism involved is not clear. We previously demonstrated that heparanase protein forms a complex and enhances the activity of the blood coagulation initiator tissue factor (TF) which leads to increased factor Xa production and subsequent activation of the coagulation system. The present study was aimed to evaluate heparanase procoagulant activity in myeloproliferative neoplasms. Forty bone marrow biopsies of patients with ET, PV, PMF and chronic myelogenous leukaemia (CML) were immunostained to heparanase, TF and TF pathway inhibitor (TFPI). Erythropoietin receptor positive cell lines U87 human glioma and MCF-7 human breast carcinoma were studied. Heparanase and TFPI staining were more prominent in ET, PV and PMF compared to CML. The strongest staining was in JAK-2 positive ET biopsies. Heparanase level and procoagulant activity were higher in U87 cells transfected to over express JAK-2 V617F mutation compared to control and the effect was reversed using JAK-2 inhibitors (Ruxolitinib, VZ3) and hydroxyurea, although the latter drug did not inhibit JAK-2 phosphorylation. Erythropoietin increased while JAK-2 inhibitors decreased the heparanase level and procoagulant activity in U87 and MCF-7 parental cells. In conclusion, JAK-2 is involved in heparanase up-regulation via the erythropoietin receptor. The present findings may potentially point to a new mechanism of thrombosis in JAK-2 positive ET patients. PMID:26489695

  4. JAK2 V617F in Myeloid Disorders: Molecular Diagnostic Techniques and Their Clinical Utility

    PubMed Central

    Steensma, David P.

    2006-01-01

    In early 2005, several groups of investigators studying myeloid malignancies described a novel somatic point mutation (V617F) in the conserved autoinhibitory pseudokinase domain of the Janus kinase 2 (JAK2) protein, which plays an important role in normal hematopoietic growth factor signaling. The V617F mutation is present in blood and marrow from a large proportion of patients with classic BCR/ABL-negative chronic myeloproliferative disorders and of a few patients with other clonal hematological diseases such as myelodysplastic syndrome, atypical myeloproliferative disorders, and acute myeloid leukemia. The JAK2 V617F mutation causes constitutive activation of the kinase, with deregulated intracellular signaling that mimics continuous hematopoietic growth factor stimulation. Within 7 months of the first electronic publication describing this new mutation, clinical molecular diagnostic laboratories in the United States and Europe began offering JAK2 mutation testing on a fee-for-service basis. Here, I review the various techniques used by research groups and clinical laboratories to detect the genetic mutation underlying JAK2 V617F, including fluorescent dye chemistry sequencing, allele-specific polymerase chain reaction (PCR), real-time PCR, DNA-melting curve analysis, pyrosequencing, and others. I also discuss diagnostic sensitivity, performance, and other practical concerns relevant to the clinical laboratorian in addition to the potential diagnostic utility of JAK2 mutation tests. PMID:16931578

  5. Stathmin 1 inhibition amplifies ruxolitinib-induced apoptosis in JAK2V617F cells

    PubMed Central

    Machado-Neto, João Agostinho; de Melo Campos, Paula; Favaro, Patricia; Lazarini, Mariana; da Silva Santos Duarte, Adriana; Lorand-Metze, Irene; Costa, Fernando Ferreira; Olalla Saad, Sara Teresinha; Traina, Fabiola

    2015-01-01

    The JAK/STAT pathway is constitutively activated in myeloproliferative neoplasms and can be inhibited by ruxolitinib, a selective JAK1/2 inhibitor. The JAK2V617F mutation leads to constitutive STAT3 phosphorylation and potentially leads to inhibition of Stathmin 1 activity via STAT3. In support of this hypothesis, we found that, in HEL JAK2V617F cells, ruxolitinib treatment decreased STAT3 and Stathmin 1 association, induced Stathmin 1 activation and microtubule instability. Silencing of Stathmin 1 significantly reduced cell proliferation and clonal growth, and increased apoptosis induced by ruxolitinib. Stathmin 1 silencing also prevented ruxolitinib-induced microtubule instability. To phenocopy the effect of Stathmin 1 inhibition, cells were treated with paclitaxel, a microtubule-stabilizing drug, in association or not with ruxolitinib; combined treatment significantly increased apoptosis, when compared to monotherapy. Notably, Stathmin 1 mRNA levels were highly expressed in CD34+ cells from primary myelofibrosis patients. We then proposed that an undesired effect of ruxolitinib treatment may constitute Stathmin 1 activation and microtubule instability in JAK2V617F cells. Induction of microtubule stability, through Stathmin 1 silencing or paclitaxel treatment, combined with ruxolitinib could be an effective strategy for promoting apoptosis in JAK2V617F cells. PMID:26356819

  6. Deletion of Stat3 enhances myeloid cell expansion and increases the severity of myeloproliferative neoplasms in Jak2V617F knock-in mice

    PubMed Central

    Yan, Dongqing; Jobe, Fatoumata; Hutchison, Robert E.; Mohi, Golam

    2015-01-01

    The JAK2V617F mutation commonly found in myeloproliferative neoplasms (MPNs) induces constitutive phosphorylation/activation of the signal transducer and activator of transcription 3 (Stat3). However, the contribution of Stat3 in MPN evoked by JAK2V617F remains unknown. To determine the role of Stat3 in JAK2V617F-induced MPN, we generated Stat3-deficient Jak2V617F-expressing mice. Whereas expression of Jak2V617F resulted in a PV-like disease characterized by increased red blood cells (RBC), hematocrit, neutrophils and platelets in the peripheral blood of Jak2V617F knock-in mice, deletion of Stat3 slightly reduced RBC, and hematocrit parameters and modestly increased platelet numbers in Jak2V617F knock-in mice. Moreover, deletion of Stat3 significantly increased the neutrophil counts/percentages and markedly reduced the survival of mice expressing Jak2V617F. These phenotypic manifestations were reproduced upon bone marrow transplantation into wild-type animals. Flow cytometric analysis showed increased hematopoietic stem cell and granulocyte-macrophage progenitor populations in the bone marrow and spleens of Stat3-deficient Jak2V617F mice. Stat3 deficiency also caused a marked expansion of Gr-1+/Mac-1+ myeloid cells in Jak2V617F knock-in mice. Histopathologic analysis revealed marked increase in granulocytes in the bone marrow, spleens and livers of Stat3-deficient Jak2V617F-expressing mice. Together, these results suggest that deletion of Stat3 increases the severity of MPN induced by Jak2V617F. PMID:26044284

  7. A role for reactive oxygen species in JAK2 V617F myeloproliferative neoplasm progression.

    PubMed

    Marty, C; Lacout, C; Droin, N; Le Couédic, J-P; Ribrag, V; Solary, E; Vainchenker, W; Villeval, J-L; Plo, I

    2013-11-01

    Although other mutations may predate the acquisition of the JAK2(V617F) mutation, the latter is sufficient to drive the disease phenotype observed in BCR-ABL-negative myeloproliferative neoplasms (MPNs). One of the consequences of JAK2(V617F) is genetic instability that could explain JAK2(V617F)-mediated MPN progression and heterogeneity. Here, we show that JAK2(V617F) induces the accumulation of reactive oxygen species (ROS) in the hematopoietic stem cell compartment of a knock-in (KI) mouse model and in patients with JAK2(V617F) MPNs. JAK2(V617F)-dependent ROS elevation was partly mediated by an AKT-induced decrease in catalase expression and was accompanied by an increased number of 8-oxo-guanines and DNA double-strand breaks (DSBs). Moreover, there was evidence for a mitotic recombination event in mice resulting in loss of heterozygosity of Jak2(V617F). Mice engrafted with 30% of Jak2(V617F) KI bone marrow (BM) cells developed a polycythemia vera-like disorder. Treatment with the anti-oxidant N-acetylcysteine (NAC) substantially restored blood parameters and reduced damages to DNA. Furthermore, NAC induced a marked decrease in splenomegaly with reduction in the frequency of the Jak2(V617F)-positive hematopoietic progenitors in BM and spleen. Altogether, overproduction of ROS is a mediator of JAK2(V617F)-induced DNA damages that promote disease progression. Targeting ROS accumulation might prevent the development of JAK2(V617F) MPNs. PMID:23558526

  8. Cardiac hypertrophy associated with myeloproliferative neoplasms in JAK2V617F transgenic mice

    PubMed Central

    2014-01-01

    Background Myeloproliferative neoplasms (MPNs) are blood malignancies manifested in increased production of red blood cells, white blood cells, and/or platelets. A major molecular lesion associated with the diseases is JAK2V617F, an activation mutation form of tyrosine kinase JAK2. Cardiovascular events represent the leading cause of morbidity and mortality associated MPNs, but the underlying mechanism is not well understood. Methods Previously, we generated JAK2V617F transgenic mice which displayed MPN-like phenotypes. In the present study, we further characterized these mice by analyzing the time course of MPN phenotype development and associated cardiac abnormalities. We performed detailed histochemical staining of cardiac sections. Results JAK2V617F transgenic mice developed cardiomegaly as a subsequent event of increased blood cell production during the course of MPN phenotype development. The cardiomegaly is manifested in increased ventricular wall thickness and enlarged cardiomyocytes. Trichrome and reticulin staining revealed extensive collagen fibrosis in the heart of JAK2V617F transgenic mice. Thrombosis in the coronary artery and inflammatory cell infiltration into cardiac muscle were also observed in JAK2V617F transgenic mice, and the latter event was accompanied by fibrosis. Conclusion JAK2V617F-induced blood disorders have a major impact on heart function and lead to cardiac hypertrophy. JAK2V617F transgenic mice represent an excellent model system to study both hematological malignancies and cardiovascular diseases. PMID:24646493

  9. TNFα facilitates clonal expansion of JAK2V617F positive cells in myeloproliferative neoplasms

    PubMed Central

    Aichberger, Karl J.; Luty, Samuel B.; Bumm, Thomas G.; Petersen, Curtis L.; Doratotaj, Shirin; Vasudevan, Kavin B.; LaTocha, Dorian H.; Yang, Fei; Press, Richard D.; Loriaux, Marc M.; Pahl, Heike L.; Silver, Richard T.; Agarwal, Anupriya; O'Hare, Thomas; Druker, Brian J.; Bagby, Grover C.

    2011-01-01

    Proinflammatory cytokines such as TNFα are elevated in patients with myeloproliferative neoplasms (MPN), but their contribution to disease pathogenesis is unknown. Here we reveal a central role for TNFα in promoting clonal dominance of JAK2V617F expressing cells in MPN. We show that JAK2V617F kinase regulates TNFα expression in cell lines and primary MPN cells and TNFα expression is correlated with JAK2V617F allele burden. In clonogenic assays, normal controls show reduced colony formation in the presence of TNFα while colony formation by JAK2V617F-positive progenitor cells is resistant or stimulated by exposure to TNFα. Ectopic JAK2V617F expression confers TNFα resistance to normal murine progenitor cells and overcomes inherent TNFα hypersensitivity of Fanconi anemia complementation group C deficient progenitors. Lastly, absence of TNFα limits clonal expansion and attenuates disease in a murine model of JAK2V617F-positive MPN. Altogether our data are consistent with a model where JAK2V617F promotes clonal selection by conferring TNFα resistance to a preneoplastic TNFα sensitive cell, while simultaneously generating a TNFα-rich environment. Mutations that confer resistance to environmental stem cell stressors are a recognized mechanism of clonal selection and leukemogenesis in bone marrow failure syndromes and our data suggest that this mechanism is also critical to clonal selection in MPN. PMID:21860020

  10. Coexisting JAK2V617F and CALR Exon 9 Mutation in Essential Thrombocythemia.

    PubMed

    Rashid, Munazza; Ahmed, Rifat Zubair; Ahmed, Shariq; Nadeem, Muhammad; Ahmed, Nuzhat; Shamsi, Tahir Sultan

    2016-06-01

    Classic "BCR-ABL1-negative" MPN is an operational sub-category of MPN that includes polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) harboring JAK2V617F as the most common mutation. JAK2V617F can be detected in about 95 % of patients with PV while remaining 5 % of PV patients carry a somatic mutation of JAK2 exon 12. Approximately one-third of patients with ET or PMF do not carry any mutation in JAK2 or MPL. In December 2013, mutations were described in calreticulin (CALR) gene in 67-71 and 56-88 % of JAK2V617F and MPL negative patients with ET and PMF, respectively. Since this discovery CALR mutations have been reported to be mutually exclusive with JAK2V617F or MPL mutations. However recently few studies (eleven published reports) reported the coexistence of JAK2V617F and CALR in MPN. In the present study we are reporting JAK2V617F positive ET patient from our center with coexisting CALR exon 9 mutation type c.1214_1225del12 (p.E405_D408del) that was never reported before as a coexisting mutation and describing in detail the clinical outcomes. PMID:27408370

  11. Sex differences in the JAK2V617F allele burden in chronic myeloproliferative disorders

    PubMed Central

    Stein, Brady L.; Williams, Donna M.; Wang, Nae-Yuh; Rogers, Ophelia; Isaacs, Mary Ann; Pemmaraju, Naveen; Spivak, Jerry L.; Moliterno, Alison R.

    2010-01-01

    Background The JAK2V617F allele burden is a variable measure, determined by the frequency of mitotic recombination events and the expansion of JAK2V617F clones. Since variability in the JAK2V617F allele burden is partly responsible for the distinct phenotypes seen in the myeloproliferative disorders, the objective of this study was to identify modifiers of the allele burden. Design and Methods Blood samples were obtained between May 2005 and January 2009 from 272 patients with essential thrombocytosis, polycythemia vera, and myelofibrosis. The JAK2V617F allele burden was measured by an allele-specific quantitative polymerase chain reaction using DNA from purified neutrophils. Repeated measures, on average 2 years apart, were available for 104 patients. Results Sex, age at diagnosis, and disease duration all independently influenced the JAK2V617F allele burden. When considering all patients with myeloproliferative disorders, women had significantly lower allele burdens than men (P=0.04). In those patients with repeated measures, the increase in allele burden per year between the first and second evaluations was significantly less in females than in males. Among those who experienced disease evolution, females were 4.5 times more likely to have evolution from essential thrombocytosis to polycythemia vera, but 0.23 times as likely to have evolution from essential thrombocytosis to myelofibrosis. Conclusions Sex is an independent factor accounting for variability in the JAK2V617F allele burden. We speculate that lower allele burdens in females reflect a lower frequency of mitotic recombination events in females than in males, and should be considered when evaluating the relationship of allele burden to disease phenotype and also in evaluating responses to JAK2V617F-inhibitors. Because sex may influence genotype and/or clonal expansion, underpinning the variability in JAK2V617F allele burden, it will be important to explore factors that determine susceptibility to

  12. JAK2V617F-positive endothelial cells contribute to clotting abnormalities in myeloproliferative neoplasms

    PubMed Central

    Etheridge, S. Leah; Roh, Michelle E.; Cosgrove, Megan E.; Sangkhae, Veena; Fox, Norma E.; Chen, Junmei; López, José A.; Kaushansky, Kenneth; Hitchcock, Ian S.

    2014-01-01

    The Janus kinase 2 (JAK2) V617F mutation is the primary pathogenic mutation in patients with Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs). Although thrombohemorrhagic incidents are the most common causes of morbidity and mortality in patients with MPNs, the events causing these clotting abnormalities remain unclear. To identify the cells responsible for the dysfunctional hemostasis, we used transgenic mice expressing JAK2V617F in specific lineages involved in thrombosis and hemostasis. When JAK2V617F was expressed in both hematopoietic and endothelial cells (ECs), the mice developed a significant MPN, characterized by thrombocytosis, neutrophilia, and splenomegaly. However, despite having significantly higher platelet counts than controls, these mice showed severely attenuated thrombosis following injury. Interestingly, platelet activation and aggregation in response to agonists was unaltered by JAK2V617F expression. Subsequent bone marrow transplants revealed the contribution of both endothelial and hematopoietic compartments to the attenuated thrombosis. Furthermore, we identified a potential mechanism for this phenotype through JAK2V617F-regulated inhibition of von Willebrand factor (VWF) function and/or secretion. JAK2V617F+ mice display a condition similar to acquired von Willebrand syndrome, exhibiting significantly less high molecular weight VWF and reduced agglutination to ristocetin. These findings greatly advance our understanding of thrombohemorrhagic events in MPNs and highlight the critical role of ECs in the pathology of hematopoietic malignancies. PMID:24469804

  13. The Burden of JAK2V617F Mutated Allele in Turkish Patients With Myeloproliferative Neoplasms

    PubMed Central

    Yonal-Hindilerden, Ipek; Daglar-Aday, Aynur; Akadam-Teker, Basak; Yilmaz, Ceylan; Nalcaci, Meliha; Yavuz, Akif Selim; Sargin, Deniz

    2015-01-01

    Background Studies regarding the impact of JAK2V617F allele burden on phenotypic properties and clinical course in Philadelphia-negative myeloproliferative neoplasms (Ph-negative MPNs) have reported variable results. We aimed to analyze the association of mutated JAK2V617F allele burden with laboratory characteristics and clinical phenotype in Turkish patients (107 essential thrombocythemia (ET) and 77 primary myelofibrosis (PMF)). Methods Peripheral blood samples of 184 patients with Ph-negative MPNs were analyzed for JAK2V617F allele status and burden. JAK2 MutaScreen assay (Ipsogen, Luminy Biotech, Marseille, France) was used to detect the JAK2V617F status and quantitative JAK2V617F allele burdens in genomic DNA using TaqMan allelic discrimination. Results Frequency of JAK2V617F-positive patients with high mutation load (allele burden > 50%) was higher in PMF compared to ET (23.4% and 4.7%, respectively; P = 0.001). We found significant association between ET patients with high JAK2V617F allele burden and lower hemoglobin (Hgb) and hematocrit (Hct), higher LDH levels and more prevalent massive splenomegaly (P = 0.001, P = 0.001, P = 0.012 and P = 0.015, respectively). ET patients with high mutation load displayed higher prevalence of bleeding compared to low mutation load and wild-type mutational status (P = 0.003). Rate of DVT was significantly higher in ET patients with mutant allele burden in upper half compared to lower half and wild-type (P = 0.029). We observed significant association between PMF patients with high JAK2V617F allele burden and higher Hgb, Hct levels and leukocyte counts (P = 0.003, P = 0.021 and P = 0.001, respectively). Conclusions Our study demonstrated JAK2V617F allele burden correlates with clinical features in ET and PMF. We conclude quantification of JAK2V617F mutation contributes to the workup of Ph-negative MPNs. PMID:25584101

  14. Prognostic significance of ASXL1, JAK2V617F mutations and JAK2V617F allele burden in Philadelphia-negative myeloproliferative neoplasms

    PubMed Central

    Yonal-Hindilerden, Ipek; Daglar-Aday, Aynur; Akadam-Teker, Basak; Yilmaz, Ceylan; Nalcaci, Meliha; Yavuz, Akif Selim; Sargin, Deniz

    2015-01-01

    Background Despite insights into the genetic basis of Philadelphia-negative myeloproliferative neoplasms (Ph-negative MPNs), a significant proportion of essential thrombocythemia (ET) and primary myelofibrosis (PMF) patients present with no known MPN disease alleles. There were no previous studies investigating the impact of ASXL1 mutations in Ph-negative MPNs in Turkey. In the current study, we investigated the prognostic significance of ASXL1 mutations in Turkish MPN patients. We also aimed to determine the prognostic significance of JAK2V617F allele burden and the relationship of JAK2V617F mutation with ASXL1 mutations in Ph-negative MPNs. Methods About 184 patients from a single center diagnosed with Ph-negative MPNs were screened for ASXL1, JAK2V617F mutations, and JAK2V617F allele burden: 107 ET and 77 PMF. Results A total of 29 ASXL1 mutations were detected in 24.7% of PMF and 8.4% of ET patients. ASXL1-mutated ET patients showed a trend toward an increase in the incidence of cerebrovascular events and higher total leukocyte counts. ASXL1-mutation in PMF was associated with older age and a higher prevalence of bleeding complications. In univariate analysis, overall survival (OS) was significantly reduced in ASXL1-mutated PMF patients. In multivariate analysis, Dynamic International Prognostic Scoring System-plus high-risk category and ASXL1 mutation status were independently associated with shorter survival in PMF. In PMF, mutational status and allele burden of JAK2V617F showed no difference in terms of OS and leukemia-free survival. Conclusion We conclude that ASXL1 mutations are molecular predictors of short OS in PMF. PMID:26082670

  15. JAK2V617F allele burden in patients with myeloproliferative neoplasms.

    PubMed

    Alshemmari, Salem H; Rajaan, Reshmi; Ameen, Reem; Al-Drees, Mohammad A; Almosailleakh, Marwa R

    2014-05-01

    Myeloproliferative neoplasms (MPNs) are clonal malignant diseases that represent a group of conditions including polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis (MF). The JAK2-V617F mutation is prevalent in almost all patients with MPNs and has become a valuable biomarker for diagnosis of MPNs. A different allele burden in these entities has long been noticed. The aim of our study was to assess the JAK2 allele burden in our JAK2V617F positive cases and its association with phenotype if any and to select a simple, sensitive assay for use in our clinical molecular diagnostic laboratory. Methodologies reported in this literature include amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) and real-time quantitative polymerase chain reaction (RQ-PCR). We analyzed 174 cases by RQ-PCR for the quantification of JAK2V617F were initially screened by ARMS-PCR. We found that V617F allele burden in the entire population of patients was 73 % ranging from 0.97 to 95 %. The median V617F allele burden in PV patients was 40 %, MF was 95 %, and ET was 25 %. ARMS-PCR and RQ-PCR were proven to be sensitive since ARMS-PCR is a qualitative method; it can be used to screen JAK2V617F mutation and RQ-PCR was used to quantify the V617F cells. Our study suggests that JAK2V617F positivity is associated with MPNs, and its allele burden is an excellent diagnostic marker for disease subtypes, prognosis, disease phenotype and complication, and evolution. The data indicates that ARMS-PCR is simple and can be easily performed for the primary screening of JAK2V617F mutation, and RQ-PCR is sensitive enough to detect low mutant allele levels (>10 %), specific enough not to produce false positive results, and can be performed for the JAK2V617F allele burden quantification. PMID:24362471

  16. Germ line variants predispose to both JAK2 V617F clonal hematopoiesis and myeloproliferative neoplasms.

    PubMed

    Hinds, David A; Barnholt, Kimberly E; Mesa, Ruben A; Kiefer, Amy K; Do, Chuong B; Eriksson, Nicholas; Mountain, Joanna L; Francke, Uta; Tung, Joyce Y; Nguyen, Huong Marie; Zhang, Haiyu; Gojenola, Linda; Zehnder, James L; Gotlib, Jason

    2016-08-25

    We conducted a genome-wide association study (GWAS) to identify novel predisposition alleles associated with Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) and JAK2 V617F clonal hematopoiesis in the general population. We recruited a web-based cohort of 726 individuals with polycythemia vera, essential thrombocythemia, and myelofibrosis and 252 637 population controls unselected for hematologic phenotypes. Using a single-nucleotide polymorphism (SNP) array platform with custom probes for the JAK2 V617F mutation (V617F), we identified 497 individuals (0.2%) among the population controls who were V617F carriers. We performed a combined GWAS of the MPN cases plus V617F carriers in the control population (n = 1223) vs the remaining controls who were noncarriers for V617F (n = 252 140). For these MPN cases plus V617F carriers, we replicated the germ line JAK2 46/1 haplotype (rs59384377: odds ratio [OR] = 2.4, P = 6.6 × 10(-89)), previously associated with V617F-positive MPN. We also identified genome-wide significant associations in the TERT gene (rs7705526: OR = 1.8, P = 1.1 × 10(-32)), in SH2B3 (rs7310615: OR = 1.4, P = 3.1 × 10(-14)), and upstream of TET2 (rs1548483: OR = 2.0, P = 2.0 × 10(-9)). These associations were confirmed in a separate replication cohort of 446 V617F carriers vs 169 021 noncarriers. In a joint analysis of the combined GWAS and replication results, we identified additional genome-wide significant predisposition alleles associated with CHEK2, ATM, PINT, and GFI1B All SNP ORs were similar for MPN patients and controls who were V617F carriers. These data indicate that the same germ line variants endow individuals with a predisposition not only to MPN, but also to JAK2 V617F clonal hematopoiesis, a more common phenomenon that may foreshadow the development of an overt neoplasm. PMID:27365426

  17. Myeloproliferative neoplasms can be initiated from a single hematopoietic stem cell expressing JAK2-V617F

    PubMed Central

    Lundberg, Pontus; Takizawa, Hitoshi; Kubovcakova, Lucia; Guo, Guoji; Hao-Shen, Hui; Dirnhofer, Stephan; Orkin, Stuart H.; Manz, Markus G.

    2014-01-01

    The majority of patients with myeloproliferative neoplasms (MPNs) carry a somatic JAK2-V617F mutation. Because additional mutations can precede JAK2-V617F, it is questioned whether JAK2-V617F alone can initiate MPN. Several mouse models have demonstrated that JAK2-V617F can cause MPN; however, in all these models disease was polyclonal. Conversely, cancer initiates at the single cell level, but attempts to recapitulate single-cell disease initiation in mice have thus far failed. We demonstrate by limiting dilution and single-cell transplantations that MPN disease, manifesting either as erythrocytosis or thrombocytosis, can be initiated clonally from a single cell carrying JAK2-V617F. However, only a subset of mice reconstituted from single hematopoietic stem cells (HSCs) displayed MPN phenotype. Expression of JAK2-V617F in HSCs promoted cell division and increased DNA damage. Higher JAK2-V617F expression correlated with a short-term HSC signature and increased myeloid bias in single-cell gene expression analyses. Lower JAK2-V617F expression in progenitor and stem cells was associated with the capacity to stably engraft in secondary recipients. Furthermore, long-term repopulating capacity was also present in a compartment with intermediate expression levels of lineage markers. Our studies demonstrate that MPN can be initiated from a single HSC and illustrate that JAK2-V617F has complex effects on HSC biology. PMID:25288396

  18. JAK2 mutants (e.g., JAK2V617F) and their importance as drug targets in myeloproliferative neoplasms

    PubMed Central

    Gäbler, Karoline; Behrmann, Iris; Haan, Claude

    2013-01-01

    The Janus kinase 2 (JAK2) mutant V617F and other JAK mutants are found in patients with myeloproliferative neoplasms and leukemias. Due to their involvement in neoplasia and inflammatory disorders, Janus kinases are promising targets for kinase inhibitor therapy. Several small-molecule compounds are evaluated in clinical trials for myelofibrosis, and ruxolitinib (INCB018424, Jakafi®) was the first Janus kinase inhibitor to receive clinical approval. In this review we provide an overview of JAK2V617F signaling and its inhibition by small-molecule kinase inhibitors. In addition, myeloproliferative neoplasms are discussed regarding the role of JAK2V617F and other mutant proteins of possible relevance. We further give an overview about treatment options with special emphasis on possible combination therapies. PMID:24069563

  19. Detection of JAK2 V617F mutation increases the diagnosis of myeloproliferative neoplasms

    PubMed Central

    ZHANG, SHU-PENG; LI, HUI; LAI, REN-SHENG

    2015-01-01

    The Janus kinase (JAK)2 gene, which is located on chromosome 9p24, is involved in the signaling transduction pathways of the hematopoietic and immune system. Mutations in the JAK2 gene have served as disease markers for myeloproliferative neoplasms (MPNs). The aim of the present study was to investigate the occurrence of the JAK2 gene mutation in 140 clinical samples, and to evaluate its clinical significance in MPNs and other hematological diseases. Genomic DNA was extracted from the peripheral blood leukocytes or bone marrow karyocytes of 140 clinical samples, which included 130 patients with various types of hematological disease and 10 control patients. In addition, exons 12 and 14 of the JAK2 gene were analyzed by direct sequencing and the mutation rates of various MPN subtypes were evaluated. Of the 140 samples, exons 12 and 14 were tested in 74 samples, however, exon 14 only was tested in 66 samples. No mutations were identified in exon 12. The V617F mutation rate in polycythemia vera was 82.1% (23/28), and the mutation rates in essential thrombocythemia histiocytosis, primary myelofibrosis and other MPNs were 53.1% (17/32), 40.0% (4/10) and 60.0% (6/10), respectively. Therefore, the total mutation rate of the JAK2 gene in MPN was 62.5% (50/80). For non-MPN hematological diseases, four V617F mutations were detected in samples of leukocytosis of unknown origin (4/12), however, no JAK2 V617F mutations were identified in the 10 controls. Therefore, JAK2 V617F mutations may present a novel marker for diagnosis of MPNs. Furthermore, the direct sequencing method appeared to be satisfactory for the clinical gene testing of hematological samples. PMID:25624900

  20. Polycythemia vera and the Jak2(V617F) mutation in a case of hereditary spherocytosis.

    PubMed

    Fleischman, Roger A

    2013-10-01

    The identification of Jak2(V617F) mutations in more than 90% of patients with polycythemia vera (PV) has greatly improved the diagnostic accuracy for this uncommon myeloproliferative disorder. Although previous cases of presumptive PV in patients with hereditary spherocytosis (HS) have been described, these earlier reports either preceded the establishment of widely accepted criteria for the diagnosis of PV or lacked definitive studies to rule out secondary causes of polycythemia. In contrast, the author describes here a novel case of PV confirmed at the molecular level in a patient with hereditary spherocytosis by the finding of a Jak2(V617F) mutation. Based on recent advances in understanding the role of Jak2 signaling in the pathogenesis of PV, the author proposes 2 independent biological mechanisms that could account for more than a chance association of these 2 disorders. PMID:23588264

  1. The Jak2V617F oncogene associated with myeloproliferative diseases requires a functional FERM domain for transformation and for expression of the Myc and Pim proto-oncogenes

    PubMed Central

    Wernig, Gerlinde; Gonneville, Jeffrey R.; Crowley, Brian J.; Rodrigues, Margret S.; Reddy, Mamatha M.; Hudon, Heidi E.; Walz, Christoph; Reiter, Andreas; Podar, Klaus; Royer, Yohan; Constantinescu, Stefan N.; Tomasson, Michael H.; Griffin, James D.; Gilliland, D. Gary

    2008-01-01

    The V617F activating point mutation in Jak2 is associated with a proportion of myeloproliferative disorders. In normal hematopoietic cells, Jak2 signals only when associated with a growth factor receptor, such as the erythropoietin receptor (EpoR). We sought to identify the molecular requirements for activation of Jak2V617F by introducing a point mutation in the FERM domain (Y114A), required for receptor binding. Whereas BaF3.EpoR cells are readily transformed by Jak2V617F to Epo independence, we found that the addition of the FERM domain mutation blocked transformation and the induction of reactive oxygen species. Further, while cells expressing Jak2V617F had constitutive activation of STAT5, cells expressing Jak2V617F/Y114A did not, suggesting that signaling is defective at a very proximal level. In addition, expression of the Myc and Pim proto-oncogenes by Jak2V617F was found to be FERM domain dependent. An inducible constitutively active STAT5 mutant expressed in BaF3 cells was sufficient to induce Myc and Pim. Finally, the FERM domain in Jak2V617F was also required for abnormal hematopoiesis in transduced primary murine fetal liver cells. Overall, our results suggest that constitutive activation of Jak2 requires an intact FERM domain for a transforming phenotype, and is necessary for activation of the major target of Jak2, STAT5. PMID:18216297

  2. Sensitive and accurate quantification of JAK2 V617F mutation in chronic myeloproliferative neoplasms by droplet digital PCR.

    PubMed

    Waterhouse, Miguel; Follo, Marie; Pfeifer, Dietmar; von Bubnoff, Nikolas; Duyster, Justus; Bertz, Hartmut; Finke, Jürgen

    2016-04-01

    The JAK2 V617F mutation can be detected with a high frequency in patients with myeloproliferative neoplasms (MPN). MPN treatment efficiency can be assessed by JAK2 V617F quantification. Real-time quantitative PCR (qPCR) is widely used for JAK2 V617F quantification. Emerging alternative technologies like digital droplet PCR (ddPCR) have been described to overcome inherent qPCR limitations. The purpose of this study was to evaluate the utility of ddPCR for JAK2 V617F quantification in patient samples with MPN. Sensitivity and specificity were established by using DNA artificial mixtures. In addition, 101 samples from 59 patients were evaluated for JAK2 V617F mutation. Limit of detection was 0.01 % for both qPCR and ddPCR. The JAK2 V617F mutation was detected in 43 out of 59 patients by both PCR platforms. However, in 14 % of the samples, JAK2 V617F mutation was detected only with ddPCR. This 14 % of discrepant samples were from patients shortly after allogeneic stem cell transplantation. Percentage of JAK2 V617F mutation measured by qPCR and ddPCR in clinical samples showed a high degree of correlation (Spearman r: 0.9637 p < 0.001) and an excellent agreement assessed by Bland-Altman analysis. In conclusion, ddPCR is a suitable, precise, and sensitive method for quantification of the JAK 2 V617F mutation. PMID:26931113

  3. JAK2V617F somatic mutation in the general population: myeloproliferative neoplasm development and progression rate

    PubMed Central

    Nielsen, Camilla; Bojesen, Stig E.; Nordestgaard, Børge G.; Kofoed, Klaus F.; Birgens, Henrik S.

    2014-01-01

    Clinical significance of the JAK2V617F mutation in patients with a myeloproliferative neoplasm has been the target of intensive research in recent years. However, there is considerably uncertainty about prognosis in JAK2V617F positive individuals without overt signs of myeloproliferative disease. In this study, we tested the hypothesis that increased JAK2V617F somatic mutation burden is associated with myeloproliferative neoplasm progression rate in the general population. Among 49,488 individuals from the Copenhagen General Population Study, 63 (0.1%) tested positive for the JAK2V617F mutation in the time period 2003–2008. Of these, 48 were available for re-examination in 2012. Level of JAK2V617F mutation burden was associated with myeloproliferative neoplasm progression rate, consistent with a biological continuum of increasing JAK2V617F mutation burden across increasing severity of myeloproliferative neoplasm from no disease (n=8 at re-examination) through essential thrombocythemia (n=20) and polycythemia vera (n=13) to primary myelofibrosis (n=7). Among those diagnosed with a myeloproliferative neoplasm only at re-examination in 2012, in the preceding years JAK2V617F mutation burden increased by 0.55% per year, erythrocyte volume fraction increased by 1.19% per year, and erythrocyte mean corpuscular volume increased by 1.25% per year, while there was no change in platelet count or erythropoietin levels. Furthermore, we established a JAK2V617F mutation burden cut-off point of 2% indicative of disease versus no disease; however, individuals with a mutation burden below 2% may suffer from a latent form of myeloproliferative disease revealed by a slightly larger spleen and/or slightly higher lactic acid dehydrogenase concentration compared to controls. Of all 63 JAK2V617F positive individuals, 48 were eventually diagnosed with a myeloproliferative neoplasm. PMID:24907356

  4. Gender and Vascular Complications in the JAK2 V617F-Positive Myeloproliferative Neoplasms

    PubMed Central

    Stein, Brady L.; Rademaker, Alfred; Spivak, Jerry L.; Moliterno, Alison R.

    2011-01-01

    We previously found that gender influenced the JAK2 V617F allele burden, but it is unknown whether this gender difference in molecular epidemiology influences complications in the myeloproliferative neoplasms (MPNs). Historically, vascular complications represented the most common cause of mortality in polycythemia vera and essential thrombocytosis and contributed to morbidity in primary myelofibrosis. To determine the influence of gender on vascular complications, we retrospectively analyzed associations between gender and vascular complications. Despite their younger age, less prevalent dyslipidemia or smoking history, lower white blood counts, and lower JAK2 V617F allele burden, women had higher rates of abdominal venous thrombosis and comparable rates of all vascular complications. Vascular risk is currently not easily stratified by MPN-disease burden or traditional risk factors. Our analysis contributes to growing literature emphasizing gender differences in the MPN and further supports the important impact of individual and host variation on MPN clinical manifestations, and especially vascular risk. PMID:22084670

  5. Familial Essential Thrombocythemia Associated with MPL W515L Mutation in Father and JAK2 V617F Mutation in Daughter

    PubMed Central

    Trifa, Adrian P.; Cucuianu, Andrei; Popp, Radu A.

    2014-01-01

    Familial essential thrombocythemia features the acquisition of somatic mutations and an evolution similar to the sporadic form of the disease. Here we report two patients—father and daughter—with essential thrombocythemia who displayed a heterogeneous pattern of somatic mutations. The JAK2 V617F mutation was found in the daughter, while the father harbored the MPL W515L mutation. This case report may constitute further proof that in familial essential thrombocythemia there are other, still undefined, constitutional, inherited genetic factors predisposing to the acquisition of various somatic mutations (e.g., JAK2 V617F and MPL). PMID:25525531

  6. Kinase domain mutations confer resistance to novel inhibitors targeting JAK2V617F in myeloproliferative neoplasms.

    PubMed

    Deshpande, A; Reddy, M M; Schade, G O M; Ray, A; Chowdary, T K; Griffin, J D; Sattler, M

    2012-04-01

    The transforming JAK2V617F kinase is frequently associated with myeloproliferative neoplasms and thought to be instrumental for the overproduction of myeloid lineage cells. Several small molecule drugs targeting JAK2 are currently in clinical development for treatment in these diseases. We performed a high-throughput in vitro screen to identify point mutations in JAK2V617F that would be predicted to have potential clinical relevance and associated with drug resistance to the JAK2 inhibitor ruxolitinib (INCB018424). Seven libraries of mutagenized JAK2V617F cDNA were screened to specifically identify mutations in the predicted drug-binding region that would confer resistance to ruxolitinib, using a BaF3 cell-based assay. We identified five different non-synonymous point mutations that conferred drug resistance. Cells containing mutations had a 9- to 33-fold higher EC(50) for ruxolitinib compared with native JAK2V617F. Our results further indicated that these mutations also conferred cross-resistance to all JAK2 kinase inhibitors tested, including AZD1480, TG101348, lestaurtinib (CEP-701) and CYT-387. Surprisingly, introduction of the 'gatekeeper' mutation (M929I) in JAK2V617F affected only ruxolitinib sensitivity (fourfold increase in EC(50)). These results suggest that JAK2 inhibitors currently in clinical trials may be prone to resistance as a result of point mutations and caution should be exercised when administering these drugs. PMID:21926964

  7. JAK2V617F Allele Burden Measurement in Peripheral Blood of Iranian Patients with Myeloproliferative Neoplasms and Effect of Hydroxyurea on JAK2V617F Allele Burden

    PubMed Central

    Ferdowsi, Shirin; Ghaffari, Seyed H.; Amirizadeh, Naser; Azarkeivan, Azita; Atarodi, Kamran; Faranoush, Mohammad; Toogeh, Gholamreza; Shirkoohi, Reza; Vaezi, Mohammad; Maghsoodlu, Mahtab; Alimoghaddam, Kamran; Ghavamzadeh, Ardeshir; Teimori Naghadeh, Hosein

    2016-01-01

    Background: Myeloproliferative neoplasms (MPNs) are clonal malignant diseases that represent a group of conditions including polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The aim of this study was to evaluate possible correlations between JAK2V617F allele burden and clinicohematologic characteristics in Iranian patients with MPNs. We also aimed at determining the correlation between JAK2V617F allele burden and use of cyto reductive treatment (hydroxyurea). Materials and Methods: We performed ARMS-PCR for all MPNs samples and subsequently performed real-time quantitative polymerase chain reaction (qRT-PCR) for JAK2V617F allele burden measurement using DNA from peripheral blood leukocytes. Results: Two distinct groups of patients were examined at a single time point: group A (n=40; 20 PV, 20 ET) was examined at the time of diagnosis; group B (n=85; 40 PV, 30 ET and 15 PMF) while under treatment with hydroxyurea (HU). The median allele burden of the JAK2 V617F was 72% for PV and 49% for ET patients at the time of diagnosis (p=0.01). For patients with HU treatment, we determined the median JAK2V617F allele burden to be 43%, 40%, and 46.5 % in PV, ET and PMF patients; respectively. HU-treated PV patients had a significant lower %JAK2V617F than PV patients at the time of diagnosis (43% vs. 72%, p=0.005). In ET group, the relationship between the JAK2 V617F allele burden and leukocyte count was significant (p=0.02 and p=0.01 in untreated and treated patients, respectively). Conclusions: Our results showed that patients with PV have a higher JAK2V617F allele burden. Moreover, our study demonstrated that the JAK2V617F allele burden correlates with clinical features in ET group. We also showed hydroxyurea can affect the JAK2V617F allele burden in PV patients. PMID:27252806

  8. The effect of long-term ruxolitinib treatment on JAK2p.V617F allele burden in patients with myelofibrosis

    PubMed Central

    Radich, Jerald; Burn, Timothy C.; Huber, Reid; Paranagama, Dilan; Verstovsek, Srdan

    2015-01-01

    The JAK2 c.1849G>T (p.V617F) mutation leads to constitutive activation of Janus kinase (JAK)2 and contributes to dysregulated JAK signaling in myelofibrosis (MF), polycythemia vera (PV), and essential thrombocythemia (ET). In the phase 3 Controlled Myelofibrosis Study with Oral JAK Inhibitor Treatment-I trial, patients with MF, post-PV MF, or post-ET MF achieved significant reductions in splenomegaly and improvements in symptoms with ruxolitinib vs placebo at week 24. This long-term follow-up analysis was performed to determine whether ruxolitinib therapy altered the JAK2p.V617F allele burden in JAK2p.V617F-positive patients. Assessments at baseline and weeks 24, 48, 120, 144, 168, and 216 demonstrated reductions in allele burden from baseline with ruxolitinib treatment that correlated with spleen volume reductions. Of 236 JAK2p.V617F-positive patients analyzed, 20 achieved partial and 6 achieved complete molecular responses, with median times to response of 22.2 and 27.5 months, respectively. Allele burden reductions were greater in patients with shorter disease duration, which suggests a potential benefit of earlier treatment. This trial was registered at www.clinicaltrials.gov as #NCT00952289. PMID:26228487

  9. Lentiginoses in polycythemia vera patient: Is there a role for JAK2 (V617F) mutation?

    PubMed Central

    Uzuncakmak, Tugba Kevser; Yilmaz, Sarenur; Karadag, Ayse Serap; Akdeniz, Necmettin; Akalin, Ibrahim

    2015-01-01

    Lentiginoses is a clinical feature in which lentigines are remarkably present in large numbers or when they occur in a distinctive distribution on apparently normal skin. This entity may be congenital or acquired and may cover a wide spectrum of diseases ranging from an isolated benign pigmentary disorder to numerous syndromes associated with molecular abnormalities.We present a 59-year-old female patient with multiple lentigines which first emerged 3 y ago concurrently with policytemia vera. The patient had found to be positive for Janus Kinase-2 (JAK-2) mutation. Over activation of the pathway due to JAK-2 V617F mutation is a well-known condition in myeloproliferative diseases but has not been reported in melanocytic disorders. Moreover, several signaling pathways have previously been defined with lentiginosis except JAK-STAT pathway. We want to draw attention to the potential effect of JAK-2 mutation in lentigogenesis with this case report. PMID:26413426

  10. Toward point-of-care testing for JAK2 V617F mutation on a microchip.

    PubMed

    Wang, Hua; Liu, Weiwei; Zhang, Xinju; Xu, Xiao; Kang, Zhihua; Li, Shibao; Wu, Zhiyuan; Yang, Zhiliu; Yao, Bo; Guan, Ming

    2015-09-01

    Molecular genetics now plays a crucial role in diagnosis, the identification of prognostic markers, and monitoring of hematological malignancies. Demonstration of acquired changes such as the JAK2 V617F mutation within myeloproliferative neoplasms (MPN) has quickly moved from a research setting to the diagnostic laboratory. Microfluidics-based assays can reduce the assay time and sample/reagent consumption and enhance the reaction efficiency; however, no current assay has integrated isothermal amplification for point-of-care MPN JAK2 V617F mutation testing with a microchip. In this report, an integrated microchip that performs the whole human blood genomic DNA extraction, loop-mediated isothermal nucleic acid amplification (LAMP) and visual detection for point-of-care genetic mutation testing is demonstrated. This method was validated on DNA from cell lines as well as on whole blood from patients with MPN. The results were compared with those obtained by unlabeled probe melting curve analysis. This chip enjoys a high accuracy, operability, and cost/time efficiency within 1h. All these benefits provide the chip with a potency toward a point-of-care genetic analysis. All samples identified as positive by unlabeled probe melting curve analysis (n=27) proved positive when tested by microchip assay. None of the 30 negative controls gave false positive results. In addition, a patient with polycythemia vera diagnosed as being JAK2 V617F-negative by unlabeled probe melting curve analysis was found to be positive by the microchip. This microchip would possibly be very attractive in developing a point-of-care platform for quick preliminary diagnosis of MPN or other severe illness in resource-limited settings. PMID:26235214

  11. Loss of Ezh2 synergizes with JAK2-V617F in initiating myeloproliferative neoplasms and promoting myelofibrosis.

    PubMed

    Shimizu, Takafumi; Kubovcakova, Lucia; Nienhold, Ronny; Zmajkovic, Jakub; Meyer, Sara C; Hao-Shen, Hui; Geier, Florian; Dirnhofer, Stephan; Guglielmelli, Paola; Vannucchi, Alessandro M; Feenstra, Jelena D Milosevic; Kralovics, Robert; Orkin, Stuart H; Skoda, Radek C

    2016-07-25

    Myeloproliferative neoplasm (MPN) patients frequently show co-occurrence of JAK2-V617F and mutations in epigenetic regulator genes, including EZH2 In this study, we show that JAK2-V617F and loss of Ezh2 in hematopoietic cells contribute synergistically to the development of MPN. The MPN phenotype induced by JAK2-V617F was accentuated in JAK2-V617F;Ezh2(-/-) mice, resulting in very high platelet and neutrophil counts, more advanced myelofibrosis, and reduced survival. These mice also displayed expansion of the stem cell and progenitor cell compartments and a shift of differentiation toward megakaryopoiesis at the expense of erythropoiesis. Single cell limiting dilution transplantation with bone marrow from JAK2-V617F;Ezh2(+/-) mice showed increased reconstitution and MPN disease initiation potential compared with JAK2-V617F alone. RNA sequencing in Ezh2-deficient hematopoietic stem cells (HSCs) and megakaryocytic erythroid progenitors identified highly up-regulated genes, including Lin28b and Hmga2, and chromatin immunoprecipitation (ChIP)-quantitative PCR (qPCR) analysis of their promoters revealed decreased H3K27me3 deposition. Forced expression of Hmga2 resulted in increased chimerism and platelet counts in recipients of retrovirally transduced HSCs. JAK2-V617F-expressing mice treated with an Ezh2 inhibitor showed higher platelet counts than vehicle controls. Our data support the proposed tumor suppressor function of EZH2 in patients with MPN and call for caution when considering using Ezh2 inhibitors in MPN. PMID:27401344

  12. Acute promyelocytic leukemia co-existing with JAK2 V617F positive myeloproliferative neoplasm: a case report

    PubMed Central

    Mamorska-Dyga, Aleksandra; Wu, Jingjing; Khattar, Pallavi; Ronny, Faisal M. H.; Islam, Humayun; Seiter, Karen

    2016-01-01

    The V617F mutation of Janus-associated kinase 2 (JAK2) is commonly seen in myeloproliferative neoplasms (MPN). Transformation of JAK2 positive MPNs to acute leukemia has been reported. We here report a case of acute promyelocytic leukemia which was later confirmed to have a co-existing JAK2 V617F positive MPN. In addition, the patient was found to have FLT3-TKD mutation, which, together with PML/RARa, could play a role in the MPN transformation to APL. PMID:27358900

  13. Allelic Expression Imbalance of JAK2 V617F Mutation in BCR-ABL Negative Myeloproliferative Neoplasms

    PubMed Central

    Kim, Yeo-Kyeoung; Kim, Hyeoung-Joon; Shin, Jong-Hee; Suh, Soon-Pal; Ryang, Dong-Wook; Shin, Myung-Geun

    2013-01-01

    The discovery of a single point mutation in the JAK2 gene in patients with BCR/ABL-negative myeloproliferative neoplasms (MPNs) has not only brought new insights and pathogenesis, but also has made the diagnosis of MPNs much easier. Although, to date, several mechanisms for the contribution of single JAK2V617F point mutation to phenotypic diversity of MPNs have been suggested in multiple studies, but it is not clear how a unique mutation can cause the phenotypic diversity of MPNs. In this study, our results show that allelic expression imbalance of JAK2 V617F mutant frequently occurs and contributes to phenotypic diversity of BCR-ABL-negative MPNs. The proportion of JAK2 V617F mutant allele was significantly augmented in RNA levels as compared with genomic DNA differently by distinct MPNs subtypes. In detail, preferential expression of JAK2 mutant allele showed threefold increase from the cDNA compared with the genomic DNA from patients with essential thrombocythemia and twofold increase in polycythemia vera. In conclusion, allelic expression imbalance of JAK2 V617F mutant proposes another plausible mechanism for the contribution of single JAK2 point mutation to phenotypic diversity of MPNs. PMID:23349688

  14. Distinct effects of concomitant Jak2V617F expression and Tet2 loss in mice promote disease progression in myeloproliferative neoplasms

    PubMed Central

    Chen, Edwin; Schneider, Rebekka K.; Breyfogle, Lawrence J.; Rosen, Emily A.; Poveromo, Luke; Elf, Shannon; Ko, Amy; Brumme, Kristina; Levine, Ross; Ebert, Benjamin L.

    2015-01-01

    Signaling mutations (eg, JAK2V617F) and mutations in genes involved in epigenetic regulation (eg, TET2) are the most common cooccurring classes of mutations in myeloproliferative neoplasms (MPNs). Clinical correlative studies have demonstrated that TET2 mutations are enriched in more advanced phases of MPNs such as myelofibrosis and leukemic transformation, suggesting that they may cooperate with JAK2V617F to promote disease progression. To dissect the effects of concomitant Jak2V617F expression and Tet2 loss within distinct hematopoietic compartments in vivo, we generated Jak2V617F/Tet2 compound mutant genetic mice. We found that the combination of Jak2V617F expression and Tet2 loss resulted in a more florid MPN phenotype than that seen with either allele alone. Concordant with this, we found that Tet2 deletion conferred a strong functional competitive advantage to Jak2V617F-mutant hematopoietic stem cells (HSCs). Transcriptional profiling revealed that both Jak2V617F expression and Tet2 loss were associated with distinct and nonoverlapping gene expression signatures within the HSC compartment. In aggregate, our findings indicate that Tet2 loss drives clonal dominance in HSCs, and Jak2V617F expression causes expansion of downstream precursor cell populations, resulting in disease progression through combinatorial effects. This work provides insight into the functional consequences of JAK2V617F-TET2 comutation in MPNs, particularly as it pertains to HSCs. PMID:25281607

  15. Coexisting JAK2V617F and CALR Exon 9 Mutations in Myeloproliferative Neoplasms - Do They Designate a New Subtype?

    PubMed

    Ahmed, Rifat Zubair; Rashid, Munazza; Ahmed, Nuzhat; Nadeem, Muhammad; Shamsi, Tahir Sultan

    2016-01-01

    The classic BCR-ABL1-negative myeloproliferative neoplasm is an operational sub-category of MPNs that includes polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The JAK2V617F mutation is found in ~ 95% of PV and 50-60% of ET or PMF. In most of the remaining JAK2V617F- negative PV cases, JAK2 exon 12 mutations are present. Amongst the JAK2V617F-negative ET or PMF 5-10% of patients carry mutations in the MPL gene. Prior to 2013, there was no specific molecular marker described in the remaining 30-40% ET and PMF. In December 2013, two research groups independently reported mutations in the gene CALR found specifically in ET (67-71%) and PMF (56-88%) but not in PV. Initially CALR mutations were reported mutually exclusive with JAK2 or MPL. However, co-occurrence of CALR mutations with JAK2V617F has been reported recently in a few MPN cases. Many studies have reported important diagnostic and prognostic significance of CALR mutations in ET and PMF patients and CALR mutation screening has been proposed to be incorporated into WHO diagnostic criteria for MPN. It is suggestive in diagnostic workup of MPN that CALR mutations should not be studied in MPN patients who carry JAK2 or MPL mutations. However JAK2V617F and CALR positive patients might have a different phenotype and clinical course, distinct from the JAK2-positive or CALR-positive subgroups and identification of the true frequency of these patients may be an important factor for defining the prognosis, risk factors and outcomes for MPN patients. PMID:27039813

  16. JAK2V617F allele burden is associated with thrombotic mechanisms activation in polycythemia vera and essential thrombocythemia patients.

