Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.2 (focal adhesion kinase)
44,029 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The first international meeting on V617F JAK2 mutation in myeloproliferative disorders (MPD) was held by the PV-Nord group on behalf of the French Society of Hematology and Paris 13 University on November 18, 2005, in Paris (France). Twelve speakers, including representatives of the three European groups who discovered the V617F JAK2 mutation and international experts in the field of Philadelphia-negative MPD, presented original biological and clinical data that allow better insight in the relevance of V617F JAK2 mutation in the pathogenesis and management of those diseases. The role of V617F JAK2 in cytokine receptors trafficking and signaling was described. Follow-up of transgenic mice expressing V617F JAK2 showed that they develop typical features of myelofibrosis. Comparisons of JAK2 mutational status to clonality of hematopoiesis in essential thrombocythemia on the one hand, and to activation of transcription factors in myelofibrosis with myeloid metaplasia on the other hand, suggest that JAK2 mutation could be a second genetic event in a subset of patients. Alternatively, other gene mutation(s) have to be found to explain the development of V617F-negative MPD. In large series of MPD patients presented, clinical characteristics of mutated and non-mutated patients were found different. Finally, the place of V617F JAK2 testing in the diagnosis and management of MPD was discussed.
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PMID:The first international meeting on V617F JAK2 mutation and its relevance in Philadelphia-negative myeloproliferative disorders. 1690 56

The JAK2-V617F mutation occurs in about 50% of patients with myelofibrosis and might be a reliable marker to monitor residual disease after allogeneic stem cell transplantation. We describe a new, highly sensitive (>or= 0.01%) real-time polymerase chain reaction (PCR) to monitor and quantify V617F-JAK2-positive cells after dose-reduced allogeneic stem cell transplantation. After 22 allogeneic stem cell transplantation procedures in 21 JAK2-positive patients with myelofibrosis, 78% became PCR negative. In 15 of 17 patients (88%), JAK2 remained negative after a median follow-up of 20 months. JAK2 negativity was achieved after a median of 89 days after allograft (range, 19-750 days). A significant inverse correlation was seen for JAK2 positivity and donor-cell chimerism (r:-0.91, P<.001). Four of 5 patients who never achieved JAK2 negativity fulfilled during the entire follow-up all criteria for complete remission recently proposed by the International Working Group, suggesting a major role for JAK2 measurement to determine depths of remission. In one case, residual JAK2-positive cells were successfully eliminated by donor lymphocyte infusion. In conclusion, allogeneic stem cell transplantation after dose-reduced conditioning induces high rates of molecular remission in JAK2-positive patients with myelofibrosis, and quantification of V617F-JAK2 mutation by real-time PCR allows the detection of minimal residual disease to guide adoptive immunotherapy.
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PMID:Monitoring of the JAK2-V617F mutation by highly sensitive quantitative real-time PCR after allogeneic stem cell transplantation in patients with myelofibrosis. 1701 57

Activation of JAK2 by chromosomal translocation or point mutation is a recurrent event in hematopoietic malignancies, including acute leukemias and myeloproliferative disorders. Although the effects of activated JAK2 signaling have been examined in cell lines and murine models, the functional consequences of deregulated JAK2 in the context of human hematopoietic cells are currently unknown. Here we report that expression of TEL-JAK2, a constitutively active variant of the JAK2 kinase, in lineage-depleted human umbilical cord blood cells results in erythropoietin-independent erythroid differentiation in vitro and induces the rapid development of myelofibrosis in an in vivo NOD/SCID xenotransplantation assay. These studies provide functional evidence that activated JAK2 signaling in primitive human hematopoietic cells is sufficient to drive key processes implicated in the pathophysiology of polycythemia vera and idiopathic myelofibrosis. Furthermore, they describe an in vivo model of myelofibrosis initiated with primary cells, highlighting the utility of the NOD/SCID xenotransplant system for the development of experimental models of human hematopoietic malignancies.
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PMID:Expression of TEL-JAK2 in primary human hematopoietic cells drives erythropoietin-independent erythropoiesis and induces myelofibrosis in vivo. 1707 40

Myeloproliferative disorders, including chronic idiopathic myelofibrosis (CIMF), polycythemia vera (PV), essential thrombocythemia (ET), and chronic myelomonocytic leukemia (CMML), are clonal diseases of hematopoietic stem or precursor cells. They often show a protracted or chronic course; however, all have the potential of progressing to severe marrow failure, associated with myelofibrosis, or of transforming into acute leukemia. At that point, hematopoietic cell transplantation (HCT) is the only current treatment strategy with curative potential. If transplantation is being considered and a suitable donor is available, HCT should be carried out before leukemic transformation has occurred, as the success rate of HCT declines steeply in patients who have evolved to leukemia. As many as 75-80% of patients with the original diagnoses of PV or ET, about 65-70% with CIMF, and 45% of patients with CMML are surviving long term after allogeneic HCT using conventional transplant regimens, with follow-up now extending to 15 years. Results with HLA-identical related and unrelated donors are comparable. Major risk factors for the outcome after HCT are the disease stage, the presence of comorbid conditions, and patient age. The development of reduced-intensity conditioning regimens has allowed for successful HCT even for older patients and patients with comorbid conditions. Studies on disease mechanisms, including the recent characterization of an activating mutation in JAK2, may provide additional prognostic guidance and are likely to lead to the development of novel treatment strategies, which will require continuous reassessment as to the optimum timing of HCT.
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PMID:Hematopoietic cell transplantation for chronic myeloproliferative disorders. 1712 83