    PubMed

    Coucelo, Margarida; Caetano, Gonçalo; Sevivas, Teresa; Almeida Santos, Susana; Fidalgo, Teresa; Bento, Celeste; Fortuna, Manuela; Duarte, Marta; Menezes, Cristina; Ribeiro, M Letícia

    2014-01-01

    The clinical courses of polycythemia vera (PV) and essential thrombocythemia (ET) are characterized by thrombohemorrhagic diathesis. Several groups have suggested an association between JAK2V617F mutation and thrombosis. We hypothesized a relationship between JAK2V617F allele burden, cellular activation parameters, and thrombosis. We evaluated a group of PV and ET patients using flow cytometry: platelet CD62P, CD63, and dense granules, platelet-leukocyte aggregates (PLA), leukocyte CD11b and monocyte tissue factor (TF) expression. All patients had increased baseline platelet CD62P and CD63 expression (p < 0.05); 71 % of PV and 47 % of ET presented with a storage pool disease. Leukocyte CD11b, TF, and PLA were elevated in all patients. TF was higher in PV compared to ET (p < 0.05) and platelet-neutrophil [polymorphonuclear (PMN)] aggregates were increased in ET versus PV (p < 0.05). In ET, PLA were correlated with platelet numbers (p < 0.05). In all patients, JAK2V617F allele burden was directly correlated with monocyte CD11b. Patients with JAK2V617F allele burden >50 % presented higher levels of leukocyte activation. In ET, thrombosis was associated with JAK2V617F mutation (p < 0.05, χ (2) = 5.2), increased monocyte CD11b (p < 0.05) and with platelet-PMN aggregates (p < 0.05). In ET patients, hydroxyurea does not significantly reduce the activation parameters. Our data demonstrate that JAK2V617F allele burden is directly correlated with activation parameters that drive mechanisms that favor thrombosis. PMID:24277659

  17. JAK2V617F allele burden and thrombosis: a direct comparison in essential thrombocythemia and polycythemia vera

    PubMed Central

    Carobbio, Alessandra; Finazzi, Guido; Antonioli, Elisabetta; Guglielmelli, Paola; Vannucchi, Alessandro M.; Dellacasa, Chiara M.; Salmoiraghi, Silvia; Delaini, Federica; Rambaldi, Alessandro; Barbui, Tiziano

    2009-01-01

    OBJECTIVE A direct comparison of the incidence and risk factors of major thrombosis in essential thrombocythemia (ET) and polycythemia vera (PV) according to their respective JAK2V617F allele burden is the object of this study. METHODS We compared the rate (%/pts/yr) of major thrombosis in 867 ET patients (57% JAK2V617F) with that of 415 PV patients (all JAK2V617F) and examined risk factors. RESULTS Patients with ET wild type, ET V617F and PV showed a rate of thrombosis of 1.4, 2.1, and 2.7 %/pt/yr respectively. This latter was found to progressively increase according to the time of diagnosis. The actuarial probability of arterial and venous thrombosis in the first 5 years of diagnosis was roughly similar in the three groups. While, in the subsequent periods, the curves of mutated ET patients diverged from wild type and after 10–15 years, ET mutated arm approached PV. CONCLUSION These findings support the concept of a continuum between ET JAK2 mutated and PV not only in reference to the hematological phenotype but also in terms of vascular events PMID:19559071

  18. Phenotypic variability within the JAK2 V617F-positive MPD: The roles of progenitor cell and neutrophil allele burdens

    PubMed Central

    Moliterno, Alison R.; Williams, Donna M.; Rogers, Ophelia; Isaacs, Mary Ann; Spivak, Jerry L.

    2008-01-01

    (1) Objective The myeloproliferative disorders (MPD), polycythemia vera (PV), essential thrombocytosis (ET) and primary myelofibrosis (PMF) differ phenotypically but share the same JAK2V617F mutation. We examined the relationship of the quantitative JAK2V617F allele burden to MPD disease phenotype among the three MPD classes and within PV. (2) Methods We measured the JAK2V617F allele percentage in genomic DNA from neutrophils, CD34+ cells, and cloned progenitors in 212 JAK2V617F –positive MPD patients and correlated the allele burdens to both disease class and disease features. (3) Results In ET and PV, the mean CD34+ cell JAK2V617F allele burdens were lower than the corresponding neutrophil allele burdens, but these were equivalent in PMF. JAK2WT progenitors were present in ET and PV when the CD34+ JAK2V617F allele burden was lower than the neutrophil allele burden, but not in PV and PMF subjects in whom the CD34+ cell and neutrophil allele burdens were similar. CD34+ cell JAK2V617F clonal dominance, defined as coherence between the CD34+ cell and neutrophil JAK2V617F allele burdens, was present in 24% of ET, 56% of PV and 93% of PMF patients, and was independent of the CD34+ cell JAK2V617F genotype. Clonally-dominant PV patients had significantly longer disease durations, higher white cell counts and larger spleens than nondominant PV patients. (4) Conclusions We conclude that the extent of JAK2V617F CD34+ cell clonal dominance is associated with disease phenotype within the MPD, and in PV, is associated with extramedullary disease, leukocytosis and disease duration. PMID:18723264

  19. Loss of Ezh2 cooperates with Jak2V617F in the development of myelofibrosis in a mouse model of myeloproliferative neoplasm.

    PubMed

    Yang, Yue; Akada, Hajime; Nath, Dipmoy; Hutchison, Robert E; Mohi, Golam

    2016-06-30

    An activating JAK2V617F mutation has been found in ∼50% patients with myelofibrosis (MF). Inactivating mutations in histone methyltransferase enhancer of zeste homolog 2 (EZH2) also have been observed in patients with MF. Interestingly, inactivating EZH2 mutations are often associated with JAK2V617F mutation in MF, although their contributions in the pathogenesis of MF remain elusive. To determine the effects of concomitant loss of EZH2 and JAK2V617F mutation in hematopoiesis, we generated Ezh2-deficient Jak2V617F-expressing mice. Whereas expression of Jak2V617F alone induced a polycythemia vera-like disease, concomitant loss of Ezh2 significantly reduced the red blood cell and hematocrit parameters but increased the platelet counts in Jak2V617F knock-in mice. Flow cytometric analysis showed impairment of erythroid differentiation and expansion of megakaryocytic precursors in Ezh2-deficient Jak2V617F mice. Moreover, loss of Ezh2 enhanced the repopulation capacity of Jak2V617F-expressing hematopoietic stem cells. Histopathologic analysis revealed extensive fibrosis in the bone marrow (BM) and spleen of Ezh2-deleted Jak2V617F mice. Transplantation of BM from Ezh2-deleted Jak2V617F mice into wild-type animals resulted in even faster progression to MF. Gene expression profiling and chromatin immunoprecipitation sequence analysis revealed that S100a8, S100a9, Ifi27l2a, and Hmga2 were transcriptionally derepressed, and the H3K27me3 levels in these gene promoters were significantly reduced on Ezh2 deletion in hematopoietic progenitors of Jak2V617F mice. Furthermore, overexpression of S100a8, S100a9, Ifi27l2a, or Hmga2 significantly increased megakaryocytic colonies in the BM of Jak2V617F mice, indicating a role for these Ezh2 target genes in altered megakaryopoiesis involved in MF. Overall, our results suggest that loss of Ezh2 cooperates with Jak2V617F in the development of MF in Jak2V617F-expressing mice. PMID:27081096

  20. Is JAK2V617F Mutation the Only Factor for Thrombosis in Philadelphia-Negative Chronic Myeloproliferative Neoplasms?

    PubMed

    Uyanik, Mehmet Sevki; Baysal, Mehmet; Pamuk, Gulsum Emel; Maden, Muhammet; Akker, Mustafa; Umit, Elif Gulsum; Demir, Muzaffer; Aydogdu, Erkan

    2016-09-01

    The most common genetic disorder in Philadelphia negative chronic myeloproliferative neoplasms is the JAK2-V617F mutation. In the present study, we aimed to determine risk factors for thrombosis in patients with essential thrombocytosis and polycythemia vera. We screened the medical records of 101 patients. Risk factors which may predict thrombosis were recorded. Venous thrombosis (VT) before diagnosis was significantly higher in JAK2 positive patients. VT after diagnosis was similar in JAK2 positive and negative groups, and was significantly higher in elderly patients. Treatment places importance on the JAK2 mutation under unmodifiable cardiovascular risk factors such as advanced age after diagnosis. PMID:27429517

  1. Melting Curve Analysis after T Allele Enrichment (MelcaTle) as a Highly Sensitive and Reliable Method for Detecting the JAK2V617F Mutation

    PubMed Central

    Morishita, Soji; Takahashi, Kochi; Araki, Marito; Hironaka, Yumi; Sunami, Yoshitaka; Edahiro, Yoko; Tsutsui, Miyuki; Ohsaka, Akimichi; Tsuneda, Satoshi; Komatsu, Norio

    2015-01-01

    Detection of the JAK2V617F mutation is essential for diagnosing patients with classical myeloproliferative neoplasms (MPNs). However, detection of the low-frequency JAK2V617F mutation is a challenging task due to the necessity of discriminating between true-positive and false-positive results. Here, we have developed a highly sensitive and accurate assay for the detection of JAK2V617F and named it melting curve analysis after T allele enrichment (MelcaTle). MelcaTle comprises three steps: 1) two cycles of JAK2V617F allele enrichment by PCR amplification followed by BsaXI digestion, 2) selective amplification of the JAK2V617F allele in the presence of a bridged nucleic acid (BNA) probe, and 3) a melting curve assay using a BODIPY-FL-labeled oligonucleotide. Using this assay, we successfully detected nearly a single copy of the JAK2V617F allele, without false-positive signals, using 10 ng of genomic DNA standard. Furthermore, MelcaTle showed no positive signals in 90 assays screening healthy individuals for JAK2V617F. When applying MelcaTle to 27 patients who were initially classified as JAK2V617F-positive on the basis of allele-specific PCR analysis and were thus suspected as having MPNs, we found that two of the patients were actually JAK2V617F-negative. A more careful clinical data analysis revealed that these two patients had developed transient erythrocytosis of unknown etiology but not polycythemia vera, a subtype of MPNs. These findings indicate that the newly developed MelcaTle assay should markedly improve the diagnosis of JAK2V617F-positive MPNs. PMID:25794279

  2. The Jak2 Inhibitor, G6, Alleviates Jak2-V617F-Mediated Myeloproliferative Neoplasia by Providing Significant Therapeutic Efficacy to the Bone Marrow1

    PubMed Central

    Kirabo, Annet; Park, Sung O; Majumder, Anurima; Gali, Meghanath; Reinhard, Mary K; Wamsley, Heather L; Zhao, Zhizhuang Joe; Cogle, Christopher R; Bisht, Kirpal S; Keserü, György M; Sayeski, Peter P

    2011-01-01

    We recently developed a Janus kinase 2 (Jak2) small-molecule inhibitor called G6 and found that it inhibits Jak2-V617F-mediated pathologic cell growth in vitro, ex vivo, and in vivo. However, its ability to inhibit Jak2-V617F-mediated myeloproliferative neoplasia, with particular emphasis in the bone marrow, has not previously been examined. Here, we investigated the efficacy of G6 in a transgenic mouse model of Jak2-V617F-mediated myeloproliferative neoplasia. We found that G6 provided therapeutic benefit to the peripheral blood as determined by elimination of leukocytosis, thrombocytosis, and erythrocytosis. G6 normalized the pathologically high plasma concentrations of interleukin 6 (IL-6). In the liver, G6 eliminated Jak2-V617F-driven extramedullary hematopoiesis. With respect to the spleen, G6 significantly reduced both the splenomegaly and megakaryocytic hyperplasia. In the critically important bone marrow, G6 normalized the pathologically high levels of phospho-Jak2 and phospho-signal transducer and activator of transcription 5 (STAT5). It significantly reduced the megakaryocytic hyperplasia in the marrow and completely normalized the M/E ratio. Most importantly, G6 selectively reduced the mutant Jak2 burden by 67%on average, with virtual elimination of mutant Jak2 cells in one third of all treated mice. Lastly, clonogenic assays using marrow stem cells from the myeloproliferative neoplasm mice revealed a time-dependent elimination of the clonogenic growth potential of these cells by G6. Collectively, these data indicate that G6 exhibits exceptional efficacy in the peripheral blood, liver, spleen, and, most importantly, in the bone marrow, thereby raising the possibility that this compound may alter the natural history of Jak2-V617F-mediated myeloproliferative neoplasia. PMID:22131881

  3. SH2B3 (LNK) mutations from Myeloproliferative Neoplasms patients have mild loss of function against wild type JAK2 and JAK2 V617F

    PubMed Central

    Koren-Michowitz, Maya; Gery, Sigal; Tabayashi, Takayuki; Lin, Dechen; Alvarez, Rocio; Nagler, Arnon; Koeffler, H. Phillip

    2013-01-01

    Summary Somatic point mutations in the PH domain of SH2B3 (LNK), an adaptor protein that is highly expressed in haematopoietic cells, were recently described in patients with myeloproliferative neoplasms. We studied the effect of these mutations on the JAK2 signalling pathway in cells expressing either wild type JAK2 or the JAK2 V617F mutation. Compared to wild type SH2B3, PH domain mutants have mild loss of function, with no evidence for a dominant-negative effect. Mutants retain binding capacity for JAK2, an established SH2B3 target, as well as for the adaptor proteins 14-3-3 and CBL. Our data suggest that the loss of SH2B3 inhibitory function conferred by the PH domain mutations is mild and may collaborate with JAK2 V617F and CBL mutations in order to promote either the development or the progression of myeloproliferative neoplasms. PMID:23590807

  4. JAK2 Exon 14 Skipping in Patients with Primary Myelofibrosis: A Minor Splice Variant Modulated by the JAK2-V617F Allele Burden

    PubMed Central

    Catarsi, Paolo; Rosti, Vittorio; Morreale, Giacomo; Poletto, Valentina; Villani, Laura; Bertorelli, Roberto; Pedrazzini, Matteo; Zorzetto, Michele; Barosi, Giovanni

    2015-01-01

    Background Primary myelofibrosis (PMF) is an acquired clonal disease of the hematopoietic stem cell compartment, characterized by bone marrow fibrosis, anemia, splenomegaly and extramedullary hematopoiesis. About 60% of patients with PMF harbor a somatic mutation of the JAK2 gene (JAK2-V617F) in their hematopoietic lineage. Recently, a splicing isoform of JAK2, lacking exon 14 (JAK2Δ14) was described in patients affected by myeloproliferative diseases. Materials and Methods By using a specific RT-qPCR method, we measured the ratio between the splicing isoform and the JAK2 full-length transcript (JAK2+14) in granulocytes, isolated from peripheral blood, of forty-four patients with PMF and nine healthy donors. Results We found that JAK2Δ14 was only slightly increased in patients and, at variance with published data, the splicing isoform was also detectable in healthy controls. We also found that, in patients bearing the JAK2-V617F mutation, the percentage of mutated alleles correlated with the observed increase in JAK2Δ14. Homozygosity for the mutation was also associated with a higher level of JAK2+14. Bioinformatic analysis indicates the possibility that the G>T transversion may interfere with the correct splicing of exon 14 by modifying a splicing regulatory sequence. Conclusions Increased levels of JAK2 full-length transcript and a small but significant increase in JAK2 exon 14 skipping, are associated with the JAK2-V617F allele burden in PMF granulocytes. Our data do not confirm a previous claim that the production of the JAK2Δ14 isoform is related to the pathogenesis of PMF. PMID:25617626

  5. Physiological Jak2V617F expression causes a lethal myeloproliferative neoplasm with differential effects on hematopoietic stem and progenitor cells

    PubMed Central

    Mullally, Ann; Lane, Steven W.; Ball, Brian; Megerdichian, Christine; Okabe, Rachel; Al-Shahrour, Fatima; Paktinat, Mahnaz; Haydu, J. Erika; Housman, Elizabeth; Lord, Allegra M.; Wernig, Gerlinde; Kharas, Michael G.; Mercher, Thomas; Kutok, Jeffery L.; Gilliland, D. Gary; Ebert, Benjamin L.

    2010-01-01

    SUMMARY We report a Jak2V617F knock-in mouse myeloproliferative neoplasm (MPN) model resembling human polycythemia vera (PV). The MPN is serially transplantable and we demonstrate that the hematopoietic stem cell (HSC) compartment has the unique capacity for disease initiation but does not have a significant selective competitive advantage over wild type HSCs. In contrast, myeloid progenitor populations are expanded and skewed towards the erythroid lineage, but cannot transplant the disease. Treatment with a JAK2 kinase inhibitor ameliorated the MPN phenotype, but did not eliminate the disease-initiating population. These findings provide insights into the consequences of JAK2 activation on HSC differentiation and function and have the potential to inform therapeutic approaches to JAK2V617F positive MPN. SIGNIFICANCE The JAK2V617F mutation is a promising candidate for molecularly targeted therapy in MPN. Early data from JAK2 inhibitor clinical trials have called into question the capacity of these compounds to alter the natural history of JAK2V617F mediated MPN. Determining the effect of JAK2 inhibitors on the disease-initiating population requires a model in which the JAK2V617F allele is expressed at physiological levels in hematopoietic stem and progenitor cells, as it is in humans. Our model demonstrates that JAK2V617F causes expansion of erythroid progenitors but that only the HSC compartment can initiate disease in a transplanted mouse. We further demonstrate that the HSC compartment, the definitive target for curative therapy of JAK2V617F mediated MPN, is resistant to treatment with a JAK2 inhibitor. PMID:20541703

  6. IRS2 silencing increases apoptosis and potentiates the effects of ruxolitinib in JAK2V617F-positive myeloproliferative neoplasms

    PubMed Central

    de Melo Campos, Paula; Machado-Neto, João A.; Eide, Christopher A.; Savage, Samantha L.; Scopim-Ribeiro, Renata; da Silva Souza Duarte, Adriana; Favaro, Patricia; Lorand-Metze, Irene; Costa, Fernando F.; Tognon, Cristina E.; Druker, Brian J.; Saad, Sara T. Olalla; Traina, Fabiola

    2016-01-01

    The recurrent V617F mutation in JAK2 (JAK2V617F) has emerged as the primary contributor to the pathogenesis of myeloproliferative neoplasms (MPN). However, the lack of complete response in most patients treated with the JAK1/2 inhibitor, ruxolitinib, indicates the need for identifying pathways that cooperate with JAK2. Activated JAK2 was found to be associated with the insulin receptor substrate 2 (IRS2) in non-hematological cells. We identified JAK2/IRS2 binding in JAK2V617F HEL cells, but not in the JAK2WT U937 cell line. In HEL cells, IRS2 silencing decreased STAT5 phosphorylation, reduced cell viability and increased apoptosis; these effects were enhanced when IRS2 silencing was combined with ruxolitinib. In U937 cells, IRS2 silencing neither reduced cell viability nor induced apoptosis. IRS1/2 pharmacological inhibition in primary MPN samples reduced cell viability in JAK2V617F-positive but not JAK2WT specimens; combination with ruxolitinib had additive effects. IRS2 expression was significantly higher in CD34+ cells from essential thrombocythemia patients compared to healthy donors, and in JAK2V617F MPN patients when compared to JAK2WT. Our data indicate that IRS2 is a binding partner of JAK2V617F in MPN. IRS2 contributes to increased cell viability and reduced apoptosis in JAK2-mutated cells. Combined pharmacological inhibition of IRS2 and JAK2 may have a potential clinical application in MPN. PMID:26755644

  7. IRS2 silencing increases apoptosis and potentiates the effects of ruxolitinib in JAK2V617F-positive myeloproliferative neoplasms.

    PubMed

    de Melo Campos, Paula; Machado-Neto, João A; Eide, Christopher A; Savage, Samantha L; Scopim-Ribeiro, Renata; da Silva Souza Duarte, Adriana; Favaro, Patricia; Lorand-Metze, Irene; Costa, Fernando F; Tognon, Cristina E; Druker, Brian J; Olalla Saad, Sara T; Traina, Fabiola

    2016-02-01

    The recurrent V617F mutation in JAK2 (JAK2V617F) has emerged as the primary contributor to the pathogenesis of myeloproliferative neoplasms (MPN). However, the lack of complete response in most patients treated with the JAK1/2 inhibitor, ruxolitinib, indicates the need for identifying pathways that cooperate with JAK2. Activated JAK2 was found to be associated with the insulin receptor substrate 2 (IRS2) in non-hematological cells. We identified JAK2/IRS2 binding in JAK2V617F HEL cells, but not in the JAK2WT U937 cell line. In HEL cells, IRS2 silencing decreased STAT5 phosphorylation, reduced cell viability and increased apoptosis; these effects were enhanced when IRS2 silencing was combined with ruxolitinib. In U937 cells, IRS2 silencing neither reduced cell viability nor induced apoptosis. IRS1/2 pharmacological inhibition in primary MPN samples reduced cell viability in JAK2V617F-positive but not JAK2WT specimens; combination with ruxolitinib had additive effects. IRS2 expression was significantly higher in CD34+ cells from essential thrombocythemia patients compared to healthy donors, and in JAK2V617F MPN patients when compared to JAK2WT. Our data indicate that IRS2 is a binding partner of JAK2V617F in MPN. IRS2 contributes to increased cell viability and reduced apoptosis in JAK2-mutated cells. Combined pharmacological inhibition of IRS2 and JAK2 may have a potential clinical application in MPN. PMID:26755644

  8. A germline JAK2 SNP is associated with predisposition to the development of JAK2V617F-positive myeloproliferative neoplasms

    PubMed Central

    Kilpivaara, Outi; Mukherjee, Semanti; Schram, Alison M; Wadleigh, Martha; Mullally, Ann; Ebert, Benjamin L; Bass, Adam; Marubayashi, Sachie; Heguy, Adriana; Garcia-Manero, Guillermo; Kantarjian, Hagop; Offit, Kenneth; Stone, Richard M; Gilliland, D Gary; Klein, Robert J; Levine, Ross L

    2013-01-01

    Polycythemia vera, essential thrombocythemia and primary myelofibrosis are myeloproliferative neoplasms (MPN) characterized by multilineage clonal hematopoiesis1–5. Given that the identical somatic activating mutation in the JAK2 tyrosine kinase gene (JAK2V617F) is observed in most individuals with polycythemia vera, essential thrombocythemia and primary myelofibrosis6–10, there likely are additional genetic events that contribute to the pathogenesis of these phenotypically distinct disorders. Moreover, family members of individuals with MPN are at higher risk for the development of MPN, consistent with the existence of MPN predisposition loci11. We hypothesized that germline variation contributes to MPN predisposition and phenotypic pleiotropy. Genome-wide analysis identified an allele in the JAK2 locus (rs10974944) that predisposes to the development of JAK2V617F-positive MPN, as well as three previously unknown MPN modifier loci. We found that JAK2V617F is preferentially acquired in cis with the predisposition allele. These data suggest that germline variation is an important contributor to MPN phenotype and predisposition. PMID:19287384

  9. JAK2 p.V617F detection and allele burden measurement in peripheral blood and bone marrow aspirates in patients with myeloproliferative neoplasms

    PubMed Central

    Takahashi, Koichi; Patel, Keyur P.; Kantarjian, Hagop; Luthra, Rajyalakshmi; Pierce, Sherry; Cortes, Jorge

    2013-01-01

    Detection of the JAK2 p.V617F mutation and measurement of its allele burden can be performed using both peripheral blood (PB) and bone marrow (BM) samples from patients with myeloproliferative neoplasms (MPNs). However, the diagnostic accuracy of detecting the JAK2 p.V617F mutation and quantifying its allele burden in PB and BM samples has not been systematically compared. We retrospectively analyzed 388 patients with MPN who had been tested for JAK2 p.V617F allele burden using both PB and BM samples within 3 months of each other. The sensitivity and specificity of detecting JAK2 p.V617F in PB when compared with BM were both 100%. Furthermore, the JAK2 p.V617F allele burden measured in PB and BM were equivalent by linear regression analysis (R2 = 0.991; P < .0001). We therefore conclude that PB is a reliable source for testing for the JAK2 p.V617F mutation and quantifying its allele burden in patients with MPN. PMID:24068492

  10. JAK2V617F leads to intrinsic changes in platelet formation and reactivity in a knock-in mouse model of essential thrombocythemia.

    PubMed

    Hobbs, Catherine M; Manning, Harriet; Bennett, Cavan; Vasquez, Louella; Severin, Sonia; Brain, Lauren; Mazharian, Alexandra; Guerrero, Jose A; Li, Juan; Soranzo, Nicole; Green, Anthony R; Watson, Steve P; Ghevaert, Cedric

    2013-11-28

    The principal morbidity and mortality in patients with essential thrombocythemia (ET) and polycythemia rubra vera (PV) stems from thrombotic events. Most patients with ET/PV harbor a JAK2V617F mutation, but its role in the thrombotic diathesis remains obscure. Platelet function studies in patients are difficult to interpret because of interindividual heterogeneity, reflecting variations in the proportion of platelets derived from the malignant clone, differences in the presence of additional mutations, and the effects of medical treatments. To circumvent these issues, we have studied a JAK2V617F knock-in mouse model of ET in which all megakaryocytes and platelets express JAK2V617F at a physiological level, equivalent to that present in human ET patients. We show that, in addition to increased differentiation, JAK2V617F-positive megakaryocytes display greater migratory ability and proplatelet formation. We demonstrate in a range of assays that platelet reactivity to agonists is enhanced, with a concomitant increase in platelet aggregation in vitro and a reduced duration of bleeding in vivo. These data suggest that JAK2V617F leads to intrinsic changes in both megakaryocyte and platelet biology beyond an increase in cell number. In support of this hypothesis, we identify multiple differentially expressed genes in JAK2V617F megakaryocytes that may underlie the observed biological differences. PMID:24085768

  11. JAK2 p.V617F detection and allele burden measurement in peripheral blood and bone marrow aspirates in patients with myeloproliferative neoplasms.

    PubMed

    Takahashi, Koichi; Patel, Keyur P; Kantarjian, Hagop; Luthra, Rajyalakshmi; Pierce, Sherry; Cortes, Jorge; Verstovsek, Srdan

    2013-11-28

    Detection of the JAK2 p.V617F mutation and measurement of its allele burden can be performed using both peripheral blood (PB) and bone marrow (BM) samples from patients with myeloproliferative neoplasms (MPNs). However, the diagnostic accuracy of detecting the JAK2 p.V617F mutation and quantifying its allele burden in PB and BM samples has not been systematically compared. We retrospectively analyzed 388 patients with MPN who had been tested for JAK2 p.V617F allele burden using both PB and BM samples within 3 months of each other. The sensitivity and specificity of detecting JAK2 p.V617F in PB when compared with BM were both 100%. Furthermore, the JAK2 p.V617F allele burden measured in PB and BM were equivalent by linear regression analysis (R(2) = 0.991; P < .0001). We therefore conclude that PB is a reliable source for testing for the JAK2 p.V617F mutation and quantifying its allele burden in patients with MPN. PMID:24068492

  12. JAK2V617F mediates resistance to DNA damage-induced apoptosis by modulating FOXO3A localization and Bcl-xL deamidation.

    PubMed

    Ahn, J S; Li, J; Chen, E; Kent, D G; Park, H J; Green, A R

    2016-04-28

    The JAK2V617F mutation is found in most patients with a myeloproliferative neoplasm (MPN). This gain-of-function mutation dysregulates cytokine signaling and is associated with increased accumulation of DNA damage, a process likely to drive disease evolution. JAK2V617F inhibits NHE-1 upregulation in response to DNA damage and consequently represses Bcl-xL deamidation and apoptosis, thus giving rise to inappropriate cell survival. However, the mechanism whereby NHE-1 expression is inhibited by JAK2V617F is unknown. In this study, we demonstrate that the accumulation of reactive oxygen species (ROS) in cells expressing JAK2V617F compromises the NHE-1/Bcl-xL deamidation pathway by repressing NHE-1 upregulation in response to DNA damage. In JAK2V617F-positive cells, increased ROS levels results from aberrant PI3K signaling, which decreases nuclear localization of FOXO3A and decreases catalase expression. Furthermore, when compared with autologous control erythroblasts, clonally derived JAK2V617F-positive erythroblasts from MPN patients displayed increased ROS levels and reduced nuclear FOXO3A. However, in hematopoietic stem cells (HSCs), FOXO3A is largely localized within the nuclei despite the presence of JAK2V617F mutation, suggesting that JAK2-FOXO signaling has a different effect on progenitors compared with stem cells. Inactivation of FOXO proteins and elevation of intracellular ROS are characteristics common to many cancers, and hence these findings are likely to be of relevance beyond the MPN field. PMID:26234675

  13. Open-label study of oral CEP-701 (lestaurtinib) in patients with polycythaemia vera or essential thrombocythaemia with JAK2-V617F mutation.

    PubMed

    Hexner, Elizabeth; Roboz, Gail; Hoffman, Ron; Luger, Selina; Mascarenhas, John; Carroll, Martin; Clementi, Regina; Bensen-Kennedy, Debra; Moliterno, Alison

    2014-01-01

    JAK2-V617F is central to the pathogenesis of myeloproliferative neoplasms. We examined whether lestaurtinib decreased JAK2-V617F allele burden and evaluated its clinical benefits and tolerability in patients with polycythaemia vera (PV) and essential thrombocythaemia (ET). This phase 2, open-label, multicentre study was designed to detect ≥15% reduction in JAK2-V617F allele burden in 15% of patients. Eligible patients received lestaurtinib 80 mg twice daily for 18 weeks and could participate in a 1-year extension phase of treatment. Of 39 enrolled patients, 27 (69%) had PV; 12 (31%) had ET. While the pre-specified responder rate of 15% was not met, lestaurtinib modestly reduced JAK2-V617F allele burden and reduced spleen size in a subset of patients. Of 37 patients in the full efficacy analysis, 5 (14%) responded clinically. Every patient had ≥1 adverse event, most commonly gastrointestinal (95%). Fifteen patients (38%) experienced serious adverse events; 23 (59%) withdrew due to adverse events. This is the first reported study of JAK2-inhibitor treatment in patients with PV/ET and highlights both the need for further studies to assess the role of JAK2 inhibition in treatment of PV/ET and the use of JAK2-V617F as a biomarker for response. This trial was registered at www.clinicaltrials.gov as NCT00586651. PMID:24903629

  14. Neurological symptoms in essential thrombocythemia: impact of JAK2V617F mutation and response to therapy.

    PubMed

    Aroldi, Andrea; Cecchetti, Caterina; Colombo, Arianna; Cattaneo, Leonardo; Pioltelli, Pietro Enrico; Pogliani, Enrico Maria; Elli, Elena Maria

    2016-06-01

    Patients with essential thrombocythemia (ET) often suffer from neurological symptoms (NS) not ever resulting from previous thrombotic cerebral events (TCE). We reported NS occurred in 282 patients, in order to identify the factors influencing ET-related NS in the absence of TCE, and the response to therapy. Overall, 116 of 282 patients (41%) presented NS; 101 of them (87%) reported subjective transient and fluctuating NS, without concurrent TCE, which we defined as ET-related NS, by frequency: cephalalgia, chronic paresthesias, dizziness or hypotension, visual disturbances, and tinnitus. In univariate analysis, ET-related NS resulted more frequently in young people (P = 0.017) and in females (P = 0.025). We found a higher prevalence of JAK2V617F mutation in ET-related NS patients (P = 0.021). In multivariate analysis, gender (P = 0.024) and JAK2V617F mutation (P = 0.041) remained significantly associated with the development of ET-related NS, with a risk of about four times higher for JAK2V617F-mutated patients (OR = 3.75). Ninety-seven of 101 patients with ET-related NS received an antiplatelet (AP) agent at the time of NS, whereas only selected high-risk ET-related NS patients were treated with a cytoreductive drug, according to the published guidelines and similarly to patients without NS. We observed that only 32 of 97 (33%) patients with ET-related NS achieved a complete response after AP treatment. Among the 65 non-responder patients, 36 (55.4%) improved NS after the introduction of cytoreductive therapy; therefore, the addition of cytoreductive treatment should be considered in this setting. PMID:26205460

  15. Budd-Chiari Syndrome in a Patient with JAK-2 V617F and Factor V G1691A Mutations

    PubMed Central

    Velarde-Félix, JS; Sanchez-Zazueta, J; Gonzalez-Ibarra, FP; González-Valdez, JA; Salcido-Gómez, B; Gallardo-Angulo, E; Murillo-Llanes, J

    2014-01-01

    ABSTRACT Myeloproliferative neoplasms (MPN) are considered a risk factor for Budd-Chiari syndrome (BCS). The current classification of MPN by the World Health Organization is based on the presence of JAK-2 V617F somatic mutation, which is present in 40 to 60% of patients with BCS. Factor V Leiden mutation is found in around 53% of patients with BCS, representing the most common prothrombotic disease associated with the disorder. We describe a 48-year old woman with a past medical history of deep venous thrombosis in the left upper extremity and one episode in both lower extremities, one episode of transient ischaemic attack and essential thrombocythemia, who presented with jaundice, ascites and hepatomegaly. Budd-Chiari syndrome was diagnosed based on findings on Doppler ultrasound and liver biopsy. Doppler ultrasound showed narrowness of hepatic veins and inferior vena cava in its hepatic portion, diffuse echotexture and portal hypertension. Liver biopsy showed congestion of sinusoids and portal fibrosis. The patient was found to be a heterozygous carrier of Factor V and homozygous wild type G20210A prothrombin mutations. The JAK-2 V617F mutation was detected by allele-specific polymerase chain reaction (AS-PCR). The association of these mutations is rare, with only a few cases reported in the literature. The patient was treated with oral anticoagulation and antiplatelets with good results and proper follow-up. In conclusion, due to the possible coexistence of multiple prothrombotic factors in patients with Budd-Chiari syndrome, the approach to these patients must be focussed on searching for multiple factors and should include the JAK-2 V617F mutation PMID:25781296

  16. BET protein inhibition shows efficacy against JAK2V617F-driven neoplasms.

    PubMed

    Wyspiańska, B S; Bannister, A J; Barbieri, I; Nangalia, J; Godfrey, A; Calero-Nieto, F J; Robson, S; Rioja, I; Li, J; Wiese, M; Cannizzaro, E; Dawson, M A; Huntly, B; Prinjha, R K; Green, A R; Gottgens, B; Kouzarides, T

    2014-01-01

    Small molecule inhibition of the BET family of proteins, which bind acetylated lysines within histones, has been shown to have a marked therapeutic benefit in pre-clinical models of mixed lineage leukemia (MLL) fusion protein-driven leukemias. Here, we report that I-BET151, a highly specific BET family bromodomain inhibitor, leads to growth inhibition in a human erythroleukemic (HEL) cell line as well as in erythroid precursors isolated from polycythemia vera patients. One of the genes most highly downregulated by I-BET151 was LMO2, an important oncogenic regulator of hematopoietic stem cell development and erythropoiesis. We previously reported that LMO2 transcription is dependent upon Janus kinase 2 (JAK2) kinase activity in HEL cells. Here, we show that the transcriptional changes induced by a JAK2 inhibitor (TG101209) and I-BET151 in HEL cells are significantly over-lapping, suggesting a common pathway of action. We generated JAK2 inhibitor resistant HEL cells and showed that these retain sensitivity to I-BET151. These data highlight I-BET151 as a potential alternative treatment against myeloproliferative neoplasms driven by constitutively active JAK2 kinase. PMID:23929215

  17. Characterization of CD34+ hematopoietic progenitor cells in JAK2V617F and CALR-mutated myeloproliferative neoplasms.

    PubMed

    Angona, Anna; Alvarez-Larrán, Alberto; Bellosillo, Beatriz; Longarón, Raquel; Camacho, Laura; Fernández-Rodríguez, M Concepción; Pairet, Silvia; Besses, Carles

    2016-09-01

    Mutations in JAK2 or CALR are observed in patients with myeloproliferative neoplasms (MPN). To get further insight in the dynamics of the mutant clone, we assessed the mutant allele burden in hematopoietic stem cells (HSCs), hematopoietic progenitor cells (HPCs) and granulocytes from 138 patients [51 polycythemia vera (PV), 58 essential thrombocythemia (ET) and 29 myelofibrosis (MF)]. CALR-mutated ET patients harbored a higher mutant load at progenitor level than JAK2V617F-positive ET (HSCs: 39.9% vs 7.5% p<0.001, HPCs: 32.7% vs 7.7% p<0.001). Moreover, HSCs of CALR-mutated ET patients showed a similar mutational load than patients with CALR-mutated MF (39.9% vs 48.2%, p=0.17). Regarding JAK2V617F MPN, PV and ET patients showed a low mutational burden at progenitor level whereas in the myelofibrotic phase the dominance of the mutated clone was a constant finding. In conclusion, the size of the mutated clone in chronic phase MPN is different according to genotype with CALR-mutated ET showing a pattern similar to that observed in MF. PMID:27427771

  18. JAK2 V617F detected in two B-cell chronic lymphocytic leukemia patients without coexisting Philadelphia chromosome-negative myeloproliferative neoplasms: A report of two cases

    PubMed Central

    YANG, YI-NING; QIN, YOU-WEN; WANG, CHUN

    2014-01-01

    The JAK2 V617F mutation has been observed in patients with Philadelphia chromosome-negative myeloproliferative neoplasms (Ph-MPNs), including polycythemia vera, essential thrombocythemia and idiopathic myelofibrosis. This mutation has also been observed in a small number of other myeloid malignancies, such as acute myeloid leukemia, chronic myeloid leukemia and myelodysplastic syndrome. The JAK2 V617F allele has rarely been evaluated in lymphoproliferative disorders. In total, 28 JAK2 V617F-positive B-cell lymphocytic leukemia (B-CLL) patients have previously been reported and all presented with Ph-MPN concomitantly. However, following investigation of the JAK2 V617F mutation in 63 B-CLL patients at the Shanghai First People’s Hospital (Shanghai, China) between January 2008 and December 2012 via allele-specific polymerase chain reaction, two B-CLL patients without a history of Ph-MPN were identified to carry the JAK2 V617F allele. PMID:25013507

  19. JAK2 p.V617F allele burden in myeloproliferative neoplasms one month after allogeneic stem cell transplantation significantly predicts outcome and risk of relapse

    PubMed Central

    Lange, Thoralf; Edelmann, Anja; Siebolts, Udo; Krahl, Rainer; Nehring, Claudia; Jäkel, Nadja; Cross, Michael; Maier, Jacqueline; Niederwieser, Dietger; Wickenhauser, Claudia

    2013-01-01

    The risk profile and prognosis of patients with myelofibrosis is well described by the Dynamic International Prognostic Scoring System risk categorization. Allogeneic stem cell transplantation is considered for intermediate-2/high risk disease. However, indicators of prognosis after transplantation are still lacking. Seventy simultaneously collected pairs of trephine and blood samples were quantified for JAK2 p.V617F allele burden to compare test sensitivity. The course of 30 patients with JAK2 p.V617F-positive myeloproliferative neoplasia was correlated with allele burden after transplantation. Monitoring can be performed on full blood samples as well as trephine biopsies, provided that techniques with ample sensitivity (0.01% to 0.001%) are available. Measurement of allele burden on day 28 after transplantation discriminates two prognostic groups: patients with a JAK2 p.V617F allele burden >1% have a significantly higher risk of relapse of JAK2 p.V617F positive neoplasia (P=0.04) and a poorer overall survival (P<0.01). In conclusion, measurement of JAK2 p.V617F allele burden early after transplantation is an important predictive parameter in monitoring patients following this treatment. As this might provide an important tool in early management of imminent early relapse it will be important to define consensus guidelines for optimal monitoring. PMID:23300178

  20. The Stilbenoid Tyrosine Kinase Inhibitor, G6, Suppresses Jak2-V617F-mediated Human Pathological Cell Growth in Vitro and in Vivo*

    PubMed Central

    Kirabo, Annet; Embury, Jennifer; Kiss, Róbert; Polgár, Tímea; Gali, Meghanath; Majumder, Anurima; Bisht, Kirpal S.; Cogle, Christopher R.; Keserű, György M.; Sayeski, Peter P.

    2011-01-01

    Using structure-based virtual screening, we previously identified a novel stilbenoid inhibitor of Jak2 tyrosine kinase named G6. Here, we hypothesized that G6 suppresses Jak2-V617F-mediated human pathological cell growth in vitro and in vivo. We found that G6 inhibited proliferation of the Jak2-V617F expressing human erythroleukemia (HEL) cell line by promoting marked cell cycle arrest and inducing apoptosis. The G6-dependent increase in apoptosis levels was concomitant with increased caspase 3/7 activity and cleavage of PARP. G6 also selectively inhibited phosphorylation of STAT5, a downstream signaling target of Jak2. Using a mouse model of Jak2-V617F-mediated hyperplasia, we found that G6 significantly decreased the percentage of blast cells in the peripheral blood, reduced splenomegaly, and corrected a pathologically low myeloid to erythroid ratio in the bone marrow by eliminating HEL cell engraftment in this tissue. In addition, drug efficacy correlated with the presence of G6 in the plasma, marrow, and spleen. Collectively, these data demonstrate that the stilbenoid compound, G6, suppresses Jak2-V617F-mediated aberrant cell growth. As such, G6 may be a potential therapeutic lead candidate against Jak2-mediated, human disease. PMID:21127060

  1. Mutation analysis of JAK2V617F, FLT3-ITD, NPM1, and DNMT3A in Chinese patients with myeloproliferative neoplasms.

    PubMed

    Wang, Min; He, Na; Tian, Tian; Liu, Lu; Yu, Shuang; Ma, Daoxin

    2014-01-01

    Since the discovery of JAK2V617F tyrosine kinase-activating mutation, several genes have been found mutated in myeloproliferative neoplasms (MPNs). FLT3-ITD, NPM1, and DNMT3A mutations frequently occurred in AML patients and have been found conferred with myeloproliferative neoplasms in mouse model. Therefore, we sought to search for mutations in JAK2V617F, FLT3-ITD, NPM1, and DNMT3A in 129 cases including 120 classic MPN cases and 9 MDS/MPN cases. JAK2V617F mutation was found in 60% of the 120 classic MPNs. However, none of the patients displayed FLT3-ITD and NPM1 mutations; only 2 patients harbored DNMT3A R882 mutation. Further studies including whole-genome sequence will be conducted to investigate the possible involvement of these genes in MPN. PMID:24895580

  2. Mutation Analysis of JAK2V617F, FLT3-ITD, NPM1, and DNMT3A in Chinese Patients with Myeloproliferative Neoplasms

    PubMed Central

    Wang, Min; He, Na; Tian, Tian; Liu, Lu; Yu, Shuang; Ma, Daoxin

    2014-01-01

    Since the discovery of JAK2V617F tyrosine kinase-activating mutation, several genes have been found mutated in myeloproliferative neoplasms (MPNs). FLT3-ITD, NPM1, and DNMT3A mutations frequently occurred in AML patients and have been found conferred with myeloproliferative neoplasms in mouse model. Therefore, we sought to search for mutations in JAK2V617F, FLT3-ITD, NPM1, and DNMT3A in 129 cases including 120 classic MPN cases and 9 MDS/MPN cases. JAK2V617F mutation was found in 60% of the 120 classic MPNs. However, none of the patients displayed FLT3-ITD and NPM1 mutations; only 2 patients harbored DNMT3A R882 mutation. Further studies including whole-genome sequence will be conducted to investigate the possible involvement of these genes in MPN. PMID:24895580

  3. Disease Burden at the Progenitor Level is a feature of Primary Myelofibrosis: A multivariable analysis of 164 JAK2 V617F-positive Myeloproliferative Neoplasm patients

    PubMed Central

    Stein, Brady L.; Williams, Donna M.; Rogers, Ophelia; Isaacs, Mary Ann; Spivak, Jerry L.; Moliterno, Alison R.

    2010-01-01

    Objective Suppression of normal hematopoiesis by the neoplastic clone (clonal dominance) is a feature of the myeloproliferative neoplasms, but the determinants that predict clonal dominance are unknown. The objective of this study was to identify clinical and laboratory variables that associate with the JAK2 V617F CD34+ progenitor allele burden and clonal dominance, which was defined by congruence of the JAK2 V617F CD34+ progenitor and neutrophil allele burdens. Methods A cross-sectional analysis was performed on 164 consecutive JAK2 V617F-positive patients: 30 with essential thrombocytosis (ET), 100 with polycythemia vera (PV), and 34 with myelofibrosis (MF), including 8 post-ETMF and 3 post-PVMF. The JAK2 V617F CD34+ progenitor and neutrophil allele burdens were measured using an allele-specific, quantitative real-time polymerase chain reaction (PCR) assay. Results After adjusting for genotype, sex, age at diagnosis and disease duration, disease type was the strongest predictor of clonal dominance, with the odds ratio being nearly 61.9 times higher for MF patients when compared to ET patients (p<0.001), and 9.7 times higher when compared to PV patients (p=0.002). Additionally, clonal dominance was associated with a clinical phenotype of an increased spleen size (p=0.006), increased white blood cell count (p=0.009), and lower hemoglobin (p <0.001), even after adjusting for disease type and duration. Conclusion These data indicate that loss of wild type clones at the progenitor level is a feature of MF (PMF, post-ETMF, and post-PVMF), presumably due to expansion of the JAK2 V617F clone and that this characteristic is surprisingly independent of JAK2 V617F homozygosity, suggesting that additional genomic lesions may contribute to this unique molecular process that distinguishes MF from ET and PV. PMID:20888389

  4. JAK2 V617F mutation negative erythrocytosis (or how to more simply perform diagnosis and treat a patient with increased hematocrit)

    PubMed Central

    2011-01-01

    Summary This case report focuses on a 71-year old patient affected by unknown dyspnea and erythrocytosis referred by his general practitioner to our center for specialist advice after a hematological examination had excluded polycythemia vera on grounds of negative test for JAK2 V617F/exon 12 mutation. An accurate clinical history and physical examination accompanied by respiratory function tests resulted in diagnosis of JAK2 V617F mutation negative erythrocytosis, and treatment could be started. The discussion examines decisional algorithms when a polyglobulic patient is referred for diagnosis. PMID:22958502

  5. TERT rs2736100 A>C SNP and JAK2 46/1 haplotype significantly contribute to the occurrence of JAK2 V617F and CALR mutated myeloproliferative neoplasms - a multicentric study on 529 patients.

    PubMed

    Trifa, Adrian P; Bănescu, Claudia; Tevet, Mihaela; Bojan, Anca; Dima, Delia; Urian, Laura; Török-Vistai, Tünde; Popov, Viola M; Zdrenghea, Mihnea; Petrov, Ljubomir; Vasilache, Anca; Murat, Meilin; Georgescu, Daniela; Popescu, Mihaela; Pătrinoiu, Oana; Balea, Marius; Costache, Roxana; Coleș, Elena; Șaguna, Carmen; Berbec, Nicoleta; Vlădăreanu, Ana-Maria; Mihăilă, Romeo G; Bumbea, Horia; Cucuianu, Andrei; Popp, Radu A

    2016-07-01

    Polycythaemia vera (PV), essential thrombocythaemia (ET) and primary myelofibrosis (PMF) represent typical myeloproliferative neoplasms (MPN), usually characterized by specific somatic driver mutations (JAK2 V617F, CALR and MPL). JAK2 46/1 haplotype and telomerase reverse transcriptase gene (TERT) rs2736100 A>C single nucleotide polymorphism (SNP) could represent a large fraction of the genetic predisposition seen in MPN. The rs10974944 C>G SNP, tagging the JAK2 46/1 haplotype, and the TERT rs2736100 A>C SNP were genotyped in 529 MPN patients with known JAK2 V617F, CALR and MPL status, and 433 controls. JAK2 46/1 haplotype strongly correlated to JAK2 V617F-positive MPN and, to a lesser extent, CALR-positive MPN. The TERT rs2736100 A>C SNP strongly correlated to all MPN, regardless of the phenotype (PV, ET or PMF) and major molecular subtype (JAK2 V617F- or CALR-positive). While both variants have a significant contribution, they have nuanced consequences, with JAK2 46/1 predisposing essentially to JAK2 V617F-positive MPN, and TERT rs2736100 A>C having a more general, non-specific effect on all MPN, regardless of phenotype or major molecular subtype. PMID:27061303

  6. Impact of JAK2(V617F) mutation status on treatment response to anagrelide in essential thrombocythemia: an observational, hypothesis-generating study

    PubMed Central

    Cascavilla, Nicola; De Stefano, Valerio; Pane, Fabrizio; Pancrazzi, Alessandro; Iurlo, Alessandra; Gobbi, Marco; Palandri, Francesca; Specchia, Giorgina; Liberati, A Marina; D’Adda, Mariella; Gaidano, Gianluca; Fjerza, Rajmonda; Achenbach, Heinrich; Smith, Jonathan; Wilde, Paul; Vannucchi, Alessandro M

    2015-01-01

    A JAK2(V617F) mutation is found in approximately 55% of patients with essential thrombocythemia (ET), and represents a key World Health Organization diagnostic criterion. This hypothesis-generating study (NCT01352585) explored the impact of JAK2(V617F) mutation status on treatment response to anagrelide in patients with ET who were intolerant/refractory to their current cytoreductive therapy. The primary objective was to compare the proportion of JAK2-positive versus JAK2-negative patients who achieved at least a partial platelet response (≤600×109/L) after anagrelide therapy. Of the 47 patients enrolled, 46 were included in the full analysis set (JAK2-positive, n=22; JAK2-negative, n=24). At 12 months, 35 patients (n=14 and n=21, respectively) had a suitable platelet sample; of these, 74.3% (n=26) achieved at least a partial response. The response rate was higher in JAK2-positive (85.7%, n=12) versus JAK2-negative patients (66.7%, n=14) (odds ratio [OR] 3.00; 95% confidence interval [CI] 0.44, 33.97). By using the last observation carried forward approach in the sensitivity analysis, which considered the imbalance in patients with suitable samples between groups, the overall response rate was 71.7% (n=33/46), with 77.3% (n=17/22) of JAK2-positive and 66.7% (n=16/24) of JAK2-negative patients achieving at least a partial response (OR 1.70; 95% CI 0.39, 8.02). There was no significant change in median allele burden over 12 months in the 12 patients who achieved a response. In conclusion, the overall platelet response rate was high in both JAK2-positive and JAK2-negative patients; however, a larger study would be required to confirm the differences observed according to JAK2(V617F) mutation status. PMID:26028965

  7. Prognostic value of CALR vs. JAK2V617F mutations on splenomegaly, leukemic transformation, thrombosis, and overall survival in patients with primary fibrosis: a meta-analysis.

    PubMed

    Pei, Yu-Qing; Wu, Yue; Wang, Fei; Cui, Wei

    2016-09-01

    The understanding of genetic basis for Philadelphia-negative myeloproliferative neoplasm (MPN) has got much progress in recent years. But the effect of CALR vs. JAK2V617F mutations on the clinical progression and prognosis of primary fibrosis (PMF) remains relatively obscure. In this meta-analysis, we searched Pubmed, Embase, and Web of Science databases for observational studies published until February 2016. Researches that evaluated CALR vs. JAK2V617F mutations on PMF-relevant complications (splenomegaly, leukemic transformation, or thrombosis) and overall survival were selected. Pooled adjust odds ratio (OR), hazard risk (HR), and the corresponding 95 % confidence intervals (CI) were calculated for the CALR-mutant versus the JAK2-mutant categories. Twelve studies involving 435 CALR-mutated and 1116 JAK2V617F PMF patients were analyzed. CALR-mutated patients displayed a lower risk of splenomegaly (OR 0.47, 95 % CI 0.29-0.78) and thrombosis (OR 0.52, 95 % CI 0.29-0.92) but showed no significant difference in the risk of leukemic transformation (OR 0.90, 95 % CI 0.55-1.47) when compared with JAK2-mutated patients. CALR mutation favorably affected overall survival while JAK2 mutation led to poorer survival rate (HR 2.58, 95 % CI 2.08-3.20). This meta-analysis confirmed that a genetic classification of PMF by CALR and JAK2 mutations carried significant prognostic relevance. PMID:27376361

  8. Uncoupling JAK2 V617F activation from cytokine-induced signalling by modulation of JH2 αC helix.

    PubMed

    Leroy, Emilie; Dusa, Alexandra; Colau, Didier; Motamedi, Amir; Cahu, Xavier; Mouton, Céline; Huang, Lily J; Shiau, Andrew K; Constantinescu, Stefan N

    2016-06-01

    The mechanisms by which JAK2 is activated by the prevalent pseudokinase (JH2) V617F mutation in blood cancers remain elusive. Via structure-guided mutagenesis and transcriptional and functional assays, we identify a community of residues from the JH2 helix αC, SH2-JH2 linker and JH1 kinase domain that mediate V617F-induced activation. This circuit is broken by altering the charge of residues along the solvent-exposed face of the JH2 αC, which is predicted to interact with the SH2-JH2 linker and JH1. Mutations that remove negative charges or add positive charges, such as E596A/R, do not alter the JH2 V617F fold, as shown by the crystal structure of JH2 V617F E596A. Instead, they prevent kinase domain activation via modulation of the C-terminal residues of the SH2-JH2 linker. These results suggest strategies for selective V617F JAK2 inhibition, with preservation of wild-type function. PMID:27029346

  9. Uncoupling JAK2 V617F activation from cytokine-induced signalling by modulation of JH2 αC helix

    PubMed Central

    Leroy, Emilie; Dusa, Alexandra; Colau, Didier; Motamedi, Amir; Cahu, Xavier; Mouton, Céline; Huang, Lily J.; Shiau, Andrew K.; Constantinescu, Stefan N.

    2016-01-01

    The mechanisms by which JAK2 is activated by the prevalent pseudokinase (JH2) V617F mutation in blood cancers remain elusive. Via structure-guided mutagenesis and transcriptional and functional assays, we identify a community of residues from the JH2 helix αC, SH2-JH2 linker and JH1 kinase domain that mediate V617F-induced activation. This circuit is broken by altering the charge of residues along the solvent-exposed face of the JH2 αC, which is predicted to interact with the SH2-JH2 linker and JH1. Mutations that remove negative charges or add positive charges, such as E596A/R, do not alter the JH2 V617F fold, as shown by the crystal structure of JH2 V617F E596A. Instead, they prevent kinase domain activation via modulation of the C-terminal residues of the SH2-JH2 linker. These results suggest strategies for selective V617F JAK2 inhibition, with preservation of wild-type function. PMID:27029346

  10. Durable response to lenalidomide in a patient with myelodysplastic syndrome associated with isolated 5q deletion and JAK2 V617F mutation despite discontinuation of treatment

    PubMed Central

    HATZIMICHAEL, ELEFTHERIA; LAGOS, KONSTANTINOS; VASSOU, AMALIA; GOUGOPOULOU, DORA; PAPOUDOU-BAI, ALEXANDRA; BRIASOULIS, EVANGELOS

    2016-01-01

    Loss of a section of the long arm of chromosome 5, as a sole cytogenetic abnormality, characterizes a rare type of myelodysplastic syndrome [del(5q) MDS] and the co-existence of the JAK2 V617F mutation occurs in a small subset of these cases. Patients with isolated del(5q) MDS have a relatively favorable prognosis, with transformation to acute myeloid leukemia occurring in <10%, and their disease responds well to lenalidomide. However the optimal therapeutic approach for patients with del(5q) MDS in coexistence with the JAK2 V617F mutation, which is common to myeloproliferative neoplasms, remains to be elucidated. The present study reports a 77-year-old, transfusion-dependent female patient diagnosed with del(5q) MDS and a concomitant JAK2 V617F mutation. The patient was started on 10 mg lenalidomide daily for 21 days in a 28 day-cycle and within the first month of treatment, the patient became transfusion-independent. The only toxicity observed was grade 3 neutropenia, which was managed with transient treatment discontinuation and dose reduction on restart (5 mg). The patient achieved a complete cytogenetic and molecular response (normal karyotype and undetected JAK2 V617F mutation) within 6 months of treatment. However, 12 months post treatment initiation and while on hematological, cytogenetic and molecular response, the patient was unwilling to continue on treatment and lenalidomide was discontinued. The patient remains in hematological response, which lasts for >5 years despite treatment discontinuation. The present case highlights the coexistence of the JAK2 V617F mutation in del(5q) MDS and suggests that lenalidomide treatment is beneficial and effective for these patients, leading to complete hematological, cytogenetic and molecular response. Hematological response may be sustained for long periods of time, even following the discontinuation of the treatment. PMID:27330758

  11. Pyoderma gangrenosum in association with Janus kinase 2 (JAK2V617F) mutation.

    PubMed

    Palanivel, J A; Macbeth, A E; Levell, N J

    2013-01-01

    Pyoderma gangrenosum (PG) commonly occurs in association with various haematological and inflammatory disorders. We report a new association, a Janus kinase (JAK)2 mutation, in a 63-year-old patient with PG. We hypothesise that PG occurs by direct activation of JAK along with signal transducers and activators of transcription (STAT), a common mechanism involved in the pathogenesis of inflammatory and haematological diseases. PMID:22607468

  12. Self-Renewal of Single Mouse Hematopoietic Stem Cells Is Reduced by JAK2V617F Without Compromising Progenitor Cell Expansion

    PubMed Central

    Kent, David G.; Li, Juan; Tanna, Hinal; Fink, Juergen; Kirschner, Kristina; Pask, Dean C.; Silber, Yvonne; Hamilton, Tina L.; Sneade, Rachel; Simons, Benjamin D.; Green, Anthony R.

    2013-01-01

    Recent descriptions of significant heterogeneity in normal stem cells and cancers have altered our understanding of tumorigenesis, emphasizing the need to understand how single stem cells are subverted to cause tumors. Human myeloproliferative neoplasms (MPNs) are thought to reflect transformation of a hematopoietic stem cell (HSC) and the majority harbor an acquired V617F mutation in the JAK2 tyrosine kinase, making them a paradigm for studying the early stages of tumor establishment and progression. The consequences of activating tyrosine kinase mutations for stem and progenitor cell behavior are unclear. In this article, we identify a distinct cellular mechanism operative in stem cells. By using conditional knock-in mice, we show that the HSC defect resulting from expression of heterozygous human JAK2V617F is both quantitative (reduced HSC numbers) and qualitative (lineage biases and reduced self-renewal per HSC). The defect is intrinsic to individual HSCs and their progeny are skewed toward proliferation and differentiation as evidenced by single cell and transplantation assays. Aged JAK2V617F show a more pronounced defect as assessed by transplantation, but mice that transform reacquire competitive self-renewal ability. Quantitative analysis of HSC-derived clones was used to model the fate choices of normal and JAK2-mutant HSCs and indicates that JAK2V617F reduces self-renewal of individual HSCs but leaves progenitor expansion intact. This conclusion is supported by paired daughter cell analyses, which indicate that JAK2-mutant HSCs more often give rise to two differentiated daughter cells. Together these data suggest that acquisition of JAK2V617F alone is insufficient for clonal expansion and disease progression and causes eventual HSC exhaustion. Moreover, our results show that clonal expansion of progenitor cells provides a window in which collaborating mutations can accumulate to drive disease progression. Characterizing the mechanism(s) of JAK2V617F

  13. Molecular genetic tests for JAK2V617F, Exon12_JAK2 and MPLW515K/L are highly informative in the evaluation of patients suspected to have BCR-ABL1-negative myeloproliferative neoplasms

    PubMed Central

    dos Santos, Marcos Tadeu; Mitne-Neto, Miguel; Miyashiro, Kozue; Chauffaille, Maria de Lourdes L Ferrari; Rizzatti, Edgar Gil

    2014-01-01

    Polycythaemia vera (PV), essential thrombocythemia (ET) and idiopathic myelofibrosis (MF), are the most common myeloproliferative neoplasms (MPN) in patients without the BCR-ABL1 gene rearrangement. They are caused by clonal expansion of haematopoietic stem cells and share, as a diagnostic criterion, the identification of JAK2V617F mutation. Classically, when other clinical criteria are present, a JAK2V617F negative case requires the analysis of Exon12_JAK2 for the diagnosis of PV, and of MPL515K/L mutations for the diagnosis of ET and MF. Here, we evaluated 78 samples from Brazilian patients suspected to have MPN, without stratification for PV, ET or MF. We found that 28 (35.9%) are JAK2V617F carriers; from the 50 remaining samples, one (2%) showed an Exon12_JAK2 mutation, and another (2%) was positive for MPLW515L mutation. In summary, the investigation of JAK2V617F, Exon12_JAK2 and MPLW515K/L was relevant for the diagnosis of 38.4% of patients suspected to have BCR-ABL1-negative MPN, suggesting that molecular genetic tests are useful for a quick and unequivocal diagnosis of MPN. PMID:23986553

  14. Molecular genetic tests for JAK2V617F, Exon12_JAK2 and MPLW515K/L are highly informative in the evaluation of patients suspected to have BCR-ABL1-negative myeloproliferative neoplasms.

    PubMed

    dos Santos, Marcos Tadeu; Mitne-Neto, Miguel; Miyashiro, Kozue; Chauffaille, Maria de Lourdes L Ferrari; Rizzatti, Edgar Gil

    2014-02-01

    Polycythaemia vera (PV), essential thrombocythemia (ET) and idiopathic myelofibrosis (MF), are the most common myeloproliferative neoplasms (MPN) in patients without the BCR-ABL1 gene rearrangement. They are caused by clonal expansion of haematopoietic stem cells and share, as a diagnostic criterion, the identification of JAK2V617F mutation. Classically, when other clinical criteria are present, a JAK2V617F negative case requires the analysis of Exon12_JAK2 for the diagnosis of PV, and of MPL515K/L mutations for the diagnosis of ET and MF. Here, we evaluated 78 samples from Brazilian patients suspected to have MPN, without stratification for PV, ET or MF. We found that 28 (35.9%) are JAK2V617F carriers; from the 50 remaining samples, one (2%) showed an Exon12_JAK2 mutation, and another (2%) was positive for MPLW515L mutation. In summary, the investigation of JAK2V617F, Exon12_JAK2 and MPLW515K/L was relevant for the diagnosis of 38.4% of patients suspected to have BCR-ABL1-negative MPN, suggesting that molecular genetic tests are useful for a quick and unequivocal diagnosis of MPN. PMID:23986553

  15. IDH mutations in primary myelofibrosis predict leukemic transformation and shortened survival: clinical evidence for leukemogenic collaboration with JAK2V617F.

    PubMed

    Tefferi, A; Jimma, T; Sulai, N H; Lasho, T L; Finke, C M; Knudson, R A; McClure, R F; Pardanani, A

    2012-03-01

    Isocitrate dehydrogenase (IDH) mutations are frequent in blast-phase myeloproliferative neoplasms and might therefore contribute to leukemic transformation. We examined this possibility in 301 consecutive patients with chronic-phase primary myelofibrosis (PMF). The mutant IDH was detected in 12 patients (4%): 7 IDH2 (5 R140Q, 1 R140W and 1 R172G) and 5 IDH1 (3 R132S and 2 R132C). In all, 6 (50%) of the 12 IDH-mutated patients also expressed JAK2V617F. Overall, 18 (6%) patients displayed only MPL and 164 (54.3%) only JAK2 mutations. Multivariable analysis that accounted for conventional risk factors disclosed inferior overall survival (OS; P=0.03) and leukemia-free survival (LFS; P=0.003) in IDH-mutated patients: OS hazard ratio (HR) was 0.39 (95% confidence interval (95% CI) 0.2-0.75), 0.50 (95% CI 0.27-0.95) and 0.53 (95% CI 0.23-1.2) for patients with no, JAK2 or MPL mutations, respectively. Further analysis disclosed a more pronounced effect for the mutant IDH on OS and LFS in the presence (P=0.0002 and P<0.0001, respectively) as opposed to the absence (P=0.34 and P=0.64) of concomitant JAK2V617F. Analysis of paired samples obtained during chronic- and blast-phase disease revealed the presence of both IDH and JAK2 mutations at both time points. Our observations suggest that IDH mutations in PMF are independent predictors of leukemic transformation and raise the possibility of leukemogenic collaboration with JAK2V617F. PMID:21912393

  16. A highly specific q-RT-PCR assay to address the relevance of the JAK2WT and JAK2V617F expression levels and control genes in Ph-negative myeloproliferative neoplasms.

    PubMed

    Fantasia, Francesca; Di Capua, Emma Nora; Cenfra, Natalia; Pessina, Gloria; Mecarocci, Sergio; Rago, Angela; Cotroneo, Ettore; Busanello, Anna; Equitani, Francesco; Lo-Coco, Francesco; Nervi, Clara; Cimino, Giuseppe

    2014-04-01

    In Ph- myeloproliferative neoplasms, the quantification of the JAK2V617F transcripts may provide some advantages over the DNA allele burden determination. We developed a q-RT-PCR to assess the JAK2WT and JAK2V617F mRNA expression in 105 cases (23 donors, 13 secondary polycythemia, 22 polycythemia vera (PV), 38 essential thrombocythemia (ET), and 9 primary myelofibrosis (PMF)). Compared with the standard allele-specific oligonucleotide (ASO)-PCR technique, our assay showed a 100 % concordance rate detecting the JAK2V617F mutation in 22/22 PV (100 %), 29/38 (76.3 %) ET, and 5/9 (55.5 %) PMF cases, respectively. The sensitivity of the assay was 0.01 %. Comparing DNA and RNA samples, we found that the JAK2V617F mutational ratios were significantly higher at the RNA level both in PV (p = 0.005) and ET (p = 0.001) samples. In PV patients, JAK2WT expression levels positively correlated with the platelets (PLTs) (p = 0.003) whereas a trend to negative correlation was observed with the Hb levels (p = 0.051). JAK2V617F-positive cases showed the lowest JAK2WT and ABL1 mRNA expression levels. In all the samples, the expression pattern of beta-glucoronidase (GUSB) was more homogeneous than that of ABL1 or β2 microglobulin (B2M). Using GUSB as normalizator gene, a significant increase of the JAK2V617F mRNA levels was seen in two ET patients at time of progression to PV. In conclusion, the proposed q-RT-PCR is a sensitive and accurate method to quantify the JAK2 mutational status that can also show clinical correlations suggesting the impact of the residual amount of the JAK2WT allele on the Ph- MPN disease phenotype. Our observations also preclude the use of ABL1 as a housekeeping gene for these neoplasms. PMID:24173087

  17. Stat5 Exerts Distinct, Vital Functions in the Cytoplasm and Nucleus of Bcr-Abl+ K562 and Jak2(V617F)+ HEL Leukemia Cells.

    PubMed

    Weber, Axel; Borghouts, Corina; Brendel, Christian; Moriggl, Richard; Delis, Natalia; Brill, Boris; Vafaizadeh, Vida; Groner, Bernd

    2015-01-01

    Signal transducers and activators of transcription (Stats) play central roles in the conversion of extracellular signals, e.g., cytokines, hormones and growth factors, into tissue and cell type specific gene expression patterns. In normal cells, their signaling potential is strictly limited in extent and duration. The persistent activation of Stat3 or Stat5 is found in many human tumor cells and contributes to their growth and survival. Stat5 activation plays a pivotal role in nearly all hematological malignancies and occurs downstream of oncogenic kinases, e.g., Bcr-Abl in chronic myeloid leukemias (CML) and Jak2(V617F) in other myeloproliferative diseases (MPD). We defined the mechanisms through which Stat5 affects growth and survival of K562 cells, representative of Bcr-Abl positive CML, and HEL cells, representative for Jak2(V617F) positive acute erythroid leukemia. In our experiments we suppressed the protein expression levels of Stat5a and Stat5b through shRNA mediated downregulation and demonstrated the dependence of cell survival on the presence of Stat5. Alternatively, we interfered with the functional capacities of the Stat5 protein through the interaction with a Stat5 specific peptide ligand. This ligand is a Stat5 specific peptide aptamer construct which comprises a 12mer peptide integrated into a modified thioredoxin scaffold, S5-DBD-PA. The peptide sequence specifically recognizes the DNA binding domain (DBD) of Stat5. Complex formation of S5-DBD-PA with Stat5 causes a strong reduction of P-Stat5 in the nuclear fraction of Bcr-Abl-transformed K562 cells and a suppression of Stat5 target genes. Distinct Stat5 mediated survival mechanisms were detected in K562 and Jak2(V617F)-transformed HEL cells. Stat5 is activated in the nuclear and cytosolic compartments of K562 cells and the S5-DBD-PA inhibitor most likely affects the viability of Bcr-Abl+ K562 cells through the inhibition of canonical Stat5 induced target gene transcription. In HEL cells, Stat5 is

  18. Stat5 Exerts Distinct, Vital Functions in the Cytoplasm and Nucleus of Bcr-Abl+ K562 and Jak2(V617F)+ HEL Leukemia Cells

    PubMed Central

    Weber, Axel; Borghouts, Corina; Brendel, Christian; Moriggl, Richard; Delis, Natalia; Brill, Boris; Vafaizadeh, Vida; Groner, Bernd

    2015-01-01

    Signal transducers and activators of transcription (Stats) play central roles in the conversion of extracellular signals, e.g., cytokines, hormones and growth factors, into tissue and cell type specific gene expression patterns. In normal cells, their signaling potential is strictly limited in extent and duration. The persistent activation of Stat3 or Stat5 is found in many human tumor cells and contributes to their growth and survival. Stat5 activation plays a pivotal role in nearly all hematological malignancies and occurs downstream of oncogenic kinases, e.g., Bcr-Abl in chronic myeloid leukemias (CML) and Jak2(V617F) in other myeloproliferative diseases (MPD). We defined the mechanisms through which Stat5 affects growth and survival of K562 cells, representative of Bcr-Abl positive CML, and HEL cells, representative for Jak2(V617F) positive acute erythroid leukemia. In our experiments we suppressed the protein expression levels of Stat5a and Stat5b through shRNA mediated downregulation and demonstrated the dependence of cell survival on the presence of Stat5. Alternatively, we interfered with the functional capacities of the Stat5 protein through the interaction with a Stat5 specific peptide ligand. This ligand is a Stat5 specific peptide aptamer construct which comprises a 12mer peptide integrated into a modified thioredoxin scaffold, S5-DBD-PA. The peptide sequence specifically recognizes the DNA binding domain (DBD) of Stat5. Complex formation of S5-DBD-PA with Stat5 causes a strong reduction of P-Stat5 in the nuclear fraction of Bcr-Abl-transformed K562 cells and a suppression of Stat5 target genes. Distinct Stat5 mediated survival mechanisms were detected in K562 and Jak2(V617F)-transformed HEL cells. Stat5 is activated in the nuclear and cytosolic compartments of K562 cells and the S5-DBD-PA inhibitor most likely affects the viability of Bcr-Abl+ K562 cells through the inhibition of canonical Stat5 induced target gene transcription. In HEL cells, Stat5 is

  19. Gene expression profiling of loss of TET2 and/or JAK2V617F mutant hematopoietic stem cells from mouse models of myeloproliferative neoplasms

    PubMed Central

    Kameda, Takuro; Shide, Kotaro; Yamaji, Takumi; Kamiunten, Ayako; Sekine, Masaaki; Hidaka, Tomonori; Kubuki, Yoko; Sashida, Goro; Aoyama, Kazumasa; Yoshimitsu, Makoto; Abe, Hiroo; Miike, Tadashi; Iwakiri, Hisayoshi; Tahara, Yoshihiro; Yamamoto, Shojiro; Hasuike, Satoru; Nagata, Kenji; Iwama, Atsushi; Kitanaka, Akira; Shimoda, Kazuya

    2015-01-01

    Myeloproliferative neoplasms (MPNs) are clinically characterized by the chronic overproduction of differentiated peripheral blood cells and the gradual expansion of malignant intramedullary/extramedullary hematopoiesis. In MPNs mutations in JAK2 MPL or CALR are detected mutually exclusive in more than 90% of cases [1], [2]. Mutations in them lead to the abnormal activation of JAK/STAT signaling and the autonomous growth of differentiated cells therefore they are considered as “driver” gene mutations. In addition to the above driver gene mutations mutations in epigenetic regulators such as TET2 DNMT3A ASXL1 EZH2 or IDH1/2 are detected in about 5%–30% of cases respectively [3]. Mutations in TET2 DNMT3A EZH2 or IDH1/2 commonly confer the increased self-renewal capacity on normal hematopoietic stem cells (HSCs) but they do not lead to the autonomous growth of differentiated cells and only exhibit subtle clinical phenotypes [[4], [6], [7], [8],5]. It was unclear how mutations in such epigenetic regulators influenced abnormal HSCs with driver gene mutations how they influenced the disease phenotype or whether a single driver gene mutation was sufficient for the initiation of human MPNs. Therefore we focused on JAK2V617F and loss of TET2—the former as a representative of driver gene mutations and the latter as a representative of mutations in epigenetic regulators—and examined the influence of single or double mutations on HSCs (Lineage−Sca-1+c-Kit+ cells (LSKs)) by functional analyses and microarray whole-genome expression analyses [9]. Gene expression profiling showed that the HSC fingerprint genes [10] was statistically equally enriched in TET2-knockdown-LSKs but negatively enriched in JAK2V617F–LSKs compared to that in wild-type-LSKs. Double-mutant-LSKs showed the same tendency as JAK2V617F–LSKs in terms of their HSC fingerprint genes but the expression of individual genes differed between the two groups. Among 245 HSC fingerprint genes 100 were more

  20. Concomitant Myeloproliferative and Lymphoid Neoplasms in Two Patients Positive for JAK2 V617F Mutation. Case Report and Literature Review.

    PubMed

    Trifa, Adrian P; Cucuianu, Andrei; Popp, Radu A; Paţiu, Mariana; Selicean, Cristina; Militaru, Mariela S; Pop, Ioan V

    2014-09-01

    The coexistence of both myeloproliferative and lymphoproliferative neoplasms in the same patient is an uncommon finding. We report two patients who presented such an association. The first patient was initially diagnosed with essential thrombocythemia, developing a clinical and haematological picture consistent with chronic lymphocytic leukaemia several years afterwards. The second patient was diagnosed concomitantly with polycythaemia vera and chronic lymphocytic leukaemia. Both patients were positive for the JAK2 V617F mutation. In the first patient the chronic lymphocytic leukaemia was asymptomatic, stage A, and did not require any additional treatment, while the second patient presented with generalized large lymphadenopathy (stage B) and chronic lymphocytic leukaemia-related symptoms, requiring chronic lymphocytic leukaemia-directed treatment. It is unclear whether there is a pathogenetic link between the myeloproliferative and lymphoproliferative diseases encountered in these patients, both being probably the result of random mutations occurring in distinct initiating cells. However, given the higher risk of lymphoproliferative neoplasms development in myeloproliferative neoplasms patients reported in larger studies, the genomic instability characteristic to myeloproliferative neoplasms may play a role in subsequent lymphoproliferative neoplasms occurrence. PMID:25332555

  1. The European Clinical, Molecular, and Pathological (ECMP) Criteria and the 2007/2008 Revisions of the World Health Organization for the Diagnosis, Classification, and Staging of Prefibrotic Myeloproliferative Neoplasms Carrying the JAK2V617F Mutation

    PubMed Central

    Michiels, Jan Jacques; Kate, Fibo Ten; Lam, King H.; Schroyens, Wilfried; Berneman, Zwi; De Raeve, Hendrik

    2014-01-01

    Objective: The prefibrotic stages of JAK2V617F essential thrombocythemia (ET) and JAK2V617F polycythemia vera (PV) can easily be diagnosed clinically without use of bone marrow biopsy histology. We assessed the 2008 WHO and European Clinical, Molecular, and Pathological (ECMP) criteria for the diagnosis of myeloproliferative neoplasms (MPNs). Materials and Methods: Studied patients included 6 JAK2V617F-mutated ET and 4 PV patients during long-term follow-up in view of critical analysis of the literature. The bone marrow biopsy histology diagnosis without use of clinical data was PV in 7 (of which 3 were cases of ET with features of early prodromal PV) and classical PV in 4. Results: The ECMP criteria distinguish 3 sequential phenotypes (1, 2, or 3) of JAK2V617F-mutated ET: normocellular ET-1; ET-2, with clinical and bone marrow features of PV (prodromal PV), and ET-3, with hypercellular dysmorphic megakaryocytic and granulocytic myeloproliferation (ET.MGM). The 3 patients with ET-2 or prodromal PV developed slow-onset PV after a follow-up of about 10 years. Bone marrow biopsy histology differentiates MPNs of various molecular etiologies from all variants of primary or secondary erythrocytoses and thrombocytoses with sensitivity and specificity of near 100%. Conclusion: Normocellular ET (WHO-ET), prodromal PV, and classical PV show overlapping bone marrow biopsy histology features with similar pleomorphic clustered megakaryocytes in the prefibrotic stages of JAK2V617F mutated MPN. Erythrocytes are below 6x1012/L in normocellular ET and prodromal PV, and are consistently above 6x1012/L in classical PV and at the time of transition from prodromal PV into classical PV. Red cell count at a cut-off level of 6x1012/L separates ET from PV and obviates the need for red cell mass measurement when bone marrow histology and JAK2V617F mutation screening are included in the diagnostic work-up of MPNs.

  2. Polycythemia Vera: An Appraisal of the Biology and Management 10 Years After the Discovery of JAK2 V617F.

    PubMed

    Stein, Brady L; Oh, Stephen T; Berenzon, Dmitriy; Hobbs, Gabriela S; Kremyanskaya, Marina; Rampal, Raajit K; Abboud, Camille N; Adler, Kenneth; Heaney, Mark L; Jabbour, Elias J; Komrokji, Rami S; Moliterno, Alison R; Ritchie, Ellen K; Rice, Lawrence; Mascarenhas, John; Hoffman, Ronald

    2015-11-20

    Polycythemia vera (PV) is a chronic myeloproliferative neoplasm that is associated with a substantial symptom burden, thrombohemorrhagic complications, and impaired survival. A decade after the seminal discovery of an activating mutation in the tyrosine kinase JAK2 in nearly all patients with PV, new treatment options are finally beginning to emerge, necessitating a critical reappraisal of the underlying pathogenesis and therapeutic modalities available for PV. Herein, we comprehensively review clinical aspects of PV including diagnostic considerations, natural history, and risk factors for thrombosis. We summarize recent studies delineating the genetic basis of PV, including their implications for evolution to myelofibrosis and secondary acute myeloid leukemia. We assess the quality of evidence to support the use of currently available therapies, including aspirin, phlebotomy, hydroxyurea, and interferon. We analyze recent studies evaluating the safety and efficacy of JAK inhibitors, such as ruxolitinib, and evaluate their role in the context of other available therapies for PV. This review provides a framework for practicing hematologists and oncologists to make rational treatment decisions for patients with PV. PMID:26324368

  3. Polycythemia Vera: An Appraisal of the Biology and Management 10 Years After the Discovery of JAK2 V617F

    PubMed Central

    Stein, Brady L.; Oh, Stephen T.; Berenzon, Dmitriy; Hobbs, Gabriela S.; Kremyanskaya, Marina; Rampal, Raajit K.; Abboud, Camille N.; Adler, Kenneth; Heaney, Mark L.; Jabbour, Elias J.; Komrokji, Rami S.; Moliterno, Alison R.; Ritchie, Ellen K.; Rice, Lawrence; Mascarenhas, John; Hoffman, Ronald

    2015-01-01

    Polycythemia vera (PV) is a chronic myeloproliferative neoplasm that is associated with a substantial symptom burden, thrombohemorrhagic complications, and impaired survival. A decade after the seminal discovery of an activating mutation in the tyrosine kinase JAK2 in nearly all patients with PV, new treatment options are finally beginning to emerge, necessitating a critical reappraisal of the underlying pathogenesis and therapeutic modalities available for PV. Herein, we comprehensively review clinical aspects of PV including diagnostic considerations, natural history, and risk factors for thrombosis. We summarize recent studies delineating the genetic basis of PV, including their implications for evolution to myelofibrosis and secondary acute myeloid leukemia. We assess the quality of evidence to support the use of currently available therapies, including aspirin, phlebotomy, hydroxyurea, and interferon. We analyze recent studies evaluating the safety and efficacy of JAK inhibitors, such as ruxolitinib, and evaluate their role in the context of other available therapies for PV. This review provides a framework for practicing hematologists and oncologists to make rational treatment decisions for patients with PV. PMID:26324368

  4. Concomitant essential thrombocythemia with JAK2 V617F mutation in a patient with chronic myeloid leukemia with major molecular response with imatinib and long-term follow-up

    PubMed Central

    PAGNANO, KATIA BORGIA BARBOSA; DELAMAIN, MÁRCIA TORRESAN; MAGNUS, MARIANA MUNARI; VASSALLO, JOSÉ; DE SOUZA, CARMINO ANTONIO; DE ALMEIDA, DAIANE; LORAND-METZE, IRENE

    2016-01-01

    The association of chronic myeloid leukemia (CML) with other myeloproliferative neoplasms (MPNs), in particular with the V617F mutation in the Janus kinase 2 (JAK2) gene, is very uncommon, and there are only a few cases reported in the literature. In the present study, the case of a 73-year-old man with CML and persistent thrombocytosis, is reported. The patient achieved a complete cytogenetic response and major molecular response (MR) with imatinib. The patient presented JAK2 V617F mutation, and bone marrow morphology was consistent with essential thrombocythemia. The patient was treated with imatinib and hydroxyurea to control the platelet count, and maintains complete MR with imatinib upon 10 years of follow-up. Although rare, the association of breakpoint cluster region-Abelson rearrangement and JAK2 V617F mutation should be investigated in patients with MPN, since both genetic anomalies may be present at diagnosis or may emerge during treatment, and require different therapeutic approaches. PMID:27347169

  5. Successful liver transplantation in a patient with splanchnic vein thrombosis and pulmonary embolism due to polycythemia vera with Jak2v617f mutation and heparin-induced thrombocytopenia.

    PubMed

    Biagioni, Emanuela; Pedrazzi, Paola; Marietta, Marco; Di Benedetto, Fabrizio; Villa, Erica; Luppi, Mario; Girardis, Massimo

    2013-10-01

    Heparin-induced thrombocytopenia (HIT) is a rare complication of heparin treatment resulting in a severe acquired thrombophilic condition with an associated mortality of about 10 %. We report the first case of successful urgent liver transplantation (LT) in a patient with end-stage liver disease due to a Budd-Chiari syndrome, portal vein thrombosis and pulmonary embolism due to acquired thrombophilia associated to polycythemia vera carrying JAK2V617F gene mutation and HIT in the acute phase. Lepirudin was used to provide anticoagulation in the LT perioperative period that was performed without haemorrhagic and thrombotic complications despite the donor received heparin during liver explantation. PMID:23277116

  6. A TET2 rs3733609 C/T genotype is associated with predisposition to the myeloproliferative neoplasms harboring JAK2V617F and confers a proliferative potential on erythroid lineages.

    PubMed

    Shen, Xiao-Hui; Sun, Nan-Nan; Yin, Ya-Fei; Liu, Su-Fang; Liu, Xiao-Liu; Peng, Hong-Ling; Dai, Chong-Wen; Xu, Yun-Xiao; Deng, Ming-Yang; Luo, Yun-Ya; Zheng, Wen-Li; Zhang, Guang-Sen

    2016-02-23

    Common germline single-nucleotide polymorphisms (SNPs) at JAK2 locus have been associated with Myeloproliferative neoplasms (MPN). And, the germline sequence variant rs2736100 C in TERT is related to risk of MPN, suggesting a complex association between SNPs and the pathogenesis of MPN. Our previous study (unpublished data) showed that there was a high frequency distribution in rs3733609 C/T genotype at Ten-Eleven Translocation 2 (TET2) locus in one Chinese familial primary myelofibrosis. In the present study, we evaluate the role and clinical significance of rs3733609 C/T genotype in JAK2V617F-positive sporadic MPN (n = 181). TET2 rs3733609 C/T genotype had a higher incidence (13.81%; 25/181) in JAK2V617F-positive sporadic MPN patients than that in normal controls (n = 236) (6.35%; 15/236), which was predisposing to MPN (odds ratio(OR) = 2.361; P = 0.01). MPN patients with rs3733609 C/T genotype had increased leukocyte and platelets counts, elevated hemoglobin concentration in comparison with T/T genotype. Thrombotic events were more common in MPN patients with rs3733609 C/T than those with T/T genotype (P < 0.01). We confirmed that rs3733609 C/T genotype downregulated TET2 mRNA transcription, and the mechanism may be involved in a disruption of the interaction between CCAAT/enhancer binding protein alpha (C/EBPA) and TET2 rs3733609 C/T locus.TET2 rs3733609 C/T genotype stimulated the erythroid hematopoiesis in MPN patients. Altogether, we found a novel hereditary susceptible factor-TET2 rs3733609 C/T variant for the development of MPN, suggesting the variant may be partially responsible for the pathogenesis and accumulation of MPN. PMID:26843622

  7. A TET2 rs3733609 C/T genotype is associated with predisposition to the myeloproliferative neoplasms harboring JAK2V617F and confers a proliferative potential on erythroid lineages

    PubMed Central

    Shen, Xiao-hui; Sun, Nan-nan; Yin, Ya-fei; Liu, Su-fang; Liu, Xiao-liu; Peng, Hong-ling; Dai, Chong-wen; Xu, Yun-xiao; Deng, Ming-yang; Luo, Yun-ya; Zheng, Wen-li; Zhang, Guang-sen

    2016-01-01

    Common germline single-nucleotide polymorphisms (SNPs) at JAK2 locus have been associated with Myeloproliferative neoplasms (MPN). And, the germline sequence variant rs2736100 C in TERT is related to risk of MPN, suggesting a complex association between SNPs and the pathogenesis of MPN. Our previous study (unpublished data) showed that there was a high frequency distribution in rs3733609 C/T genotype at Ten-Eleven Translocation 2 (TET2) locus in one Chinese familial primary myelofibrosis. In the present study, we evaluate the role and clinical significance of rs3733609 C/T genotype in JAK2V617F-positive sporadic MPN (n = 181). TET2 rs3733609 C/T genotype had a higher incidence (13.81%; 25/181) in JAK2V617F-positive sporadic MPN patients than that in normal controls (n = 236) (6.35%; 15/236), which was predisposing to MPN (odds ratio(OR) = 2.361; P = 0.01). MPN patients with rs3733609 C/T genotype had increased leukocyte and platelets counts, elevated hemoglobin concentration in comparison with T/T genotype. Thrombotic events were more common in MPN patients with rs3733609 C/T than those with T/T genotype (P < 0.01). We confirmed that rs3733609 C/T genotype downregulated TET2 mRNA transcription, and the mechanism may be involved in a disruption of the interaction between CCAAT/enhancer binding protein alpha (C/EBPA) and TET2 rs3733609 C/T locus.TET2 rs3733609 C/T genotype stimulated the erythroid hematopoiesis in MPN patients. Altogether, we found a novel hereditary susceptible factor-TET2 rs3733609 C/T variant for the development of MPN, suggesting the variant may be partially responsible for the pathogenesis and accumulation of MPN. PMID:26843622

  8. The PIM inhibitor AZD1208 synergizes with ruxolitinib to induce apoptosis of ruxolitinib sensitive and resistant JAK2-V617F-driven cells and inhibit colony formation of primary MPN cells

    PubMed Central

    Mazzacurati, Lucia; Lambert, Que T.; Pradhan, Anuradha; Griner, Lori N.; Huszar, Dennis; Reuther, Gary W.

    2015-01-01

    Classical myeloproliferative neoplasms (MPNs) are hematopoietic stem cell disorders that exhibit excess mature myeloid cells, bone marrow fibrosis, and risk of leukemic transformation. Aberrant JAK2 signaling plays an etiological role in MPN formation. Because neoplastic cells in patients are largely insensitive to current anti-JAK2 therapies, effective therapies remain needed. Members of the PIM family of serine/threonine kinases are induced by JAK/STAT signaling, regulate hematopoietic stem cell growth, protect hematopoietic cells from apoptosis, and exhibit hematopoietic cell transforming properties. We hypothesized that PIM kinases may offer a therapeutic target for MPNs. We treated JAK2-V617F-dependent MPN model cells as well as primary MPN patient cells with the PIM kinase inhibitors SGI-1776 and AZD1208 and the JAK2 inhibitor ruxolitinib. While MPN model cells were rather insensitive to PIM inhibitors, combination of PIM inhibitors with ruxolitinib led to a synergistic effect on MPN cell growth due to enhanced apoptosis. Importantly, PIM inhibitor mono-therapy inhibited, and AZD1208/ruxolitinib combination therapy synergistically suppressed, colony formation of primary MPN cells. Enhanced apoptosis by combination therapy was associated with activation of BAD, inhibition of downstream components of the mTOR pathway, including p70S6K and S6 protein, and activation of 4EBP1. Importantly, PIM inhibitors re-sensitized ruxolitinib-resistant MPN cells to ruxolitinib by inducing apoptosis. Finally, exogenous expression of PIM1 induced ruxolitinib resistance in MPN model cells. These data indicate that PIMs may play a role in MPNs and that combining PIM and JAK2 kinase inhibitors may offer a more efficacious therapeutic approach for MPNs over JAK2 inhibitor mono-therapy. PMID:26472029

  9. Limited efficacy of BMS-911543 in a murine model of Janus kinase 2 V617F myeloproliferative neoplasm

    PubMed Central

    Pomicter, Anthony D.; Eiring, Anna M.; Senina, Anna V.; Zabriskie, Matthew S.; Marvin, James E.; Prchal, Josef T.; O’Hare, Thomas; Deininger, Michael W.

    2015-01-01

    Activation of JAK2, frequently as a result of the JAK2V617F mutation, is a characteristic feature of the classical myeloproliferative neoplasms (MPN) polycythemia vera, essential thrombocythemia and myelofibrosis and is thought to be responsible for the constitutional symptoms associated with these diseases. BMS-911543 is a JAK2 selective inhibitor that induces apoptosis in JAK2-dependent cell lines and inhibits the growth of CD34+ progenitor cells from patients with JAK2V617F - positive MPN. To explore the clinical potential of this inhibitor, we tested BMS-911543 in a murine retroviral transduction – transplantation model of JAK2V617F MPN. Treatment was initiated at two dose levels (3 mg/kg and 10 mg/kg) when the hematocrit exceeded 70%. Following the first week, white blood cell counts were reduced to normal in the high dose group and were maintained well below the vehicle-treated mice throughout the study. However, BMS-911543 had no effect on red blood cell parameters. After 42 days of treatment, the proportion of JAK2V617F - positive cells in hematopoietic tissues was identical or slightly increased compared to controls. Plasma concentrations of IL-6, IL-15, and TNFα were elevated in MPN mice and reduced in the high dose treatment group, while other cytokines were unchanged. Inhibitor activity after dosing was confirmed in a cell culture assay using the plasma of dosed mice and pSTAT5 flow cytometry. Collectively, these results show that BMS-911543 has limited activity in this murine model of JAK2V617F – driven MPN and suggest that targeting JAK2 alone may be insufficient to achieve effective disease control. PMID:25912019

  10. Establishing optimal quantitative-polymerase chain reaction assays for routine diagnosis and tracking of minimal residual disease in JAK2-V617F-associated myeloproliferative neoplasms: a joint European LeukemiaNet/MPN&MPNr-EuroNet (COST action BM0902) study

    PubMed Central

    Jovanovic, J V; Ivey, A; Vannucchi, A M; Lippert, E; Oppliger Leibundgut, E; Cassinat, B; Pallisgaard, N; Maroc, N; Hermouet, S; Nickless, G; Guglielmelli, P; van der Reijden, B A; Jansen, J H; Alpermann, T; Schnittger, S; Bench, A; Tobal, K; Wilkins, B; Cuthill, K; McLornan, D; Yeoman, K; Akiki, S; Bryon, J; Jeffries, S; Jones, A; Percy, M J; Schwemmers, S; Gruender, A; Kelley, T W; Reading, S; Pancrazzi, A; McMullin, M F; Pahl, H L; Cross, N C P; Harrison, C N; Prchal, J T; Chomienne, C; Kiladjian, J J; Barbui, T; Grimwade, D

    2013-01-01

    Reliable detection of JAK2-V617F is critical for accurate diagnosis of myeloproliferative neoplasms (MPNs); in addition, sensitive mutation-specific assays can be applied to monitor disease response. However, there has been no consistent approach to JAK2-V617F detection, with assays varying markedly in performance, affecting clinical utility. Therefore, we established a network of 12 laboratories from seven countries to systematically evaluate nine different DNA-based quantitative PCR (qPCR) assays, including those in widespread clinical use. Seven quality control rounds involving over 21 500 qPCR reactions were undertaken using centrally distributed cell line dilutions and plasmid controls. The two best-performing assays were tested on normal blood samples (n=100) to evaluate assay specificity, followed by analysis of serial samples from 28 patients transplanted for JAK2-V617F-positive disease. The most sensitive assay, which performed consistently across a range of qPCR platforms, predicted outcome following transplant, with the mutant allele detected a median of 22 weeks (range 6–85 weeks) before relapse. Four of seven patients achieved molecular remission following donor lymphocyte infusion, indicative of a graft vs MPN effect. This study has established a robust, reliable assay for sensitive JAK2-V617F detection, suitable for assessing response in clinical trials, predicting outcome and guiding management of patients undergoing allogeneic transplant. PMID:23860450

  11. A Multiplex Snapback Primer System for the Enrichment and Detection of JAK2 V617F and MPL W515L/K Mutations in Philadelphia-Negative Myeloproliferative Neoplasms

    PubMed Central

    Zhang, Yunqing; Zhang, Xinju; Xu, Xiao; Kang, Zhihua; Li, Shibao; Zhang, Chen; Su, Bing

    2014-01-01

    A multiplex snapback primer system was developed for the simultaneous detection of JAK2 V617F and MPL W515L/K mutations in Philadelphia chromosome- (Ph-) negative myeloproliferative neoplasms (MPNs). The multiplex system comprises two snapback versus limiting primer sets for JAK2 and MPL mutation enrichment and detection, respectively. Linear-After exponential (LATE) PCR strategy was employed for the primer design to maximize the amplification efficiency of the system. Low ionic strength buffer and rapid PCR protocol allowed for selective amplification of the mutant alleles. Amplification products were analyzed by melting curve analysis for mutation identification. The multiplex system archived 0.1% mutation load sensitivity and <5% coefficient of variation inter-/intra-assay reproducibility. 120 clinical samples were tested by the multiplex snapback primer assay, and verified with amplification refractory system (ARMS), quantitative PCR (qPCR) and Sanger sequencing method. The multiplex system, with a favored versatility, provided the molecular diagnosis of Ph-negative MPNs with a suitable implement and simplified the genetic test process. PMID:24729973

  12. Combination treatment in vitro with Nutlin, a small-molecule antagonist of MDM2, and pegylated interferon-α 2a specifically targets JAK2V617F-positive polycythemia vera cells

    PubMed Central

    Lu, Min; Wang, Xiaoli; Li, Yan; Tripodi, Joseph; Mosoyan, Goar; Mascarenhas, John; Kremyanskaya, Marina; Najfeld, Vesna

    2012-01-01

    Interferon (IFN-α) is effective therapy for polycythemia vera (PV) patients, but it is frequently interrupted because of adverse events. To permit the long-term use of IFN, we propose combining low doses of IFN with Nutlin-3, an antagonist of MDM2, which is also capable of promoting PV CD34+ cell apoptosis. Combination treatment with subtherapeutic doses of Peg IFN-α 2a and Nutlin-3 inhibited PV CD34+ cell proliferation by 50% while inhibiting normal CD34+ cells by 30%. Combination treatment with Nutlin-3 and Peg IFN-α 2a inhibited PV colony formation by 55%-90% while inhibiting normal colony formation by 22%-30%. The combination of these agents also decreased the proportion of JAK2V617F-positive hematopoietic progenitor cells in 6 PV patients studied. Treatment with low doses of Peg IFN-α 2a combined with Nutlin-3 increased phospho-p53 and p21 protein levels in PV CD34+ cells and increased the degree of apoptosis. These 2 reagents affect the tumor suppressor p53 through different pathways with Peg IFN-α 2a activating p38 MAP kinase and STAT1, leading to increased p53 transcription, whereas Nutlin-3 prevents the degradation of p53. These data suggest that treatment with low doses of both Nutlin-3 combined with Peg IFN-α 2a can target PV hematopoietic progenitor cells, eliminating the numbers of malignant hematopoietic progenitor cells. PMID:22872685

  13. Potent and selective inhibition of polycythemia by the quinoxaline JAK2 inhibitor NVP-BSK805.

    PubMed

    Baffert, Fabienne; Régnier, Catherine H; De Pover, Alain; Pissot-Soldermann, Carole; Tavares, Gisele A; Blasco, Francesca; Brueggen, Josef; Chène, Patrick; Drueckes, Peter; Erdmann, Dirk; Furet, Pascal; Gerspacher, Marc; Lang, Marc; Ledieu, David; Nolan, Lynda; Ruetz, Stephan; Trappe, Joerg; Vangrevelinghe, Eric; Wartmann, Markus; Wyder, Lorenza; Hofmann, Francesco; Radimerski, Thomas

    2010-07-01

    The recent discovery of an acquired activating point mutation in JAK2, substituting valine at amino acid position 617 for phenylalanine, has greatly improved our understanding of the molecular mechanism underlying chronic myeloproliferative neoplasms. Strikingly, the JAK2(V617F) mutation is found in nearly all patients suffering from polycythemia vera and in roughly every second patient suffering from essential thrombocythemia and primary myelofibrosis. Thus, JAK2 represents a promising target for the treatment of myeloproliferative neoplasms and considerable efforts are ongoing to discover and develop inhibitors of the kinase. Here, we report potent inhibition of JAK2(V617F) and JAK2 wild-type enzymes by a novel substituted quinoxaline, NVP-BSK805, which acts in an ATP-competitive manner. Within the JAK family, NVP-BSK805 displays more than 20-fold selectivity towards JAK2 in vitro, as well as excellent selectivity in broader kinase profiling. The compound blunts constitutive STAT5 phosphorylation in JAK2(V617F)-bearing cells, with concomitant suppression of cell proliferation and induction of apoptosis. In vivo, NVP-BSK805 exhibited good oral bioavailability and a long half-life. The inhibitor was efficacious in suppressing leukemic cell spreading and splenomegaly in a Ba/F3 JAK2(V617F) cell-driven mouse mechanistic model. Furthermore, NVP-BSK805 potently suppressed recombinant human erythropoietin-induced polycythemia and extramedullary erythropoiesis in mice and rats. PMID:20587663

  14. Interferon-α induces marked alterations in circulating regulatory T cells, NK cell subsets, and dendritic cells in patients with JAK2V617F-positive essential thrombocythemia and polycythemia vera.