The identification of JAK2V617F mutations in polycythemia vera (PV), essential thrombocytosis (ET), and myelofibrosis (MF) represents an important advance in our understanding of these myeloproliferative disorders (MPD). Most, if not all, patients with PV and a significant number of patients with ET and MF are JAK2V617F positive, and the mutation likely arises in the hematopoietic stem cell compartment. JAK2V617F is a constitutively active tyrosine kinase that is able to activate JAK-STAT signaling most efficiently when co-expressed with the erythropoietin receptor (EPOR), the thrombopoietin receptor (MPL), or the granulocyte colony-stimulating factor receptor (GCSFR). Data from murine models supports the central role of JAK2V617F in the pathogenesis of MPD, as expression of JAK2V617F in a bone marrow transplantation assay results in polycythemia and myelofibrosis in recipient mice. Activation of JAK-STAT signaling by JAK2V617F in some, but not all MPD patients with ET and MF led to the identification of the constitutively active MPLW515L allele in ET and MF. Small molecule inhibitors of JAK-STAT signaling are currently being developed, which offer potential for molecularly targeted therapy for patients with PV, ET, and MF. Despite these advances, many questions remain regarding the role of a single disease allele in three phenotypically distinct MPD, the potential clinical efficacy of JAK2 inhibitors, and the identity of oncogenic alleles in JAK2V617F/MPLW515-negative MPD.
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PMID:Role of JAK-STAT signaling in the pathogenesis of myeloproliferative disorders. 1712 66

JAK2V617F, a somatic gain-of-function mutation involving the JAK2 tyrosine kinase gene, occurs in nearly all patients with polycythemia vera (PV) but also in a variable proportion of patients with other myeloid disorders; mutational frequency is estimated at approximately 50% in both essential thrombocythemia (ET) and myelofibrosis (MF), up to 20% in certain subcategories of atypical myeloproliferative disorder (atypical MPD), less than 3% in de novo myelodysplastic syndrome (MDS) or acute myeloid leukemia, and 0% in chronic myeloid leukemia (CML). Accordingly, there is now molecular justification for grouping PV, ET, and MF together in a distinct MPD category (i.e., classic, BCR-ABL(-) MPD) that is separate from chronic myeloid leukemia (CML), MDS, and atypical MPD. To date, JAK2V617F has not been described in patients with reactive myeloproliferation, lymphoid disorders, or solid tumor. Therefore, the presence of JAK2V617F strongly suggests an underlying MPD and it is therefore reasonable to consider JAK2V617F-based laboratory tests for the evaluation of polycythemia, primary thrombocytosis, unexplained leukocytosis, bone marrow fibrosis, or abdominal vein thrombosis. Current information on disease-specific prognostic relevance of JAK2V617F is inconclusive and confounded by inter-study differences in the performance of mutation screening assays. Regardless, the discovery of JAK2V617F has reinforced the pathogenetic contribution of JAK-STAT signaling in MPD and identifies JAK2 as a valid drug target.
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PMID:Classification, diagnosis and management of myeloproliferative disorders in the JAK2V617F era. 1712 67

Chromosomal aberrations in polycythemia vera (PV) are heterogenous and nonrandom. A prognostic predictive value of these aberrations has not been established. The V617F mutation in the JAK2 gene on chromosome 9p24.1 was identified recently in peripheral blood leukocytes in the majority of patients with PV and in approximately half of patients with essential thrombocythemia and idiopathic myelofibrosis. Within the JAK2 V617F-positive PV patients, however, clinical presentation and degree of myeloproliferation varies to a great extent. Here we report four cases of chronic myeloproliferative disorders [two with PV, one with PV in transformation to idiopathic myelofibrosis (IMF) and one IMF patient], with the distinct karyotypic abberations der(18) t(9;18) (p13;p11) and der(9;18)(p10;q10). Two patients had hyperproliferative PV and two had "transitional PV" and IMF, respectively. All four patients harbored the JAK2 V617F mutation. Our data, together with previously published data, clearly indicate an association of these chromosomal abnormalities with a highly proliferative PV phenotype with a propensity to transform into postpolycythemic myelofibrosis. Cytogenetic analysis seems to identify a subgroup of patients with a distinct prognostic profile, and should be performed in conjunction with a JAK2 mutation analysis in patients suspected of a chronic myeloproliferative disease.
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PMID:A der(18)t(9;18)(p13;p11) and a der(9;18)(p10;q10) in polycythemia vera associated with a hyperproliferative phenotype in transformation to postpolycythemic myelofibrosis. 1721 18