    PubMed

    Riley, Caroline H; Brimnes, Marie K; Hansen, Morten; Jensen, Morten Krogh; Hasselbalch, Hans C; Kjaer, Lasse; Straten, Per Thor; Svane, Inge Marie

    2016-07-01

    Long-term therapy with IFN-α2 is associated with sustained major molecular remissions in JAK2-positive ET and PV. The efficacy of IFN-α2 may be partly mediated by modulation of immune cells, which was investigated in twenty patients with ET (n = 6) and PV (n = 14). The frequency of CD4(+) CD25(+) Foxp3(+) T cells was significantly increased during IFN-α2 treatment in all patients (P < 0.0001). A significant expansion of the CD56(bright) NK cells (P = 0.0002) and a concomitant decrease in the frequency of CD56(dim) NK cells (P < 0.0001) were also detected. Myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) were studied in nine patients, and decreased frequencies of both cell types were observed during the course of treatment. On both mDCs and pDCs, HLA-ABC expression was upregulated (P = 0.003), but decreasing expression levels of HLA-DR was detected on mDCs. The expression of CD40 (P = 0.002), CD83 (P = 0.03), and CD86 (P = 0.01) increased, but was confined to pDCs. Furthermore, PD-L1 expression was reduced on mDC (P = 0.003) and increased on pDCs (P = 0.02). No significant correlations were found between the changes in immune cells and hematological or molecular responses achieved in our cohort of patients. So forth, it remains to be revealed whether the profound changes in circulating immune cells contribute to the beneficial effects of long-term IFN-α2 treatment in some patients. PMID:26385526

  15. JAK2 haplotype is a major risk factor for the development of myeloproliferative neoplasms

    PubMed Central

    Jones, Amy V; Chase, Andrew; Silver, Richard T; Oscier, David; Zoi, Katerina; Wang, Y Lynn; Cario, Holger; Pahl, Heike L; Collins, Andrew; Reiter, Andreas; Grand, Francis; Cross, Nicholas C P

    2014-01-01

    Chronic myeloproliferative neoplasms (MPNs) are a group of related conditions characterized by the overproduction of cells from one or more myeloid lineages. More than 95% of cases of polycythemia vera, and roughly half of essential thrombocythemia and primary myelofibrosis acquire a unique somatic 1849G>T JAK2 mutation (encoding V617F) that is believed to be a critical driver of excess proliferation1–4. We report here that JAK2V617F-associated disease is strongly associated with a specific constitutional JAK2 haplotype, designated 46/1, in all three disease entities compared to healthy controls (polycythemia vera, n = 192, P = 2.9 × 10−16; essential thrombocythemia, n = 78, P = 8.2 × 10−9 and myelofibrosis, n = 41, P = 8.0 × 10−5). Furthermore, JAK2V617F specifically arises on the 46/1 allele in most cases. The 46/1 JAK2 haplotype thus predisposes to the development of JAK2V617F-associated MPNs (OR = 3.7; 95% CI = 3.1–4.3) and provides a model whereby a constitutional genetic factor is associated with an increased risk of acquiring a specific somatic mutation. PMID:19287382

  16. Genetic basis of MPN: Beyond JAK2-V617F.

    PubMed

    Them, Nicole C C; Kralovics, Robert

    2013-12-01

    The clonal blood disorders polycythemia vera, essential thrombocythemia and primary myelofibrosis belong to the BCR-ABL1-negative myeloproliferative neoplasms and are specified by increased production of terminally differentiated myeloid cells. Clonal evolution, disease initiation and progression are influenced by genetic alterations, often affecting cytokine signaling and gene expression. This review outlines somatic changes discovered in myeloproliferative neoplasms and how these genetic aberrations influence the pathogenesis of myeloproliferative neoplasms. Furthermore, genetic responses to drug treatments in myeloproliferative neoplasms are discussed. PMID:24190690

  17. Ab Initio Modeling and Experimental Assessment of Janus Kinase 2 (JAK2) Kinase-Pseudokinase Complex Structure

    PubMed Central

    McClendon, Christopher L.; Huang, Lily Jun-shen; Huang, Niu

    2013-01-01

    The Janus Kinase 2 (JAK2) plays essential roles in transmitting signals from multiple cytokine receptors, and constitutive activation of JAK2 results in hematopoietic disorders and oncogenesis. JAK2 kinase activity is negatively regulated by its pseudokinase domain (JH2), where the gain-of-function mutation V617F that causes myeloproliferative neoplasms resides. In the absence of a crystal structure of full-length JAK2, how JH2 inhibits the kinase domain (JH1), and how V617F hyperactivates JAK2 remain elusive. We modeled the JAK2 JH1–JH2 complex structure using a novel informatics-guided protein-protein docking strategy. A detailed JAK2 JH2-mediated auto-inhibition mechanism is proposed, where JH2 traps the activation loop of JH1 in an inactive conformation and blocks the movement of kinase αC helix through critical hydrophobic contacts and extensive electrostatic interactions. These stabilizing interactions are less favorable in JAK2-V617F. Notably, several predicted binding interfacial residues in JH2 were confirmed to hyperactivate JAK2 kinase activity in site-directed mutagenesis and BaF3/EpoR cell transformation studies. Although there may exist other JH2-mediated mechanisms to control JH1, our JH1–JH2 structural model represents a verifiable working hypothesis for further experimental studies to elucidate the role of JH2 in regulating JAK2 in both normal and pathological settings. PMID:23592968

  18. Efficacy of NS-018, a potent and selective JAK2/Src inhibitor, in primary cells and mouse models of myeloproliferative neoplasms

    PubMed Central

    Nakaya, Y; Shide, K; Niwa, T; Homan, J; Sugahara, S; Horio, T; Kuramoto, K; Kotera, T; Shibayama, H; Hori, K; Naito, H; Shimoda, K

    2011-01-01

    Aberrant activation of Janus kinase 2 (JAK2) caused by somatic mutation of JAK2 (JAK2V617F) or the thrombopoietin receptor (MPLW515L) plays an essential role in the pathogenesis of myeloproliferative neoplasms (MPNs), suggesting that inhibition of aberrant JAK2 activation would have a therapeutic benefit. Our novel JAK2 inhibitor, NS-018, was highly active against JAK2 with a 50% inhibition (IC50) of <1 n, and had 30–50-fold greater selectivity for JAK2 over other JAK-family kinases, such as JAK1, JAK3 and tyrosine kinase 2. In addition to JAK2, NS-018 inhibited Src-family kinases. NS-018 showed potent antiproliferative activity against cell lines expressing a constitutively activated JAK2 (the JAK2V617F or MPLW515L mutations or the TEL–JAK2 fusion gene; IC50=11–120 n), but showed only minimal cytotoxicity against most other hematopoietic cell lines without a constitutively activated JAK2. Furthermore, NS-018 preferentially suppressed in vitro erythropoietin-independent endogenous colony formation from polycythemia vera patients. NS-018 also markedly reduced splenomegaly and prolonged the survival of mice inoculated with Ba/F3 cells harboring JAK2V617F. In addition, NS-018 significantly reduced leukocytosis, hepatosplenomegaly and extramedullary hematopoiesis, improved nutritional status, and prolonged survival in JAK2V617F transgenic mice. These results suggest that NS-018 will be a promising candidate for the treatment of MPNs. PMID:22829185

  19. Genetic variation at MECOM, TERT, JAK2 and HBS1L-MYB predisposes to myeloproliferative neoplasms.

    PubMed

    Tapper, William; Jones, Amy V; Kralovics, Robert; Harutyunyan, Ashot S; Zoi, Katerina; Leung, William; Godfrey, Anna L; Guglielmelli, Paola; Callaway, Alison; Ward, Daniel; Aranaz, Paula; White, Helen E; Waghorn, Katherine; Lin, Feng; Chase, Andrew; Baxter, E Joanna; Maclean, Cathy; Nangalia, Jyoti; Chen, Edwin; Evans, Paul; Short, Michael; Jack, Andrew; Wallis, Louise; Oscier, David; Duncombe, Andrew S; Schuh, Anna; Mead, Adam J; Griffiths, Michael; Ewing, Joanne; Gale, Rosemary E; Schnittger, Susanne; Haferlach, Torsten; Stegelmann, Frank; Döhner, Konstanze; Grallert, Harald; Strauch, Konstantin; Tanaka, Toshiko; Bandinelli, Stefania; Giannopoulos, Andreas; Pieri, Lisa; Mannarelli, Carmela; Gisslinger, Heinz; Barosi, Giovanni; Cazzola, Mario; Reiter, Andreas; Harrison, Claire; Campbell, Peter; Green, Anthony R; Vannucchi, Alessandro; Cross, Nicholas C P

    2015-01-01

    Clonal proliferation in myeloproliferative neoplasms (MPN) is driven by somatic mutations in JAK2, CALR or MPL, but the contribution of inherited factors is poorly characterized. Using a three-stage genome-wide association study of 3,437 MPN cases and 10,083 controls, we identify two SNPs with genome-wide significance in JAK2(V617F)-negative MPN: rs12339666 (JAK2; meta-analysis P=1.27 × 10(-10)) and rs2201862 (MECOM; meta-analysis P=1.96 × 10(-9)). Two additional SNPs, rs2736100 (TERT) and rs9376092 (HBS1L/MYB), achieve genome-wide significance when including JAK2(V617F)-positive cases. rs9376092 has a stronger effect in JAK2(V617F)-negative cases with CALR and/or MPL mutations (Breslow-Day P=4.5 × 10(-7)), whereas in JAK2(V617F)-positive cases rs9376092 associates with essential thrombocythemia (ET) rather than polycythemia vera (allelic χ(2) P=7.3 × 10(-7)). Reduced MYB expression, previously linked to development of an ET-like disease in model systems, associates with rs9376092 in normal myeloid cells. These findings demonstrate that multiple germline variants predispose to MPN and link constitutional differences in MYB expression to disease phenotype. PMID:25849990

  20. Genetic variation at MECOM, TERT, JAK2 and HBS1L-MYB predisposes to myeloproliferative neoplasms

    PubMed Central

    Tapper, William; Jones, Amy V.; Kralovics, Robert; Harutyunyan, Ashot S.; Zoi, Katerina; Leung, William; Godfrey, Anna L.; Guglielmelli, Paola; Callaway, Alison; Ward, Daniel; Aranaz, Paula; White, Helen E.; Waghorn, Katherine; Lin, Feng; Chase, Andrew; Joanna Baxter, E.; Maclean, Cathy; Nangalia, Jyoti; Chen, Edwin; Evans, Paul; Short, Michael; Jack, Andrew; Wallis, Louise; Oscier, David; Duncombe, Andrew S.; Schuh, Anna; Mead, Adam J.; Griffiths, Michael; Ewing, Joanne; Gale, Rosemary E.; Schnittger, Susanne; Haferlach, Torsten; Stegelmann, Frank; Döhner, Konstanze; Grallert, Harald; Strauch, Konstantin; Tanaka, Toshiko; Bandinelli, Stefania; Giannopoulos, Andreas; Pieri, Lisa; Mannarelli, Carmela; Gisslinger, Heinz; Barosi, Giovanni; Cazzola, Mario; Reiter, Andreas; Harrison, Claire; Campbell, Peter; Green, Anthony R.; Vannucchi, Alessandro; Cross, Nicholas C.P.

    2015-01-01

    Clonal proliferation in myeloproliferative neoplasms (MPN) is driven by somatic mutations in JAK2, CALR or MPL, but the contribution of inherited factors is poorly characterized. Using a three-stage genome-wide association study of 3,437 MPN cases and 10,083 controls, we identify two SNPs with genome-wide significance in JAK2V617F-negative MPN: rs12339666 (JAK2; meta-analysis P=1.27 × 10−10) and rs2201862 (MECOM; meta-analysis P=1.96 × 10−9). Two additional SNPs, rs2736100 (TERT) and rs9376092 (HBS1L/MYB), achieve genome-wide significance when including JAK2V617F-positive cases. rs9376092 has a stronger effect in JAK2V617F-negative cases with CALR and/or MPL mutations (Breslow–Day P=4.5 × 10−7), whereas in JAK2V617F-positive cases rs9376092 associates with essential thrombocythemia (ET) rather than polycythemia vera (allelic χ2 P=7.3 × 10−7). Reduced MYB expression, previously linked to development of an ET-like disease in model systems, associates with rs9376092 in normal myeloid cells. These findings demonstrate that multiple germline variants predispose to MPN and link constitutional differences in MYB expression to disease phenotype. PMID:25849990

  1. JAK2 Exon 14 Deletion in Patients with Chronic Myeloproliferative Neoplasms

    PubMed Central

    Ma, Wanlong; Kantarjian, Hagop; Zhang, Xi; Wang, Xiuqiang; Zhang, Zhong; Yeh, Chen-Hsiung; O'Brien, Susan; Giles, Francis; Bruey, Jean Marie; Albitar, Maher

    2010-01-01

    Background The JAK2 V617F mutation in exon 14 is the most common mutation in chronic myeloproliferative neoplasms (MPNs); deletion of the entire exon 14 is rarely detected. In our previous study of >10,000 samples from patients with suspected MPNs tested for JAK2 mutations by reverse transcription-PCR (RT-PCR) with direct sequencing, complete deletion of exon 14 (Δexon14) constituted <1% of JAK2 mutations. This appears to be an alternative splicing mutation, not detectable with DNA-based testing. Methodology/Principal Findings We investigated the possibility that MPN patients may express the JAK2 Δexon14 at low levels (<15% of total transcript) not routinely detectable by RT-PCR with direct sequencing. Using a sensitive RT-PCR–based fluorescent fragment analysis method to quantify JAK2 Δexon14 mRNA expression relative to wild-type, we tested 61 patients with confirmed MPNs, 183 with suspected MPNs (93 V617F-positive, 90 V617F-negative), and 46 healthy control subjects. The Δexon14 variant was detected in 9 of the 61 (15%) confirmed MPN patients, accounting for 3.96% to 33.85% (mean  = 12.04%) of total JAK2 transcript. This variant was also detected in 51 of the 183 patients with suspected MPNs (27%), including 20 of the 93 (22%) with V617F (mean [range] expression  = 5.41% [2.13%–26.22%]) and 31 of the 90 (34%) without V617F (mean [range] expression  = 3.88% [2.08%–12.22%]). Immunoprecipitation studies demonstrated that patients expressing Δexon14 mRNA expressed a corresponding truncated JAK2 protein. The Δexon14 variant was not detected in the 46 control subjects. Conclusions/Significance These data suggest that expression of the JAK2 Δexon14 splice variant, leading to a truncated JAK2 protein, is common in patients with MPNs. This alternatively spliced transcript appears to be more frequent in MPN patients without V617F mutation, in whom it might contribute to leukemogenesis. This mutation is missed if DNA rather than RNA is used for

  2. Myeloproliferative neoplasms: From JAK2 mutations discovery to JAK2 inhibitor therapies

    PubMed Central

    Passamonti, Francesco; Maffioli, Margherita; Caramazza, Domenica; Cazzola, Mario

    2011-01-01

    Most BCR-ABL1-negative myeloproliferative neoplasms (MPN) carry an activating JAK2 mutation. Approximately 96% of patients with polycythemia vera (PV) harbors the V617F mutation in JAK2 exon 14, whereas the minority of JAK2 (V617F)-negative subjects shows several mutations in exon 12. Other mutation events as MPL, TET2, LNK, EZH2 have been described in chronic phase, while NF1, IDH1, IDH2, ASX1, CBL and Ikaros in blast phase of MPN. The specific pathogenic implication of these mutations is under investigation, but they may have a role in refinement of diagnostic criteria and in development of new prognostic models. Several trials with targeted therapy (JAK inhibitors) are ongoing mostly involving patients with PMF, post-PV MF and post-essential thrombocythemia (ET) MF. Treatment with ruxolitinib and TG101348 has shown clinically significant benefits, particularly in improvement of splenomegaly and constitutional symptoms in MF patients. On the other hand, JAK inhibitors have not thus far shown disease-modifying activity therefore any other deduction on these new drugs seems premature. PMID:21646683

  3. Analysis of Jak2 signaling reveals resistance of mouse embryonic hematopoietic stem cells to myeloproliferative disease mutation

    PubMed Central

    Mascarenhas, Maria I.; Bacon, Wendi A.; Kapeni, Chrysa; Fitch, Simon R.; Kimber, Gillian; Cheng, S. W. Priscilla; Li, Juan; Green, Anthony R.

    2016-01-01

    The regulation of hematopoietic stem cell (HSC) emergence during development provides important information about the basic mechanisms of blood stem cell generation, expansion, and migration. We set out to investigate the role that cytokine signaling pathways play in these early processes and show here that the 2 cytokines interleukin 3 and thrombopoietin have the ability to expand hematopoietic stem and progenitor numbers by regulating their survival and proliferation. For this, they differentially use the Janus kinase (Jak2) and phosphatidylinositol 3-kinase (Pi3k) signaling pathways, with Jak2 mainly relaying the proproliferation signaling, whereas Pi3k mediates the survival signal. Furthermore, using Jak2-deficient embryos, we demonstrate that Jak2 is crucially required for the function of the first HSCs, whereas progenitors are less dependent on Jak2. The JAK2V617F mutation, which renders JAK2 constitutively active and has been linked to myeloproliferative neoplasms, was recently shown to compromise adult HSC function, negatively affecting their repopulation and self-renewal ability, partly through the accumulation of JAK2V617F-induced DNA damage. We report here that nascent HSCs are resistant to the JAK2V617F mutation and show no decrease in repopulation or self-renewal and no increase in DNA damage, even in the presence of 2 mutant copies. More importantly, this unique property of embryonic HSCs is stably maintained through ≥1 round of successive transplantations. In summary, our dissection of cytokine signaling in embryonic HSCs has uncovered unique properties of these cells that are of clinical importance. PMID:26864339

  4. RECQL5 suppresses oncogenic JAK2-induced replication stress and genomic instability

    PubMed Central

    Chen, Edwin; Ahn, Jong Sook; Sykes, David B.; Breyfogle, Lawrence J.; Godfrey, Anna L.; Nangalia, Jyoti; Ko, Amy; DeAngelo, Daniel J.; Green, Anthony R.; Mullally, Ann

    2015-01-01

    JAK2V617F is the most common oncogenic lesion in patients with myeloproliferative neoplasms (MPN). Despite the ability of JAK2V617F to instigate DNA damage in vitro, MPN is nevertheless characterized by genomic stability. In this study, we address this paradox by identifying the DNA helicase RECQL5 as a suppressor of genomic instability in MPN. We report increased RECQL5 expression in JAK2V617F-expressing cells and demonstrate that RECQL5 is required to counteract JAK2V617F-induced replication stress. Moreover, RECQL5 depletion sensitizes JAK2V617F-mutant cells to hydroxyurea (HU), a pharmacological inducer of replication stress and the most common treatment for MPN. Using single-fiber chromosome combing we show that RECQL5 depletion in JAK2V617F-mutant cells impairs replication dynamics following HU treatment, resulting in increased double-stranded breaks and apoptosis. Cumulatively, these findings identify RECQL5 as a critical regulator of genome stability in MPN and demonstrate that replication stress-associated cytotoxicity can be amplified specifically in JAK2V617F-mutant cells through RECQL5-targeted synthetic lethality. PMID:26686625

  5. Genetic resistance to JAK2 enzymatic inhibitors is overcome by HSP90 inhibition

    PubMed Central

    Weigert, Oliver; Lane, Andrew A.; Bird, Liat; Kopp, Nadja; Chapuy, Bjoern; van Bodegom, Diederik; Toms, Angela V.; Marubayashi, Sachie; Christie, Amanda L.; McKeown, Michael; Paranal, Ronald M.; Bradner, James E.; Yoda, Akinori; Gaul, Christoph; Vangrevelinghe, Eric; Romanet, Vincent; Murakami, Masato; Tiedt, Ralph; Ebel, Nicolas; Evrot, Emeline; De Pover, Alain; Régnier, Catherine H.; Erdmann, Dirk; Hofmann, Francesco; Eck, Michael J.; Sallan, Stephen E.; Levine, Ross L.; Kung, Andrew L.; Baffert, Fabienne

    2012-01-01

    Enzymatic inhibitors of Janus kinase 2 (JAK2) are in clinical development for the treatment of myeloproliferative neoplasms (MPNs), B cell acute lymphoblastic leukemia (B-ALL) with rearrangements of the cytokine receptor subunit cytokine receptor–like factor 2 (CRLF2), and other tumors with constitutive JAK2 signaling. In this study, we identify G935R, Y931C, and E864K mutations within the JAK2 kinase domain that confer resistance across a panel of JAK inhibitors, whether present in cis with JAK2 V617F (observed in MPNs) or JAK2 R683G (observed in B-ALL). G935R, Y931C, and E864K do not reduce the sensitivity of JAK2-dependent cells to inhibitors of heat shock protein 90 (HSP90), which promote the degradation of both wild-type and mutant JAK2. HSP90 inhibitors were 100–1,000-fold more potent against CRLF2-rearranged B-ALL cells, which correlated with JAK2 degradation and more extensive blockade of JAK2/STAT5, MAP kinase, and AKT signaling. In addition, the HSP90 inhibitor AUY922 prolonged survival of mice xenografted with primary human CRLF2-rearranged B-ALL further than an enzymatic JAK2 inhibitor. Thus, HSP90 is a promising therapeutic target in JAK2-driven cancers, including those with genetic resistance to JAK enzymatic inhibitors. PMID:22271575

  6. SOCS3 tyrosine phosphorylation as a potential bio-marker for myeloproliferative neoplasms associated with mutant JAK2 kinases

    PubMed Central

    Elliott, Joanne; Suessmuth, Yvonne; Scott, Linda M.; Nahlik, Krystyna; McMullin, Mary Frances; Constantinescu, Stefan N.; Green, Anthony R.; Johnston, James A.

    2009-01-01

    JAK2 V617F, identified in the majority of patients with myeloproliferative neoplasms, tyrosine phosphorylates SOCS3 and escapes its inhibition. Here, we demonstrate that the JAK2 exon 12 mutants described in a subset of V617F-negative MPN cases, also stabilize tyrosine phosphorylated SOCS3. SOCS3 tyrosine phosphorylation was also observed in peripheral blood mononuclear cells and granulocytes isolated from patients with JAK2 H538QK539L or JAK2 F537-K539delinsL mutations. JAK kinase inhibitors, which effectively inhibited the proliferation of cells expressing V617F or K539L, also caused a dose-dependent reduction in both mutant JAK2 and SOCS3 tyrosine phosphorylation. We propose, therefore, that SOCS3 tyrosine phosphorylation may be a novel bio-marker of myeloproliferative neoplasms resulting from a JAK2 mutation and a potential reporter of effective JAK2 inhibitor therapy currently in clinical development. PMID:19229050

  7. mTOR Inhibitors Alone and in Combination with JAK2 Inhibitors Effectively Inhibit Cells of Myeloproliferative Neoplasms

    PubMed Central

    Martinelli, Serena; Tozzi, Lorenzo; Guglielmelli, Paola; Bosi, Alberto; Vannucchi, Alessandro M.

    2013-01-01

    Background Dysregulated signaling of the JAK/STAT pathway is a common feature of chronic myeloproliferative neoplasms (MPN), usually associated with JAK2V617F mutation. Recent clinical trials with JAK2 inhibitors showed significant improvements in splenomegaly and constitutional symptoms in patients with myelofibrosis but meaningful molecular responses were not documented. Accordingly, there remains a need for exploring new treatment strategies of MPN. A potential additional target for treatment is represented by the PI3K/AKT/mammalian target of rapamycin (mTOR) pathway that has been found constitutively activated in MPN cells; proof-of-evidence of efficacy of the mTOR inhibitor RAD001 has been obtained recently in a Phase I/II trial in patients with myelofibrosis. The aim of the study was to characterize the effects in vitro of mTOR inhibitors, used alone and in combination with JAK2 inhibitors, against MPN cells. Findings Mouse and human JAK2V617F mutated cell lines and primary hematopoietic progenitors from MPN patients were challenged with an allosteric (RAD001) and an ATP-competitive (PP242) mTOR inhibitor and two JAK2 inhibitors (AZD1480 and ruxolitinib). mTOR inhibitors effectively reduced proliferation and colony formation of cell lines through a slowed cell division mediated by changes in cell cycle transition to the S-phase. mTOR inhibitors also impaired the proliferation and prevented colony formation from MPN hematopoietic progenitors at doses significantly lower than healthy controls. JAK2 inhibitors produced similar antiproliferative effects in MPN cell lines and primary cells but were more potent inducers of apoptosis, as also supported by differential effects on cyclinD1, PIM1 and BcLxL expression levels. Co-treatment of mTOR inhibitor with JAK2 inhibitor resulted in synergistic activity against the proliferation of JAK2V617F mutated cell lines and significantly reduced erythropoietin-independent colony growth in patients with polycythemia vera

  8. Stimulation of the amino acid transporter SLC6A19 by JAK2

    SciTech Connect

    Bhavsar, Shefalee K.; Hosseinzadeh, Zohreh; Merches, Katja; Gu, Shuchen; Broeer, Stefan; Lang, Florian

    2011-10-28

    Highlights: Black-Right-Pointing-Pointer The amino acid transporter SLC6A19 is upregulated by Janus kinase-2 JAK2. Black-Right-Pointing-Pointer The {sup V617F}JAK2 mutant, causing myeloproliferative disease, is more effective. Black-Right-Pointing-Pointer JAK2 inhibitor AG490 reverses stimulation of SLC6A19 by {sup V617F}JAK2. Black-Right-Pointing-Pointer JAK2 enhances SLC6A19 protein insertion into the cell membrane. Black-Right-Pointing-Pointer SLC6A19 may contribute to amino acid uptake into {sup V617F}JAK2 expressing tumor cells. -- Abstract: JAK2 (Janus kinase-2) is expressed in a wide variety of cells including tumor cells and contributes to the proliferation and survival of those cells. The gain of function mutation {sup V617F}JAK2 mutant is found in the majority of myeloproliferative diseases. Cell proliferation depends on the availability of amino acids. Concentrative cellular amino acid uptake is in part accomplished by Na{sup +} coupled amino acid transport through SLC6A19 (B(0)AT). The present study thus explored whether JAK2 activates SLC6A19. To this end, SLC6A19 was expressed in Xenopus oocytes with or without wild type JAK2, {sup V617F}JAK2 or inactive {sup K882E}JAK2 and electrogenic amino acid transport determined by dual electrode voltage clamp. In SLC6A19-expressing oocytes but not in oocytes injected with water or JAK2 alone, the addition of leucine (2 mM) to the bath generated a current (I{sub le}), which was significantly increased following coexpression of JAK2 or {sup V617F}JAK2, but not by coexpression of {sup K882E}JAK2. Coexpression of JAK2 enhanced the maximal transport rate without significantly modifying the affinity of the carrier. Exposure of the oocytes to the JAK2 inhibitor AG490 (40 {mu}M) resulted in a gradual decline of I{sub le}. According to chemiluminescence JAK2 enhanced the carrier protein abundance in the cell membrane. The decline of I{sub le} following inhibition of carrier insertion by brefeldin A (5 {mu}M) was similar

  9. Uses and Abuses of JAK2 and MPL Mutation Tests in Myeloproliferative Neoplasms

    PubMed Central

    Tefferi, Ayalew; Noel, Pierre; Hanson, Curtis A.

    2011-01-01

    JAK2V617F is sufficiently prevalent in BCR-ABL1-negative myeloproliferative neoplasms (MPNs) to be useful as a clonal marker. JAK2V617F mutation screening is indicated for the evaluation of erythrocytosis, thrombocytosis, splanchnic vein thrombosis, and otherwise unexplained BCR-ABL1-negative granulocytosis. However, the mutation does not provide additional value in the presence of unequivocal morphologic diagnosis, and its presence does not necessarily distinguish one MPN from another or provide useful prognostic information. In general, quantitative cell-based JAK2V617F mutation assays are preferred because the additional information obtained on mutant allele burden enhances diagnostic certainty and facilitates monitoring of response to treatment. JAK2 exon 12 mutation screening is indicated only in the presence of JAK2V617F-negative erythrocytosis that is associated with a subnormal serum erythropoietin level. MPL mutations are neither frequent nor specific enough to warrant their routine use for MPN diagnosis, but they may be useful in resolving specific diagnostic problems. The practice of en bloc screening for JAK2V617F, JAK2 exon 12, and MPL mutations is scientifically irrational and economically irresponsible. PMID:21723416

  10. Analysis of phenotype and outcome in essential thrombocythemia with CALR or JAK2 mutations

    PubMed Central

    Al Assaf, Carla; Van Obbergh, Florence; Billiet, Johan; Lierman, Els; Devos, Timothy; Graux, Carlos; Hervent, Anne-Sophie; Emmerechts, Jan; Tousseyn, Thomas; De Paepe, Pascale; Papadopoulos, Petros; Michaux, Lucienne; Vandenberghe, Peter

    2015-01-01

    The JAK2 V617F mutation, the thrombopoietin receptor MPL W515K/L mutation and calreticulin (CALR) mutations are mutually exclusive in essential thrombocythemia and support a novel molecular categorization of essential thrombocythemia. CALR mutations account for approximately 30% of cases of essential thrombocythemia. In a retrospective study, we examined the frequency of MPL and CALR mutations in JAK2 V617F-negative cases of essential thrombocythemia (n=103). In addition, we compared the clinical phenotype and outcome of CALR mutant cases of essential thrombocythemia with a cohort of JAK2 V617F-positive essential thrombocythemia (n=57). CALR-positive cases represented 63.7% of double-negative cases of essential thrombocythemia, and most carried CALR type 1 or type 2 indels. However, we also identified one patient who was positive for both the JAK2 V617F and the CALR mutations. This study revealed that CALR mutant essential thrombocythemia is associated with younger age, higher platelet counts, lower erythrocyte counts, leukocyte counts, hemoglobin, and hematocrit, and increased risk of progression to myelofibrosis in comparison with JAK2 V617F-positive essential thrombocythemia. Analysis of the CALR mutant group according to indel type showed that CALR type 1 deletion is strongly associated with male gender. CALR mutant patients had a better overall survival than JAK2 V617F-positive patients, in particular patients of age 60 years or younger. In conclusion, this study in a Belgian cohort of patients supports and extends the growing body of evidence that CALR mutant cases of essential thrombocythemia are phenotypically distinct from JAK2 V617F-positive cases, with regards to clinical and hematologic presentation as well as overall survival. PMID:25934766

  11. The C allele of JAK2 rs4495487 is an additional candidate locus that contributes to myeloproliferative neoplasm predisposition in the Japanese population

    PubMed Central

    2012-01-01

    Background Polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) are myeloproliferative neoplasms (MPNs) characterized in most cases by a unique somatic mutation, JAK2 V617F. Recent studies revealed that JAK2 V617F occurs more frequently in a specific JAK2 haplotype, named JAK2 46/1 or GGCC haplotype, which is tagged by rs10974944 (C/G) and/or rs12343867 (T/C). This study examined the impact of single nucleotide polymorphisms (SNPs) of the JAK2 locus on MPNs in a Japanese population. Methods We sequenced 24 JAK2 SNPs in Japanese patients with PV. We then genotyped 138 MPN patients (33 PV, 96 ET, and 9 PMF) with known JAK2 mutational status and 107 controls for a novel SNP, in addition to two SNPs known to be part of the 46/1 haplotype (rs10974944 and rs12343867). Associations with risk of MPN were estimated by odds ratios and their 95% confidence intervals using logistic regression. Results A novel locus, rs4495487 (T/C), with a mutated T allele was significantly associated with PV. Similar to rs10974944 and rs12343867, rs4495487 in the JAK2 locus is significantly associated with JAK2-positive MPN. Based on the results of SNP analysis of the three JAK2 locus, we defined the "GCC genotype" as having at least one minor allele in each SNP (G allele in rs10974944, C allele in rs4495487, and C allele in rs12343867). The GCC genotype was associated with increased risk of both JAK2 V617F-positive and JAK2 V617F-negative MPN. In ET patients, leukocyte count and hemoglobin were significantly associated with JAK2 V617F, rather than the GCC genotype. In contrast, none of the JAK2 V617F-negative ET patients without the GCC genotype had thrombosis, and splenomegaly was frequently seen in this subset of ET patients. PV patients without the GCC genotype were significantly associated with high platelet count. Conclusions Our results indicate that the C allele of JAK2 rs4495487, in addition to the 46/1 haplotype, contributes significantly to the

  12. Therapy with JAK2 inhibitors for Myeloproliferative Neoplasms

    PubMed Central

    Santos, Fabio P. S.; Verstovsek, Srdan

    2015-01-01

    The development of JAK2 inhibitors followed the discovery of activating mutation of JAK2 (JAK2V617F) in patients with classic Philadelphia-negative myeloproliferative neoplasms (Ph-negative MPNs). It is now known that mutations activating the JAK-STAT pathway are ubiquitous in Ph-negative MPNs, and that deregulated JAK-STAT pathway plays a central role in the pathogenesis of these disorders. JAK2 inhibitors thus are effective in both patients with and without the JAK2V617F mutation. Clinical trials conducted in patients with myelofibrosis have demonstrated that these drugs lead to substantial improvements in systemic symptoms, splenomegaly, leukocytosis and thrombocytosis. Results of one randomized clinical trial suggest that JAK2 inhibition may also lead to improved survival. There are still significant challenges to be overcome, as these drugs do not improve bone marrow fibrosis and do not lead to significant reduction in the allele burden of JAK2V617F. In this manuscript we review the rationale for using JAK2 inhibitors in Ph-negative MPNs and results of more recent clinical trials with these drugs. PMID:23009939

  13. Antagonistic activities of the immunomodulator and PP2A-activating drug FTY720 (Fingolimod, Gilenya) in Jak2-driven hematologic malignancies.

    PubMed

    Oaks, Joshua J; Santhanam, Ramasamy; Walker, Christopher J; Roof, Steve; Harb, Jason G; Ferenchak, Greg; Eisfeld, Ann-Kathrin; Van Brocklyn, James R; Briesewitz, Roger; Saddoughi, Sahar A; Nagata, Kyosuke; Bittman, Robert; Caligiuri, Michael A; Abdel-Wahab, Omar; Levine, Ross; Arlinghaus, Ralph B; Quintas-Cardama, Alfonso; Goldman, John M; Apperley, Jane; Reid, Alistair; Milojkovic, Dragana; Ziolo, Mark T; Marcucci, Guido; Ogretmen, Besim; Neviani, Paolo; Perrotti, Danilo

    2013-09-12

    FTY720 (Fingolimod, Gilenya) is a sphingosine analog used as an immunosuppressant in multiple sclerosis patients. FTY720 is also a potent protein phosphatase 2A (PP2A)-activating drug (PAD). PP2A is a tumor suppressor found inactivated in different types of cancer. We show here that PP2A is inactive in polycythemia vera (PV) and other myeloproliferative neoplasms characterized by the expression of the transforming Jak2(V617F) oncogene. PP2A inactivation occurs in a Jak2(V617F) dose/kinase-dependent manner through the PI-3Kγ-PKC-induced phosphorylation of the PP2A inhibitor SET. Genetic or PAD-mediated PP2A reactivation induces Jak2(V617F) inactivation/downregulation and impairs clonogenic potential of Jak2(V617F) cell lines and PV but not normal CD34(+) progenitors. Likewise, FTY720 decreases leukemic allelic burden, reduces splenomegaly, and significantly increases survival of Jak2(V617F) leukemic mice without adverse effects. Mechanistically, we show that in Jak2(V617F) cells, FTY720 antileukemic activity requires neither FTY720 phosphorylation (FTY720-P) nor SET dimerization or ceramide induction but depends on interaction with SET K209. Moreover, we show that Jak2(V617F) also utilizes an alternative sphingosine kinase-1-mediated pathway to inhibit PP2A and that FTY720-P, acting as a sphingosine-1-phosphate-receptor-1 agonist, elicits signals leading to the Jak2-PI-3Kγ-PKC-SET-mediated PP2A inhibition. Thus, PADs (eg, FTY720) represent suitable therapeutic alternatives for Jak2(V617F) MPNs. PMID:23926298

  14. CYT387, a novel JAK2 inhibitor, induces hematologic responses and normalizes inflammatory cytokines in murine myeloproliferative neoplasms

    PubMed Central

    Tyner, Jeffrey W.; Bumm, Thomas G.; Deininger, Jutta; Wood, Lisa; Aichberger, Karl J.; Loriaux, Marc M.; Druker, Brian J.; Burns, Christopher J.; Fantino, Emmanuelle

    2010-01-01

    Activating alleles of Janus kinase 2 (JAK2) such as JAK2V617F are central to the pathogenesis of myeloproliferative neoplasms (MPN), suggesting that small molecule inhibitors targeting JAK2 may be therapeutically useful. We have identified an aminopyrimidine derivative (CYT387), which inhibits JAK1, JAK2, and tyrosine kinase 2 (TYK2) at low nanomolar concentrations, with few additional targets. Between 0.5 and 1.5μM CYT387 caused growth suppression and apoptosis in JAK2-dependent hematopoietic cell lines, while nonhematopoietic cell lines were unaffected. In a murine MPN model, CYT387 normalized white cell counts, hematocrit, spleen size, and restored physiologic levels of inflammatory cytokines. Despite the hematologic responses and reduction of the JAK2V617F allele burden, JAK2V617F cells persisted and MPN recurred upon cessation of treatment, suggesting that JAK2 inhibitors may be unable to eliminate JAK2V617F cells, consistent with preliminary results from clinical trials of JAK2 inhibitors in myelofibrosis. While the clinical benefit of JAK2 inhibitors may be substantial, not the least due to reduction of inflammatory cytokines and symptomatic improvement, our data add to increasing evidence that kinase inhibitor monotherapy of malignant disease is not curative, suggesting a need for drug combinations to optimally target the malignant cells. PMID:20385788

  15. Structure-Function Correlation of G6, a Novel Small Molecule Inhibitor of Jak2

    PubMed Central

    Majumder, Anurima; Govindasamy, Lakshmanan; Magis, Andrew; Kiss, Róbert; Polgár, Tímea; Baskin, Rebekah; Allan, Robert W.; Agbandje-McKenna, Mavis; Reuther, Gary W.; Keserű, György M.; Bisht, Kirpal S.; Sayeski, Peter P.

    2010-01-01

    Somatic mutations in the Jak2 protein, such as V617F, cause aberrant Jak/STAT signaling and can lead to the development of myeloproliferative neoplasms. This discovery has led to the search for small molecule inhibitors that target Jak2. Using structure-based virtual screening, our group recently identified a novel small molecule inhibitor of Jak2 named G6. Here, we identified a structure-function correlation of this compound. Specifically, five derivative compounds of G6 having structural similarity to the original lead compound were obtained and analyzed for their ability to (i) inhibit Jak2-V617F-mediated cell growth, (ii) inhibit the levels of phospho-Jak2, phospho-STAT3, and phospho-STAT5; (iii) induce apoptosis in human erythroleukemia cells; and (iv) suppress pathologic cell growth of Jak2-V617F-expressing human bone marrow cells ex vivo. Additionally, we computationally examined the interactions of these compounds with the ATP-binding pocket of the Jak2 kinase domain. We found that the stilbenoid core-containing derivatives of G6 significantly inhibited Jak2-V617F-mediated cell proliferation in a time- and dose-dependent manner. They also inhibited phosphorylation of Jak2, STAT3, and STAT5 proteins within cells, resulting in higher levels of apoptosis via the intrinsic apoptotic pathway. Finally, the stilbenoid derivatives inhibited the pathologic growth of Jak2-V617F-expressing human bone marrow cells ex vivo. Collectively, our data demonstrate that G6 has a stilbenoid core that is indispensable for maintaining its Jak2 inhibitory potential. PMID:20667821

  16. High frequency of JAK2 exon 12 mutations in Korean patients with polycythaemia vera: novel mutations and clinical significance.

    PubMed

    Park, Chang-Hun; Lee, Ki-O; Jang, Jun-Ho; Jung, Chul Won; Kim, Jong-Won; Kim, Sun-Hee; Kim, Hee-Jin

    2016-08-01

    Gain-of-function mutations in JAK2 are the molecular hallmarks of polycythaemia vera (PV), one of the myeloproliferative neoplasms. Most (∼95%) patients harbour V617F mutation in exon 15, while the rest have small insertion/deletion mutations in exon 12. We investigated JAK2 mutations in 42 Korean patients with PV. V617F was detected by sequencing and allele-specific PCR. When V617F was negative, sequencing and fragment length analyses were performed to detect exon 12 mutations. As a result, all patients had JAK2 mutations: 37 (88%) harboured V617F, and 5 (12%) had exon 12 mutations. Two patients had novel exon 12 mutations (H538_R541delinsLII and F537_K539delinsVL). Genotype-phenotype correlations demonstrated lower white blood cell and platelet counts in exon 12 mutations than V617F. The frequency of JAK2 exon 12 mutations was higher than expected in Korean patients with PV. Molecular genetic testing for JAK2 exon 12 mutations is mandatory for diagnosis and genotype-phenotype correlations in patients with erythrocytosis and suspected PV. PMID:27198504

  17. Association between JAK2 rs4495487 Polymorphism and Risk of Budd-Chiari Syndrome in China

    PubMed Central

    Zhang, Peijin; Zhang, Yanyan; Zhang, Jing; Wang, Hui; Ma, He; Wang, Wei; Gao, Xiuyin; Xu, Hao; Lu, Zhaojun

    2015-01-01

    Myeloproliferative neoplasms (MPNs) are the leading cause of Budd-Chiari syndrome (BCS), and the C allele of JAK2 rs4495487 was reported to be an additional candidate locus that contributed to MPNs. In the present study, we examined the role of JAK2 rs4495487 in the etiology and clinical presentation of Chinese BCS patients. 300 primary BCS patients and 311 healthy controls were enrolled to evaluate the association between JAK2 rs4495487 polymorphism and risk of BCS. All subjects were detected for JAK2 rs4495487 by real-time PCR. Results. The JAK2 rs4495487 polymorphism was associated with JAK2 V617F-positive BCS patients compared with controls (P < 0.01). The CC genotype increased the risk of BCS in patients with JAK2 V617F mutation compared with individuals presenting TT genotype (OR = 13.60, 95% CI = 2.04–90.79) and non-CC genotype (OR = 12.00, 95% CI = 2.07–69.52). We also observed a significantly elevated risk of combined-type BCS associated with CC genotype in the recessive model (OR = 4.44, 95% CI = 1.31–15.12). This study provides statistical evidence that the JAK2 rs4495487 polymorphism is susceptibility factor JAK2 V617F positive BCS and combined BCS in China. Further larger studies are required to confirm these findings. PMID:26557140

  18. The JAK2 46/1 haplotype predisposes to MPL-mutated myeloproliferative neoplasms

    PubMed Central

    Jones, Amy V.; Campbell, Peter J.; Beer, Philip A.; Schnittger, Susanne; Vannucchi, Alessandro M.; Zoi, Katerina; Percy, Melanie J.; McMullin, Mary Frances; Scott, Linda M.; Tapper, William; Silver, Richard T.; Oscier, David; Harrison, Claire N.; Grallert, Harald; Kisialiou, Aliaksei; Strike, Paul; Chase, Andrew J.; Green, Anthony R.

    2010-01-01

    The 46/1 JAK2 haplotype predisposes to V617F-positive myeloproliferative neoplasms, but the underlying mechanism is obscure. We analyzed essential thrombocythemia patients entered into the PT-1 studies and, as expected, found that 46/1 was overrepresented in V617F-positive cases (n = 404) versus controls (n = 1492, P = 3.9 × 10−11). The 46/1 haplotype was also overrepresented in cases without V617F (n = 347, P = .009), with an excess seen for both MPL exon 10 mutated and V617F, MPL exon 10 nonmutated cases. Analysis of further MPL-positive, V617F-negative cases confirmed an excess of 46/1 (n = 176, P = .002), but no association between MPL mutations and MPL haplotype was seen. An excess of 46/1 was also seen in JAK2 exon 12 mutated cases (n = 69, P = .002), and these mutations preferentially arose on the 46/1 chromosome (P = .029). No association between 46/1 and clinical or laboratory features was seen in the PT-1 cohort either with or without V617F. The excess of 46/1 in JAK2 exon 12 cases is compatible with both the “hypermutability” and “fertile ground” hypotheses, but the excess in MPL-mutated cases argues against the former. No difference in sequence, splicing, or expression of JAK2 was found on 46/1 compared with other haplotypes, suggesting that any functional difference of JAK2 on 46/1, if it exists, must be relatively subtle. PMID:20304805

  19. Dual PI3K/AKT/mTOR inhibitor BEZ235 synergistically enhances the activity of JAK2 inhibitor against cultured and primary human myeloproliferative neoplasm cells.

    PubMed

    Fiskus, Warren; Verstovsek, Srdan; Manshouri, Taghi; Smith, Jacqueline E; Peth, Karissa; Abhyankar, Sunil; McGuirk, Joseph; Bhalla, Kapil N

    2013-05-01

    Hemopoietic progenitor cells (HPC) from myeloproliferative neoplasms (MPN) such as myelofibrosis commonly express mutant JAK2-V617F or other mutations that are associated with increased activities of JAK-STAT5/3, RAS/RAF/MAPK, and PI3K/AKT/mTOR pathways. This confers proliferative and survival advantage on the MPN HPCs. Treatment with JAK tyrosine kinase inhibitor (TKI), for example, TG101209, TG101348 (SAR302503), or INCB018424 (ruxolitinib), inhibits mutant JAK2-mediated signaling. Although effective in reducing constitutional symptoms and splenomegaly, treatment with JAK-TKI does not ameliorate myelofibrosis or significantly improve survival of patients with advanced myelofibrosis. Here, we show that treatment with the dual phosphoinositide-3-kinase (PI3K)/AKT and mTOR inhibitor BEZ235 attenuated PI3K/AKT and mTOR signaling, as well as induced cell-cycle growth arrest and apoptosis of the cultured human JAK2-V617F-expressing HEL92.1.7 (HEL), UKE1 cells, and primary CD34+ myelofibrosis (MF)-MPN cells. Treatment with BEZ235 also induced significant apoptosis of the JAK2-TKI resistant HEL/TGR cells that were selected for resistance against JAK-TKI. Cotreatment with BEZ235 and JAK2-TKI (TG101209 and SAR302503) synergistically induced lethal activity against the cultured and primary CD34+ MPN cells while relatively sparing the normal CD34+ HPCs. These findings create a compelling rationale to determine the in vivo activity of dual PI3K/mTOR inhibitors in combination with JAK inhibitors against myelofibrosis HPCs. PMID:23445613

  20. Co-targeting the PI3K/mTOR and JAK2 signalling pathways produces synergistic activity against myeloproliferative neoplasms

    PubMed Central

    Bartalucci, Niccolò; Tozzi, Lorenzo; Bogani, Costanza; Martinelli, Serena; Rotunno, Giada; Villeval, Jean-Luc; Vannucchi, Alessandro M

    2013-01-01

    Aberrant JAK2 signalling plays a central role in myeloproliferative neoplasms (MPN). JAK2 inhibitors have proven to be clinically efficacious, however, they are not mutation-specific and competent enough to suppress neoplastic clonal haematopoiesis. We hypothesized that, by simultaneously targeting multiple activated signalling pathways, MPN could be more effectively treated. To this end we investigated the efficacy of BEZ235, a dual PI3K/mTOR inhibitor, alone and in combination with the JAK1/JAK2 inhibitor ruxolitinib, in different preclinical models of MPN. Single-agent BEZ235 inhibited the proliferation and induced cell cycle arrest and apoptosis of mouse and human JAK2V617F mutated cell lines at concentrations significantly lower than those required to inhibit the wild-type counterpart, and preferentially prevented colony formation from JAK2V617F knock-in mice and patients' progenitor cells compared with normal ones. Co-treatment of BEZ235 and ruxolitinib produced significant synergism in all these in-vitro models. Co-treatment was also more effective than single drugs in reducing the extent of disease and prolonging survival of immunodeficient mice injected with JAK2V617F-mutated Ba/F3-EPOR cells and in reducing spleen size, decreasing reticulocyte count and improving spleen histopathology in conditional JAK2V617F knock-in mice. In conclusion, combined inhibition of PI3K/mTOR and JAK2 signalling may represent a novel therapeutic strategy in MPN. PMID:24237791

  1. Germline and somatic JAK2 mutations and susceptibility to chronic myeloproliferative neoplasms

    PubMed Central

    2009-01-01

    Myeloproliferative neoplasms (MPNs) are a group of closely related stem-cell-derived clonal proliferative diseases. Most cases are sporadic but first-degree relatives of MPN patients have a five- to seven-fold increased risk for developing an MPN. The tumors of most patients carry a mutation in the Janus kinase 2 gene (JAK2V617F). Recently, three groups have described a strong association of JAK2 germline polymorphisms with MPN in patients positive for JAK2V617F. The somatic mutation occurs primarily on one particular germline JAK2 haplotype, which may account for as much as 50% of the risk to first-degree relatives. This finding provides new directions for unraveling the pathogenesis of MPN. PMID:19490586

  2. Relationship between the 46/1 haplotype of the JAK2 gene and the JAK2 mutational status and allele burden, the initial findings, and the survival of patients with myelofibrosis.

    PubMed

    Martínez-Trillos, Alejandra; Maffioli, Margherita; Colomer, Dolors; Alvarez-Larrán, Alberto; Pereira, Arturo; Angona, Anna; Bellosillo, Beatriz; Cervantes, Francisco

    2014-05-01

    An association has been reported between a specific haplotype of the JAK2 gene, the homozygous 46/1 haplotype, and a predisposition to the development of chromosome Philadelphia-negative myeloproliferative neoplasms. Concerning myelofibrosis (MF), controversy remains on the relationship between the above JAK2 haplotype and the patients' clinicohematological features and survival. Among 132 patients with MF (60 % primary MF, 20 % postpolycythemia vera MF, 20 % post-essential thrombocythemia MF; 59 % JAK2V617F positive) who were analyzed for the JAK2 46/1 haplotype, 29 were found to be homozygous and 53 heterozygous. The homozygous 46/1 haplotype was more often observed in JAK2V617F-positive patients (29.5 versus 11 %, p = 0.012). Moreover, among JAK2V617F-positive patients, those who were homozygous for the 46/1 haplotype had a higher allele burden than the remainder (92 versus 48 %, p = 0.0017). Overall, patients with homozygous 46/1 haplotype showed significantly higher hemoglobin values and higher leukocyte counts, but no association was seen with other clinicohematological features. Finally, no relationship was observed between the JAK2 46/1 haplotype and either the patients' prognostic score or survival. PMID:24337516

  3. JAK2 inhibition has different therapeutic effects according to myeloproliferative neoplasm development in mice

    PubMed Central

    Debeurme, Franck; Lacout, Catherine; Moratal, Claudine; Bagley, Rebecca G; Vainchenker, William; Adrian, Francisco; Villeval, Jean-Luc

    2015-01-01

    JAK2 inhibition therapy is used to treat patients suffering from myeloproliferative neoplasms (MPN). Conflicting data on this therapy are reported possibly linked to the types of inhibitors or disease type. Therefore, we decided to compare in mice the effect of a JAK2 inhibitor, Fedratinib, in MPN models of increasing severity: polycythemia vera (PV), post-PV myelofibrosis (PPMF) and rapid post-essential thrombocythemia MF (PTMF). The models were generated through JAK2 activation by the JAK2V617F mutation or MPL constant stimulation. JAK2 inhibition induced a correction of splenomegaly, leucocytosis and microcytosis in all three MPN models. However, the effects on fibrosis, osteosclerosis, granulocytosis, erythropoiesis or platelet counts varied according to the disease severity stage. Strikingly, complete blockade of fibrosis and osteosclerosis was observed in the PPMF model, linked to correction of MK hyper/dysplasia, but not in the PTMF model, suggesting that MF development may also become JAK2-independent. Interestingly, we originally found a decreased in the JAK2V617F allele burden in progenitor cells from the spleen but not in other cell types. Overall, this study shows that JAK2 inhibition has different effects according to disease phenotypes and can (i) normalize platelet counts, (ii) prevent the development of marrow fibrosis/osteosclerosis at an early stage and (iii) reduce splenomegaly through blockage of stem cell mobilization in the spleen. PMID:26176817

  4. JAK2 Allele Burden in the Myeloproliferative Neoplasms: Effects on Phenotype, Prognosis and Change with Treatment

    PubMed Central

    Vannucchi, Alessandro M.; Pieri, Lisa; Guglielmelli, Paola

    2011-01-01

    The field of Philadelphia-chromosome-negative chronic myeloproliferative neoplasms (MPNs) has recently witnessed tremendous advances in the basic knowledge of disease pathophysiology that followed the identification of mutations in JAK2 and MPL. These discoveries led to a revision of the criteria employed for diagnosis by the World Health Organization. The prognostic role of the JAK2V617F mutation and of its allelic burden has been the objective of intensive research using a variety of cellular and animal models as well as in large series of patients. While a definitive position cannot yet been taken on all of the issues, there is a consensus that the presence of higher V617F allele burden, that is on the basis of a stronger activation of intracellular signalling pathways, is associated with the clinical phenotype of polycythemia vera and with defined haematological and clinical markers indicative of a more aggressive phenotype. On the other hand, a low allele burden in myelofibrosis is associated with reduced survival. Finally, a significant reduction of JAK2 V617F allele burden has been demonstrated in patients treated with interferon, while the effects of novel JAK1 and JAK2 inhibitors have not yet been fully ascertained. PMID:23556073

  5. JAK2 or CALR mutation status defines subtypes of essential thrombocythemia with substantially different clinical course and outcomes.

    PubMed

    Rumi, Elisa; Pietra, Daniela; Ferretti, Virginia; Klampfl, Thorsten; Harutyunyan, Ashot S; Milosevic, Jelena D; Them, Nicole C C; Berg, Tiina; Elena, Chiara; Casetti, Ilaria C; Milanesi, Chiara; Sant'antonio, Emanuela; Bellini, Marta; Fugazza, Elena; Renna, Maria C; Boveri, Emanuela; Astori, Cesare; Pascutto, Cristiana; Kralovics, Robert; Cazzola, Mario

    2014-03-01

    Patients with essential thrombocythemia may carry JAK2 (V617F), an MPL substitution, or a calreticulin gene (CALR) mutation. We studied biologic and clinical features of essential thrombocythemia according to JAK2 or CALR mutation status and in relation to those of polycythemia vera. The mutant allele burden was lower in JAK2-mutated than in CALR-mutated essential thrombocythemia. Patients with JAK2 (V617F) were older, had a higher hemoglobin level and white blood cell count, and lower platelet count and serum erythropoietin than those with CALR mutation. Hematologic parameters of patients with JAK2-mutated essential thrombocythemia or polycythemia vera were related to the mutant allele burden. While no polycythemic transformation was observed in CALR-mutated patients, the cumulative risk was 29% at 15 years in those with JAK2-mutated essential thrombocythemia. There was no significant difference in myelofibrotic transformation between the 2 subtypes of essential thrombocythemia. Patients with JAK2-mutated essential thrombocythemia and those with polycythemia vera had a similar risk of thrombosis, which was twice that of patients with the CALR mutation. These observations are consistent with the notion that JAK2-mutated essential thrombocythemia and polycythemia vera represent different phenotypes of a single myeloproliferative neoplasm, whereas CALR-mutated essential thrombocythemia is a distinct disease entity. PMID:24366362

  6. Molecular drug targets in myeloproliferative neoplasms: mutant ABL1, JAK2, MPL, KIT, PDGFRA, PDGFRB and FGFR1

    PubMed Central

    Tefferi, Ayalew

    2009-01-01

    Abstract Therapeutically validated oncoproteins in myeloproliferative neoplasms (MPN) include BCR-ABL1 and rearranged PDGFR proteins. The latter are products of intra- (e.g. FIP1L1-PDGFRA) or inter-chromosomal (e.g.ETV6-PDGFRB) gene fusions. BCR-ABL1 is associated with chronic myelogenous leukaemia (CML) and mutant PDGFR with an MPN phenotype characterized by eosinophilia and in addition, in case of FIP1L1-PDGFRA, bone marrow mastocytosis. These genotype-phenotype associations have been effectively exploited in the development of highly accurate diagnostic assays and molecular targeted therapy. It is hoped that the same will happen in other MPN with specific genetic alterations: polycythemia vera (JAK2V617F and other JAK2 mutations), essential thrombocythemia (JAK2V617F and MPL515 mutations), primary myelofibrosis (JAK2V617F and MPL515 mutations), systemic mastocytosis (KITD816V and other KIT mutations) and stem cell leukaemia/lymphoma (ZNF198-FGFR1 and other FGFR1 fusion genes). The current review discusses the above-listed mutant molecules in the context of their value as drug targets. PMID:19175693

  7. Correlation between JAK2 allele burden and pulmonary arterial hypertension and hematological parameters in Philadelphia negative JAK2 positive myeloproliferative neoplasms. An Egyptian experience.

    PubMed

    Mattar, Mervat M; Morad, Mohammed Abdel Kader; El Husseiny, Noha M; Ali, Noha H; El Demerdash, Doaa M

    2016-10-01

    Myeloproliferative neoplasms are characterized by a common stem cell-derived clonal proliferation, but are phenotypically diverse. JAK2 is mutated (V617F) in more than 90 % of patients with polycythemia vera (PV) and approximately 60 % of patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF). Pulmonary arterial hypertension (PAH) is a major complication of several hematological disorders. Chronic myeloproliferative disorders associated with PAH have been included in group five for which the etiology is unclear and/or multifactorial. The aim of this study is to screen Egyptian Philadelphia negative JAK2 positive myeloproliferative neoplasm patients for the presence of PAH and its correlation with JAK2 allele burden. We also made a review for correlation of JAK2 allele with hematological parameters comparing our results to others. We enrolled 60 patients with Philadelphia negative myeloproliferative neoplasms. All patients enrolled in the study were subjected to laboratory and imaging workup in the form of CBC, liver, kidney profile, bone marrow examination, abdominal ultrasonography, and transthoracic echocardiography. Our results revealed that 7 patients out of 60 (11.67 %) had pulmonary arterial hypertension, 3 patients with PMF, 2 patients with PRV, and 2 patients with ET, and its correlation with JAK2 allele burden was not statistically significant. Correlation analysis between JAK2 V617F allele burden and other parameters revealed: statistical significant correlation with age, HB, HCT, PLT, UA, LDH, and splenic diameter but insignificant correlation with WBCs and PAH. Pulmonary arterial hypertension prevalence in our study was 11.67 % and no significant correlation with JAK 2 allele burden. Our study is the largest one up to our knowledge that studies the association between its prevalence and JAK2 burden. PMID:27468853

  8. Safety and Efficacy of TG101348, a Selective JAK2 Inhibitor, in Myelofibrosis

    PubMed Central

    Pardanani, Animesh; Gotlib, Jason R.; Jamieson, Catriona; Cortes, Jorge E.; Talpaz, Moshe; Stone, Richard M.; Silverman, Michael H.; Gilliland, D. Gary; Shorr, Jolene; Tefferi, Ayalew

    2011-01-01

    Purpose Myelofibrosis is a myeloid malignancy associated with anemia, splenomegaly, and constitutional symptoms. Patients frequently harbor JAK-STAT activating mutations that are sensitive to TG101348, a selective small-molecule Janus kinase 2 (JAK2) inhibitor. Patients and Methods In a multicenter phase I trial, oral TG101348 was administered once a day to patients with high- or intermediate-risk primary or post–polycythemia vera/essential thrombocythemia myelofibrosis. Results Fifty-nine patients were treated, including 28 in the dose-escalation phase. The maximum-tolerated dose was 680 mg/d, and dose-limiting toxicity was a reversible and asymptomatic increase in the serum amylase level. Forty-three patients (73%) continued treatment beyond six cycles; the median cumulative exposure to TG101348 was 380 days. Adverse events included nausea, vomiting, diarrhea, anemia, and thrombocytopenia; corresponding grades 3 to 4 incidence rates were 3%, 3%, 10%, 35%, and 24%. TG101348 treatment had modest effect on serum cytokine levels, but greater than half of the patients with early satiety, night sweats, fatigue, pruritus, and cough achieved rapid and durable improvement in these symptoms. By six and 12 cycles of treatment, 39% and 47% of patients, respectively, had achieved a spleen response per International Working Group criteria. The majority of patients with leukocytosis or thrombocytosis at baseline (n = 28 and n = 10, respectively) achieved normalization of blood counts after six (57% and 90%, respectively) and 12 (56% and 88%, respectively) cycles. A significant decrease in JAK2 V617F allele burden was observed at 6 months in mutation-positive patients (n = 51; P = .04), particularly in the subgroup with allele burden greater than 20% (n = 23; P < .01); the decrease was durable at 12 months. Conclusion TG101348 is well tolerated and produces significant reduction in disease burden and durable clinical benefit in patients with myelofibrosis. PMID:21220608

  9. Bleeding complications after arthroscopy in a JAK2V617F-positive patient with essential thrombocythemia and acquired von Willebrand syndrome (AVWS).

    PubMed

    Rupa-Matysek, Joanna; Lewandowski, Krzysztof; Lewandowska, Maria; Wojtasińska, Ewelina; Wojtaszewska, Marzena Liliana; Walczak, Michał; Bykowska, Ksenia; Komarnicki, Mieczysław

    2015-04-01

    Acquired von Willebrand syndrome (AVWS) is an acquired bleeding disorder with clinical and laboratory features similar to those of the inherited form of the disease. AVWS is reported in many disorders, most frequently in myeloproliferative neoplasms and in, among others, essential thrombocythemia (ET). Interestingly, ET is associated with both the thrombotic and haemorrhagic complications, which occur in 20 % and 5-30 % of patients, respectively. The present report concerns a 38-year-old man, suffering from ET, who presented with two episodes of post-arthroscopic joint bleeding after synovectomy required for the treatment of synovial hypertrophy and chronic left knee joint synovitis. We discuss the current diagnostic approaches, as well as the risk factors predisposing to bleeding and its management, in patients with essential thrombocythemia. PMID:25432436

  10. ATP binding to the pseudokinase domain of JAK2 is critical for pathogenic activation.

    PubMed

    Hammarén, Henrik M; Ungureanu, Daniela; Grisouard, Jean; Skoda, Radek C; Hubbard, Stevan R; Silvennoinen, Olli

    2015-04-14

    Pseudokinases lack conserved motifs typically required for kinase activity. Nearly half of pseudokinases bind ATP, but only few retain phosphotransfer activity, leaving the functional role of nucleotide binding in most cases unknown. Janus kinases (JAKs) are nonreceptor tyrosine kinases with a tandem pseudokinase-kinase domain configuration, where the pseudokinase domain (JAK homology 2, JH2) has important regulatory functions and harbors mutations underlying hematological and immunological diseases. JH2 of JAK1, JAK2, and TYK2 all bind ATP, but the significance of this is unclear. We characterize the role of nucleotide binding in normal and pathogenic JAK signaling using comprehensive structure-based mutagenesis. Disruption of JH2 ATP binding in wild-type JAK2 has only minor effects, and in the presence of type I cytokine receptors, the mutations do not affect JAK2 activation. However, JH2 mutants devoid of ATP binding ameliorate the hyperactivation of JAK2 V617F. Disrupting ATP binding in JH2 also inhibits the hyperactivity of other pathogenic JAK2 mutants, as well as of JAK1 V658F, and prevents induction of erythrocytosis in a JAK2 V617F myeloproliferative neoplasm mouse model. Molecular dynamic simulations and thermal-shift analysis indicate that ATP binding stabilizes JH2, with a pronounced effect on the C helix region, which plays a critical role in pathogenic activation of JAK2. Taken together, our results suggest that ATP binding to JH2 serves a structural role in JAKs, which is required for aberrant activity of pathogenic JAK mutants. The inhibitory effect of abrogating JH2 ATP binding in pathogenic JAK mutants may warrant novel therapeutic approaches. PMID:25825724

  11. Discovery of 1-methyl-1H-imidazole derivatives as potent Jak2 inhibitors.

    PubMed

    Su, Qibin; Ioannidis, Stephanos; Chuaqui, Claudio; Almeida, Lynsie; Alimzhanov, Marat; Bebernitz, Geraldine; Bell, Kirsten; Block, Michael; Howard, Tina; Huang, Shan; Huszar, Dennis; Read, Jon A; Rivard Costa, Caroline; Shi, Jie; Su, Mei; Ye, Minwei; Zinda, Michael

    2014-01-01

    Structure based design, synthesis, and biological evaluation of a novel series of 1-methyl-1H-imidazole, as potent Jak2 inhibitors to modulate the Jak/STAT pathway, are described. Using the C-ring fragment from our first clinical candidate AZD1480 (24), optimization of the series led to the discovery of compound 19a, a potent, orally bioavailable Jak2 inhibitor. Compound 19a displayed a high level of cellular activity in hematopoietic cell lines harboring the V617F mutation and in murine BaF3 TEL-Jak2 cells. Compound 19a demonstrated significant tumor growth inhibition in a UKE-1 xenograft model within a well-tolerated dose range. PMID:24359159

  12. High Resolution Melting Analysis for JAK2 Exon 14 and Exon 12 Mutations

    PubMed Central

    Rapado, Inmaculada; Grande, Silvia; Albizua, Enriqueta; Ayala, Rosa; Hernández, José-Angel; Gallardo, Miguel; Gilsanz, Florinda; Martinez-Lopez, Joaquin

    2009-01-01

    JAK2 mutations are important criteria for the diagnosis of Philadelphia chromosome-negative myeloproliferative neoplasms. We aimed to assess JAK2 exon 14 and exon 12 mutations by high-resolution melting (HRM) analysis, which allows variation screening. The exon 14 analysis included 163 patients with polycythemia vera, secondary erythrocytoses, essential thrombocythemia, or secondary thrombocytoses, and 126 healthy subjects. The study of exon 12 included 40 JAK2 V617F-negative patients (nine of which had polycythemia vera, and 31 with splanchnic vein thrombosis) and 30 healthy subjects. HRM analyses of JAK2 exons 14 and 12 gave analytical sensitivities near 1% and both intra- and interday coefficients of variation of less than 1%. For HRM analysis of JAK2 exon 14 in polycythemia vera and essential thrombocythemia, clinical sensitivities were 93.5% and 67.9%, clinical specificities were 98.8% and 97.0%, positive predictive values were 93.5% and 79.2%, and negative predictive values were 98.8% and 94.6, respectively. Correlations were observed between the results from HRM and three commonly used analytical methods. The JAK2 exon 12 HRM results agreed completely with those from sequencing analysis, and the three mutations in exon 12 were detected by both methods. Hence, HRM analysis of exons 14 and 12 in JAK2 shows better diagnostic values than three other routinely used methods against which it was compared. In addition, HRM analysis has the advantage of detecting unknown mutations. PMID:19225136

  13. Resolution of bone marrow fibrosis in a patient receiving JAK1/JAK2 inhibitor treatment with ruxolitinib

    PubMed Central

    Wilkins, Bridget S.; Radia, Deepti; Woodley, Claire; Farhi, Sarah El; Keohane, Clodagh; Harrison, Claire N.

    2013-01-01

    Ruxolitinib, a JAK1/JAK2 inhibitor, is currently the only pharmacological agent approved for the treatment of myelofibrosis. Approval was based on findings from two phase 3 trials comparing ruxolitinib with placebo (COMFORT-I) and with best available therapy (COMFORT-II) for the treatment of primary or secondary myelofibrosis. In those pivotal trials, ruxolitinib rapidly improved splenomegaly, disease-related symptoms, and quality of life and prolonged survival compared with both placebo and conventional treatments. However, for reasons that are currently unclear, there were only modest histomorphological changes in the bone marrow, and only a subset of patients had significant reductions in JAK2 V617F clonal burden. Here we describe a patient with post-polycythemia vera myelofibrosis who received ruxolitinib at our institution (Guy’s and St. Thomas’ NHS Foundation Trust, London, United Kingdom) as part of the COMFORT-II study. While on treatment, the patient had dramatic improvements in splenomegaly and symptoms shortly after starting ruxolitinib. With longer treatment, the patient had marked reductions in JAK2 V617F allele burden, and fibrosis of the bone marrow resolved after approximately 3 years of ruxolitinib treatment. To our knowledge, this is the first detailed case report of resolution of fibrosis with a JAK1/JAK2 inhibitor. Trial registration: ClinicalTrials.gov Identifier: NCT00934544. PMID:24056820

  14. JAK2 inhibitors do not affect stem cells present in the spleens of patients with myelofibrosis.

    PubMed

    Wang, Xiaoli; Ye, Fei; Tripodi, Joseph; Hu, Cing Siang; Qiu, Jiajing; Najfeld, Vesna; Novak, Jesse; Li, Yan; Rampal, Raajit; Hoffman, Ronald

    2014-11-01

    Dysregulation of Janus kinase (JAK)-signal transducer and activator of transcription signaling is central to the pathogenesis of myelofibrosis (MF). JAK2 inhibitor therapy in MF patients results in a rapid reduction of the degree of splenomegaly, yet the mechanism underlying this effect remains unknown. The in vitro treatment of splenic and peripheral blood MF CD34(+) cells with the JAK1/2/3 inhibitor, AZD1480, reduced the absolute number of CD34(+), CD34(+)CD90(+), and CD34(+)CXCR4(+) cells as well as assayable hematopoietic progenitor cells (HPCs) irrespective of the JAK2 and calreticulin mutational status. Furthermore, AZD1480 treatment resulted in only a modest reduction in the proportion of HPCs that were JAK2V617F(+) or had a chromosomal abnormality. To study the effect of the drug on MF stem cells (MF-SCs), splenic CD34(+) cells were treated with AZD1480 and transplanted into immunodeficient mice. JAK2 inhibitor therapy did not affect the degree of human cell chimerism or the proportion of malignant donor cells. These data indicate that JAK2 inhibitor treatment affects a subpopulation of MF-HPCs, while sparing another HPC subpopulation as well as MF-SCs. This pattern of activity might account for the reduction in spleen size observed with JAK2 inhibitor therapy as well as the rapid increase in spleen size observed frequently with its discontinuation. PMID:25193869

  15. JAK2 inhibitors do not affect stem cells present in the spleens of patients with myelofibrosis

    PubMed Central

    Wang, Xiaoli; Ye, Fei; Tripodi, Joseph; Hu, Cing Siang; Qiu, Jiajing; Najfeld, Vesna; Novak, Jesse; Li, Yan; Rampal, Raajit

    2014-01-01

    Dysregulation of Janus kinase (JAK)–signal transducer and activator of transcription signaling is central to the pathogenesis of myelofibrosis (MF). JAK2 inhibitor therapy in MF patients results in a rapid reduction of the degree of splenomegaly, yet the mechanism underlying this effect remains unknown. The in vitro treatment of splenic and peripheral blood MF CD34+ cells with the JAK1/2/3 inhibitor, AZD1480, reduced the absolute number of CD34+, CD34+CD90+, and CD34+CXCR4+ cells as well as assayable hematopoietic progenitor cells (HPCs) irrespective of the JAK2 and calreticulin mutational status. Furthermore, AZD1480 treatment resulted in only a modest reduction in the proportion of HPCs that were JAK2V617F+ or had a chromosomal abnormality. To study the effect of the drug on MF stem cells (MF-SCs), splenic CD34+ cells were treated with AZD1480 and transplanted into immunodeficient mice. JAK2 inhibitor therapy did not affect the degree of human cell chimerism or the proportion of malignant donor cells. These data indicate that JAK2 inhibitor treatment affects a subpopulation of MF-HPCs, while sparing another HPC subpopulation as well as MF-SCs. This pattern of activity might account for the reduction in spleen size observed with JAK2 inhibitor therapy as well as the rapid increase in spleen size observed frequently with its discontinuation. PMID:25193869

  16. Discovery of novel Jak2-Stat pathway inhibitors with extended residence time on target.

    PubMed

    Guan, Huiping; Lamb, Michelle L; Peng, Bo; Huang, Shan; Degrace, Nancy; Read, Jon; Hussain, Syeed; Wu, Jiaquan; Rivard, Caroline; Alimzhanov, Marat; Bebernitz, Geraldine; Bell, Kirsten; Ye, Minwei; Zinda, Michael; Ioannidis, Stephanos

    2013-05-15

    The discovery of the activating mutation V617F in the JH2 domain of Jak2 and the modulation of oncogenic Stat3 by Jak2 inhibitors have spurred a great interest in the inhibition of the Jak2/Stat pathway in oncology. In this Letter, we communicate the discovery of novel inhibitors of the Jak2/Stat5 axis, the N-(1H-pyrazol-3-yl)pyrimidin-2-amino derivatives. The rationale, synthesis and biological evaluation of these derivatives are reported. Two lead analogs from this series, 6 and 9, displayed prolonged residence time on Jak2, at enzymatic level. Although 6 and 9 exhibited moderate selectivity in a selected kinase panel, we chose to test these inhibitors in vivo as a consequence to their long residence time. However, extended inhibition of Jak2 due to the long residence time, in the form of inhibiting phosphorylation of downstream Stat5, was not recapitulated in an in vivo setting. PMID:23562594

  17. [JAK2 inhibitors].

    PubMed

    Hernández Boluda, Juan Carlos; Gómez, Montse; Pérez, Ariadna

    2016-07-15

    Pharmacological inhibition of the kinase activity of JAK proteins can interfere with the signaling of immunomodulatory cytokines and block the constitutive activation of the JAK-STAT pathway that characterizes certain malignancies, including chronic myeloproliferative neoplasms. JAK inhibitors may, therefore, be useful to treat malignancies as well as inflammatory or immune disorders. Currently, the most significant advances have been made in the treatment of myelofibrosis, where these drugs may lead to a remarkable improvement in the control of hyperproliferative manifestations. However, available data suggest that this treatment is not curative of myelofibrosis. In general, JAK2 inhibition induces cytopaenias, with this being considered a class side-effect. By contrast, the extrahaematologic toxicity profile varies significantly among the different JAK inhibitors. At present, there are several clinical trials evaluating the combination of ruxolitinib with other drugs, in order to improve its therapeutic activity as well as reducing haematologic toxicity. PMID:27033437

  18. Combined Targeting of JAK2 and Bcl-2/Bcl-xL to Cure Mutant JAK2-Driven Malignancies and Overcome Acquired Resistance to JAK2 Inhibitors

    PubMed Central

    Waibel, Michaela; Solomon, Vanessa S.; Knight, Deborah A.; Ralli, Rachael A.; Kim, Sang-Kyu; Banks, Kellie-Marie; Vidacs, Eva; Virely, Clemence; Sia, Keith C.S.; Bracken, Lauryn S.; Collins-Underwood, Racquel; Drenberg, Christina; Ramsey, Laura B.; Meyer, Sara C.; Takiguchi, Megumi; Dickins, Ross A.; Levine, Ross; Ghysdael, Jacques; Dawson, Mark A.; Lock, Richard B.; Mullighan, Charles G.; Johnstone, Ricky W.

    2013-01-01

    Summary To design rational therapies for JAK2-driven hematological malignancies, we functionally dissected the key survival pathways downstream of hyperactive JAK2. In tumors driven by mutant JAK2, Stat1, Stat3, Stat5, and the Pi3k and Mek/Erk pathways were constitutively active, and gene expression profiling of TEL-JAK2 T-ALL cells revealed the upregulation of prosurvival Bcl-2 family genes. Combining the Bcl-2/Bcl-xL inhibitor ABT-737 with JAK2 inhibitors mediated prolonged disease regressions and cures in mice bearing primary human and mouse JAK2 mutant tumors. Moreover, combined targeting of JAK2 and Bcl-2/Bcl-xL was able to circumvent and overcome acquired resistance to single-agent JAK2 inhibitor treatment. Thus, inhibiting the oncogenic JAK2 signaling network at two nodal points, at the initiating stage (JAK2) and the effector stage (Bcl-2/Bcl-xL), is highly effective and provides a clearly superior therapeutic benefit than targeting just one node. Therefore, we have defined a potentially curative treatment for hematological malignancies expressing constitutively active JAK2. PMID:24268771

  19. Discovery of the macrocycle 11-(2-pyrrolidin-1-yl-ethoxy)-14,19-dioxa-5,7,26-triaza-tetracyclo[19.3.1.1(2,6).1(8,12)]heptacosa-1(25),2(26),3,5,8,10,12(27),16,21,23-decaene (SB1518), a potent Janus kinase 2/fms-like tyrosine kinase-3 (JAK2/FLT3) inhibitor for the treatment of myelofibrosis and lymphoma.

    PubMed

    William, Anthony D; Lee, Angeline C-H; Blanchard, Stéphanie; Poulsen, Anders; Teo, Ee Ling; Nagaraj, Harish; Tan, Evelyn; Chen, Dizhong; Williams, Meredith; Sun, Eric T; Goh, Kee Chuan; Ong, Wai Chung; Goh, Siok Kun; Hart, Stefan; Jayaraman, Ramesh; Pasha, Mohammed Khalid; Ethirajulu, Kantharaj; Wood, Jeanette M; Dymock, Brian W

    2011-07-14

    Discovery of the activating mutation V617F in Janus Kinase 2 (JAK2(V617F)), a tyrosine kinase critically involved in receptor signaling, recently ignited interest in JAK2 inhibitor therapy as a treatment for myelofibrosis (MF). Herein, we describe the design and synthesis of a series of small molecule 4-aryl-2-aminopyrimidine macrocycles and their biological evaluation against the JAK family of kinase enzymes and FLT3. The most promising leads were assessed for their in vitro ADME properties culminating in the discovery of 21c, a potent JAK2 (IC(50) = 23 and 19 nM for JAK2(WT) and JAK2(V617F), respectively) and FLT3 (IC(50) = 22 nM) inhibitor with selectivity against JAK1 and JAK3 (IC(50) = 1280 and 520 nM, respectively). Further profiling of 21c in preclinical species and mouse xenograft and allograft models is described. Compound 21c (SB1518) was selected as a development candidate and progressed into clinical trials where it is currently in phase 2 for MF and lymphoma. PMID:21604762

  20. Molecular insights into regulation of JAK2 in myeloproliferative neoplasms

    PubMed Central

    Hubbard, Stevan R.

    2015-01-01

    The critical role of Janus kinase-2 (JAK2) in regulation of myelopoiesis was established 2 decades ago, but identification of mutations in the pseudokinase domain of JAK2 in myeloproliferative neoplasms (MPNs) and in other hematologic malignancies highlighted the role of JAK2 in human disease. These findings have revolutionized the diagnostics of MPNs and led to development of novel JAK2 therapeutics. However, the molecular mechanisms by which mutations in the pseudokinase domain lead to hyperactivation of JAK2 and clinical disease have been unclear. Here, we describe recent advances in the molecular characterization of the JAK2 pseudokinase domain and how pathogenic mutations lead to constitutive activation of JAK2. PMID:25824690

  1. A case of myeloproliferative neoplasm with a normal complete blood cell count: A novel problem of the JAK2 era

    PubMed Central

    YE, XIU-PENG; BAO, SHEN; GAO, HUAN-MIN; GUO, YING; WEI, YU-PING

    2016-01-01

    The present study reported a case of a myeloproliferative neoplasm (MPN) in a patient with a normal complete blood cell count. Bone marrow biopsy showed bone marrow hyperplasia, an elevated megakaryocyte count, megakaryocytic dysplasia and pleomorphic changes, multiple megakaryocyte clusters and focal reticulin fiber hyperplasia. Furthermore, genetic analysis revealed that the patient was positive for the JAK2-V617F mutation, and negative for the JAK2 exon 12 and 13 mutations and the BCR-ABL (p210) fusion gene. The patient's condition was basically stable and at the time of writing, the patient remained in a stable condition with no specific symptoms of disease. The present study also analyzed the diagnostic and clinical features of MPNs, and a literature review was performed. MPN with a normal complete blood cell count is a rare disease, and attention should be focused on this entity in the clinic. PMID:26998136

  2. Evaluation of the association between the JAK2 46/1 haplotype and chronic myeloproliferative neoplasms in a Brazilian population

    PubMed Central

    Silva, Sarah Pagliarini- e-; Santos, Bruna Cunha; de Figueiredo Pereira, Elizangela Mendes; Ferreira, Mari Ellen; Baraldi, Elaine Cristina; Sell, Ana Maria; Visentainer, Jeane Eliete Laguila

    2013-01-01

    OBJECTIVE: The JAK2 46/1 haplotype has recently been described as a major contributing factor to the development of myeloproliferative neoplasm, whether positive or negative for the JAK2 V617F mutation. The G allele, identified by a single-nucleotide polymorphism known as JAK2 rs10974944, is part of the JAK2 46/1 haplotype. The aim of this study was to verify the association between the presence of the G allele and the development of BCR-ABL-negative chronic myeloproliferative neoplasms in our population. METHODS: Blood and oral mucosa swab samples were obtained from 56 patients of two local Brazilian hospitals who had previously been diagnosed with BCR-ABL-negative chronic myeloproliferative neoplasms. Blood samples from 90 local blood donors were used as controls. The presence of the G allele was assessed using a PCR-RFLP assay after extracting DNA from the samples. RESULTS: The presence of the G allele was strongly associated with the presence of BCR-ABL-negative chronic myeloproliferative neoplasms (p = 0.0001; OR = 2.674; 95% CI = 1.630−4.385) in the studied population. CONCLUSION: In agreement with previous reports, the JAK2 46/1 haplotype, represented in this study by the presence of the G allele, is an important predisposing factor in the oncogenetic development of these neoplasms in our population. PMID:23420150

  3. JAK2 exon 12 mutant mice display isolated erythrocytosis and changes in iron metabolism favoring increased erythropoiesis.

    PubMed

    Grisouard, Jean; Li, Sai; Kubovcakova, Lucia; Rao, Tata Nageswara; Meyer, Sara C; Lundberg, Pontus; Hao-Shen, Hui; Romanet, Vincent; Murakami, Masato; Radimerski, Thomas; Dirnhofer, Stephan; Skoda, Radek C

    2016-08-11

    Mutations in JAK2 exon 12 are frequently found in patients with polycythemia vera (PV) that do not carry a JAK2-V617F mutation. The majority of these patients display isolated erythrocytosis. We generated a mouse model that expresses JAK2-N542-E543del, the most frequent JAK2 exon 12 mutation found in PV patients. Mice expressing the human JAK2-N542-E543del (Ex12) showed a strong increase in red blood cell parameters but normal neutrophil and platelet counts, and reduced overall survival. Erythropoiesis was increased in the bone marrow and spleen, with normal megakaryopoiesis and absence of myelofibrosis in histopathology. Erythroid progenitors and precursors were increased in hematopoietic tissues, but the numbers of megakaryocytic precursors were unchanged. Phosphorylation Stat3 and Erk1/2 proteins were increased, and a trend toward increased phospho-Stat5 and phospho-Stat1 was noted. However, Stat1 knock out in Ex12 mice induced no changes in platelet or red cell parameters, indicating that Stat1 does not play a central role in mediating the effects of Ex12 signaling on megakaryopoiesis or erythropoiesis. Ex12 mice showed decreased expression of hepcidin and increased expression of transferrin receptor-1 and erythroferrone, suggesting that the strong erythroid phenotype in Ex12 mutant mice is favored by changes in iron metabolism that optimize iron availability to allow maximal production of red cells. PMID:27288519

  4. The mutation profile of JAK2 and CALR in Chinese Han patients with Philadelphia chromosome-negative myeloproliferative neoplasms

    PubMed Central

    2014-01-01

    Mutations in JAK2, MPL and CALR are highly relevant to the Philadelphia chromosome (Ph)-negative myeloproliferative neoplasms (MPNs). We performed high resolution melting analysis and Sanger sequencing together with T-A cloning to elucidate the unique mutation profile of these genes, in Chinese patients with MPNs. Peripheral blood DNA samples were obtained from 80 patients with polycythemia vera (PV), 80 patients with essential thrombocytosis (ET) and 50 patients with primary myelofibrosis (PMF). Ten PV patients were identified with diverse JAK2 exon 12 mutations. Five novel JAK2 Exon 12 mutation patterns (M532V/E543G, N533D, M535I/H538Y/K549I, E543G and D544N) were described. JAK2 V617F was detected in 140 samples (66 PV, 45 ET and 29 PMF). JAK2 Exon 12 mutations were prevalent (13%) and variable in the Chinese patients. Compared with PV patients with JAK2 V617F mutations, PV patients with JAK2 exon 12 mutations had an earlier median onset of disease (P = 0.0013). MPL W515L/K mutations were discerned in 4 ET and 3 PMF patients. Two kinds of CALR mutation, c. 1179_1230del and c. 1234_1235insTTGTC were detected in 20 ET and 16 PMF patients. A novel CALR mutation pattern (c. 1173_1223del/c. 1179_1230del) was identified in 2 PMF samples. In addition, 17 scattered point mutations in CALR c.1153 to c.1255 were also detected in 13 cases with CALR frame-shifting variations and 2 cases without CALR frame-shifting variations. Female patients showed a predisposition to CALR mutations (P = 0.0035). Chinese Ph-negative MPN patients have a unique mutation landscape in the common molecular markers of MPN diagnosis. Validation of the molecular diagnostic pipeline should be emphasized since there is a considerable ethnical diversity in the molecular profiles of Ph-negative MPNs. PMID:25023898

  5. Whole-exome sequencing identifies novel MPL and JAK2 mutations in triple-negative myeloproliferative neoplasms

    PubMed Central

    Milosevic Feenstra, Jelena D.; Nivarthi, Harini; Gisslinger, Heinz; Leroy, Emilie; Rumi, Elisa; Chachoua, Ilyas; Bagienski, Klaudia; Kubesova, Blanka; Pietra, Daniela; Gisslinger, Bettina; Milanesi, Chiara; Jäger, Roland; Chen, Doris; Berg, Tiina; Schalling, Martin; Schuster, Michael; Bock, Christoph; Constantinescu, Stefan N.; Cazzola, Mario

    2016-01-01

    Essential thrombocythemia (ET) and primary myelofibrosis (PMF) are chronic diseases characterized by clonal hematopoiesis and hyperproliferation of terminally differentiated myeloid cells. The disease is driven by somatic mutations in exon 9 of CALR or exon 10 of MPL or JAK2-V617F in >90% of the cases, whereas the remaining cases are termed “triple negative.” We aimed to identify the disease-causing mutations in the triple-negative cases of ET and PMF by applying whole-exome sequencing (WES) on paired tumor and control samples from 8 patients. We found evidence of clonal hematopoiesis in 5 of 8 studied cases based on clonality analysis and presence of somatic genetic aberrations. WES identified somatic mutations in 3 of 8 cases. We did not detect any novel recurrent somatic mutations. In 3 patients with clonal hematopoiesis analyzed by WES, we identified a somatic MPL-S204P, a germline MPL-V285E mutation, and a germline JAK2-G571S variant. We performed Sanger sequencing of the entire coding region of MPL in 62, and of JAK2 in 49 additional triple-negative cases of ET or PMF. New somatic (T119I, S204F, E230G, Y591D) and 1 germline (R321W) MPL mutation were detected. All of the identified MPL mutations were gain-of-function when analyzed in functional assays. JAK2 variants were identified in 5 of 57 triple-negative cases analyzed by WES and Sanger sequencing combined. We could demonstrate that JAK2-V625F and JAK2-F556V are gain-of-function mutations. Our results suggest that triple-negative cases of ET and PMF do not represent a homogenous disease entity. Cases with polyclonal hematopoiesis might represent hereditary disorders. PMID:26423830

  6. Tyrosines 868, 966, and 972 in the Kinase Domain of JAK2 Are Autophosphorylated and Required for Maximal JAK2 Kinase Activity

    PubMed Central

    Argetsinger, Lawrence S.; Stuckey, Jeanne A.; Robertson, Scott A.; Koleva, Rositsa I.; Cline, Joel M.; Marto, Jarrod A.; Myers, Martin G.; Carter-Su, Christin

    2010-01-01

    Janus kinase 2 (JAK2) is activated by a majority of cytokine family receptors including receptors for GH, leptin, and erythropoietin. To identify novel JAK2-regulatory and/or -binding sites, we set out to identify autophosphorylation sites in the kinase domain of JAK2. Two-dimensional phosphopeptide mapping of in vitro autophosphorylated JAK2 identified tyrosines 868, 966, and 972 as sites of autophosphorylation. Phosphorylated tyrosines 868 and 972 were also identified by mass spectrometry analysis of JAK2 activated by an erythropoietin-bound chimeric erythropoietin receptor/leptin receptor. Phosphospecific antibodies suggest that the phosphorylation of all three tyrosines increases in response to GH. Compared with wild-type JAK2, which is constitutively active when overexpressed, JAK2 lacking tyrosine 868, 966, or 972 has substantially reduced activity. Coexpression with GH receptor and protein tyrosine phosphatase1B allowed us to investigate GH-dependent activation of these mutated JAK2s in human embryonic kidney 293T cells. All three mutated JAK2s are activated by GH, although to a lesser extent than wild-type JAK2. The three mutated JAK2s also mediate GH activation of signal transducer and activator of transcription 3 (Stat3), signal transducer and activator of transcription 5b (Stat5b) and ERK1, but at reduced levels. Coexpression with Src-homology 2B1β (SH2B1β), like coexpression with GH-bound GH receptor, partially restores the activity of all three JAK2 mutants. Based on these results and the crystal structure of the JAK2 kinase domain, we hypothesize that small changes in the conformation of the regions of JAK2 surrounding tyrosines 868, 966, and 972 due to e.g. phosphorylation, binding to a ligand-bound cytokine receptor, and/or binding to Src-homology 2B1, may be essential for JAK2 to assume a maximally active conformation. PMID:20304997

  7. The Small Molecule Inhibitor G6 Significantly Reduces Bone Marrow Fibrosis and the Mutant Burden in a Mouse Model of Jak2-Mediated Myelofibrosis

    PubMed Central

    Kirabo, Annet; Park, Sung O.; Wamsley, Heather L.; Gali, Meghanath; Baskin, Rebekah; Reinhard, Mary K.; Zhao, Zhizhuang J.; Bisht, Kirpal S.; Keserű, György M.; Cogle, Christopher R.; Sayeski, Peter P.

    2013-01-01

    Philadelphia chromosome–negative myeloproliferative neoplasms, including polycythemia vera, essential thrombocytosis, and myelofibrosis, are disorders characterized by abnormal hematopoiesis. Among these myeloproliferative neoplasms, myelofibrosis has the most unfavorable prognosis. Furthermore, currently available therapies for myelofibrosis have little to no efficacy in the bone marrow and hence, are palliative. We recently developed a Janus kinase 2 (Jak2) small molecule inhibitor called G6 and found that it exhibits marked efficacy in a xenograft model of Jak2-V617F–mediated hyperplasia and a transgenic mouse model of Jak2-V617F–mediated polycythemia vera/essential thrombocytosis. However, its efficacy in Jak2-mediated myelofibrosis has not previously been examined. Here, we hypothesized that G6 would be efficacious in Jak2-V617F–mediated myelofibrosis. To test this, mice expressing the human Jak2-V617F cDNA under the control of the vav promoter were administered G6 or vehicle control solution, and efficacy was determined by measuring parameters within the peripheral blood, liver, spleen, and bone marrow. We found that G6 significantly reduced extramedullary hematopoiesis in the liver and splenomegaly. In the bone marrow, G6 significantly reduced pathogenic Jak/STAT signaling by 53%, megakaryocytic hyperplasia by 70%, and the Jak2 mutant burden by 68%. Furthermore, G6 significantly improved the myeloid to erythroid ratio and significantly reversed the myelofibrosis. Collectively, these results indicate that G6 is efficacious in Jak2-V617F–mediated myelofibrosis, and given its bone marrow efficacy, it may alter the natural history of this disease. PMID:22796437

  8. JAK2 Inhibition: Reviewing a New Therapeutical Option in Myeloproliferative Neoplasms

    PubMed Central

    Bellido, Mar; te Boekhorst, Peter A. W.

    2012-01-01

    JAK2 is a tyrosine kinase gene that plays an essential role in the development of normal haematopoiesis. Hyperactivation of JAK2 occurs in myeloproliferative neoplasms by different mechanisms. As a consequence, JAK2 inhibitors have been designed to suppress the cytokine signalling cascade caused by the constitutive activation of JAK2. In clinical trials, JAK2 inhibitors are efficient in decreasing spleen size, controlling clinical symptoms, and improving quality of life in patients with myeloproliferative neoplasms. However, JAK2 inhibitors are unable to target uncommitted hematopoietic progenitors responsible of the initiation of the myeloproliferative disease. It is expected that, in order to cure the myeloproliferative disease, JAK2 inhibitors should be combined with other drugs to target simultaneously different pathways and to target the initiator hematopoietic cell population in myeloproliferative disorders. Taking advantage of the inhibition of the cytokine cascade of JAK2 inhibitors, these compounds are going to be used not only to treat patients with hematological neoplasms but may also be beneficial to treat patients with rheumatoid arthritis or other inflammatory diseases. PMID:22400031

  9. Improved targeting of JAK2 leads to increased therapeutic efficacy in myeloproliferative neoplasms

    PubMed Central

    Bhagwat, Neha; Koppikar, Priya; Keller, Matthew; Marubayashi, Sachie; Shank, Kaitlyn; Rampal, Raajit; Qi, Jun; Kleppe, Maria; Patel, Hardik J.; Shah, Smit K.; Taldone, Tony; Bradner, James E.; Chiosis, Gabriela

    2014-01-01

    The discovery of JAK2/MPL mutations in patients with myeloproliferative neoplasms (MPN) led to clinical development of Janus kinase (JAK) inhibitors for treatment of MPN. These inhibitors improve constitutional symptoms and splenomegaly but do not significantly reduce mutant allele burden in patients. We recently showed that chronic exposure to JAK inhibitors results in inhibitor persistence via JAK2 transactivation and persistent JAK–signal transducer and activator of transcription signaling. We performed genetic and pharmacologic studies to determine whether improved JAK2 inhibition would show increased efficacy in MPN models and primary samples. Jak2 deletion in vivo led to profound reduction in disease burden not seen with JAK inhibitors, and deletion of Jak2 following chronic ruxolitinib therapy markedly reduced mutant allele burden. This demonstrates that JAK2 remains an essential target in MPN cells that survive in the setting of chronic JAK inhibition. Combination therapy with the heat shock protein 90 (HSP90) inhibitor PU-H71 and ruxolitinib reduced total and phospho-JAK2 and achieved more potent inhibition of downstream signaling than ruxolitinib monotherapy. Combination treatment improved blood counts, spleen weights, and reduced bone marrow fibrosis compared with ruxolitinib alone. These data suggest alternate approaches that increase JAK2 targeting, including combination JAK/HSP90 inhibitor therapy, are warranted in the clinical setting. PMID:24470592

  10. A Structure-Function Perspective of Jak2 Mutations and Implications for Alternate Drug Design Strategies: The Road not Taken

    PubMed Central

    Gnanasambandan, Kavitha; Sayeski, Peter P.

    2013-01-01

    Jak2 is a non-receptor tyrosine kinase that is involved in the control of cellular growth and proliferation. Due to its significant role in hematopoiesis, Jak2 is a frequent target for mutations in cancer, especially myeloid leukemia, lymphoid leukemia and the myeloproliferative neoplasms (MPN). These mutations are common amongst different populations all over the world and there is a great deal of effort to develop therapeutic drugs for the affected patients. Jak2 mutations, whether they are point, deletion, or gene fusion, most commonly result in constitutive kinase activation. Here, we explore the structure-function relation of various Jak2 mutations identified in cancer and understand how they disrupt Jak2 regulation. Current Jak2 inhibitors target the highly conserved active site in the kinase domain and therefore, these inhibitors may lack specificity. Based on our knowledge regarding structure-function correlations as they pertain to regulation of Jak2 kinase activity, an alternative approach for specific Jak2 targeting could be via allosteric inhibitor design. Successful reports of allosteric inhibitors developed against other kinases provide precedent for the development of Jak2 allosteric inhibitors. Here, we suggest plausible target sites in the Jak2 structure for allosteric inhibition. Such targets include the type II inhibitor pocket and substrate binding site in the kinase domain, the kinase-pseudokinase domain interface, SH2-JH2 linker region and the FERM domain. Thus, future Jak2 inhibitors that target these sites via allosteric mechanisms may provide alternative therapeutic strategies to existing ATP competitive inhibitors. PMID:21864276

  11. A phase 2 randomized dose-ranging study of the JAK2-selective inhibitor fedratinib (SAR302503) in patients with myelofibrosis

    PubMed Central

    Pardanani, A; Tefferi, A; Jamieson, C; Gabrail, N Y; Lebedinsky, C; Gao, G; Liu, F; Xu, C; Cao, H; Talpaz, M

    2015-01-01

    In this phase 2 open-label randomized study, 31 patients with intermediate-2 or high-risk myelofibrosis received fedratinib 300, 400 or 500 mg once daily in consecutive 4-week cycles. Mean spleen volume reductions at 12 weeks (primary end point) were 30.3% (300 mg), 33.1% (400 mg) and 43.3% (500 mg). Spleen response rates (patients achieving ⩾35% spleen reduction) at 12/24 weeks were 30%/30% (300 mg), 50%/60% (400 mg) and 64%/55% (500 mg), respectively. By 4 weeks, improvements in myelofibrosis (MF)-associated symptoms were observed. At 48 weeks, 68% of patients remained on fedratinib and 16% had discontinued because of adverse events (AEs). Common grade 3/4 AEs were anemia (58%), fatigue (13%), diarrhea (13%), vomiting (10%) and nausea (6%). Serious AEs included one case of reversible hepatic failure and one case of Wernicke's encephalopathy (after analysis cutoff). Fedratinib treatment led to reduced STAT3 phosphorylation but no meaningful change in JAK2V617F allele burden. Significant modulation (P<0.05, adjusted for multiple comparisons) of 28 cytokines was observed, many of which correlated with spleen reduction. These data confirm the clinical activity of fedratinib in MF. After the analysis cutoff date, additional reports of Wernicke's encephalopathy in other fedratinib trials led to discontinuation of the sponsored clinical development program. PMID:26252788

  12. Contribution of JAK2 mutations to T-cell lymphoblastic lymphoma development

    PubMed Central

    Roncero, A M; López-Nieva, P; Cobos-Fernández, M A; Villa-Morales, M; González-Sánchez, L; López-Lorenzo, J L; Llamas, P; Ayuso, C; Rodríguez-Pinilla, S M; Arriba, M C; Piris, M A; Fernández-Navarro, P; Fernández, A F; Fraga, M F; Santos, J; Fernández-Piqueras, J

    2016-01-01

    The JAK-STAT pathway has a substantial role in lymphoid precursor cell proliferation, survival and differentiation. Nonetheless, the contribution of JAK2 to T-cell lymphoblastic lymphoma (T-LBL) development remains poorly understood. We have identified one activating TEL-JAK2 translocation and four missense mutations accumulated in 2 out of 16 T-LBL samples. Two of them are novel JAK2 mutations and the other two are reported for the first time in T-LBL. Notably, R683G and I682T might have arisen owing to RNA editing. Mutated samples showed different mutated transcripts suggesting sub-clonal heterogeneity. Functional approaches revealed that two JAK2 mutations (H574R and R683G) constitutively activate JAK-STAT signaling in γ2A cells and can drive the proliferation of BaF3-EpoR cytokine-dependent cell line. In addition, aberrant hypermethylation of SOCS3 might contribute to enhance the activation of JAK-STAT signaling. Of utmost interest is that primary T-LBL samples harboring JAK2 mutations exhibited increased expression of LMO2, suggesting a mechanistic link between JAK2 mutations and the expression of LMO2, which was confirmed for the four missense mutations in transfected γ2A cells. We therefore propose that active JAK2 contribute to T-LBL development by two different mechanisms, and that the use of pan-JAK inhibitors in combination with epigenetic drugs should be considered in future treatments. PMID:26216197

  13. Contribution of JAK2 mutations to T-cell lymphoblastic lymphoma development.

    PubMed

    Roncero, A M; López-Nieva, P; Cobos-Fernández, M A; Villa-Morales, M; González-Sánchez, L; López-Lorenzo, J L; Llamas, P; Ayuso, C; Rodríguez-Pinilla, S M; Arriba, M C; Piris, M A; Fernández-Navarro, P; Fernández, A F; Fraga, M F; Santos, J; Fernández-Piqueras, J

    2016-01-01

    The JAK-STAT pathway has a substantial role in lymphoid precursor cell proliferation, survival and differentiation. Nonetheless, the contribution of JAK2 to T-cell lymphoblastic lymphoma (T-LBL) development remains poorly understood. We have identified one activating TEL-JAK2 translocation and four missense mutations accumulated in 2 out of 16 T-LBL samples. Two of them are novel JAK2 mutations and the other two are reported for the first time in T-LBL. Notably, R683G and I682T might have arisen owing to RNA editing. Mutated samples showed different mutated transcripts suggesting sub-clonal heterogeneity. Functional approaches revealed that two JAK2 mutations (H574R and R683G) constitutively activate JAK-STAT signaling in γ2A cells and can drive the proliferation of BaF3-EpoR cytokine-dependent cell line. In addition, aberrant hypermethylation of SOCS3 might contribute to enhance the activation of JAK-STAT signaling. Of utmost interest is that primary T-LBL samples harboring JAK2 mutations exhibited increased expression of LMO2, suggesting a mechanistic link between JAK2 mutations and the expression of LMO2, which was confirmed for the four missense mutations in transfected γ2A cells. We therefore propose that active JAK2 contribute to T-LBL development by two different mechanisms, and that the use of pan-JAK inhibitors in combination with epigenetic drugs should be considered in future treatments. PMID:26216197

  14. Targeting JAK2 in the therapy of myeloproliferative neoplasms

    PubMed Central

    Reddy, Mamatha M.; Deshpande, Anagha; Sattler, Martin

    2014-01-01

    Introduction Myeloproliferative neoplasms (MPNs) are a group of stem cell diseases, including polycythemia vera, essential thrombocythemia and primary myelofibrosis. Currently, there is no curative therapy for these diseases other than bone marrow transplant; therefore there is an apparent need for palliative treatment. MPNs are frequently associated with activating mutations in Janus Kinase 2 (JAK2); small molecule drugs targeting this molecule have entered clinical trials. Areas covered In this review novel JAK2 inhibitors will be discussed and alternative approaches to inhibiting their transforming potential will be highlighted. Expert opinion Current clinical approaches do not only aim at blocking JAK2 activity, but also at reducing its stability and expression. Inhibition of heat shock protein 90 (HSP90) and deacetylase inhibitors (DACi) have the potential to significantly enhance the efficacy of JAK2 inhibitors. Preliminary results from clinical trials indicate the feasibility and efficacy of JAK2 targeted approaches. However, JAK2 inhibitor treatment is limited by dose-dependent toxicity and combination treatment might be required. The discovery of JAK2 mutations that cause secondary resistance in vitro would further highlight the need for the development of next generation JAK2 inhibitors and novel synergistic approaches. PMID:22339244

  15. The role of JAK2 abnormalities in hematologic neoplasms

    PubMed Central

    Alabdulaali, Mohammed K.

    2009-01-01

    In 2005, an activating mutation in the Janus kinase 2 (JAK2) was identified in a significant proportion of patients with myeloproliferative neoplasms, mainly polycythemia vera, essential thrombocythemia and primary myelofibrosis. Many types of mutations in the JAK-STAT pathway have been identified, the majority are related to JAK2. Currently JAK2 mutations are important in the area of diagnosis of myeloid neoplasms, but its role beyond the confirmation of clonality is growing and widening our knowledge about these disorders. In addition to that, clinical trials to target JAK2-STAT pathway will widen our knowledge and hopefully will offer more therapeutic options. In this review, we will discuss the role of JAK2 abnormalities in the pathogenesis, diagnosis, classification, severity and management of hematologic neoplasms.

  16. [Recurrent deep vein thrombosis and myeloproliferative syndrom: emergence of JAK2 mutation five years after the initial event].