The Philadelphia chromosome (Ph)-negative myeloproliferative disorders (MPDs) include essential thrombocythemia (ET), idiopathic myelofibrosis (IMF), and polycythemia vera (PV). All of these disorders are clonal hematologic malignancies originating at the level of the pluripotent hematopoietic stem cell. Recently, activating mutations of the intracellular cytokine-signaling molecule JAK2 have been identified in > 90% of patients with PV and in 50% of those with IMF and ET. In addition, a mutation of the thrombopoietin receptor, MPLW515L, has been documented in some patients with IMF. Both mutations activate JAK-STAT signaling pathways and likely play a role in disease progression. Both ET and PV are associated with prolonged clinical courses associated with frequent thrombotic and hemorrhagic events, and progression to myelofibrosis and acute leukemia. IMF has a much poorer prognosis and is associated with cytopenias, splenomegaly, extramedullary hematopoiesis, and bone marrow fibrosis. Stratification of risk for the development of complications from Ph-negative MPDs has guided the identification of appropriate therapies for this population. Intermediate/high-risk IMF or myelofibrosis after ET or PV is associated with a sufficiently poor prognosis to justify the use of allogeneic stem cell transplantation, which is capable of curing such patients. Reduced-intensity conditioning in preparation for allogeneic stem cell transplantation has permitted older patients with IMF to undergo transplantation with increasing success.
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PMID:Philadelphia chromosome-negative myeloproliferative disorders: biology and treatment. 1722 72

The V617F JAK2 mutation reported in Ph-negative myeloproliferative diseases (MPDs) induces the constitutive activation of JAK2, which produces an increased phosphorylation of signal transducer activator of transcription (STAT). In this study, we have analyzed a series of 114 patients (54 with polycythemia vera [PV], 44 with essential thrombocythemia [ET], 12 with idiopathic myelofibrosis [IM], and 4 with myelofibrosis secondary to MPD) for the expression pattern of phosphorylated STAT-3 and STAT-5 (pSTAT-3 and pSTAT-5, respectively) by immunostaining bone marrow biopsies. We found 3 specific patterns of pSTAT-3 and pSTAT-5 expression, significantly different from the normal staining pattern: uniformly increased pSTAT-3 and pSTAT-5 expression in PV, increased pSTAT-3 and reduced pSTAT-5 expression in ET, and uniformly reduced pSTAT-3 and pSTAT-5 expression in IM. A moderate increase of pSTAT-3 and pSTAT-5 expression was observed in secondary forms of erythrocytosis and thrombocytosis. In all evaluated MPDs, the pSTAT-5 and pSTAT-3 expression pattern was not influenced by the presence of V617F JAK2 mutation. These findings underline the importance of bone marrow histology in the differential diagnosis of Ph-negative MPD and support the hypothesis that V617F mutation simply contributes with other molecular defects in allowing the PV, ET, or IM phenotype to emerge.
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PMID:Different STAT-3 and STAT-5 phosphorylation discriminates among Ph-negative chronic myeloproliferative diseases and is independent of the V617F JAK-2 mutation. 1737 89

Chronic myeloproliferative disorders are clonal hematopoietic stem cell disorders characterized by proliferation of one or more myeloid cell lineages in the bone marrow. The WHO classification describes six major groups of chronic myeloproliferative disorders, as follows: chronic myeloid leukemia, chronic neutrophilic leukemia, chronic eosinophilic leukemia, polycythemia vera, essential thrombocythemia and chronic idiopathic myelofibrosis. The diagnosis of chronic myeloid leukemia and certain types of chronic eosinophilic leukemia are based on the detection of fusion genes (in chronic myeloid leukemia the BCR/ABL fusion gene, and in chronic eosinophilic leukemia the FIP1L1-PDGFRalpha gene). On the other hand molecular markers for polycythemia vera, essential thrombocythemia and chronic idiopathic myelofibrosis were lacking, making it difficult to identify these disorders clearly. The authors investigated the incidence of the newly identified somatic point mutation V617F of the Janus-2 tyrosine kinase in patients with polycythemia vera, essential thrombocythemia and myelofibrosis. Janus-2 kinase is a cytoplasmic, non-receptor protein-tyrosine kinase with a key role in signal transduction from multiple hematopoietic growth factor receptors. The mutant protein is constitutively phosphorylated and is able to activate its downstream signaling pathways in the absence of any cytokine, thereby contributing to the pathogenesis of chronic myeloproliferative disorders. The authors investigated DNA samples from 132 patients with chronic myeloproliferative disorders. The V617F mutation was detected by allele-specific polymerase chain reaction, and the patients were genotyped by a DNA tetra-primer amplification refractory mutation system assay. Approximately 73% of polycythemia vera, 60% of essential thrombocythemia and 67% of myelofibrosis showed the JAK2 V617F mutation. Using the amplification refractory mutation system assay, the frequency of homozygotes was 17.5% in polycythemia vera, 5.4% in essential thrombocythemia and 0% in myelofibrosis. The authors established an effective polymerase chain reaction based method for the identification of JAK2 mutation in the routine oncohematologic diagnostics.
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PMID:[Novel method in diagnosis of chronic myeloproliferative disorders--detection of JAK2 mutation]. 1740 11


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