    PubMed

    Salort, A; Seinturier, C; Molina, L; Lévèque, P; Imbert, B; Pernod, G

    2014-05-01

    JAK 2 mutation is the molecular event responsible for 95% of polycythemia cases and 50% of thrombocythemia vera and myelofibrosis cases. It can be used as a tool for the diagnosis of myeloproliferative disorders. We report a case illustrating the fact that a negative result does not definitively eliminate the diagnosis. A 40-year old woman, with a medical history of familial deep vein thrombosis, developed thrombosis of the inferior vena cava with extension to the suprahepatic veins and pulmonary embolism. No constitutional or acquired thrombophilia was diagnosed; search for JAK 2 mutation was negative. The patient was treated with fluindione. Five years later, she relapsed with popliteo-femoral and vena cava deep vein thrombosis. The etiological work-up included a PET scan which revealed diffuse uptake in bones and suspected neoplasic bone marrow invasion. Progenitor cell cultures were positive and JAK 2 mutation was confirmed. The bone marrow aspirate had the cytologic appearance of a myeloproliferative disorder. This case illustrates the fact that JAK 2 mutation can be identified several years after onset of a latent myeloproliferative disorder. Cases with a high clinical likelihood should lead to renewed search for this mutation. Secondary discovery of this mutation can be explained by a higher proportion of mutation expressing clones. PMID:24721000

  17. A multi-level model accounting for the effects of JAK2-STAT5 signal modulation in erythropoiesis.

    PubMed

    Lai, Xin; Nikolov, Svetoslav; Wolkenhauer, Olaf; Vera, Julio

    2009-08-01

    We develop a multi-level model, using ordinary differential equations, based on quantitative experimental data, accounting for murine erythropoiesis. At the sub-cellular level, the model includes a description of the regulation of red blood cell differentiation through Epo-stimulated JAK2-STAT5 signalling activation, while at the cell population level the model describes the dynamics of (STAT5-mediated) red blood cell differentiation from their progenitors. Furthermore, the model includes equations depicting the hypoxia-mediated regulation of hormone erythropoietin blood levels. Take all together, the model constitutes a multi-level, feedback loop-regulated biological system, involving processes in different organs and at different organisational levels. We use our model to investigate the effect of deregulation in the proteins involved in the JAK2-STAT5 signalling pathway in red blood cells. Our analysis results suggest that down-regulation in any of the three signalling system components affects the hematocrit level in an individual considerably. In addition, our analysis predicts that exogenous Epo injection (an already existing treatment for several blood diseases) may compensate the effects of single down-regulation of Epo hormone level, STAT5 or EpoR/JAK2 expression level, and that it may be insufficient to counterpart a combined down-regulation of all the elements in the JAK2-STAT5 signalling cascade. PMID:19660986

  18. Novel quinazoline derivatives exhibit antitumor activity by inhibiting JAK2/STAT3.

    PubMed

    Qiao, Haishi; Zhao, Dan; Shi, Hengfei; Ren, Ke; Li, Jianxin; Li, Erguang

    2015-10-01

    Quinazoline core-containing compounds such as gefitinib and erlotinib constitute an important group of antitumor drugs that act as receptor tyrosine kinase inhibitors against epidermal growth factor receptor (EGFR) kinase activity. We investigated a group of recently prepared 2-alkyl-substituted quinazolines (2-ASQs) for their antitumor activity against non-small cell lung carcinoma (NSCLC) cells. The compounds showed antitumor activity against A549, H1299, and H460 cells by induction of apoptosis. The IC50 values for (E)-2-propyl-4-styrylquinazoline (compound #4) and (E)-2‑cyclopropyl-4-styrylquinazoline (compound #7) against these cell lines were 2-5 times lower than that of gefitinib. Unlike gefitinib that blocks EGFR phosphorylation, these compounds showed no activity against EGFR activation. Instead, the compounds suppressed both constitutive and IL-6-induced activation of JAK2/STAT3 phosphorylation and downstream gene expression. Transient expression of a constitutively active mutant of STAT3 reversed the pro-apoptotic effect of compound #7. Using a nude mouse model bearing A549 xenografts, we showed that administration of #7 at 15 and 30 mg/kg suppressed tumor growth. The present study therefore demonstrated that 2-alkyl substituted quinazolines target the JAK2/STAT3 pathway for their antitumor activity. PMID:26238612

  19. JAK2 Tyrosine Kinase Phosphorylates and Is Negatively Regulated by Centrosomal Protein Ninein

    PubMed Central

    Jay, Jennifer; Hammer, Alan; Nestor-Kalinoski, Andrea

    2014-01-01

    JAK2 is a cytoplasmic tyrosine kinase critical for cytokine signaling. In this study, we have identified a novel centrosome-associated complex containing ninein and JAK2. We have found that active JAK2 localizes around the mother centrioles, where it partly colocalizes with ninein, a protein involved in microtubule (MT) nucleation and anchoring. We demonstrated that JAK2 is an important regulator of centrosome function. Depletion of JAK2 or use of JAK2-null cells causes defects in MT anchoring and increased numbers of cells with mitotic defects; however, MT nucleation is unaffected. We showed that JAK2 directly phosphorylates the N terminus of ninein while the C terminus of ninein inhibits JAK2 kinase activity in vitro. Overexpressed wild-type (WT) or C-terminal (amino acids 1179 to 1931) ninein inhibits JAK2. This ninein-dependent inhibition of JAK2 significantly decreases prolactin- and interferon gamma (IFN-γ)-induced tyrosyl phosphorylation of STAT1 and STAT5. Downregulation of ninein enhances JAK2 activation. These results indicate that JAK2 is a novel member of centrosome-associated complex and that this localization regulates both centrosomal function and JAK2 kinase activity, thus controlling cytokine-activated molecular pathways. PMID:25332239

  20. Somatic CALR Mutations in Myeloproliferative Neoplasms with Nonmutated JAK2

    PubMed Central

    Baxter, E.J.; Nice, F.L.; Gundem, G.; Wedge, D.C.; Avezov, E.; Li, J.; Kollmann, K.; Kent, D.G.; Aziz, A.; Godfrey, A.L.; Hinton, J.; Martincorena, I.; Van Loo, P.; Jones, A.V.; Guglielmelli, P.; Tarpey, P.; Harding, H.P.; Fitzpatrick, J.D.; Goudie, C.T.; Ortmann, C.A.; Loughran, S.J.; Raine, K.; Jones, D.R.; Butler, A.P.; Teague, J.W.; O’Meara, S.; McLaren, S.; Bianchi, M.; Silber, Y.; Dimitropoulou, D.; Bloxham, D.; Mudie, L.; Maddison, M.; Robinson, B.; Keohane, C.; Maclean, C.; Hill, K.; Orchard, K.; Tauro, S.; Du, M.-Q.; Greaves, M.; Bowen, D.; Huntly, B.J.P.; Harrison, C.N.; Cross, N.C.P.; Ron, D.; Vannucchi, A.M.; Papaemmanuil, E.; Campbell, P.J.; Green, A.R.

    2014-01-01

    BACKGROUND Somatic mutations in the Janus kinase 2 gene (JAK2) occur in many myeloproliferative neoplasms, but the molecular pathogenesis of myeloproliferative neoplasms with nonmutated JAK2 is obscure, and the diagnosis of these neoplasms remains a challenge. METHODS We performed exome sequencing of samples obtained from 151 patients with myeloproliferative neoplasms. The mutation status of the gene encoding calreticulin (CALR) was assessed in an additional 1345 hematologic cancers, 1517 other cancers, and 550 controls. We established phylogenetic trees using hematopoietic colonies. We assessed calreticulin subcellular localization using immunofluorescence and flow cytometry. RESULTS Exome sequencing identified 1498 mutations in 151 patients, with medians of 6.5, 6.5, and 13.0 mutations per patient in samples of polycythemia vera, essential thrombocythemia, and myelofibrosis, respectively. Somatic CALR mutations were found in 70 to 84% of samples of myeloproliferative neoplasms with nonmutated JAK2, in 8% of myelodysplasia samples, in occasional samples of other myeloid cancers, and in none of the other cancers. A total of 148 CALR mutations were identified with 19 distinct variants. Mutations were located in exon 9 and generated a +1 base-pair frameshift, which would result in a mutant protein with a novel C-terminal. Mutant calreticulin was observed in the endoplasmic reticulum without increased cell-surface or Golgi accumulation. Patients with myeloproliferative neoplasms carrying CALR mutations presented with higher platelet counts and lower hemoglobin levels than patients with mutated JAK2. Mutation of CALR was detected in hematopoietic stem and progenitor cells. Clonal analyses showed CALR mutations in the earliest phylogenetic node, a finding consistent with its role as an initiating mutation in some patients. CONCLUSIONS Somatic mutations in the endoplasmic reticulum chaperone CALR were found in a majority of patients with myeloproliferative neoplasms with

  1. Triple-negative breast cancers with amplification of JAK2 at the 9p24 locus demonstrate JAK2-specific dependence.

    PubMed

    Balko, Justin M; Schwarz, Luis J; Luo, Na; Estrada, Mónica V; Giltnane, Jennifer M; Dávila-González, Daniel; Wang, Kai; Sánchez, Violeta; Dean, Phillip T; Combs, Susan E; Hicks, Donna; Pinto, Joseph A; Landis, Melissa D; Doimi, Franco D; Yelensky, Roman; Miller, Vincent A; Stephens, Phillip J; Rimm, David L; Gómez, Henry; Chang, Jenny C; Sanders, Melinda E; Cook, Rebecca S; Arteaga, Carlos L

    2016-04-13

    Amplifications at 9p24 have been identified in breast cancer and other malignancies, but the genes within this locus causally associated with oncogenicity or tumor progression remain unclear. Targeted next-generation sequencing of postchemotherapy triple-negative breast cancers (TNBCs) identified a group of 9p24-amplified tumors, which contained focal amplification of the Janus kinase 2 (JAK2) gene. These patients had markedly inferior recurrence-free and overall survival compared to patients with TNBC without JAK2 amplification. Detection of JAK2/9p24 amplifications was more common in chemotherapy-treated TNBCs than in untreated TNBCs or basal-like cancers, or in other breast cancer subtypes. Similar rates of JAK2 amplification were confirmed in patient-derived TNBC xenografts. In patients for whom longitudinal specimens were available, JAK2 amplification was selected for during neoadjuvant chemotherapy and eventual metastatic spread, suggesting a role in tumorigenicity and chemoresistance, phenotypes often attributed to a cancer stem cell-like cell population. In TNBC cell lines with JAK2 copy gains or amplification, specific inhibition of JAK2 signaling reduced mammosphere formation and cooperated with chemotherapy in reducing tumor growth in vivo. In these cells, inhibition of JAK1-signal transducer and activator of transcription 3 (STAT3) signaling had little effect or, in some cases, counteracted JAK2-specific inhibition. Collectively, these results suggest that JAK2-specific inhibitors are more efficacious than dual JAK1/2 inhibitors against JAK2-amplified TNBCs. Furthermore, JAK2 amplification is a potential biomarker for JAK2 dependence, which, in turn, can be used to select patients for clinical trials with JAK2 inhibitors. PMID:27075627

  2. REG3A accelerates pancreatic cancer cell growth under IL-6-associated inflammatory condition: Involvement of a REG3A-JAK2/STAT3 positive feedback loop.

    PubMed

    Liu, Xiulan; Wang, Jun; Wang, Hongjie; Yin, Guoxiao; Liu, Yang; Lei, Xiang; Xiang, Ming

    2015-06-28

    Regenerating gene protein (REG) 3A is a 19 kD secretory pancreas protein with pro-growth function. Previously we demonstrated that overexpression of REG3A, acting as a key molecule for up-regulation of the JAK2/STAT3 pathway, contributed to inflammation-related pancreatic cancer (PaC) development. However the exact network associated with REG3A signaling still remains unclear. Here we determined that exposure of human PaC cells to cytokine IL-6 activated the oncogenic JAK2/STAT3 pathway, which directly upregulated REG3A expression, accelerated cell cycle progression by promoting CyclinD1 expression, and enhancing the expression of the anti-apoptosis Bcl family. Importantly, the activation of REG3A would instead enhance the JAK2/STAT3 pathway to constitute a REG3A-JAK2/STAT3 positive feedback loop, which leads to the amplification of the oncogenic effects of IL-6/JAK2/STAT3, a classic pathway linking to inflammation-related tumorigenesis, ultimately resulting in PaC cell over-proliferation and tumor formation both in vitro and in vivo. Moreover, EGFR was found to mediate the REG3A signal for PaC cell growth and JAK2/STAT3 activation, thus functioning as a REG3A receptor. Collectively, our results provide the first evidence for the presence of the synergistic effect of REG3A and IL-6 on PaC development via a REG3A-JAK2/STAT3 positive feedback loop. PMID:25779676

  3. Protein flexibility oriented virtual screening strategy for JAK2 inhibitors

    NASA Astrophysics Data System (ADS)

    Xiong, Xiao; Yuan, Haoliang; Zhang, Yanmin; Xu, Jinxing; Ran, Ting; Liu, Haichun; Lu, Shuai; Xu, Anyang; Li, Hongmei; Jiang, Yulei; Lu, Tao; Chen, Yadong

    2015-10-01

    JAK2 has been considered as an important target for the development of anti-cancer agents. In this study, considering the flexibility of its binding site, an integrated strategy combining Bayesian categorization modeling and ensemble docking was established. Four representative crystal structures were selected for ensemble docking by the hierarchical clustering of 34 crystal structures according to the volume overlaps of each structure. A retrospective virtual screening was performed to validate this integrated strategy. As the preliminary filtration, the Bayesian model enhanced the ratio of actives by reducing the large amount of decoys. After docking the remaining compounds, the comparison between the ensemble and individual results showed that the enrichment of ensemble docking improved significantly. The results of analysis on conformational changes of two top ranked active inhibitors when docking into different proteins indicated that compounds with flexible conformations well fitted the different binding site shapes were more likely to be potential JAK2 inhibitors. This high efficient strategy will facilitate virtual screening for novel JAK2 inhibitors and could be even applied in drug discovery against other targets.

  4. The role of the JAK2 GGCC haplotype and the TET2 gene in familial myeloproliferative neoplasms

    PubMed Central

    Olcaydu, Damla; Rumi, Elisa; Harutyunyan, Ashot; Passamonti, Francesco; Pietra, Daniela; Pascutto, Cristiana; Berg, Tiina; Jäger, Roland; Hammond, Emma; Cazzola, Mario; Kralovics, Robert

    2011-01-01

    Background Myeloproliferative neoplasms constitute a group of diverse chronic myeloid malignancies that share pathogenic features such as acquired mutations in the JAK2, TET2, CBL and MPL genes. There are recent reports that a JAK2 gene haplotype (GGCC or 46/1) confers susceptibility to JAK2 mutation-positive myeloproliferative neoplasms. The aim of this study was to examine the role of the JAK2 GGCC haplotype and germline mutations of TET2, CBL and MPL in familial myeloproliferative neoplasms. Design and Methods We investigated patients with familial (n=88) or sporadic (n=684) myeloproliferative neoplasms, and a control population (n=203) from the same demographic area in Italy. Association analysis was performed using tagged single nucleotide polymorphisms (rs10974944 and rs12343867) of the JAK2 haplotype. Sequence analysis of TET2, CBL and MPL was conducted in the 88 patients with familial myeloproliferative neoplasms. Results Association analysis revealed no difference in haplotype frequency between familial and sporadic cases of myeloproliferative neoplasms (P=0.6529). No germline mutations in TET2, CBL or MPL that segregate with the disease phenotype were identified. As we observed variability in somatic mutations in the affected members of a pedigree with myeloproliferative neoplasms, we postulated that somatic mutagenesis is increased in familial myeloproliferative neoplasms. Accordingly, we compared the incidence of malignant disorders between sporadic and familial patients. Although the overall incidence of malignant disorders did not differ significantly between cases of familial and sporadic myeloproliferative neoplasms, malignancies were more frequent in patients with familial disease aged between 50 to 70 years (P=0.0198) than in patients in the same age range with sporadic myeloproliferative neoplasms. Conclusions We conclude that the JAK2 GGCC haplotype and germline mutations of TET2, CBL or MPL do not explain familial clustering of

  5. HSP90 is a therapeutic target in JAK2-dependent myeloproliferative neoplasms in mice and humans

    PubMed Central

    Marubayashi, Sachie; Koppikar, Priya; Taldone, Tony; Abdel-Wahab, Omar; West, Nathan; Bhagwat, Neha; Caldas-Lopes, Eloisi; Ross, Kenneth N.; Gönen, Mithat; Gozman, Alex; Ahn, James H.; Rodina, Anna; Ouerfelli, Ouathek; Yang, Guangbin; Hedvat, Cyrus; Bradner, James E.; Chiosis, Gabriela; Levine, Ross L.

    2010-01-01

    JAK2 kinase inhibitors were developed for the treatment of myeloproliferative neoplasms (MPNs), following the discovery of activating JAK2 mutations in the majority of patients with MPN. However, to date JAK2 inhibitor treatment has shown limited efficacy and apparent toxicities in clinical trials. We report here that an HSP90 inhibitor, PU-H71, demonstrated efficacy in cell line and mouse models of the MPN polycythemia vera (PV) and essential thrombocytosis (ET) by disrupting JAK2 protein stability. JAK2 physically associated with both HSP90 and PU-H71 and was degraded by PU-H71 treatment in vitro and in vivo, demonstrating that JAK2 is an HSP90 chaperone client. PU-H71 treatment caused potent, dose-dependent inhibition of cell growth and signaling in JAK2 mutant cell lines and in primary MPN patient samples. PU-H71 treatment of mice resulted in JAK2 degradation, inhibition of JAK-STAT signaling, normalization of peripheral blood counts, and improved survival in MPN models at doses that did not degrade JAK2 in normal tissues or cause substantial toxicity. Importantly, PU-H71 treatment also reduced the mutant allele burden in mice. These data establish what we believe to be a novel therapeutic rationale for HSP90 inhibition in the treatment of JAK2-dependent MPN. PMID:20852385

  6. Resveratrol Induces Cell Cycle Arrest and Apoptosis in Malignant NK Cells via JAK2/STAT3 Pathway Inhibition

    PubMed Central

    Quoc Trung, Ly; Espinoza, J. Luis; Takami, Akiyoshi; Nakao, Shinji

    2013-01-01

    Natural killer (NK) cell malignancies, particularly aggressive NK cell leukaemias and lymphomas, have poor prognoses. Although recent regimens with L-asparaginase substantially improved outcomes, novel therapeutic approaches are still needed to enhance clinical response. Resveratrol, a naturally occurring polyphenol, has been extensively studied for its anti-inflammatory, cardioprotective and anti-cancer activities. In this study, we investigated the potential anti-tumour activities of resveratrol against the NK cell lines KHYG-1, NKL, NK-92 and NK-YS. Resveratrol induced robust G0/G1 cell cycle arrest, significantly suppressed cell proliferation and induced apoptosis in a dose- and time-dependent manner for all four cell lines. In addition, resveratrol suppressed constitutively active STAT3 in all the cell lines and inhibited JAK2 phosphorylation but had no effect on other upstream mediators of STAT3 activation, such as PTEN, TYK2, and JAK1. Resveratrol also induced downregulation of the anti-apoptotic proteins MCL1 and survivin, two downstream effectors of the STAT3 pathway. Finally, resveratrol induced synergistic effect on the apoptotic and antiproliferative activities of L-asparaginase against KHYG-1, NKL and NK-92 cells. These results suggest that resveratrol may have therapeutic potential against NK cell malignancies. Furthermore, our finding that resveratrol is a bonafide JAK2 inhibitor extends its potential benefits to other diseases with dysregulated JAK2 signaling. PMID:23372833

  7. JAK2 and MPL protein levels determine TPO-induced megakaryocyte proliferation vs differentiation

    PubMed Central

    Besancenot, Rodolphe; Roos-Weil, Damien; Tonetti, Carole; Abdelouahab, Hadjer; Lacout, Catherine; Pasquier, Florence; Willekens, Christophe; Rameau, Philippe; Lecluse, Yann; Micol, Jean-Baptiste; Constantinescu, Stefan N.; Vainchenker, William; Solary, Eric

    2014-01-01

    Megakaryopoiesis is a 2-step differentiation process, regulated by thrombopoietin (TPO), on binding to its cognate receptor myeloproliferative leukemia (MPL). This receptor associates with intracytoplasmic tyrosine kinases, essentially janus kinase 2 (JAK2), which regulates MPL stability and cell-surface expression, and mediates TPO-induced signal transduction. We demonstrate that JAK2 and MPL mediate TPO-induced proliferation arrest and megakaryocytic differentiation of the human megakaryoblastic leukemia cell line UT7-MPL. A decrease in JAK2 or MPL protein expression, and JAK2 chemical inhibition, suppress this antiproliferative action of TPO. The expression of JAK2 and MPL, which progressively increases along normal human megakaryopoiesis, is decreased in platelets of patients diagnosed with JAK2- or MPL-mutated essential thrombocytemia and primary myelofibrosis, 2 myeloproliferative neoplasms in which megakaryocytes (MKs) proliferate excessively. Finally, low doses of JAK2 chemical inhibitors are shown to induce a paradoxical increase in MK production, both in vitro and in vivo. We propose that JAK2 and MPL expression levels regulate megakaryocytic proliferation vs differentiation in both normal and pathological conditions, and that JAK2 chemical inhibitors could promote a paradoxical thrombocytosis when used at suboptimal doses. PMID:25143485

  8. Genetic studies reveal an unexpected negative regulatory role for Jak2 in thrombopoiesis

    PubMed Central

    Meyer, Sara C.; Keller, Matthew D.; Woods, Brittany A.; LaFave, Lindsay M.; Bastian, Lennart; Kleppe, Maria; Bhagwat, Neha; Marubayashi, Sachie

    2014-01-01

    JAK inhibitor treatment is limited by the variable development of anemia and thrombocytopenia thought to be due to on-target JAK2 inhibition. We evaluated the impact of Jak2 deletion in platelets (PLTs) and megakaryocytes (MKs) on blood counts, stem/progenitor cells, and Jak-Stat signaling. Pf4-Cre–mediated Jak2 deletion in PLTs and MKs did not compromise PLT formation but caused thrombocytosis, and resulted in expansion of MK progenitors and Lin−Sca1+Kit+ cells. Serum thrombopoietin (TPO) was maintained at normal levels in Pf4-Cre–positive Jak2f/f mice, consistent with reduced internalization/turnover by Jak2-deficient PLTs. These data demonstrate that Jak2 in terminal megakaryopoiesis is not required for PLT production, and that Jak2 loss in PLTs and MKs results in non-autonomous expansion of stem/progenitors and of MKs and PLTs via dysregulated TPO turnover. This suggests that the thrombocytopenia frequently seen with JAK inhibitor treatment is not due to JAK2 inhibition in PLTs and MKs, but rather due to JAK2 inhibition in stem/progenitor cells. PMID:25115888

  9. The Relevance of JAK2 in the Regulation of Cellular Transport.

    PubMed

    Sopjani, Mentor; Konjufca, Vjollca; Rinnerthaler, Mark; Rexhepaj, Rexhep; Dërmaku-Sopjani, Miribane

    2016-01-01

    Janus kinase-2 (JAK2) is a non-receptor tyrosine kinase signaling molecule that mediates the effects of various hormones and cytokines, including interferon, erythropoietin, leptin, and growth hormone. It also fosters tumor growth and modifies the activity of several nutrient transporters. JAK2 contributes to the regulation of the cell volume, protectS cells during energy depletion, proliferation, and aids the survival of tumor cells. Recently, JAK2 was identified as a powerful regulator of transport processes across the plasma membrane. Either directly or indirectly JAK2 may stimulate or inhibit transporter proteins, including ion channels, carriers and Na(+)/K(+) pumps. As a powerful regulator of transport mechanisms across the cell membrane, JAK2 regulates a wide variety of potassium, calcium, sodium and chloride ion channels, multiple Na+-coupled cellular carriers including EAAT1-4, NaPi-IIa, SGLT1, BoaT1, PepT1-2, CreaT1, SMIT1, and BGT1 as well as Na(+)/K(+)-ATPase. These cellular transport regulations contribute to various physiological and pathophysiological processes and thus exerting JAK2-sensitive effects. Future investigations will be important to determine whether JAK2 regulates cell-surface expression of other transporters and further elucidate underlying mechanisms governing JAK2 actions. PMID:26639094

  10. 9H-Carbazole-1-carboxamides as potent and selective JAK2 inhibitors.

    PubMed

    Zimmermann, Kurt; Sang, Xiaopeng; Mastalerz, Harold A; Johnson, Walter L; Zhang, Guifen; Liu, Qingjie; Batt, Douglas; Lombardo, Louis J; Vyas, Dinesh; Trainor, George L; Tokarski, John S; Lorenzi, Matthew V; You, Dan; Gottardis, Marco M; Lippy, Jonathan; Khan, Javed; Sack, John S; Purandare, Ashok V

    2015-07-15

    The discovery, synthesis, and characterization of 9H-carbazole-1-carboxamides as potent and selective ATP-competitive inhibitors of Janus kinase 2 (JAK2) are discussed. Optimization for JAK family selectivity led to compounds 14 and 21, with greater than 45-fold selectivity for JAK2 over all other members of the JAK kinase family. PMID:25987372

  11. Prolactin-induced Jak2 phosphorylation of RUSH: a key element in Jak/RUSH signaling.

    PubMed

    Helmer, Rebecca A; Panchoo, Marlyn; Dertien, Janet S; Bhakta, Suhani M; Hewetson, Aveline; Chilton, Beverly S

    2010-08-30

    Jak2/Stat-mediated prolactin signaling culminates in Stat5a-DNA-binding. However, not all Jak2-dependent genes have Stat5 sites. Western analysis with inhibitors showed Jak2 is a proximal intermediate in prolactin-induced RUSH phosphorylation. Transfection assays with HRE-H9 cells showed the RUSH-binding site mediated the ability of prolactin to augment progesterone-dependent transcription of the RUSH gene. Jak2 inhibitors or targeted RUSH-site mutation blocked the prolactin effect. RUSH co-immunoprecipitated with phospho-Jak2 from nuclear extracts. Jak2 inhibitors abolished the nuclear pool of phospho-RUSH not the nuclear content of RUSH in HRE-H9 cells. Nucleolar-affiliated partners, e.g. nucleolin, were identified by microLC/MS/MS analysis of nuclear proteins that co-immunoprecipitated with RUSH/GST-RING. RUSH did not exclusively co-localize with fibrillarin to the nucleolus. MG-132 (proteasomal inhibitor) failed to block Tyrene CR4-mediated decrease in phospho-RUSH, and did not promote RUSH accumulation in the nucleolus. These studies authenticate prolactin-dependent Jak2 phosphorylation of RUSH, and provide functional implications on the RUSH network of nuclear interactions. PMID:20562009

  12. Mechanisms of endothelial cell protection by blockade of the JAK2 pathway.

    PubMed

    Neria, Fernando; Caramelo, Carlos; Peinado, Héctor; González-Pacheco, Francisco R; Deudero, Juan J P; de Solis, Alain J; Fernández-Sánchez, Ruth; Peñate, Silvia; Cano, Amparo; Castilla, María Angeles

    2007-03-01

    Inhibition of the JAK2/STAT pathway has been implicated recently in cytoprotective mechanisms in both vascular smooth muscle cells and astrocytes. The advent of JAK2-specific inhibitors provides a practical tool for the study of this pathway in different cellular types. An interest in finding methods to improve endothelial cell (EC) resistance to injury led us to examine the effect of JAK2/STAT inhibition on EC protection. Furthermore, the signaling pathways involved in JAK2/STAT inhibition-related actions were examined. Our results reveal, for the first time, that blockade of JAK2 with the tyrosine kinase inhibitor AG490 strongly protects cultured EC against cell detachment-dependent death and serum deprivation and increases reseeding efficiency. Confirmation of the specificity of the effects of JAK2 inhibition was attained by finding protective effects on transfection with a dominant negative JAK2. Furthermore, AG490 blocked serum deprivation-induced phosphorylation of JAK2. In terms of mechanism, treatment with AG490 induces several relevant responses, both in monolayer and detached cells. These mechanisms include the following: 1) Increase and nuclear translocation of the active, dephosphorylated form of beta-catenin. In functional terms, this translocation is transcriptionally active, and its protective effect is further supported by the stimulation of EC cytoprotection by transfectionally induced excess of beta-catenin. 2) Increase of platelet endothelial cell adhesion molecule (PECAM)/CD31 levels. 3) Increase in total and phosphorylated AKT. 4) Increase in phosphorylated glycogen synthase kinase (GSK)3alpha/beta. The present findings imply potential practical applications of JAK2 inhibition on EC. These applications affect not only EC in the monolayer but also circulating detached cells and involve mechanistic interactions not previously described. PMID:17035297

  13. JAK2-STAT3 signaling pathway mediates thrombin-induced proinflammatory actions of microglia in vitro.

    PubMed

    Huang, Chengfang; Ma, Rong; Sun, Shenggang; Wei, Guirong; Fang, Yuan; Liu, Rengang; Li, Gang

    2008-11-15

    The present study shows that JAK2-STAT3 inflammatory signaling mediates thrombin-stimulated microglia activation. In rat primary microglia, thrombin rapidly activated JAK2 and induced phosphorylation of STAT3. In addition, thrombin increased transcription of the inflammation-associated genes tumor necrosis factor (TNF)-alpha, inducible nitric oxide synthase (iNOS), production of TNF-alpha, NO and induced neurodegeneration of dopaminergic neurons in mesencephalic cultures. AG490, a JAK inhibitor, markedly reduced activation of JAK2 and STAT3 in thrombin-treated microglia. AG490 also inhibited thrombin-induced transcription and expression of TNF-alpha, iNOS and/or NO release, moreover rescued dopaminergic neurons. These results suggest that JAK2-STAT3 signaling pathway plays a critical role in mediating thrombin-induced activation of microglia and degeneration of dopaminergic neurons. PMID:18710787

  14. Discovery of pyrazol-3-ylamino pyrazines as novel JAK2 inhibitors.

    PubMed

    Ioannidis, Stephanos; Lamb, Michelle L; Davies, Audrey M; Almeida, Lynsie; Su, Mei; Bebernitz, Geraldine; Ye, Minwei; Bell, Kirsten; Alimzhanov, Marat; Zinda, Michael

    2009-12-01

    The design, synthesis and biological evaluation of a series of pyrazol-3-ylamino pyrazines as potent and selective JAK2 kinase inhibitors is reported, along with the pharmacokinetic and pharmacodynamic properties of lead compounds. PMID:19857966

  15. A sesquiterpene lactone antrocin from Antrodia camphorata negatively modulates JAK2/STAT3 signaling via microRNA let-7c and induces apoptosis in lung cancer cells.

    PubMed

    Yeh, Chi-Tai; Huang, Wen-Chien; Rao, Yerra Koteswara; Ye, Min; Lee, Wei-Hwa; Wang, Liang-Shun; Tzeng, David T W; Wu, Chih-Hsiung; Shieh, Yi-Shing; Huang, Chi-Ying F; Chen, Yu-Jen; Hsiao, Michael; Wu, Alexander T H; Yang, Zhen; Tzeng, Yew-Min

    2013-12-01

    Lung cancer is the leading cause of cancer deaths worldwide and current therapies fail to treat this disease in majority of cases. Antrodia camphorata is a medicinal mushroom being widely used as food dietary supplement for cancer prevention. The sesquiterpene lactone antrocin is the most potent among >100 secondary metabolites isolated from A. camphorata. However, the molecular mechanisms of antrocin-mediated anticancer effects remain unclear. In this study, we found that antrocin inhibited cell proliferation in two non-small-cell lung cancer cells, namely H441 (wild-type epidermal growth factor receptor, IC50 = 0.75 μM) and H1975 (gefitnib-resistant mutant T790M, IC50 = 0.83 μM). Antrocin dose dependently suppressed colony formation and induced apoptosis as evidenced by activated caspase-3 and increased Bax/Bcl2 ratio. Gene profiling studies indicated that antrocin downregulated Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway. We further demonstrated that antrocin suppressed both constitutively activated and interleukin 6-induced STAT3 phosphorylation and its subsequent nuclear translocation. Such inhibition is found to be achieved through the suppression of JAK2 and interaction between STAT3 and extracellular signal-regulated kinase. Additionally, antrocin increased microRNA let-7c expression and suppressed STAT signaling. The combination of antrocin and JAK2/STAT3 gene silencing significantly increased apoptosis in H441 cells. Such dual interruption of JAK2 and STAT3 pathways also induced downregulation of antiapoptotic protein mcl-1 and increased caspase-3 expression. In vivo intraperitoneal administration of antrocin significantly suppressed the growth of lung cancer tumor xenografts. Our results indicate that antrocin may be a potential therapeutic agent for human lung cancer cells through constitutive inhibition of JAK2/STAT3 pathway. PMID:23880305

  16. Fos-Zippered GH Receptor Cytosolic Tails Act as Jak2 Substrates and Signal Transducers.

    PubMed

    Nespital, Tobias; van der Velden, Lieke M; Mensinga, Anneloes; van der Vaart, Elisabeth D; Strous, Ger J

    2016-03-01

    Members of the Janus kinase (Jak) family initiate the majority of downstream signaling events of the cytokine receptor family. The prevailing principle is that the receptors act in dimers: 2 Jak2 molecules bind to the cytosolic tails of a cytokine receptor family member and initiate Jak-signal transducer and activator of transcription signaling upon a conformational change in the receptor complex, induced by the cognate cytokine. Due to the complexity of signaling complexes, there is a strong need for in vitro model systems. To investigate the molecular details of the Jak2 interaction with the GH receptor (GHR), we used cytosolic tails provided with leucine zippers derived from c-Fos to mimic the dimerized state of GHR. Expressed together with Jak2, fos-zippered tails, but not unzippered tails, were stabilized. In addition, the Jak-signal transducer and activator of transcription signaling pathway was activated by the fos-zippered tails. The stabilization depended also on α-helix rotation of the zippers. Fos-zippered GHR tails and Jak2, both purified from baculovirus-infected insect cells, interacted via box1 with a binding affinity of approximately 40nM. As expected, the Jak kinase inhibitor Ruxolitinib inhibited the stabilization but did not affect the c-Fos-zippered GHR tail-Jak2 interaction. Analysis by blue-native gel electrophoresis revealed high molecular-weight complexes containing both Jak2 and nonphosphorylated GHR tails, whereas Jak2-dissociated tails were highly phosphorylated and monomeric, implying that Jak2 detaches from its substrate upon phosphorylation. PMID:26859362

  17. Discovery of a Highly Selective JAK2 Inhibitor, BMS-911543, for the Treatment of Myeloproliferative Neoplasms

    PubMed Central

    2015-01-01

    JAK2 kinase inhibitors are a promising new class of agents for the treatment of myeloproliferative neoplasms and have potential for the treatment of other diseases possessing a deregulated JAK2-STAT pathway. X-ray structure and ADME guided refinement of C-4 heterocycles to address metabolic liability present in dialkylthiazole 1 led to the discovery of a clinical candidate, BMS-911543 (11), with excellent kinome selectivity, in vivo PD activity, and safety profile. PMID:26288683

  18. Safety and efficacy of CYT387, a JAK1 and JAK2 inhibitor, in myelofibrosis

    PubMed Central

    Pardanani, A; Laborde, R R; Lasho, T L; Finke, C; Begna, K; Al-Kali, A; Hogan, W J; Litzow, M R; Leontovich, A; Kowalski, M; Tefferi, A

    2013-01-01

    JAK-STAT is a rational drug target in myelofibrosis (MF) given its association with JAK2/MPL mutations and aberrant inflammatory cytokine expression. We conducted a Phase 1/2 trial of CYT387, a potent JAK1/2 inhibitor, in patients with high- or intermediate-risk primary or post-polycythemia vera/essential thrombocythemia MF. Pre-planned safety and efficacy analysis has been completed for the initial 60 patients. In the dose-escalation phase (n=21), the maximum-tolerated dose was 300 mg/day based on reversible grade 3 headache and asymptomatic hyperlipasemia. Twenty-one and 18 additional patients were accrued at two biologically effective doses, 300 mg/day and 150 mg/day, respectively. Anemia and spleen responses, per International Working Group criteria, were 59% and 48%, respectively. Among 33 patients who were red cell-transfused in the month prior to study entry, 70% achieved a minimum 12-week period without transfusions (range 4.7–>18.3 months). Most patients experienced constitutional symptoms improvement. Grade 3/4 adverse reactions included thrombocytopenia (32%), hyperlipasemia (5%), elevated liver transaminases (3%) and headache (3%). New-onset treatment-related peripheral neuropathy was observed in 22% of patients (sensory symptoms, grade 1). CYT387 is well tolerated and produces significant anemia, spleen and symptom responses in MF patients. Plasma cytokine and gene expression studies suggested a broad anticytokine drug effect. PMID:23459451

  19. IFN-γ induces lipogenesis in mouse mesangial cells via the JAK2/STAT1 pathway.

    PubMed

    Hao, Jun; Zhang, Yu-jun; Lv, Xin; Xu, Ning; Liu, Qin-juan; Zhao, Song; Feng, Xiao-juan; Xing, Ling-ling; Kang, Peng-peng; Li, Gui-ying; Liu, Shu-xia

    2013-04-15

    The objective is to investigate the effect of high mobility group box-1 (HMGB1) on lipid deposition in γ-interferon (IFN-γ)-stimulated mouse mesangial cell line (MMC) and to determine whether the Janus kinase 2 and signal transducer and activator of transcription 1 (JAK2/STAT1) signaling pathway plays an important role in this process. We employed a control group, an IFN-γ stimulation group, and an IFN-γ + AG490 (JAK2 inhibitor) group. RNA interference aimed at sterol regulatory element-binding protein-1 (SREBP-1) or HMGB1 was used to investigate the effect of these proteins on IFN-γ-induced lipid deposition. Western blotting was used to detect phospho (p)-JAK2, JAK2, p-STAT1, STAT1, SREBP-1, fatty acid synthase (FAS), and HMGB1 protein expression. RT-PCR was used to detect SREBP-1, FAS, and HMGB1 mRNA. Oil Red O staining and the triglyceride assay were used to detect lipid deposition and triglyceride content. Results were as follows: 1) IFN-γ increased MMC cell lipid deposition, triglyceride content, and p-JAK2, p-STAT1, SREBP-1, and FAS expression; 2) SREBP-1 inhibition prevented FAS upregulation and attenuated IFN-γ-induced MMC cell lipid deposition and triglyceride content; 3) HMGB1 upregulated SREBP-1 and FAS mRNA and protein levels, which increased lipid deposition in MMC cells. Small interfering RNA-mediated inhibition of HMGB1 decreased SREBP-1 and FAS expression and lipid accumulation; 4) AG490 decreased upregulation of HMGB1 and p-JAK2/p-STAT1, as well as IFN-γ-induced lipogenesis. In conclusion, the JAK2/STAT1 pathway mediates IFN-γ-induced lipogenesis in MMC cells through regulation of HMGB1/SREBP-1/FAS. PMID:23407880

  20. Phosphorylation of the JAK2–STAT5 Pathway in Response to Acute Aerobic Exercise

    PubMed Central

    Consitt, Leslie A.; Wideman, Laurie; Hickey, Matthew S.; Morrison, Ron F.

    2010-01-01

    Growth hormone (GH) is a powerful stimulator of the Janus kinase 2 (JAK2)–signal transducer and activator of transcription 5 (STAT5) pathway. Acute exercise is a known stimulus for GH secretion. Purpose The purpose of this study was to determine the phosphorylation of the JAK2–STAT5 pathway in human skeletal muscle in response to acute aerobic exercise. Methods Eleven young (22.5 ± 0.6, mean ± SE), healthy, aerobically trained males performed 30 min of cycling at 70% V̇O2max. Blood samples were collected at 10- to 15-min intervals and analyzed for human GH, immunofunctional (IF) GH, GH binding protein, and insulin-like growth factor I (IGF-I). Muscle biopsies were taken from the vastus lateralis before exercise, immediately after exercise, as well as, 30 and 60 min postexercise. Muscle samples were analyzed for changes in JAK2 and STAT5 tyrosine phosphorylation, as well as changes in JAK2 and STAT5 protein content. Results Multivariate ANOVA with post hoc comparisons demonstrated that GH and IF GH were significantly elevated immediately after exercise compared with preexercise (P < 0.001). Exercise significantly increased the phosphorylation of JAK2 immediately after exercise (P = 0.004). A trend toward increasing levels of STAT5 phosphorylation was observed immediately after exercise (P = 0.08) and was significantly elevated 30 min after exercise (P = 0.002), compared with preexercise levels. Muscle JAK2 and STAT5 protein content did not change. Conclusion The results demonstrate that the JAK2–STAT5 pathway is activated in response to acute aerobic exercise in human skeletal muscle and suggests that the exercise-induced release of GH may play a role in the activation of this pathway. PMID:18461004

  1. Novel synthetic derivatives of the natural product berbamine inhibit Jak2/Stat3 signaling and induce apoptosis of human melanoma cells

    PubMed Central

    Nam, Sangkil; Xie, Jun; Perkins, Angela; Ma, Yuelong; Yang, Fan; Wu, Jun; Wang, Yan; Xu, Rong-zhen; Huang, Wendong; Horne, David A.; Jove, Richard

    2012-01-01

    Persistent Jak/Stat3 signal transduction plays a crucial role in tumorigenesis and immune development. Activated Jak/Stat3 signaling has been validated as a promising molecular target for cancer therapeutics discovery and development. Berbamine (BBM), a natural bis-benzylisoquinoline alkaloid, was identified from the traditional Chinese herbal medicine Berberis amurensis used for treatment of cancer patients. While BBM has been shown to have potent antitumor activities with low toxicity in various cancer types, the molecular mechanism of action of BBM remains largely unknown. Here, we determine the antitumor activities of thirteen synthetic berbamine derivatives (BBMDs) against human solid tumor cells. BBMD3, which is the most potent in this series of novel BBMDs, exhibits over 6-fold increase in biological activity compared to natural BBM. Moreover, BBMD3, directly inhibits Jak2 autophosphorylation kinase activity in vitro with IC50 = 0.69 μM. Autophosphorylation of Jak2 kinase at Tyr1007/1008 sites also was strongly inhibited in the range of 1 μM to 5 μM of BBMD3 in human melanoma cells at 4 h after treatment. Following inhibition of autophosphorylation of Jak2, BBMD3 blocked constitutive activation of downstream Stat3 signaling in melanoma cells. BBMD3 also down-regulated expression of the Stat3 target proteins Mcl-1 and Bcl-xL, associated with induction of apoptosis. In sum, our findings demonstrate that the novel berbamine derivative BBMD3 is an inhibitor of the Jak2/Stat3 signaling pathway, providing evidence for a molecular mechanism whereby BBMD3 exerts at least in part the apoptosis of human melanoma cells. In addition, BBMD3 represents a promising lead compound for development of new therapeutics for cancer treatment. PMID:22717603

  2. Regulation of PHLDA1 Expression by JAK2-ERK1/2-STAT3 Signaling Pathway.

    PubMed

    Lyu, Ji Hyo; Huang, Bin; Park, Dae-Weon; Baek, Suk-Hwan

    2016-02-01

    Toll-like receptor 2 (TLR2)-mediated signaling cascades and gene regulation are mainly involved in diseases, such as immunity and inflammation. In this study, microarray analysis was performed using bone marrow-derived macrophages (BMDM) and Raw 264.7 cells to identify novel proteins involved in the TLR2-mediated cellular response. We found that pleckstrin homology-like domain family, member 1 (PHLDA1) is a novel gene up-regulated by TLR2 stimulation and determined the unique signaling pathway for its expression. Treatment with TLR2 agonist Pam3 CSK4 increased mRNA, protein, and fluorescence staining of PHLDA1. Induction of PHLDA1 by TLR2 stimulation disappeared from TLR2 KO mice-derived BMDM. Among janus kinase (JAK) family members, JAK2 was involved in TLR2-stimulated PHLDA1 expression. Signal transducer and activator of transcription 3 (STAT3) also participated in PHLDA1 expression downstream of the JAK2. Interestingly, ERK1/2 was an intermediate between JAK2 and STAT3. In silico analysis revealed the presence of highly conserved γ-activated sites within mouse PHLDA1 promoter and confirmed the JAK2-STAT3 pathway is important to Pam3 CSK4 -induced PHLDA1 transcription. These findings suggest that the JAK2-ERK1/2-STAT3 pathway is an important signaling pathway for PHLDA1 expression and that these proteins may play a critical role in eliciting TLR2-mediated immune and inflammatory response. PMID:26239656

  3. Procaine Attenuates Pain Behaviors of Neuropathic Pain Model Rats Possibly via Inhibiting JAK2/STAT3

    PubMed Central

    Li, Donghua; Yan, Yurong; Yu, Lingzhi; Duan, Yong

    2016-01-01

    Neuropathic pain (NPP) is the main culprit among chronic pains affecting the normal life of patients. Procaine is a frequently-used local anesthesia with multiple efficacies in various diseases. However, its role in modulating NPP has not been reported yet. This study aims at uncovering the role of procaine in NPP. Rats were pretreated with procaine by intrathecal injection. Then NPP rat model was induced by sciatic nerve chronic compression injury (CCI) and behavior tests were performed to analyze the pain behaviors upon mechanical, thermal and cold stimulations. Spinal expression of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) was detected by qRT-PCR and western blot. JAK2 was also overexpressed in procaine treated model rats for behavior tests. Results showed that procaine pretreatment improved the pain behaviors of model rats upon mechanical, thermal and cold stimulations, with the best effect occurring on the 15th day post model construction (p<0.05). Procaine also inhibited JAK2 and STAT3 expression in both mRNA (p<0.05) and protein levels. Overexpression of JAK2 increased STAT3 level and reversed the improvement effects of procaine in pain behaviors (p<0.01). These findings indicate that procaine is capable of attenuating NPP, suggesting procaine is a potential therapeutic strategy for treating NPP. Its role may be associated with the inhibition on JAK2/STAT3 signaling. PMID:27530113

  4. JAK2/STAT3 Inhibition Attenuates Noise-Induced Hearing Loss

    PubMed Central

    Wilson, Teresa; Omelchenko, Irina; Foster, Sarah; Zhang, Yuan; Shi, Xiaorui; Nuttall, Alfred L.

    2014-01-01

    Signal transducers and activators of transcription 3 (STAT3) is a stress responsive transcription factor that plays a key role in oxidative stress-mediated tissue injury. As reactive oxygen species (ROS) are a known source of damage to tissues of the inner ear following loud sound exposure, we examined the role of the Janus kinase 2 (JAK2)/STAT3 signaling pathway in noise induce hearing loss using the pathway specific inhibitor, JSI-124. Mice were exposed to a moderately damaging level of loud sound revealing the phosphorylation of STAT3 tyrosine 705 residues and nuclear localization in many cell types in the inner ear including the marginal cells of the stria vascularis, type II, III, and IV fibrocytes, spiral ganglion cells, and in the inner hair cells. Treatment of the mice with the JAK2/STAT3 inhibitor before noise exposure reduced levels of phosphorylated STAT3 Y705. We performed auditory brain stem response and distortion product otoacoustic emission measurements and found increased recovery of hearing sensitivity at two weeks after noise exposure with JAK2/STAT3 inhibition. Performance of cytocochleograms revealed improved outer hair cell survival in JSI-124 treated mice relative to control. Finally, JAK2/STAT3 inhibition reduced levels of ROS detected in outer hair cells at two hours post noise exposure. Together, these findings demonstrate that inhibiting the JAK2/STAT3 signaling pathway is protective against noise-induced cochlear tissue damage and loss of hearing sensitivity. PMID:25275304

  5. JAK2 in the Diagnosis and Treatment of Lymphoid Malignancies: A Review of the Literature.

    PubMed

    Fonseka, Lakshan N; Germán, Beatriz; Expósito, Francisco; Conde, Enrique; Bárcena, Sergio; Tirado, Carlos A

    2016-01-01

    In 2016, there will be an estimated 6,590 new cases of acute lymphocytic leukemia and 18,960 new cases of chronic lymphocytic leukemia in the United States. These and other lymphoid malignancies have a key player in common, JAK2, an enzyme from the Janus kinase (JAK) family. Deviations from the normal functioning of JAK2, particularly in the JAK-signal transducer and activator of transcription (STAT) pathway, can disrupt homeostasis and drive the accumulation of intermediate progenitors, contributing to the development of myeloid and lymphoid malignancies. In this review, the recent literature on JAK2 mutations in lymphoid malignancies is summarized, concluding with a discussion of the treatment of lymphoid malignancies. New directions for future research have been underlined to advance the clinical management of lymphoid malignancies. PMID:27606950

  6. The JAK2 inhibitor AZD1480 potently blocks Stat3 signaling and oncogenesis in solid tumors.

    PubMed

    Hedvat, Michael; Huszar, Dennis; Herrmann, Andreas; Gozgit, Joseph M; Schroeder, Anne; Sheehy, Adam; Buettner, Ralf; Proia, David; Kowolik, Claudia M; Xin, Hong; Armstrong, Brian; Bebernitz, Geraldine; Weng, Shaobu; Wang, Lin; Ye, Minwei; McEachern, Kristen; Chen, Huawei; Morosini, Deborah; Bell, Kirsten; Alimzhanov, Marat; Ioannidis, Stephanos; McCoon, Patricia; Cao, Zhu A; Yu, Hua; Jove, Richard; Zinda, Michael

    2009-12-01

    Persistent activation of Stat3 is oncogenic and is prevalent in a wide variety of human cancers. Chronic cytokine stimulation is associated with Stat3 activation in some tumors, implicating cytokine receptor-associated Jak family kinases. Using Jak2 inhibitors, we demonstrate a central role of Jaks in modulating basal and cytokine-induced Stat3 activation in human solid tumor cell lines. Inhibition of Jak2 activity is associated with abrogation of Stat3 nuclear translocation and tumorigenesis. The Jak2 inhibitor AZD1480 suppresses the growth of human solid tumor xenografts harboring persistent Stat3 activity. We demonstrate the essential role of Stat3 downstream of Jaks by inhibition of tumor growth using short hairpin RNA targeting Stat3. Our data support a key role of Jak kinase activity in Stat3-dependent tumorigenesis. PMID:19962667

  7. Jak2 inhibitor--a jackpot for pharmaceutical industries: a comprehensive computational method in the discovery of new potent Jak2 inhibitors.

    PubMed

    Singh, Kh Dhanachandra; Naveena, Queen; Karthikeyan, Muthusamy

    2014-08-01

    A potent Jak2 inhibitor could solve numerous diseases including hypertension and cardiovascular diseases, myeloproliferative neoplasms, polycythemia vera, essential thrombocythemia, primary myelofibrosis, psoriasis and rheumatoid arthritis. So, identifying potent Jak2 inhibitors is of great interest to researchers and pharmaceutical companies. Virtual screening and molecular docking are important tools for structure based drug discovery but selecting an appropriate method to calculate the electrostatic potential is critical. In this study, four semi empirical (AM1, RM1, PM3, and MNDO) and two empirical (DFT, HF) charges were investigated for their performance on the prediction of docking pose using Glide XP. The result shows that AM1 has the best charge model for our study. Further, we performed a 3D-quantitative structure-activity relationship (3D-QSAR) study of 76 decaene derivatives. Since 3D-QSAR methods are known to be highly sensitive to ligand conformation and alignment method, we did a comparative 3D-QSAR study of AM1 charge docked pose alignment based QSAR (structure based) and pharmacophore based QSAR. We found a better QSAR model in the structure based method. Hence, the results clearly demonstrate that selecting an appropriate method to calculate the electrostatic potential for docking studies and a good alignment of the ligand for 3D-QSAR is critical. Finally, extensive pharmacophore and e-pharmacophore based virtual screening followed by subsequent docking studies identified 27 lead molecules which could be potent Jak2 inhibitors. PMID:24874539

  8. Repeated exposure to far infrared ray attenuates acute restraint stress in mice via inhibition of JAK2/STAT3 signaling pathway by induction of glutathione peroxidase-1.

    PubMed

    Tran, Thai-Ha Nguyen; Mai, Huynh Nhu; Shin, Eun-Joo; Nam, Yunsung; Nguyen, Bao Trong; Lee, Yu Jeung; Jeong, Ji Hoon; Tran, Hoang-Yen Phi; Cho, Eun-Hee; Nah, Seung-Yeol; Lei, Xin Gen; Nabeshima, Toshitaka; Kim, Nam Hun; Kim, Hyoung-Chun

    2016-03-01

    Exposure to far-infrared ray (FIR) has been shown to exert beneficial effects on cardiovascular and emotional disorders. However, the precise underlying mechanism mediated by FIR remains undetermined. Since restraint stress induces cardiovascular and emotional disorders, the present study investigated whether exposure to FIR affects acute restraint stress (ARS) in mice. c-Fos-immunoreactivity (IR) was significantly increased in the paraventricular hypothalamic nucleus (PVN) and dorsomedial hypothalamic nucleus (DMH) in response to ARS. The increase in c-Fos-IR parallels that in oxidative burdens in the hypothalamus against ARS. Exposure to FIR significantly attenuated increases in the c-Fos-IR, oxidative burdens and corticosterone level. ARS elicited decreases in GSH/GSSG ratio, cytosolic Cu/Zn-superoxide dismutase (SOD-1), glutathione peroxidase (GPx), and glutathione reductase (GR) activities. FIR-mediated attenuation was particularly observed in ARS-induced decrease in GPx, but not in SOD-1 or GR activity. Consistently, ARS-induced decreases in GPx-1-immunoreactivity in PVN and DMH, and decreases in GPx-1 expression in the hypothalamus were significantly attenuated by FIR. ARS-induced significant increases in phosphorylation of JAK2/STAT3, and nuclear translocation and DNA-binding activity of NFκB were observed in the hypothalamus. Exposure to FIR selectively attenuated phosphorylation of JAK2/STAT3, but did not diminish nuclear translocation and DNA-binding activity of NFκB, suggesting that JAK2/STAT3 constitutes a critical target for FIR-mediated pharmacological potential. ARS-induced increase in c-Fos-IR in the PVN and DMH of non-transgenic mice was significantly attenuated by FIR exposure or JAK2/STAT3 inhibitor AG490. GPx-1 overexpressing transgenic mice significantly protected increases in the c-Fos-IR and corticosterone level induced by ARS. However, neither FIR exposure nor AG490 significantly affected attenuations by genetic overexpression of GPx-1

  9. Combination of PIM and JAK2 inhibitors synergistically suppresses cell proliferation and overcomes drug resistance of myeloproliferative neoplasms

    PubMed Central

    Greco, Rita; Li, Zhifang; Sun, Fangxian; Barberis, Claude; Tabart, Michel; Patel, Vinod; Schio, Laurent; Hurley, Raelene; Chen, Bo; Cheng, Hong; Lengauer, Christoph; Pollard, Jack; Watters, James; Garcia-Echeverria, Carlos; Wiederschain, Dmitri; Adrian, Francisco; Zhang, JingXin

    2014-01-01

    Inhibitors of JAK2 kinase are emerging as an important treatment modality for myeloproliferative neoplasms (MPN). However, similar to other kinase inhibitors, resistance to JAK2 inhibitors may eventually emerge through a variety of mechanisms. Effective drug combination is one way to enhance therapeutic efficacy and combat resistance against JAK2 inhibitors. To identify potential combination partners for JAK2 compounds in MPN cell lines, we performed pooled shRNA screen targeting 5,000 genes in the presence or absence of JAK2 blockade. One of the top hits identified was MYC, an oncogenic transcription factor that is difficult to inhibit directly, but could be targeted by modulation of upstream regulatory elements such as kinases. We demonstrate herein that PIM kinase inhibitors efficiently suppress MYC protein levels in MPN cell lines. Overexpression of MYC restores the viability of PIM inhibitor-treated cells, revealing causal relationship between MYC down-regulation and cell growth inhibition by PIM compounds. Combination of various PIM inhibitors with a JAK2 inhibitor results in significant synergistic growth inhibition of multiple MPN cancer cell lines and induction of apoptosis. Mechanistic studies revealed strong downregulation of phosphorylated forms of S6 and 4EBP1 by JAK2/PIM inhibitor combination treatment. Finally, such combination was effective in eradicating in vitro JAK2 inhibitor-resistant MPN clones, where MYC is consistently up-regulated. These findings demonstrate that simultaneous suppression of JAK2 and PIM kinase activity by small molecule inhibitors is more effective than either agent alone in suppressing MPN cell growth. Our data suggest that JAK2 and PIM combination might warrant further investigation for the treatment of JAK2-driven hematologic malignancies. PMID:24830942

  10. Synthetic Lethal Screen Demonstrates That a JAK2 Inhibitor Suppresses a BCL6-dependent IL10RA/JAK2/STAT3 Pathway in High Grade B-cell Lymphoma.

    PubMed

    Beck, Daniel; Zobel, Jenny; Barber, Ruth; Evans, Sian; Lezina, Larissa; Allchin, Rebecca L; Blades, Matthew; Elliott, Richard; Lord, Christopher J; Ashworth, Alan; Porter, Andrew C G; Wagner, Simon D

    2016-08-01

    We demonstrate the usefulness of synthetic lethal screening of a conditionally BCL6-deficient Burkitt lymphoma cell line, DG75-AB7, with a library of small molecules to determine survival pathways suppressed by BCL6 and suggest mechanism-based treatments for lymphoma. Lestaurtinib, a JAK2 inhibitor and one of the hits from the screen, repressed survival of BCL6-deficient cells in vitro and reduced growth and proliferation of xenografts in vivo BCL6 deficiency in DG75-AB7 induced JAK2 mRNA and protein expression and STAT3 phosphorylation. Surface IL10RA was elevated by BCL6 deficiency, and blockade of IL10RA repressed STAT3 phosphorylation. Therefore, we define an IL10RA/JAK2/STAT3 pathway each component of which is repressed by BCL6. We also show for the first time that JAK2 is a direct BCL6 target gene; BCL6 bound to the JAK2 promoter in vitro and was enriched by ChIP-seq. The place of JAK2 inhibitors in the treatment of diffuse large B-cell lymphoma has not been defined; we suggest that JAK2 inhibitors might be most effective in poor prognosis ABC-DLBCL, which shows higher levels of IL10RA, JAK2, and STAT3 but lower levels of BCL6 than GC-DLBCL and might be usefully combined with novel approaches such as inhibition of IL10RA. PMID:27268052

  11. Combination of JAK2 and HSP90 inhibitors: an effective therapeutic option in drug-resistant chronic myelogenous leukemia

    PubMed Central

    Perazzona, Bastianella; Sun, Xiaoping; Lin, Yu-Hsi; Arlinghaus, Ralph B.

    2016-01-01

    Recent studies suggest that JAK2 serves as a novel therapeutic target in Bcr-Abl+ chronic myelogenous leukemia (CML). We have reported the existence of an HSP90- associated high molecular weight network complex (HMWNC) that is composed of HSP90 client proteins BCR-ABL, JAK2, and STAT3 in wild type Bcr-Abl+ leukemic cells. Here we showed that the HSP90-HMWNC is present in leukemia cells from CML patients in blast stage, and in Imatinib (IM)-resistant 32Dp210 (T315I) leukemia cells. We found that the HSP90-HMWNC could be disassembled by depleting JAK2 with either Jak2-specific shRNA or treatment with JAK2 inhibitors (TG101209 or Ruxolitinib) and HSP90 inhibitor (AUY922). Combinational treatment with JAK2 and HSP90 inhibitors diminished the activation of BCR-ABL, JAK2 and its downstream targets. As a result, the IM-resistant 32Dp210 T315I cells underwent apoptosis. When administered in mice bearing 32Dp210 T315I leukemia, combinational therapy using Ruxolitinib and AUY922 prolonged the survival significantly. Thus, a combination of JAK2 and HSP90 inhibitors could be a powerful strategy for the treatment of CML, especially in IM-resistant patients. PMID:27551334

  12. Combination of JAK2 and HSP90 inhibitors: an effective therapeutic option in drug-resistant chronic myelogenous leukemia.

    PubMed

    Chakraborty, Sandip N; Leng, Xiaohong; Perazzona, Bastianella; Sun, Xiaoping; Lin, Yu-Hsi; Arlinghaus, Ralph B

    2016-05-01

    Recent studies suggest that JAK2 serves as a novel therapeutic target in Bcr-Abl+ chronic myelogenous leukemia (CML). We have reported the existence of an HSP90- associated high molecular weight network complex (HMWNC) that is composed of HSP90 client proteins BCR-ABL, JAK2, and STAT3 in wild type Bcr-Abl+ leukemic cells. Here we showed that the HSP90-HMWNC is present in leukemia cells from CML patients in blast stage, and in Imatinib (IM)-resistant 32Dp210 (T315I) leukemia cells. We found that the HSP90-HMWNC could be disassembled by depleting JAK2 with either Jak2-specific shRNA or treatment with JAK2 inhibitors (TG101209 or Ruxolitinib) and HSP90 inhibitor (AUY922). Combinational treatment with JAK2 and HSP90 inhibitors diminished the activation of BCR-ABL, JAK2 and its downstream targets. As a result, the IM-resistant 32Dp210 T315I cells underwent apoptosis. When administered in mice bearing 32Dp210 T315I leukemia, combinational therapy using Ruxolitinib and AUY922 prolonged the survival significantly. Thus, a combination of JAK2 and HSP90 inhibitors could be a powerful strategy for the treatment of CML, especially in IM-resistant patients. PMID:27551334

  13. Calmodulin physically interacts with the erythropoietin receptor and enhances Jak2-mediated signaling

    SciTech Connect

    Kakihana, Kazuhiko; Yamamoto, Masahide; Iiyama, Mitsuko; Miura, Osamu . E-mail: miura.hema@tmd.ac.jp

    2005-09-23

    Stimulation of the erythropoietin receptor (EpoR) induces a transient increase in intracellular Ca{sup 2+} level as well as activation of the Jak2 tyrosine kinase to stimulate various downstream signaling pathways. Here, we demonstrate that the universal Ca{sup 2+} receptor calmodulin (CaM) binds EpoR in a Ca{sup 2+}-dependent manner in vitro. Binding studies using various EpoR mutants in hematopoietic cells showed that CaM binds the membrane-proximal 65-amino-acid cytoplasmic region (amino acids 258-312) of EpoR that is critical for activation of Jak2-mediated EpoR signaling. Structurally unrelated CaM antagonists, W-13 and CMZ, inhibited activation of Jak2-mediated EpoR signaling pathways, whereas W-12, a W-13 analog, did not show any significant inhibitory effect. Moreover, overexpression of CaM augmented Epo-induced tyrosine phosphorylation of the EpoR. W-13, but not W-12, also inhibited Epo-induced proliferation and survival. Together, these results indicate that CaM binds to the membrane-proximal EpoR cytoplasmic region and plays an essential role in activation of Jak2-mediated EpoR signaling.

  14. JAK2 inhibition sensitizes resistant EGFR-mutant lung adenocarcinoma to tyrosine kinase inhibitors

    PubMed Central

    Gao, Sizhi P.; Chang, Qing; Mao, Ninghui; Daly, Laura A.; Vogel, Robert; Chan, Tyler; Liu, Shu Hui; Bournazou, Eirini; Schori, Erez; Zhang, Haiying; Brewer, Monica Red; Pao, William; Morris, Luc; Ladanyi, Marc; Arcila, Maria; Manova-Todorova, Katia; de Stanchina, Elisa; Norton, Larry; Levine, Ross L.; Altan-Bonnet, Gregoire; Solit, David; Zinda, Michael; Huszar, Dennis; Lyden, David; Bromberg, Jacqueline F.

    2016-01-01

    Lung adenocarcinomas with mutant epidermal growth factor receptor (EGFR) respond to EGFR-targeted tyrosine kinase inhibitors (TKIs), but resistance invariably occurs. We found that the Janus kinase (JAK)/signal transduction and activator of transcription 3 (STAT3) signaling pathway was aberrantly increased in TKI-resistant EGFR-mutant non–small cell lung cancer (NSCLC) cells. JAK2 inhibition restored sensitivity to the EGFR inhibitor erlotinib in TKI-resistant cell lines and xenograft models of EGFR-mutant TKI-resistant lung cancer. JAK2 inhibition uncoupled EGFR from its negative regulator, suppressor of cytokine signaling 5 (SOCS5), consequently increasing EGFR abundance and restoring the tumor cells’ dependence on EGFR signaling. Furthermore, JAK2 inhibition led to heterodimerization of mutant and wild-type EGFR subunits, the activity of which was then blocked by TKIs. Our results reveal a mechanism whereby JAK2 inhibition overcomes acquired resistance to EGFR inhibitors and support the use of combination therapy with JAK and EGFR inhibitors for the treatment of EGFR-dependent NSCLC. PMID:27025877

  15. Inhibition of the JAK2/STAT3 signaling pathway exerts a therapeutic effect on osteosarcoma.

    PubMed

    Yan, Jun; Wang, Qianliang; Zou, Kang; Wang, Li; Schwartz, Eric B; Fuchs, James R; Zheng, Zugen; Wu, Jianqiang

    2015-07-01

    Osteosarcoma (OS) is the most common type of malignant bone tumor. Despite aggressive multimodal treatments, including surgical resection, chemotherapy and adjunctive immunotherapies, patients with OS with high-grade malignancy have a poor five-year survival rate that has remained unchanged over the past two decades, highlighting the urgent requirement for novel therapeutic approaches. Signal transducers and activators of transcription 3 (STAT3) has been implicated as an oncogene and therapeutic target in a variety of neoplastic diseases. The aim of the present study was to determine whether inhibition of the janus kinase 2 (JAK2)/STAT3 pathway by FLLL32, a specific JAK2/STAT3 inhibitor, is able to provide a potential therapy for OS. FLLL32 inhibited OS cell growth in vitro and delayed OS growth in an OS xenograft nude mouse model. STAT3 knockdown by short hairpin RNA delayed OS formation in vivo. Thus, the JAK2/STAT3 pathway is important in OS formation. Efficacy of the FLLL32 pharmacological inhibitor in delaying OS growth suggests that targeting JAK2/STAT3 may be a potential therapeutic strategy for patients with OS. PMID:25760445

  16. Association of common JAK2 variants with body fat, insulin sensitivity and lipid profile

    PubMed Central

    Ge, Dongliang; Gooljar, Sakina B; Kyriakou, Theodosios; Collins, Laura J; Swaminathan, Ramasamyiyer; Snieder, Harold; Spector, Tim D; O'Dell, Sandra D

    2007-01-01

    The leptin signal is transduced via the JAK2-STAT3 pathway at the leptin receptor. JAK2 also phosphorylates IRS, integral to insulin and leptin action and is required for optimum ABCA1-dependent transport of lipids from cells to apoA-I. We hypothesised that common variation in the JAK2 gene may be associated with body fat, insulin sensitivity and modulation of the serum lipid profile in the general population. Ten tagging SNPs spanning the gene were genotyped in 2760 Caucasian female twin subjects (mean age 47.3±12.6 years) from the St Thomas' UK Adult Twin Registry (Twins UK). Minor allele frequencies were between 0.170 and 0.464. The major allele of rs7849191 was associated with higher central fat (P=0.030), % central fat (P=0.014) and waist circumference (P=0.027) and the major allele of rs3780378 with higher serum apoA (P=0.026), total cholesterol (P=0.014) and LDL cholesterol (P=0.012) and lower triglyceride (P=0.023). However, no associations were significant at a level which took account of multiple testing. Although JAK2 is a critical element in leptin and insulin signalling and has a role in cellular cholesterol transport, we failed to establish associations of common SNPs with relevant phenotypes in this human study. PMID:18239666

  17. JAK2 inhibition sensitizes resistant EGFR-mutant lung adenocarcinoma to tyrosine kinase inhibitors.

    PubMed

    Gao, Sizhi P; Chang, Qing; Mao, Ninghui; Daly, Laura A; Vogel, Robert; Chan, Tyler; Liu, Shu Hui; Bournazou, Eirini; Schori, Erez; Zhang, Haiying; Red Brewer, Monica; Pao, William; Morris, Luc; Ladanyi, Marc; Arcila, Maria; Manova-Todorova, Katia; de Stanchina, Elisa; Norton, Larry; Levine, Ross L; Altan-Bonnet, Gregoire; Solit, David; Zinda, Michael; Huszar, Dennis; Lyden, David; Bromberg, Jacqueline F

    2016-01-01

    Lung adenocarcinomas with mutant epidermal growth factor receptor (EGFR) respond to EGFR-targeted tyrosine kinase inhibitors (TKIs), but resistance invariably occurs. We found that the Janus kinase (JAK)/signal transduction and activator of transcription 3 (STAT3) signaling pathway was aberrantly increased in TKI-resistant EGFR-mutant non-small cell lung cancer (NSCLC) cells. JAK2 inhibition restored sensitivity to the EGFR inhibitor erlotinib in TKI-resistant cell lines and xenograft models of EGFR-mutant TKI-resistant lung cancer. JAK2 inhibition uncoupled EGFR from its negative regulator, suppressor of cytokine signaling 5 (SOCS5), consequently increasing EGFR abundance and restoring the tumor cells' dependence on EGFR signaling. Furthermore, JAK2 inhibition led to heterodimerization of mutant and wild-type EGFR subunits, the activity of which was then blocked by TKIs. Our results reveal a mechanism whereby JAK2 inhibition overcomes acquired resistance to EGFR inhibitors and support the use of combination therapy with JAK and EGFR inhibitors for the treatment of EGFR-dependent NSCLC. PMID:27025877

  18. AURKA regulates JAK2-STAT3 activity in human gastric and esophageal cancers.

    PubMed

    Katsha, Ahmed; Arras, Janet; Soutto, Mohammed; Belkhiri, Abbes; El-Rifai, Wael

    2014-12-01

    Aurora kinase A is a frequently amplified and overexpressed gene in upper gastrointestinal adenocarcinomas (UGCs). Using in vitro cell models of UGCs, we investigated whether AURKA can regulate Signal Transducer and Activator of Transcription 3 (STAT3). Our data indicate that overexpression of AURKA in FLO-1 and AGS cells increase STAT3 phosphorylation at the Tyr705 site, whereas AURKA genetic depletion by siRNA results in decreased phosphorylation levels of STAT3 in FLO-1 and MKN45 cells. Immunofluorescence analysis showed that AURKA overexpression enhanced STAT3 nuclear translocation while AURKA genetic knockdown reduced the nuclear translocation of STAT3 in AGS and FLO-1 cells, respectively. Using a luciferase reporter assay, we demonstrated that AURKA expression induces transcriptional activity of STAT3. Pharmacological inhibition of AURKA by MLN8237 reduced STAT3 phosphorylation along with down-regulation of STAT3 pro-survival targets, BCL2 and MCL1. Moreover, by using clonogenic cells survival assay, we showed that MLN8237 single dose treatment reduced the ability of FLO-1 and AGS cells to form colonies. Additional experiments utilizing cell models of overexpression and knockdown of AURKA indicated that STAT3 upstream non-receptor tyrosine kinase Janus kinase 2 (JAK2) is mediating the effect of AURKA on STAT3. The inhibition of JAK2 using JAK2-specific inhibitor AZD1480 or siRNA knockdown, in presence of AURKA overexpression, abrogated the AURKA-mediated STAT3 activation. These results confirm that the AURKA-JAK2 axis is the main mechanism by which AURKA regulates STAT3 activity. In conclusion, we report, for the first time, that AURKA promotes STAT3 activity through regulating the expression and phosphorylation levels of JAK2. This highlights the importance of targeting AURKA as a therapeutic approach to treat gastric and esophageal cancers. PMID:24953013

  19. The role of the Janus-faced transcription factor PAX5-JAK2 in acute lymphoblastic leukemia

    PubMed Central

    Schinnerl, Dagmar; Fortschegger, Klaus; Kauer, Maximilian; Marchante, João R. M.; Kofler, Reinhard; Den Boer, Monique L.

    2015-01-01

    PAX5-JAK2 has recently been identified as a novel recurrent fusion gene in B-cell precursor acute lymphoblastic leukemia, but the function of the encoded chimeric protein has not yet been characterized in detail. Herein we show that the PAX5-JAK2 chimera, which consists of the DNA-binding paired domain of PAX5 and the active kinase domain of JAK2, is a nuclear protein that has the ability to bind to wild-type PAX5 target loci. Moreover, our data provide compelling evidence that PAX5-JAK2 functions as a nuclear catalytically active kinase that autophosphorylates and in turn phosphorylates and activates downstream signal transducers and activators of transcription (STATs) in an apparently noncanonical mode. The chimeric protein also enables cytokine-independent growth of Ba/F3 cells and therefore possesses transforming potential. Importantly, the kinase activity of PAX5-JAK2 can be efficiently blocked by JAK2 inhibitors, rendering it a potential target for therapeutic intervention. Together, our data show that PAX5-JAK2 simultaneously deregulates the PAX5 downstream transcriptional program and activates the Janus kinase-STAT signaling cascade and thus, by interfering with these two important pathways, may promote leukemogenesis. PMID:25515960

  20. Enhancing specificity in the Janus kinases: a study on the thienopyridine JAK2 selective mechanism combined molecular dynamics simulation.

    PubMed

    Li, Jiao Jiao; Cheng, Peng; Tu, Jing; Zhai, Hong Lin; Zhang, Xiao Yun

    2016-02-01

    The selective inhibition for JAK2 over the other JAK family kinases (JAK1, JAK3 and TYK2) has shared an immense challenge due to high conservatism. In this paper, the highly JAK2 selective mechanism of the thienopyridine derivative was identified at the molecular level, based on insights into the inhibitory effects of compound on four JAK kinases by molecular docking, molecular dynamic simulations, free energy calculation and decomposition. The results clearly indicated that the nonpolar contribution and the H-bond network in the hinge region played a critical selective role in stabilizing ligand JAK2, and the residues Glu930, Leu932 and Gly935 in JAK2 kinase were the key differences compared to the equivalence residues of JAK1, JAK3 and TYK2, which were further verified by simulating four complexes of JAK kinases with another highly selective thienopyridine JAK2 inhibitor . Finally, several novel molecules were designed according to above findings and further verified by the same comprehensive modeling protocol. The obtained results not only demonstrated the rationality of our models and analyses, but also suggested that the designed molecules with higher JAK2 selectivity and bioactivity potential would provide an update of JAK2 inhibitors. PMID:26687880

  1. Proinflammatory Cytokine IL-6 and JAK-STAT Signaling Pathway in Myeloproliferative Neoplasms

    PubMed Central

    Čokić, Vladan P.; Mitrović-Ajtić, Olivera; Beleslin-Čokić, Bojana B.; Marković, Dragana; Buač, Marijana; Diklić, Miloš; Kraguljac-Kurtović, Nada; Damjanović, Svetozar; Milenković, Pavle; Gotić, Mirjana; Raj, Puri K.

    2015-01-01

    The recent JAK1/2 inhibitor trial in myeloproliferative neoplasms (MPNs) showed that reducing inflammation can be more beneficial than targeting gene mutants. We evaluated the proinflammatory IL-6 cytokine and JAK-STAT signaling pathway related genes in circulating CD34+ cells of MPNs. Regarding laboratory data, leukocytosis has been observed in polycythemia vera (PV) and JAK2V617F mutation positive versus negative primary myelofibrosis (PMF) patients. Moreover, thrombocytosis was reduced by JAK2V617F allele burden in essential thrombocythemia (ET) and PMF. 261 significantly changed genes have been detected in PV, 82 in ET, and 94 genes in PMF. The following JAK-STAT signaling pathway related genes had augmented expression in CD34+ cells of MPNs: CCND3 and IL23A regardless of JAK2V617F allele burden; CSF3R, IL6ST, and STAT1/2 in ET and PV with JAK2V617F mutation; and AKT2, IFNGR2, PIM1, PTPN11, and STAT3 only in PV. STAT5A gene expression was generally reduced in MPNs. IL-6 cytokine levels were increased in plasma, as well as IL-6 protein levels in bone marrow stroma of MPNs, dependent on JAK2V617F mutation presence in ET and PMF patients. Therefore, the JAK2V617F mutant allele burden participated in inflammation biomarkers induction and related signaling pathways activation in MPNs. PMID:26491227

  2. Thiophene carboxamide inhibitors of JAK2 as potential treatments for myleoproliferative neoplasms.

    PubMed

    Haidle, Andrew M; Zabierek, Anna A; Childers, Kaleen K; Rosenstein, Craig; Mathur, Anjili; Altman, Michael D; Chan, Grace; Xu, Lin; Bachman, Eric; Mo, Jan-Rung; Bouthillette, Melaney; Rush, Thomas; Tempest, Paul; Marshall, C Gary; Young, Jonathan R

    2014-04-15

    A series of carboxamide-substituted thiophenes demonstrating inhibition of JAK2 is described. Development of this chemical series began with the bioisosteric replacement of a urea substituent by a pyridyl ring. Issues of chemical and metabolic stability were solved using the results of both in vitro and in vivo studies, ultimately delivering compounds such as 24 and 25 that performed well in an acute PK/PD model measuring p-STAT5 inhibition. PMID:24666646

  3. JAK2/STAT3 targeted therapy suppresses tumor invasion via disruption of the EGFRvIII/JAK2/STAT3 axis and associated focal adhesion in EGFRvIII-expressing glioblastoma

    PubMed Central

    Zheng, Qifan; Han, Lei; Dong, Yucui; Tian, Jing; Huang, Wei; Liu, Zhaoyu; Jia, Xiuzhi; Jiang, Tao; Zhang, Jianning; Li, Xia; Kang, Chunsheng; Ren, Huan

    2014-01-01

    Background As a commonly mutated form of the epidermal growth factor receptor, EGFRvIII strongly promotes glioblastoma (GBM) tumor invasion and progression, but the mechanisms underlying this promotion are not fully understood. Methods Through gene manipulation, we established EGFRvIII-, wild-type EGFR-, and vector-expressing GBM cells. We used cDNA microarrays, bioinformatics analysis, target-blocking migration and invasion assays, Western blotting, and an orthotopic U87MG GBM model to examine the phenotypic shifts and treatment effects of EGFRvIII expression in vitro and in vivo. Confocal imaging, co-immunoprecipitation, and siRNA assays detected the focal adhesion-associated complex and their relationships to the EGFRvIII/JAK2/STAT3 axis in GBM cells. Results The activation of JAK2/STAT3 signaling is vital for promoting migration and invasion in EGFRvIII-GBM cells. AG490 or WP1066, the JAK2/STAT3 inhibitors, specifically destroyed EGFRvIII/JAK2/STAT3-related focal adhesions and depleted the activation of EGFR/Akt/FAK and JAK2/STAT3 signaling, thereby abolishing the ability of EGFRvIII-expressing GBM cells to migrate and invade. Furthermore, the RNAi silencing of JAK2 in EGFRvIII-expressing GBM cells significantly attenuated their ability to migrate and invade; however, as a result of a potential EGFRvIII-JAK2-STAT3 activation loop, neither EGFR nor STAT3 knockdown yielded the same effects. Moreover, AG490 or JAK2 gene knockdown greatly suppressed tumor invasion and progression in the U87MG-EGFRvIII orthotopic models. Conclusion Taken together, our data demonstrate that JAK2/STAT3 signaling is essential for EGFRvIII-driven migration and invasion by promoting focal adhesion and stabilizing the EGFRvIII/JAK2/STAT3 axis. Targeting JAK2/STAT3 therapy, such as AG490, may have potential clinical implications for the tailored treatment of GBM patients bearing EGFRvIII-positive tumors. PMID:24861878

  4. Activation of JAK2 kinase mediated by the interleukin 6 signal transducer gp130.

    PubMed Central

    Narazaki, M; Witthuhn, B A; Yoshida, K; Silvennoinen, O; Yasukawa, K; Ihle, J N; Kishimoto, T; Taga, T

    1994-01-01

    The interleukin 6 receptor-associated signal transducer, gp130, is shared by receptor complexes for leukemia inhibitory factor, oncostatin M, ciliary neurotrophic factor, and interleukin 11. We show here that JAK2 kinase is rapidly tyrosine phosphorylated in mouse embryonic stem cells whose pluripotentiality is maintained only by gp130-sharing cytokines after stimulation that is known to induce gp130 homodimerization. JAK1 is also tyrosine phosphorylated, but to a lesser extent, under the same conditions. Comparable results are obtained with hemopoietic lineage cells such as myeloid leukemic M1 cells and pro-B-cell line-derived transfectants expressing gp130, the former of which differentiate into macrophages after stimulation of gp130 and the latter of which initiate DNA synthesis. gp130-dimerizing stimulus upregulates kinase activity of JAK2 as revealed by immunocomplex kinase assay. Deletion or point mutation in the membrane-proximal cytoplasmic motifs in gp130 that are conserved in the hemopoietic cytokine receptor family results in the loss of tyrosine phosphorylation of JAK2, which coincides with the lack of signal transducing capability of gp130 mutants. Images PMID:8134389

  5. Crystal Structure of the FERM-SH2 Module of Human Jak2.

    PubMed

    McNally, Randall; Toms, Angela V; Eck, Michael J

    2016-01-01

    Jak-family tyrosine kinases mediate signaling from diverse cytokine receptors. Binding of Jaks to their cognate receptors is mediated by their N-terminal region, which contains FERM and SH2 domains. Here we describe the crystal structure of the FERM-SH2 region of Jak2 at 3.0Å resolution. The structure reveals that these domains and their flanking linker segments interact intimately to form an integrated structural module. The Jak2 FERM-SH2 structure closely resembles that recently described for Tyk2, another member of the Jak family. While the overall architecture and interdomain orientations are preserved between Jak2 and Tyk2, we identify residues in the putative receptor-binding groove that differ between the two and may contribute to the specificity of receptor recognition. Analysis of Jak mutations that are reported to disrupt receptor binding reveals that they lie in the hydrophobic core of the FERM domain, and are thus expected to compromise the structural integrity of the FERM-SH2 unit. Similarly, analysis of mutations in Jak3 that are associated with severe combined immunodeficiency suggests that they compromise Jak3 function by destabilizing the FERM-SH2 structure. PMID:27227461

  6. JAK2/STAT3 pathway mediating inflammatory responses in heatstroke-induced rats

    PubMed Central

    Tao, Zhen; Cheng, Ming; Wang, Shu-Cai; Lv, Wei; Hu, Huai-Qiang; Li, Chuan-Fen; Cao, Bing-Zhen

    2015-01-01

    Heatstroke not only directly induces cell injury, but also causes large amounts of inflammatory mediators release and cells with extensive biological activities to induce a systemic inflammatory response and immune dysfunction. This study aimed to observe the effects of JAK2 inhibitor AG490 on the brain injury and inflammatory responses of rats with systemic heatstroke. Under the light microscope, the hippocampus tissues of rat with heatstroke were edema and apoptotic rate was increased. Up-regulation of malondialdehyde (MDA), nitric oxide synthase (iNOS), reactive oxygen species (ROS) and down-regulation of superoxide dismutase (SOD) were also found after heatstroke in rats, which compared with that of the control group. Heatstroke induced inflammation factors secretions and up-regulated levels of matrix metallopeptidase 2 and 9 (MMP2 and MMP-9) and systemic inflammatory response molecules including intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-beta 1 (TNF-β1) and cyclooxygenase-2 (COX-2). However, the JAK2 inhibitor AG490 was significantly attenuated the brain injury and inflammatory responses induced by heatstroke in rats. The survival time of heatstroke rats showed that AG490 notably lived longer than heatstroke rats without AG490 treatment. These findings suggest that AG490 may prevent the occurrence of heatstroke via inhibiting the JAK2/STAT3 pathway and the systemic inflammatory responses. PMID:26261556

  7. Crystal Structure of the FERM-SH2 Module of Human Jak2

    PubMed Central

    McNally, Randall; Toms, Angela V.; Eck, Michael J.

    2016-01-01

    Jak-family tyrosine kinases mediate signaling from diverse cytokine receptors. Binding of Jaks to their cognate receptors is mediated by their N-terminal region, which contains FERM and SH2 domains. Here we describe the crystal structure of the FERM-SH2 region of Jak2 at 3.0Å resolution. The structure reveals that these domains and their flanking linker segments interact intimately to form an integrated structural module. The Jak2 FERM-SH2 structure closely resembles that recently described for Tyk2, another member of the Jak family. While the overall architecture and interdomain orientations are preserved between Jak2 and Tyk2, we identify residues in the putative receptor-binding groove that differ between the two and may contribute to the specificity of receptor recognition. Analysis of Jak mutations that are reported to disrupt receptor binding reveals that they lie in the hydrophobic core of the FERM domain, and are thus expected to compromise the structural integrity of the FERM-SH2 unit. Similarly, analysis of mutations in Jak3 that are associated with severe combined immunodeficiency suggests that they compromise Jak3 function by destabilizing the FERM-SH2 structure. PMID:27227461

  8. JAK2/STAT3 pathway mediating inflammatory responses in heatstroke-induced rats.

    PubMed

    Tao, Zhen; Cheng, Ming; Wang, Shu-Cai; Lv, Wei; Hu, Huai-Qiang; Li, Chuan-Fen; Cao, Bing-Zhen

    2015-01-01

    Heatstroke not only directly induces cell injury, but also causes large amounts of inflammatory mediators release and cells with extensive biological activities to induce a systemic inflammatory response and immune dysfunction. This study aimed to observe the effects of JAK2 inhibitor AG490 on the brain injury and inflammatory responses of rats with systemic heatstroke. Under the light microscope, the hippocampus tissues of rat with heatstroke were edema and apoptotic rate was increased. Up-regulation of malondialdehyde (MDA), nitric oxide synthase (iNOS), reactive oxygen species (ROS) and down-regulation of superoxide dismutase (SOD) were also found after heatstroke in rats, which compared with that of the control group. Heatstroke induced inflammation factors secretions and up-regulated levels of matrix metallopeptidase 2 and 9 (MMP2 and MMP-9) and systemic inflammatory response molecules including intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-beta 1 (TNF-β1) and cyclooxygenase-2 (COX-2). However, the JAK2 inhibitor AG490 was significantly attenuated the brain injury and inflammatory responses induced by heatstroke in rats. The survival time of heatstroke rats showed that AG490 notably lived longer than heatstroke rats without AG490 treatment. These findings suggest that AG490 may prevent the occurrence of heatstroke via inhibiting the JAK2/STAT3 pathway and the systemic inflammatory responses. PMID:26261556

  9. AZD1480, a JAK inhibitor, inhibits cell growth and survival of colorectal cancer via modulating the JAK2/STAT3 signaling pathway.

    PubMed

    Wang, Shu-Wei; Hu, Jun; Guo, Qin-Hao; Zhao, Yan; Cheng, Jie-Jing; Zhang, Dong-Sheng; Fei, Qiang; Li, Juan; Sun, Yue-Ming

    2014-11-01

    Interleukin (IL)-6 and the downstream Janus kinase (JAK)/signal activator of transcription (STAT) pathway have been found to be important in the development of colorectal cancer (CRC). To develop novel therapies for CRC, we have explored the effects of a novel small-molecule JAK inhibitor (AZD1480) on IL-6/JAK/STAT3 pathway and its potential antitumor activity on the human CRC cell lines (HCT116, HT29 and SW480). The results showed that, AZD1480 effectively prevents constitutive and IL-6-induced JAK2 and STAT-3 phosphorylation and exerted antitumor functional effects by a decrease in proliferation and an increase in apoptosis in CRC cells. The inhibition of tumorigenesis was consistent with the decreased phosphorylated JAK2 and phosphorylated STAT3, and the decreased expression of STAT3‑targeted genes c-Myc, cyclin D2 and IL-6. Thus, AZD1480 is a potential new clinical therapeutic agent for patients with CRC. PMID:25216185

  10. Sodium orthovanadate suppresses palmitate-induced cardiomyocyte apoptosis by regulation of the JAK2/STAT3 signaling pathway.

    PubMed

    Liu, Jing; Fu, Hui; Chang, Fen; Wang, Jinlan; Zhang, Shangli; Caudle, Yi; Zhao, Jing; Yin, Deling

    2016-05-01

    Elevated circulatory free fatty acids (FFAs) especially saturated FFAs, such as palmitate (PA), are detrimental to the heart. However, mechanisms responsible for this phenomenon remain unknown. Here, the role of JAK2/STAT3 in PA-induced cytotoxicity was investigated in cardiomyocytes. We demonstrate that PA suppressed the JAK2/STAT3 pathway by dephosphorylation of JAK2 (Y1007/1008) and STAT3 (Y705), and thus blocked the translocation of STAT3 into the nucleus. Conversely, phosphorylation of S727, another phosphorylated site of STAT3, was increased in response to PA treatment. Pretreatment of JNK inhibitor, but not p38 MAPK inhibitor, inhibited STAT3 (S727) activation induced by PA and rescued the phosphorylation of STAT3 (Y705). The data suggested that JNK may be another upstream factor regulating STAT3, and verified the important function of P-STAT3 (Y705) in PA-induced cardiomyocyte apoptosis. Sodium orthovanadate (SOV), a protein tyrosine phosphatase inhibitor, obviously inhibited PA-induced apoptosis by restoring JAK2/STAT3 pathways. This effect was diminished by STAT3 inhibitor Stattic. Collectively, our data suggested a novel mechanism that the inhibition of JAK2/STAT3 activation was responsible for palmitic lipotoxicity and SOV may act as a potential therapeutic agent by targeting JAK2/STAT3 in lipotoxic cardiomyopathy treatment. PMID:26921179

  11. Inflammation as a Driver of Clonal Evolution in Myeloproliferative Neoplasm

    PubMed Central

    Fleischman, Angela G.

    2015-01-01

    Our understanding of inflammation's role in the pathogenesis of myeloproliferative neoplasm (MPN) is evolving. The impact of chronic inflammation, a characteristic feature of MPN, likely goes far beyond its role as a driver of constitutional symptoms. An inflammatory response to the neoplastic clone may be responsible for some pathologic aspects of MPN. Moreover, JAK2V617F mutated hematopoietic stem and progenitor cells are resistant to inflammation, and this gives the neoplastic clone a selective advantage allowing for its clonal expansion. Because inflammation plays a central role in MPN inflammation is a logical therapeutic target in MPN. PMID:26538830

  12. Jak2-Independent Activation of Stat3 by Intracellular Angiotensin II in Human Mesangial Cells.

    PubMed

    Singh, Rekha

    2011-01-01

    Ang II is shown to mediate the stimulatory effect of high glucose on TGF-b1 and extracellular matrix proteins in glomerular mesangial cells. Also inhibition of Ang II formation in cell media (extracellular) and lysates (intracellular) blocks high-glucose effects on TGF-b1 and matrix more effectively compared to inhibition of extracellular Ang II alone. To investigate whether intracellular Ang II can stimulate TGF-b1 and matrix independent of extracellular Ang II, cultured human mesangial cells were transfected with Ang II to increase intracellular Ang II levels and its effects on TGF-b1 and matrix proteins were determined. Prior to transfection, cells were treated with candesartan to block extracellular Ang II-induced responses via cell membrane AT1 receptors. Transfection of cells with Ang II resulted in increased levels of intracellular Ang II which was accompanied by increased production of TGF-b1, collagen IV, fibronectin, and cell proliferation as well. On further examination, intracellular Ang II was found to activate Stat3 transcription factor including increased Stat3 protein expression, tyrosine 705 phosphorylation, and DNA-binding activity. Treatment with AG-490, an inhibitor of Jak2, did not block intracellular Ang II-induced Stat3 phosphorylation at tyrosine 705 residue indicating a Jak2-independent mechanism used by intracellular Ang II for Stat3 phosphorylation. In contrast, extracellular Ang II-induced tyrosine 705 phosphorylation of Stat3 was inhibited by AG-490 confirming the presence of a Jak2-dependent pathway. These findings suggest that intracellular Ang II increases TGF-b1 and matrix in human mesangial cells and also activates Stat3 transcription factor without involvement of the extracellular Ang II signaling pathway. PMID:21915376

  13. RANKL downregulates cell surface CXCR6 expression through JAK2/STAT3 signaling pathway during osteoclastogenesis

    SciTech Connect

    Li, Changhong; Zhao, Jinxia; Sun, Lin; Yao, Zhongqiang; Liu, Rui; Huang, Jiansheng; Liu, Xiangyuan

    2012-12-14

    Highlights: Black-Right-Pointing-Pointer CXCR6 is down-regulated during RANKL-induced osteoclastogenesis in RAW264.7 cells. Black-Right-Pointing-Pointer CXCR6 reduction was nearly reversed by inhibition of JAK2/STAT3 signaling pathway. Black-Right-Pointing-Pointer CXCL16 alone does not positively regulate osteoclastogenesis. -- Abstract: The receptor activator of nuclear factor-{kappa}B ligand (RANKL), as a member of the tumor necrosis factor (TNF) family, plays an essential role in osteoclast differentiation and function. Chemokines and their receptors have recently been shown to play critical roles in osteoclastogenesis, however, whether CXCL16-CXCR6 plays role in RANKL-mediated osteoclastogenesis is unknown. In this study, we first reported that RANKL decreased CXCR6 in a dose-dependent manner, which may be through deactivation of Akt and STAT3 signaling induced by CXCL16. Interestingly, RANKL-mediated CXCR6 reduction may be associated to the activation of STAT3 by phosphorylation. When STAT3 activation was blocked by JAK2/STAT3 inhibitor AG490, RANKL failed to shut down CXCR6 expression during osteoclastogenesis. However, CXCL16 alone did not augment RANKL-mediated osteoclast differentiation and did not alter RANKL-receptor RANK mRNA expression. These results demonstrate that reduction of CXCL16-CXCR6 is critical in RANKL-mediated osteoclastogenesis, which is mainly through the activation of JAK2/STAT3 signaling. CXCL16-CXCR6 axis may become a novel target for the therapeutic intervention of bone resorbing diseases such as rheumatoid arthritis and osteoporosis.

  14. The expression of Death Inducer-Obliterator (DIDO) variants in Myeloproliferative Neoplasms.

    PubMed

    Berzoti-Coelho, Maria Gabriela; Ferreira, Aline Fernanda; de Souza Nunes, Natalia; Pinto, Mariana Tomazini; Júnior, Maurício Cristiano Rocha; Simões, Belinda Pinto; Martínez-A, Carlos; Souto, Elizabeth Xisto; Panepucci, Rodrigo Alexandre; Covas, Dimas Tadeu; Kashima, Simone; Castro, Fabíola Attié

    2016-07-01

    Chronic Myeloid Leukemia (CML), Polycythemia Vera (PV), Essential Thrombocythemia (ET) and Primary Myelofibrosis (PMF) are Myeloproliferative Neoplasms (MPN) characterized by clonal myeloproliferation without cell maturation impairment. CML pathogenesis is associated with the Ph chromosome leading to BCR-ABL tyrosine-kinase constitutive expression. The Ph negative MPN (PV, ET and PMF) are characterized by the mutation JAK2(V617F) of the JAK2 protein in the auto-inhibitory JH2 domain, which is found in most PV patients and in approximately half of ET and PMF patients. Considerable effort is being made to understand the role of JAK2(V617F) at the MPN initiation and to clarify the pathogenesis and apoptosis resistance in CML, PV, ET and PMF patients. In the present investigation, we evaluated the Death Inducer-Obliterator (DIDO) (variants DIDO 1, 2 and 3) levels in CML, PV, ET and PMF patients. Our data reported the DIDO 1, 2 and 3 differential expressions in Myeloproliferative Neoplasms. PMID:27282563

  15. Mutational analysis of JAK2, CBL, RUNX1, and NPM1 genes in familial aggregation of hematological malignancies.

    PubMed

    Hamadou, Walid S; Bourdon, Violaine; Gaildrat, Pascaline; Besbes, Sawsen; Fabre, Aurélie; Youssef, Yosra B; Regaieg, Haifa; Laatiri, Mohamed A; Eisinger, François; Mari, Véronique; Gesta, Paul; Dreyfus, Hélène; Bonadona, Valérie; Dugast, Catherine; Zattara, Hélène; Faivre, Laurence; Jemni, Saloua Yacoub; Noguchi, Testsuro; Khélif, Abderrahim; Sobol, Hagay; Soua, Zohra

    2016-06-01

    Familial aggregation of hematological malignancies has been reported highlighting inherited genetic predisposition. In this study, we targeted four candidate genes: JAK2 and RUNX1 genes assuring a prominent function in hematological process and CBL and NPM1 as proto-oncogenes. Their disruption was described in several sporadic hematological malignancies. The aim of this study is to determine whether JAK2, CBL, RUNX1, and NPM1 germline genes mutations are involved in familial hematological malignancies. Using direct sequencing, we analyzed JAK2 (exons 12 and 14); CBL (exons 7, 8 and 9); NPM1 (exon 12) and the entire RUNX1 in 88 independent families belonging to Tunisian and French populations. Twenty-one sporadic acute leukemias were included in this study. We reported a heterozygous intronic c.1641 + 6 T > C JAK2 variant (rs182123615) found in two independent familial cases diagnosed with gastric lymphoma and Hodgkin lymphoma. The in silico analysis suggested a potential impact on splicing, but the functional splicing minigene reporter assay on rs182123615 variant showed no aberrant transcripts. In one sporadic acute myeloblastic leukemia, we reported an insertion 846 in. TGTT in exon 12 of NPM1 gene that may impact the normal reading frame. The rs182123615 JAK2 variant was described in several contexts including myeloproliferative neoplasms and congenital erythrocytosis and was supposed to be pathogenic. Through this current study, we established the assessment of pathogenicity of rs182123615 and we classified it rather as rare polymorphism. PMID:27106701

  16. miR-204 suppresses non-small-cell lung carcinoma (NSCLC) invasion and migration by targeting JAK2.

    PubMed

    Wang, P; Lv, H Y; Zhou, D M; Zhang, E N

    2016-01-01

    Aberrant expression of microRNA is associated with the development and progression of cancers. MicroRNA-204 (miR-204) down-regulation has been previously demonstrated in non-small-cell lung carcinoma (NSCLC); however, the underlying mechanism by which miR-204 suppresses tumorigenesis in NSCLC remains elusive. In this study, miR-204 expression was found to be down-regulated, and that of Janus kinase 2 (JAK2) was found to be up-regulated in four NSCLC cell lines (A549, H1299, H1650, and H358) compared to the normal lung cell line. The overexpression of miR-204 suppressed the invasive and migratory capacities of H1299 cells. A luciferase assay confirmed that the binding of miR-124 to the -untranslated region of JAK2 inhibited the expression of JAK2 proteins in H1299 cells. JAK-2 overexpression effectively reversed miR-204-repressed NSCLC metastasis. Taken together, our findings revealed that miR-204 functions as a tumor suppressor in NSCLC by targeting JAK2, and that miR-204 may therefore serve as a biomarker for the diagnosis and treatment of NSCLC. PMID:27323056

  17. Targeting substrate-site in Jak2 kinase prevents emergence of genetic resistance.

    PubMed

    Kesarwani, Meenu; Huber, Erika; Kincaid, Zachary; Evelyn, Chris R; Biesiada, Jacek; Rance, Mark; Thapa, Mahendra B; Shah, Neil P; Meller, Jarek; Zheng, Yi; Azam, Mohammad

    2015-01-01

    Emergence of genetic resistance against kinase inhibitors poses a great challenge for durable therapeutic response. Here, we report a novel mechanism of JAK2 kinase inhibition by fedratinib (TG101348) that prevents emergence of genetic resistance. Using in vitro drug screening, we identified 211 amino-acid substitutions conferring resistance to ruxolitinib (INCB018424) and cross-resistance to the JAK2 inhibitors AZD1480, CYT-387 and lestaurtinib. In contrast, these resistant variants were fully sensitive to fedratinib. Structural modeling, coupled with mutagenesis and biochemical studies, revealed dual binding sites for fedratinib. In vitro binding assays using purified proteins showed strong affinity for the substrate-binding site (Kd = 20 nM) while affinity for the ATP site was poor (Kd = ~8 μM). Our studies demonstrate that mutations affecting the substrate-binding pocket encode a catalytically incompetent kinase, thereby preventing emergence of resistant variants. Most importantly, our data suggest that in order to develop resistance-free kinase inhibitors, the next-generation drug design should target the substrate-binding site. PMID:26419724

  18. Targeting substrate-site in Jak2 kinase prevents emergence of genetic resistance

    PubMed Central

    Kesarwani, Meenu; Huber, Erika; Kincaid, Zachary; Evelyn, Chris R.; Biesiada, Jacek; Rance, Mark; Thapa, Mahendra B.; Shah, Neil P.; Meller, Jarek; Zheng, Yi; Azam, Mohammad

    2015-01-01

    Emergence of genetic resistance against kinase inhibitors poses a great challenge for durable therapeutic response. Here, we report a novel mechanism of JAK2 kinase inhibition by fedratinib (TG101348) that prevents emergence of genetic resistance. Using in vitro drug screening, we identified 211 amino-acid substitutions conferring resistance to ruxolitinib (INCB018424) and cross-resistance to the JAK2 inhibitors AZD1480, CYT-387 and lestaurtinib. In contrast, these resistant variants were fully sensitive to fedratinib. Structural modeling, coupled with mutagenesis and biochemical studies, revealed dual binding sites for fedratinib. In vitro binding assays using purified proteins showed strong affinity for the substrate-binding site (Kd = 20 nM) while affinity for the ATP site was poor (Kd = ~8 μM). Our studies demonstrate that mutations affecting the substrate-binding pocket encode a catalytically incompetent kinase, thereby preventing emergence of resistant variants. Most importantly, our data suggest that in order to develop resistance-free kinase inhibitors, the next-generation drug design should target the substrate-binding site. PMID:26419724

  19. Pyrvinium selectively induces apoptosis of lymphoma cells through impairing mitochondrial functions and JAK2/STAT5.

    PubMed

    Xiao, Meifang; Zhang, Liming; Zhou, Yizheng; Rajoria, Pasupati; Wang, Changfu

    2016-01-15

    Targeting mitochondrial respiration has emerged as an attractive therapeutic strategy in blood cancer due to their unique metabolic dependencies. In this study, we show that pyrvinium, a FDA-approved anthelmintic drug, selectively targets lymphoma T-cells though inhibition of mitochondrial functions and JAK2/STAT5. Pyrvinium induces apoptosis of malignant T-cell line Jurkat and primary T-cells from lymphoma patients while sparing T-cells from healthy donors. Increased level of active caspase-3 and decreased levels of Bcl-2 and Mcl-1 were also observed in Jurkat and lymphoma T-cells but not normal T-cells treated with pyrvinium. In addition, pyrvinium impairs mitochondrial functions by inhibit mitochondrial respiration, suppressing mitochondrial respiratory complex I activity, increasing ROS and decreasing ATP levels. However, the effects of pyrvinium were abolished in mitochondrial respiration-deficient Jurkat ρ(0) cells, confirming that pyrvinium acts on lymphoma T-cells via targeting mitochondrial respiration. We further show that lymphoma T-cells derived from patients depend more on mitochondrial respiration than normal T-cells, and this explains the selective toxicity of pyrvinium in lymphoma versus normal T-cells. Finally, we demonstrate that pyrvinium also suppresses JAK2/STAT5 signaling pathway in Jurkat cells. Our study suggests that pyrvinium is a useful addition to T-cell lymphoma treatment, and emphasizes the potential therapeutic value of the differences in the mitochondrial characteristics between malignant and normal T-cells in blood cancer. PMID:26707639

  20. The simultaneous occurrence of multiple myeloma and JAK2 positive myeloproliferative neoplasms - Report on two cases

    PubMed Central

    Badelita, S; Dobrea, C; Colita, A; Dogaru, M; Dragomir, M; Jardan, C; Coriu, D

    2015-01-01

    Multiple myeloma and JAK2 positive chronic myeloproliferative neoplasms are hematologic malignancies with a completely different cellular origin. Two cases of simultaneous occurrence of multiple myeloma, one with primary myelofibrosis and another one with essential thrombocythemia are reported in this article. In such cases, an accurate diagnosis requires a molecular testing, including gene sequencing and differential diagnosis of pancytosis associated with splenic amyloidosis. In general, in such cases, of two coexisting malignant hematologic diseases, the treatment of the most aggressive one is recommended. For our two cases, it was decided to start a Velcade based therapy. The main concern was the medullar toxicity, especially when a multiple myeloma was associated with a primary myelofibrosis. Abbreviations:JAK2 = Janus kinase 2 gene, PMF = primary myelofibrosis, MPNs = myeloproliferative neoplasms, ET = essential thrombocythemia, PV = polycythemia vera, MM = multiple myeloma, WBC = white blood cells, Hb = haemoglobin, Ht = haematocrit, Plt = platelets, BMB = bone marrow biopsy, CBC = blood cell count, CT = computerized tomography, LAP = leukocyte alkaline phosphatase, MGUS = monoclonal gammopathy of undetermined significance. PMID:25914740

  1. Pharmacologic Blockade of JAK1/JAK2 Reduces GvHD and Preserves the Graft-Versus-Leukemia Effect

    PubMed Central

    Choi, Jaebok; Cooper, Matthew L.; Alahmari, Bader; Ritchey, Julie; Collins, Lynne; Holt, Matthew; DiPersio, John F.

    2014-01-01

    We have recently reported that interferon gamma receptor deficient (IFNγR−/−) allogeneic donor T cells result in significantly less graft-versus-host disease (GvHD) than wild-type (WT) T cells, while maintaining an anti-leukemia or graft-versus-leukemia (GvL) effect after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We demonstrated that IFNγR signaling regulates alloreactive T cell trafficking to GvHD target organs through expression of the chemokine receptor CXCR3 in alloreactive T cells. Since IFNγR signaling is mediated via JAK1/JAK2, we tested the effect of JAK1/JAK2 inhibition on GvHD. While we demonstrated that pharmacologic blockade of JAK1/JAK2 in WT T cells using the JAK1/JAK2 inhibitor, INCB018424 (Ruxolitinib), resulted in a similar effect to IFNγR−/− T cells both in vitro (reduction of CXCR3 expression in T cells) and in vivo (mitigation of GvHD after allo-HSCT), it remains to be determined if in vivo administration of INCB018424 will result in preservation of GvL while reducing GvHD. Here, we report that INCB018424 reduces GvHD and preserves the beneficial GvL effect in two different murine MHC-mismatched allo-HSCT models and using two different murine leukemia models (lymphoid leukemia and myeloid leukemia). In addition, prolonged administration of INCB018424 further improves survival after allo-HSCT and is superior to other JAK1/JAK2 inhibitors, such as TG101348 or AZD1480. These data suggest that pharmacologic inhibition of JAK1/JAK2 might be a promising therapeutic approach to achieve the beneficial anti-leukemia effect and overcome HLA-barriers in allo-HSCT. It might also be exploited in other diseases besides GvHD, such as organ transplant rejection, chronic inflammatory diseases and autoimmune diseases. PMID:25289677

  2. Pharmacologic blockade of JAK1/JAK2 reduces GvHD and preserves the graft-versus-leukemia effect.

    PubMed

    Choi, Jaebok; Cooper, Matthew L; Alahmari, Bader; Ritchey, Julie; Collins, Lynne; Holt, Matthew; DiPersio, John F

    2014-01-01

    We have recently reported that interferon gamma receptor deficient (IFNγR-/-) allogeneic donor T cells result in significantly less graft-versus-host disease (GvHD) than wild-type (WT) T cells, while maintaining an anti-leukemia or graft-versus-leukemia (GvL) effect after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We demonstrated that IFNγR signaling regulates alloreactive T cell trafficking to GvHD target organs through expression of the chemokine receptor CXCR3 in alloreactive T cells. Since IFNγR signaling is mediated via JAK1/JAK2, we tested the effect of JAK1/JAK2 inhibition on GvHD. While we demonstrated that pharmacologic blockade of JAK1/JAK2 in WT T cells using the JAK1/JAK2 inhibitor, INCB018424 (Ruxolitinib), resulted in a similar effect to IFNγR-/- T cells both in vitro (reduction of CXCR3 expression in T cells) and in vivo (mitigation of GvHD after allo-HSCT), it remains to be determined if in vivo administration of INCB018424 will result in preservation of GvL while reducing GvHD. Here, we report that INCB018424 reduces GvHD and preserves the beneficial GvL effect in two different murine MHC-mismatched allo-HSCT models and using two different murine leukemia models (lymphoid leukemia and myeloid leukemia). In addition, prolonged administration of INCB018424 further improves survival after allo-HSCT and is superior to other JAK1/JAK2 inhibitors, such as TG101348 or AZD1480. These data suggest that pharmacologic inhibition of JAK1/JAK2 might be a promising therapeutic approach to achieve the beneficial anti-leukemia effect and overcome HLA-barriers in allo-HSCT. It might also be exploited in other diseases besides GvHD, such as organ transplant rejection, chronic inflammatory diseases and autoimmune diseases. PMID:25289677

  3. Combination of AG490, a Jak2 inhibitor, and methylsulfonylmethane synergistically suppresses bladder tumor growth via the Jak2/STAT3 pathway.

    PubMed

    Joung, Youn Hee; Na, Yoon Mi; Yoo, Young Bum; Darvin, Pramod; Sp, Nipin; Kang, Dong Young; Kim, Sang Yoon; Kim, Hong Sup; Choi, Yoon Hee; Lee, Hak Kyo; Park, Kyung Do; Cho, Byung Wook; Kim, Heui Soo; Park, Jong Hwan; Yang, Young Mok

    2014-03-01

    Human urinary bladder cancer is the fifth most common cancer, with a worldwide estimate of about two million patients. Recurrence after complete transurethral prostatic resection is the most important problem in therapy. Combination therapy is a new approach in the treatment of cancers that do not respond to current therapies. These therapies have many advantages over conventional therapies, such as fewer side-effects and greater efficiency. Research efforts using natural compounds for the elimination or growth suppression of the cancer arise from studies on methylsulfonylmethane (MSM). MSM is a natural sulfur compound with no side-effects. AG490 is a tyrosine kinase inhibitor that has been extensively used for inhibiting Jak2 in vitro and in vivo. In our study, the combinatorial effect of these two agents on human bladder cancer cell lines and xenografts was analyzed. We observed that the combination of AG490 and MSM inhibited cancer cell viability and cell migration in vitro. This combination inhibited VEGF mRNA expression in bladder cancer cell lines. In vivo experiments showed that oral administration of AG490 and MSM combination significantly inhibited the growth of tumor xenografts in mice. Our study clearly demonstrates that the predominant effect of this combination is the reduction of signaling molecules including STAT3, STAT5b, IGF-1R, VEGF and VEGF-R2 which are involved in the growth, progression and metastasis of human bladder cancer. The anti-metastatic ability of this drug combination is confirmed using metastatic animal models. Therefore, this combination could have the effect of genesistasis and powerful anticancer effects against bladder cancer. PMID:24402583

  4. The Ashwell-Morell receptor regulates hepatic thrombopoietin production via JAK2-STAT3 signaling

    PubMed Central

    Grozovsky, Renata; Begonja, Antonija Jurak; Liu, Kaifeng; Visner, Gary; Hartwig, John H.; Falet, Hervé; Hoffmeister, Karin M.

    2015-01-01

    The hepatic Ashwell-Morell receptor (AMR) can bind and remove desialylated platelets. We demonstrate that platelets become desialylated as they circulate and age in blood. Binding of desialylated platelets to the AMR induces hepatic thrombopoietin (TPO) gene transcription and translation, thereby regulating platelet production. The highly conserved endocytic AMR signals through Janus kinase 2 (JAK2) and the acute phase response signal transducer and activator of transcription 3 (STAT3) in vivo and in vitro. Recognition of this novel physiological feedback mechanism illuminates the pathophysiology of platelet diseases, such as Essential Thrombocythemia and Immune Thrombocytopenia, and contributes to our understanding of the mechanisms of thrombocytopenia observed with JAK1/2 inhibition. PMID:25485912

  5. Regulation of TRPM7 Function by IL-6 through the JAK2-STAT3 Signaling Pathway

    PubMed Central

    Wang, Jing; Zhao, Yin; Luo, Zhenzhao; Gao, Yan; Shi, Jing

    2016-01-01

    Aims Previous studies have demonstrated that expression of the TRPM7 channel, which may induce delayed cell death by mediating calcium influx, is precisely regulated. However, functional regulation of TRPM7 channels by endogenous molecules has not been elucidated. The proinflammatory cytokine IL-6 contributes to regulation of Ca2+ influx in cerebral ischemia, but the role of IL-6 in regulating TRPM7 functioning is unknown. Thus, we here investigated the interaction between IL-6 and TRPM7 channels and the relevant mechanisms. Materials and Methods Using whole-cell patch-clamping, we first investigated the effect of IL-6 on TRPM7-like currents in primary cultured cortical neurons. Next, TRPM7-overexpressing HEK293 cells were used to confirm the effect of IL-6/sIL-6R on TRPM7. Finally, we used specific signaling pathway inhibitors to investigate the signaling pathways involved. Results IL-6 or IL-6/sIL-6R dose-dependently inhibited inward TRPM7 currents, in both primary cultured neurons and HEK293 cells overexpressing TRPM7. In intracellular Mg2+-free conditions, extracellular Ca2+ or the α-kinase domain of TRPM7 did not participate in this regulation. The inhibitory effect of IL-6 on TRPM7 could be blocked by specific inhibitors of the JAK2−STAT3 pathway, but not of the PI3K, ERK1/2, or PLC pathways. Conclusions IL-6 inhibits the inward TRPM7 current via the JAK2−STAT3 signaling pathway. PMID:27010689

  6. CONSISTENT UPREGULATION OF STAT3 INDEPENDENTLY OF JAK2 MUTATIONS IN A NEW MURINE MODEL OF ESSENTIAL THROMBOCYTHEMIA

    PubMed Central

    Senyuk, Vitalyi; Rinaldi, Ciro Roberto; Li, Donglan; Cattaneo, Francesca; Stojanovic, Aleksandra; Pane, Fabrizio; Du, Xiaoping; Mahmud, Nadim; Dickstein, Jerome; Nucifora, Giuseppina

    2008-01-01

    JAK2 mutations are common in myeloproliferative disorders (MPD), however, while they are detected in virtually all polycythemia vera (PV) patients, they are found in about 50% of essential thrombocythemia (ET) patients, suggesting that converging pathways/abnormalities underlie the onset of ET. Recently, the chromosomal translocation 3;21, leading to the fusion gene AML1/MDS1/EVI1 (AME), was observed in an ET patient. After we forced the expression of AME in the bone marrow (BM) of C57BL/6J mice, all the reconstituted mice died of a disease with symptoms similar to ET with a latency of 8-16 months. Peripheral blood smears consistently showed an elevated number of dysplastic platelets with anisocytosis, degranulation, and giant size. While the AME-positive mice did not harbor Jak2 mutations, the BM of most of them had significantly higher levels of activated Stat3 than the controls. With combined biochemical and biological assays we found that AME binds to the Stat3 promoter leading to its upregulation. STAT3 analysis of a small group of ET patients shows that in about half of the patients there is STAT3 hyperactivation independently of JAK2 mutations, suggesting that the hyperactivation of STAT3 by JAK2 mutations or promoter activation may be a critical step in development of ET. PMID:19118011

  7. Expression, purification, characterization and crystallization of non- and phosphorylated states of JAK2 and JAK3 kinase domain

    SciTech Connect

    Hall, Troii; Emmons, Thomas L.; Chrencik, Jill E.; Gormley, Jennifer A.; Weinberg, Robin A.; Leone, Joseph W.; Hirsch, Jeffrey L.; Saabye, Matthew J.; Schindler, John F.; Day, Jacqueline E.; Williams, Jennifer M.; Kiefer, James R.; Lightle, Sandra A.; Harris, Melissa S.; Guru, Siradanahalli; Fischer, H. David; Tomasselli, Alfredo G.

    2012-05-29

    Janus-associated kinases (JAKs) play critical roles in cytokine signaling, and have emerged as viable therapeutic targets in inflammation and oncology related diseases. To date, targeting JAK proteins with highly selective inhibitor compounds have remained elusive. We have expressed the active kinase domains for both JAK2 and JAK3 and devised purification protocols to resolve the non-, mono- (Y1007) and diphosphorylated (Y1007 and Y1008) states of JAK2 and non- and monophosphorylated states of JAK3 (Y980). An optimal purified protein yield of 20, 29 and 69 mg per 20 L cell culture was obtained for the three JAK2 forms, respectively, and 12.2 and 2.3 mg per 10 L fermentation for the two JAK3 forms allowing detailed biochemical and biophysical studies. To monitor the purification process we developed a novel HPLC activity assay where a sequential order of phosphorylation was observed whereby the first tyrosine residue was completely phosphorylated prior to phosphorylation of the tandem tyrosine residue. A Caliper-based microfluidics assay was used to determine the kinetic parameters (K{sub m} and k{sub cat}) for each phosphorylated state, showing that monophosphorylated (Y1007) JAK2 enzyme activity increased 9-fold over that of the nonphosphorylated species, and increased an additional 6-fold for the diphosphorylated (Y1007/Y1008) species, while phosphorylation of JAK3 resulted in a negligible increase in activity. Moreover, crystal structures have been generated for each isolated state of JAK2 and JAK3 with resolutions better than 2.4 {angstrom}. The generation of these reagents has enabled kinetic and structural characterization to inform the design of potent and selective inhibitors of the JAK family.

  8. Genomic and functional analysis of leukemic transformation of myeloproliferative neoplasms

    PubMed Central

    Rampal, Raajit; Ahn, Jihae; Abdel-Wahab, Omar; Nahas, Michelle; Wang, Kai; Lipson, Doron; Otto, Geoff A.; Yelensky, Roman; Hricik, Todd; McKenney, Anna Sophia; Chiosis, Gabriela; Chung, Young Rock; Pandey, Suveg; van den Brink, Marcel R. M.; Armstrong, Scott A.; Dogan, Ahmet; Intlekofer, Andrew; Manshouri, Taghi; Park, Christopher Y.; Verstovsek, Srdan; Rapaport, Franck; Stephens, Philip J.; Miller, Vincent A.; Levine, Ross L.

    2014-01-01

    Patients with myeloproliferative neoplasms (MPNs) are at significant, cumulative risk of leukemic transformation to acute myeloid leukemia (AML), which is associated with adverse clinical outcome and resistance to standard AML therapies. We performed genomic profiling of post-MPN AML samples; these studies demonstrate somatic tumor protein 53 (TP53) mutations are common in JAK2V617F-mutant, post-MPN AML but not in chronic-phase MPN and lead to clonal dominance of JAK2V617F/TP53-mutant leukemic cells. Consistent with these data, expression of JAK2V617F combined with Tp53 loss led to fully penetrant AML in vivo. JAK2V617F-mutant, Tp53-deficient AML was characterized by an expanded megakaryocyte erythroid progenitor population that was able to propagate the disease in secondary recipients. In vitro studies revealed that post-MPN AML cells were sensitive to decitabine, the JAK1/2 inhibitor ruxolitinib, or the heat shock protein 90 inhibitor 8-(6-iodobenzo[d][1.3]dioxol-5-ylthio)-9-(3-(isopropylamino)propyl)-9H-purine-6-amine (PU-H71). Treatment with ruxolitinib or PU-H71 improved survival of mice engrafted with JAK2V617F-mutant, Tp53-deficient AML, demonstrating therapeutic efficacy for these targeted therapies and providing a rationale for testing these therapies in post-MPN AML. PMID:25516983

  9. Single Nucleotide Polymorphism (SNP)-Based Loss of Heterozygosity (LOH) Testing by Real Time PCR in Patients Suspect of Myeloproliferative Disease

    PubMed Central

    Huijsmans, Cornelis J. J.; Poodt, Jeroen; Damen, Jan; van der Linden, Johannes C.; Savelkoul, Paul H. M.; Pruijt, Johannes F. M.; Hilbink, Mirrian; Hermans, Mirjam H. A.

    2012-01-01

    During tumor development, loss of heterozygosity (LOH) often occurs. When LOH is preceded by an oncogene activating mutation, the mutant allele may be further potentiated if the wild-type allele is lost or inactivated. In myeloproliferative neoplasms (MPN) somatic acquisition of JAK2V617F may be followed by LOH resulting in loss of the wild type allele. The occurrence of LOH in MPN and other proliferative diseases may lead to a further potentiating the mutant allele and thereby increasing morbidity. A real time PCR based SNP profiling assay was developed and validated for LOH detection of the JAK2 region (JAK2LOH). Blood of a cohort of 12 JAK2V617F-positive patients (n = 6 25–50% and n = 6>50% JAK2V617F) and a cohort of 81 patients suspected of MPN was stored with EDTA and subsequently used for validation. To generate germ-line profiles, non-neoplastic formalin-fixed paraffin-embedded tissue from each patient was analyzed. Results of the SNP assay were compared to those of an established Short Tandem Repeat (STR) assay. Both assays revealed JAK2LOH in 1/6 patients with 25–50% JAK2V617F. In patients with >50% JAK2V617F, JAK2LOH was detected in 6/6 by the SNP assay and 5/6 patients by the STR assay. Of the 81 patients suspected of MPN, 18 patients carried JAK2V617F. Both the SNP and STR assay demonstrated the occurrence of JAK2LOH in 5 of them. In the 63 JAK2V617F-negative patients, no JAK2LOH was observed by SNP and STR analyses. The presented SNP assay reliably detects JAK2LOH and is a fast and easy to perform alternative for STR analyses. We therefore anticipate the SNP approach as a proof of principle for the development of LOH SNP-assays for other clinically relevant LOH loci. PMID:22768290

  10. Myeloproliferative neoplasms and the JAK/STAT signaling pathway: an overview

    PubMed Central

    de Freitas, Renata Mendes; da Costa Maranduba, Carlos Magno

    2015-01-01

    Myeloproliferative neoplasms are caused by a clonal proliferation of a hematopoietic progenitor. First described in 1951 as ‘Myeloproliferative Diseases’ and reevaluated by the World Health Organization classification system in 2011, myeloproliferative neoplasms include polycythemia vera, essential thrombocythemia and primary myelofibrosis in a subgroup called breakpoint cluster region-Abelson fusion oncogene-negative neoplasms. According to World Health Organization regarding diagnosis criteria for myeloproliferative neoplasms, the presence of the JAK2 V617F mutation is considered the most important criterion in the diagnosis of breakpoint cluster region-Abelson fusion oncogene-negative neoplasms and is thus used as a clonal marker. The V617F mutation in the Janus kinase 2 (JAK2) gene produces an altered protein that constitutively activates the Janus kinase/signal transducers and activators of transcription pathway and other pathways downstream as a result of signal transducers and activators of transcription which are subsequently phosphorylated. This affects the expression of genes involved in the regulation of apoptosis and regulatory proteins and modifies the proliferation rate of hematopoietic stem cells. PMID:26408371

  11. The JAK2 inhibitor AZD1480 inhibits hepatitis A virus replication in Huh7 cells.

    PubMed

    Jiang, Xia; Kanda, Tatsuo; Nakamoto, Shingo; Saito, Kengo; Nakamura, Masato; Wu, Shuang; Haga, Yuki; Sasaki, Reina; Sakamoto, Naoya; Shirasawa, Hiroshi; Okamoto, Hiroaki; Yokosuka, Osamu

    2015-03-20

    The JAK2 inhibitor AZD1480 has been reported to inhibit La protein expression. We previously demonstrated that the inhibition of La expression could inhibit hepatitis A virus (HAV) internal ribosomal entry-site (IRES)-mediated translation and HAV replication in vitro. In this study, we analyzed the effects of AZD1480 on HAV IRES-mediated translation and replication. HAV IRES-mediated translation in COS7-HAV-IRES cells was inhibited by 0.1-1 μM AZD1480, a dosage that did not affect cell viability. Results showed a significant reduction in intracellular HAV HA11-1299 genotype IIIA RNA levels in Huh7 cells treated with AZD1480. Furthermore, AZD1480 inhibited the expression of phosphorylated-(Tyr-705)-signal transducer and activator of transcription 3 (STAT3) and La in Huh7 cells. Therefore, we propose that AZD1480 can inhibit HAV IRES activity and HAV replication through the inhibition of the La protein. PMID:25704089

  12. Off-Target Effects of BCR-ABL and JAK2 Inhibitors.

    PubMed

    Green, Myke R; Newton, Michael D; Fancher, Karen M

    2016-02-01

    The advent of targeted oncolytic agents has created a revolution in the treatment of malignancies. Perhaps best exemplified in myeloproliferative neoplasms (MPN), the tyrosine kinase inhibitors, including inhibitors of BCR-ABL tyrosine kinase and JAK2, have dramatically changed outcomes in persons with MPN. However, clinically relevant dosing of these adenosine triphosphate-mimetic agents in humans leads to inhibition of numerous tyrosine kinases beyond those touted by drug manufacturers and studied in landmark clinical trials. These so-called off-target effects have been linked to both clinical efficacy and toxicity. Rational drug development and serendipitous discovery of drug molecules allows the clinician to select targeted oncolytic agents to treat a specific clinical diagnosis and/or avoid exacerbation of concomitant disease states due to effects upon signaling pathways. Understanding the off-target binding and effects upon signaling pathway of the agents approved for the treatment of MPN will empower the clinician to adroitly select pharmacotherapy, predict toxicities, and utilize these agents in clinical practice for indications beyond MPN. PMID:24351780

  13. Ponicidin Induces Apoptosis via JAK2 and STAT3 Signaling Pathways in Gastric Carcinoma

    PubMed Central

    Liu, Yuan-Fei; Lu, Yun-Min; Qu, Guo-Qiang; Liu, Yuan; Chen, Wei-Xiong; Liao, Xiao-Hong; Kong, Wu-Ming

    2015-01-01

    Ponicidin has a variety of biological effects such as immunoregulatory and anti-inflammatory functions as well as anti-viral functions especially in the upper respiratory tract infection. This study was aimed to elucidate the antitumor effect of ponicidin in gastric carcinoma MKN28 cells and the possible molecular mechanism involved. Cell viability was measured by the Cell Count Kit-8 (CCK8). Cell apoptosis was assessed by flow cytometry as well as cell cycle and reactive oxygen species (ROS) analysis. Western blot analysis was used to detect the active form of caspase-3 as well as Bax and B-cell lymphoma-2 (Bcl-2) expressions after cells were treated with different concentrations of ponicidin. The results revealed that ponicidin could inhibit the growth of MKN28 cells significantly in both a time- and dose-dependent manner. The cell cycle was blocked and ROS generation was increased after the cells were treated with ponicidin. Bcl-2 expression was down-regulated remarkably while Bax expression and the active form of caspase-3 were increased after apoptosis occurred. We therefore conclude that ponicidin exhibited significant growth inhibition of gastric carcinoma cell line MKN28 and induced apoptosis of MKN28 cells via the signaling pathway regulated by Janus kinase 2 (JAK2) and signal transducers and activators of transcription 3 (STAT3). Ponicidin may serve as a potential therapeutic agent for gastric carcinoma. PMID:25588213

  14. CHZ868, a Type II JAK2 Inhibitor, Reverses Type I JAK Inhibitor Persistence and Demonstrates Efficacy in Myeloproliferative Neoplasms

    PubMed Central

    Meyer, Sara C.; Keller, Matthew D.; Chiu, Sophia; Koppikar, Priya; Guryanova, Olga A.; Rapaport, Franck; Xu, Ke; Manova, Katia; Pankov, Dmitry; O’Reilly, Richard J.; Kleppe, Maria; McKenney, Anna Sophia; Shih, Alan H.; Shank, Kaitlyn; Ahn, Jihae; Papalexi, Eftymia; Spitzer, Barbara; Socci, Nick; Viale, Agnes; Mandon, Emeline; Ebel, Nicolas; Andraos, Rita; Rubert, Joëlle; Dammassa, Ernesta; Romanet, Vincent; Dölemeyer, Arno; Zender, Michael; Heinlein, Melanie; Rampal, Rajit; Weinberg, Rona Singer; Hoffman, Ron; Sellers, William R.; Hofmann, Francesco; Murakami, Masato; Baffert, Fabienne; Gaul, Christoph; Radimerski, Thomas; Levine, Ross L.

    2015-01-01

    Summary Although clinically tested JAK inhibitors reduce splenomegaly and systemic symptoms, molecular responses are not observed in most myeloproliferative neoplasms (MPN) patients. We previously demonstrated that MPN cells become persistent to type I JAK inhibitors that bind the active conformation of JAK2. We investigated if CHZ868, a type II JAK inhibitor, would demonstrate activity in JAK inhibitor persistent cells, murine MPN models, and MPN patient samples. JAK2- and MPL-mutant cell lines were sensitive to CHZ868, including type I JAK inhibitor persistent cells. CHZ868 showed significant activity in murine MPN models and induced reductions in mutant allele burden not observed with type I JAK inhibitors. These data demonstrate that type II JAK inhibition is a viable therapeutic approach for MPN patients. PMID:26175413

  15. Phosphorylation and internalization of gp130 occur after IL-6 activation of Jak2 kinase in hepatocytes.

    PubMed Central

    Wang, Y; Fuller, G M

    1994-01-01

    Recent evidence has shown that members of the Jak kinase family are activated after IL-6 binds to its receptor complex, leading to a tyrosine phosphorylation of gp130, the IL-6 signal-transducing subunit. The different members of the IL-6 cytokine subfamily induce distinct patterns of Jak-Tyk phosphorylation in different cell types. Using monospecific antibodies to gp130, Jak2 kinase, and phosphotyrosine, we investigated the kinetics of IL-6 stimulation of members of this pathway in primary hepatocytes. Our findings show that Jak 2 is maximally activated within 2 min of exposure to IL-6, followed by gp130 phosphorylation that reaches its peak in another 2 min then declines to basal level by 60 min. In vitro phosphorylation experiments show that activated Jak 2 is able to phosphorylate both native gp130 and a fusion peptide containing its cytoplasmic domain, demonstrating gp130 is a direct substrate of Jak 2 kinase. Experiments designed to explore the cell surface expression of gp130 show that > or = 2 h are required to get a second round of phosphorylation after the addition of more cytokines. This finding suggests that activated gp130 is internalized from the cell surface after IL-6 stimulation. Additional experiments using protein synthesis inhibitors reveal that new protein synthesis is required to get a second cycle of gp130 phosphorylation indicating gp130 must be synthesized de novo and inserted into the membrane. These findings provide strong evidence that down regulation of the IL-6 signal in hepatocytes involves the internalization and cytosol degradation of gp130. Images PMID:7812050

  16. Association of common variants in JAK2 gene with reduced risk of metabolic syndrome and related disorders

    PubMed Central

    2011-01-01

    Background Disturbances in leptin and insulin signaling pathways are related to obesity and metabolic syndrome (MS) with increased risk of diabetes and cardiovascular disease. Janus kinase 2 (JAK2) is a tyrosine kinase involved in the activation of mechanisms that mediate leptin and insulin actions. We conducted a population cross-sectional study to explore the association between two common variants in JAK2 gene and MS related traits in 724 Argentinean healthy male subjects. Methods A total of 724 unrelated men aged 37.11 ± 10.91 yr were included in a cross-sectional study. Physical examination, anthropometric measurements and biochemical analysis were determined by a standardized protocol. rs7849191 and rs3780378 were genotyped. Analyses were done separately for each SNP and followed up by haplotype analysis. Results rs7849191 and rs3780378 were both associated with reduced risk of MS [p = 0.005; OR (95%CI) = 0.52 (0.33-0.80) and p = 0.006; OR (95% CI) = 0.59 (0.40-0.86) respectively, assuming a dominant model]. rs3780378 T allele was associated with triglyceridemia values under 150 mg/dl [p = 0.007; OR (95%CI) = 0.610 (0.429-0.868)] and TT carriers showed lower triglycerides (p = 0.017), triglycerides/HDL-C ratio (p = 0.022) and lipid accumulation product (p = 0.007) compared to allele C carriers. The two-SNPs-haplotype analysis was consistent with single locus analysis. Conclusions It was found for the first time, significant associations of JAK2 common variants and related haplotypes with reduced risk of MS. These findings could be explained by the role of JAK2 in insulin and/or leptin signaling. PMID:22185674

  17. Calpain-mediated proteolysis of polycystin-1 C-terminus induces JAK2 and ERK signal alterations

    SciTech Connect

    Kim, Hyunho; Kang, Ah-Young; Ko, Ah-ra; Park, Hayne Cho; So, Insuk; Park, Jong Hoon; Cheong, Hae Il; Hwang, Young-Hwan; and others

    2014-01-01

    Autosomal dominant polycystic kidney disease (ADPKD), a hereditary renal disease caused by mutations in PKD1 (85%) or PKD2 (15%), is characterized by the development of gradually enlarging multiple renal cysts and progressive renal failure. Polycystin-1 (PC1), PKD1 gene product, is an integral membrane glycoprotein which regulates a number of different biological processes including cell proliferation, apoptosis, cell polarity, and tubulogenesis. PC1 is a target of various proteolytic cleavages and proteosomal degradations, but its role in intracellular signaling pathways remains poorly understood. Herein, we demonstrated that PC1 is a novel substrate for μ- and m-calpains, which are calcium-dependent cysteine proteases. Overexpression of PC1 altered both Janus-activated kinase 2 (JAK2) and extracellular signal-regulated kinase (ERK) signals, which were independently regulated by calpain-mediated PC1 degradation. They suggest that the PC1 function on JAK2 and ERK signaling pathways might be regulated by calpains in response to the changes in intracellular calcium concentration. - Highlights: • Polycystin-1 is a target of ubiquitin-independent degradation by calpains. • The PEST domain is required for calpain-mediated degradation of polycystin-1. • Polycystin-1 may independently regulate JAK2 and ERK signaling pathways.

  18. The JAK2/STAT3 and mitochondrial pathways are essential for quercetin nanoliposome-induced C6 glioma cell death

    PubMed Central

    Wang, G; Wang, J J; Chen, X L; Du, S M; Li, D S; Pei, Z J; Lan, H; Wu, L B

    2013-01-01

    The formulation of quercetin nanoliposomes (QUE-NLs) has been shown to enhance QUE antitumor activity in C6 glioma cells. At high concentrations, QUE-NLs induce necrotic cell death. In this study, we probed the molecular mechanisms of QUE-NL-induced C6 glioma cell death and examined whether QUE-NL-induced programmed cell death involved Bcl-2 family and mitochondrial pathway through STAT3 signal transduction pathway. Downregulation of Bcl-2 and the overexpression of Bax by QUE-NL supported the involvement of Bcl-2 family proteins upstream of C6 glioma cell death. In addition, the activation of JAK2 and STAT3 were altered following exposure to QUE-NLs in C6 glioma cells, suggesting that QUE-NLs downregulated Bcl-2 mRNAs expression and enhanced the expression of mitochondrial mRNAs through STAT3-mediated signaling pathways either via direct or indirect mechanisms. There are several components such as ROS, mitochondrial, and Bcl-2 family shared by the necrotic and apoptotic pathways. Our studies indicate that the signaling cross point of the mitochondrial pathway and the JAK2/STAT3 signaling pathway in C6 glioma cell death is modulated by QUE-NLs. In conclusion, regulation of JAK2/STAT3 and ROS-mediated mitochondrial pathway agonists alone or in combination with treatment by QUE-NLs could be a more effective method of treating chemical-resistant glioma. PMID:23907460

  19. Berberine Inhibits Invasion and Metastasis of Colorectal Cancer Cells via COX-2/PGE2 Mediated JAK2/STAT3 Signaling Pathway.

    PubMed

    Liu, Xuan; Ji, Qing; Ye, Naijing; Sui, Hua; Zhou, Lihong; Zhu, Huirong; Fan, Zhongze; Cai, Jianfeng; Li, Qi

    2015-01-01

    Berberin, extracted from Chinese herbal medicine Coptis chinensis, has been found to have anti-tumor activities. However, the underlying mechanisms have not been fully elucidated. Our current study demonstrated that berberin inhibited the in vitro and in vivo growth, migration/invasion of CRC cells, via attenuating the expression levels of COX-2/PGE2, following by reducing the phosphorylation of JAK2 and STAT3, as well as the MMP-2/-9 expression. We further clarified that an increase of COX-2/PGE2 expression offset the repressive activity of Berberin on JAK2/STAT3 signaling, and a JAK2 inhibitor AZD1480 blocked the effect of COX-2/PGE2 on MMP-2/-9 expression. In summary, Berberin inhibited CRC invasion and metastasis via down-regulation of COX-2/PGE2- JAK2/STAT3 signaling pathway. PMID:25954974

  20. Berberine Inhibits Invasion and Metastasis of Colorectal Cancer Cells via COX-2/PGE2 Mediated JAK2/STAT3 Signaling Pathway

    PubMed Central

    Ye, Naijing; Sui, Hua; Zhou, Lihong; Zhu, Huirong; Fan, Zhongze; Cai, Jianfeng; Li, Qi

    2015-01-01

    Berberin, extracted from Chinese herbal medicine Coptis chinensis, has been found to have anti-tumor activities. However, the underlying mechanisms have not been fully elucidated. Our current study demonstrated that berberin inhibited the in vitro and in vivo growth, migration/invasion of CRC cells, via attenuating the expression levels of COX-2/PGE2, following by reducing the phosphorylation of JAK2 and STAT3, as well as the MMP-2/-9 expression. We further clarified that an increase of COX-2/PGE2 expression offset the repressive activity of Berberin on JAK2/STAT3 signaling, and a JAK2 inhibitor AZD1480 blocked the effect of COX-2/PGE2 on MMP-2/-9 expression. In summary, Berberin inhibited CRC invasion and metastasis via down-regulation of COX-2/PGE2- JAK2/STAT3 signaling pathway. PMID:25954974

  1. The Jak2 Small Molecule Inhibitor, G6, Reduces the Tumorigenic Potential of T98G Glioblastoma Cells In Vitro and In Vivo

    PubMed Central

    Keserű, György M.; Bisht, Kirpal S.; Wamsley, Heather L.; Sayeski, Peter P.

    2014-01-01

    Glioblastoma multiforme (GBM) is the most common and the most aggressive form of primary brain tumor. Jak2 is a non-receptor tyrosine kinase that is involved in proliferative signaling through its association with various cell surface receptors. Hyperactive Jak2 signaling has been implicated in numerous hematological disorders as well as in various solid tumors including GBM. Our lab has developed a Jak2 small molecule inhibitor known as G6. It exhibits potent efficacy in vitro and in several in vivo models of Jak2-mediated hematological disease. Here, we hypothesized that G6 would inhibit the pathogenic growth of GBM cells expressing hyperactive Jak2. To test this, we screened several GBM cell lines and found that T98G cells express readily detectable levels of active Jak2. We found that G6 treatment of these cells reduced the phosphorylation of Jak2 and STAT3, in a dose-dependent manner. In addition, G6 treatment reduced the migratory potential, invasive potential, clonogenic growth potential, and overall viability of these cells. The effect of G6 was due to its direct suppression of Jak2 function and not via off-target kinases, as these effects were recapitulated in T98G cells that received Jak2 specific shRNA. G6 also significantly increased the levels of caspase-dependent apoptosis in T98G cells, when compared to cells that were treated with vehicle control. Lastly, when T98G cells were injected into nude mice, G6 treatment significantly reduced tumor volume and this was concomitant with significantly decreased levels of phospho-Jak2 and phospho-STAT3 within the tumors themselves. Furthermore, tumors harvested from mice that received G6 had significantly less vimentin protein levels when compared to tumors from mice that received vehicle control solution. Overall, these combined in vitro and in vivo results indicate that G6 may be a viable therapeutic option against GBM exhibiting hyperactivation of Jak2. PMID:25162558

  2. The combination of analytical-scale HPLC separation with a TR-FRET assay to investigate JAK2 inhibitory compounds in a Boysenberry drink.

    PubMed

    McGhie, Tony K; Martin, Harry; Lunken, Rona C M

    2012-11-01

    We report the detection of JAK2 inhibitory activity in a Boysenberry (Rubus loganbaccus x R. baileyanus Britt.) drink using a combination of analytical-scale high performance liquid chromatography (HPLC) with a high-sensitivity time-resolved fluorescence coupled with fluorescence resonance energy transfer (TR-FRET) method. Phytochemical components of a Boysenberry drink were separated by reversed phase HPLC , and 84 separate fractions were collected. HPLC fractions corresponding to the ellagitannin and ellagic acid peaks observed in the chromatogram inhibited JAK2 activity. Anthocyanins, while they were the major phytochemical components of the Boysenberry drink, had no JAK2 inhibitory activity even though anthocyanins have previously been shown to be anti-inflammatory. This study demonstrates the usefulness of combining rapid analytical-scale HPLC separation with a highly sensitive fluorescence bioassay for characterising bioactivity in complex plant extracts. Ellagic acid was found to have an IC(50) of 92 nM against JAK2 and complete inhibition of JAK2 activity was observed in HPLC fractions of Boysenberry extract which had been diluted several hundred fold. To the best of our knowledge, this is the first demonstration that ellagitannins and other natural ellagic acid analogues are potent inhibitors of JAK2. Thus a drink containing Boysenberry juice concentrate may have anti-inflammatory properties. PMID:22899007

  3. Myeloproliferative disorders

    PubMed Central

    Gilliland, D. Gary

    2008-01-01

    In 1951 William Dameshek classified polycythemia vera (PV), essential thombocytosis (ET), and primary myelofibrosis (PMF) as pathogenetically related myeloproliferative disorders (MPD). Subsequent studies demonstrated that PV, ET, and PMF are clonal disorders of multipotent hematopoietic progenitors. In 2005, a somatic activating mutation in the JAK2 nonreceptor tyrosine kinase (JAK2V617F) was identified in most patients with PV and in a significant proportion of patients with ET and PMF. Subsequent studies identified additional mutations in the JAK-STAT pathway in some patients with JAK2V617F− MPD, suggesting that constitutive activation of this signaling pathway is a unifying feature of these disorders. Although the discovery of mutations in the JAK-STAT pathway is important from a pathogenetic and diagnostic perspective, important questions remain regarding the role of this single disease allele in 3 related but clinically distinct disorders, and the role of additional genetic events in MPD disease pathogenesis. In addition, these observations provide a foundation for development of small molecule inhibitors of JAK2 that are currently being tested in clinical trials. This review will discuss our understanding of the pathogenesis of PV, ET, and PMF, the potential role of JAK2-targeted therapy, and the important unanswered questions that need to be addressed to improve clinical outcome. PMID:18779404

  4. Frequencies, Laboratory Features, and Granulocyte Activation in Chinese Patients with CALR-Mutated Myeloproliferative Neoplasms

    PubMed Central

    Tian, Ruiyuan; Chang, Jianmei; Li, Jianlan; Tan, Yanhong; Xu, Zhifang; Ren, Fanggang; Zhao, Junxia; Pan, Jie; Zhang, Na; Wang, Xiaojuan; He, Jianxia; Yang, Wanfang; Wang, Hongwei

    2015-01-01

    Somatic mutations in the CALR gene have been recently identified as acquired alterations in myeloproliferative neoplasms (MPNs). In this study, we evaluated mutation frequencies, laboratory features, and granulocyte activation in Chinese patients with MPNs. A combination of qualitative allele-specific polymerase chain reaction and Sanger sequencing was used to detect three driver mutations (i.e., CALR, JAK2V617F, and MPL). CALR mutations were identified in 8.4% of cases with essential thrombocythemia (ET) and 5.3% of cases with primary myelofibrosis (PMF). Moreover, 25% of polycythemia vera, 29.5% of ET, and 48.1% of PMF were negative for all three mutations (JAK2V617F, MPL, and CALR). Compared with those patients with JAK2V617F mutation, CALR-mutated ET patients displayed unique hematological phenotypes, including higher platelet counts, and lower leukocyte counts and hemoglobin levels. Significant differences were not found between Chinese PMF patients with mutants CALR and JAK2V617F in terms of laboratory features. Interestingly, patients with CALR mutations showed markedly decreased levels of leukocyte alkaline phosphatase (LAP) expression, whereas those with JAK2V617F mutation presented with elevated levels. Overall, a lower mutant rate of CALR gene and a higher triple-negative rate were identified in the cohort of Chinese patients with MPNs. This result indicates that an undiscovered mutant gene may have a significant role in these patients. Moreover, these pathological features further imply that the disease biology varies considerably between mutants CALR and JAK2V617F. PMID:26375990

  5. Screening for hotspot mutations in PI3K, JAK2, FLT3 and NPM1 in patients with myelodysplastic syndromes

    PubMed Central

    Machado-Neto, João Agostinho; Traina, Fabiola; Lazarini, Mariana; de Melo Campos, Paula; Pagnano, Katia Borgia Barbosa; Lorand-Metze, Irene; Costa, Fernando Ferreira; Olalla Saad, Sara T

    2011-01-01

    INTRODUCTION: Myelodysplastic syndromes encompass a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis, refractory cytopenia and a tendency to progress toward acute myeloid leukemia. The accumulation of genetic alterations is closely associated with the progression of myelodysplastic syndromes toward acute myeloid leukemia. OBJECTIVE: To investigate the presence of mutations in the points most frequent for mutations (hotspot mutations) in phosphatidylinositol-3-kinase (PI3K), Janus kinase 2 (JAK2), FMS-like tyrosine kinase 3 (FLT3) and nucleophosmin (NPM1), which are involved in leukemia and other cancers, in a population of Brazilian MDS patients. METHODS: Fifty-one myelodysplastic syndromes patients were included in the study. According to French-American-British classification, the patients were distributed as follows: 31 with refractory anemia, 8 with refractory anemia with ringed sideroblasts, 7 with refractory anemia with excess blasts, 3 with refractory anemia with excess blasts in transformation and 2 with chronic myelomonocytic leukemia. Bone marrow samples were obtained and screened for the presence of hotspot mutations using analysis based on amplification with the polymerase chain reaction, sequencing, fragment size polymorphisms or restriction enzyme digestion. All patients were screened for mutations at the time of diagnosis, and 5 patients were also screened at the time of disease progression. RESULTS: In the genes studied, no mutations were detected in the patients at the time of diagnosis. One patient with chronic myelomonocytic leukemia was heterozygous for a Janus kinase 2 mutation after disease progression. CONCLUSIONS: These results show that hotspot mutations in the PI3K, JAK2, FLT3 and NPM1 genes are not common in MDS patients; nevertheless, JAK2 mutations may be present in myelodysplasia during disease progression. PMID:21789382

  6. Allogeneic stem cell transplant for myelofibrosis patients over age 60: likely impact of the JAK2 inhibitors

    PubMed Central

    Fauble, V; Leis, J; Mesa, R A

    2012-01-01

    The myeloproliferative neoplasm, myelofibrosis (MF), has only one therapeutic intervention that is potentially curative in these individuals, specifically that of allogeneic stem cell transplantation (ASCT). ASCT has been utilized up to this juncture, primarily in younger individuals with higher risk disease. There is more limited data on outcomes in individuals over the age of 60 years. The choice of an individualized therapeutic intervention for a patient with MF is a very complex issue and is dependent on several factors. The first factor being their overall prognosis with their illness (which can vary from a median of 2 years in high-risk patients to over 10 years in low-risk patients) and the potential impact of a therapeutic intervention not only on survival but also on quality of life. Current available therapies have been strictly palliative for disease-associated anemia and/or splenomegaly. At present, we have a new generation of inhibitors of JAK2 (Ruxolitinib, CYT387, SB1518, TG101348, with others in development), which have been shown to improve splenomegaly, improve symptomatic burden of illness and improve quality of life. In addition, these inhibitors of JAK2 may have an impact on the natural history of MF, but confirmation of the presence and degree of this impact is still pending. Clinical availability of JAK2 inhibitors may alter the timing of transplant in marginal transplant candidates (that is, those over the age of 60), may have a role preceding ASCT to improve spleen size and performance status before transplant and might be frontline therapy in intermediate and high-risk patients who are not candidates for ASCT. PMID:27175229

  7. In vivo treatment of rat arterial adventitia with interleukin‑1β induces intimal proliferation via the JAK2/STAT3 signaling pathway.

    PubMed

    Wang, Xiao; Chen, Lihua; Liu, Jie; Yan, Tao; Wu, Gangyong; Xia, Yang; Zong, Gangjun; Li, Fengsheng

    2016-04-01

    Previous studies have indicated that adventitial inflammation is involved in the development of atherosclerosis. The aim of this study was to investigate the effect of arterial adventitia inflammation induced by interleukin (IL)‑1β on intimal proliferation and the mechanisms involved in this process. The left common carotid artery adventitia of male rats in the experimental and control groups (25 rats/group) was wrapped with agar containing or without a sustained‑release suspension of 2.5 µg IL‑1β, respectively. Five animals in each group were randomly selected for sacrifice at 2 h, 8 h, 24 h, 48 h, and 1 week post‑treatment. Hematoxylin and eosin staining was performed for to analyze the morphology of the adventitia. The expression of janus kinase (JAK)2, signal transducer and activator of transcription (STAT)3, phosphorylated (p‑)JAK2 and p‑STAT3 were detected by western blot analysis or immunohistochemistry staining. A model of adventitial inflammation was successfully created by wrapping IL‑1β around the rat carotid artery. IL‑1β treatment induced vascular smooth muscle cell proliferation and migration as well as intimal proliferation. In addition, the expression of p‑JAK2 and p‑STAT3 increased after IL‑1β treatment. Furthermore, an inhibitor of JAK2/STAT3 pathway, AG490, suppressed IL‑1β‑induced intimal proliferation and phosphorylation of JAK2 and STAT3. Thus, the JAK2/STAT3 signaling pathway is involved in intimal proliferation caused by vascular adventitial inflammation. Inhibiting the JAK2/STAT3 signaling pathway may be a novel method for the clinical treatment of artery atherosclerosis. PMID:26955959

  8. In vivo treatment of rat arterial adventitia with interleukin-1β induces intimal proliferation via the JAK2/STAT3 signaling pathway

    PubMed Central

    WANG, XIAO; CHEN, LIHUA; LIU, JIE; YAN, TAO; WU, GANGYONG; XIA, YANG; ZONG, GANGJUN; LI, FENGSHENG

    2016-01-01

    Previous studies have indicated that adventitial inflammation is involved in the development of atherosclerosis. The aim of this study was to investigate the effect of arterial adventitia inflammation induced by interleukin (IL)-1β on intimal proliferation and the mechanisms involved in this process. The left common carotid artery adventitia of male rats in the experimental and control groups (25 rats/group) was wrapped with agar containing or without a sustained-release suspension of 2.5 µg IL-1β, respectively. Five animals in each group were randomly selected for sacrifice at 2 h, 8 h, 24 h, 48 h, and 1 week post-treatment. Hematoxylin and eosin staining was performed for to analyze the morphology of the adventitia. The expression of janus kinase (JAK)2, signal transducer and activator of transcription (STAT)3, phosphorylated (p-)JAK2 and p-STAT3 were detected by western blot analysis or immunohistochemistry staining. A model of adventitial inflammation was successfully created by wrapping IL-1β around the rat carotid artery. IL-1β treatment induced vascular smooth muscle cell proliferation and migration as well as intimal proliferation. In addition, the expression of p-JAK2 and p-STAT3 increased after IL-1β treatment. Furthermore, an inhibitor of JAK2/STAT3 pathway, AG490, suppressed IL-1β-induced intimal proliferation and phosphorylation of JAK2 and STAT3. Thus, the JAK2/STAT3 signaling pathway is involved in intimal proliferation caused by vascular adventitial inflammation. Inhibiting the JAK2/STAT3 signaling pathway may be a novel method for the clinical treatment of artery atherosclerosis. PMID:26955959

  9. JAK2 and genomic instability in the myeloproliferative neoplasms: a case of the chicken or the egg?

    PubMed Central

    Scott, Linda M.; Rebel, Vivienne I.

    2012-01-01

    The myeloproliferative neoplasms (MPNs) are a particularly useful model for studying mutation accumulation in neoplastic and the mechanisms of the molecular cells, understanding underlying defects our current This review summarizes acquisition. present their in patients with an MPN, and the effects of mutations targeting Janus kinase 2 (JAK2)-mediated intracellular signaling on DNA damage, and on the elimination of mutation-bearing cells by programmed cell death. Moreover, we discuss findings that suggest that the acquisition of disease-initiating mutations in hematopoietic stem cells of some MPN patients may be the consequence of an inherent genomic instability that was not previously appreciated. PMID:22641564

  10. MicroRNA-204 targets JAK2 in breast cancer and induces cell apoptosis through the STAT3/BCl-2/survivin pathway

    PubMed Central

    Wang, Xilong; Qiu, Wenxiu; Zhang, Guoqiang; Xu, Shujian; Gao, Qiang; Yang, Zhenlin

    2015-01-01

    MicroRNAs (miRNAs) have emerged as important regulators that potentially play critical roles in cancer cell biological processes. Previous studies have shown that miR-204 plays an important role in various human cancers. However, the underlying mechanisms of this microRNA in breast cancer remain largely unknown. In the present study, we investigated that miR-204 expression level was markedly reduced in both the human breast cancer tissue and cultured breast cancer cell lines (MCF-7, MDA-MB-231). Overexpression of miR-204 inhibited the proliferation and promoted the apoptosis in breast cancer cells, which were reversed by co-transfection of miR-204 inhibitor. We validated that Janus kinase 2 (JAK2), as a direct target of miR-204, is overexpressed in breast cancer. Knockdown of JAK2 suppressed cell viability and induced apoptosis in breast cancer cells. Moreover, the level of miR-204 is negatively correlated with p-STAT3 and anti-apoptotic genes BCl-2 and surviving in breast cancer. In conclusions, miR-204 targets JAK2 and suppressed JAK2 and p-JAK2 expression in breast cancer, which further inhibit the activation of STAT3, BCl-2 and survivin. These findings indicate that manipulation of miR-204 expression may represent a novel therapeutic strategy in the treatment of breast cancer. PMID:26191195