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)

Somatic insertions/deletions in the calreticulin gene have recently been discovered to be causative alterations in myeloproliferative neoplasms. A combination of qualitative and quantitative allele-specific polymerase chain reaction, fragment-sizing, high resolution melting and Sanger-sequencing was applied for the detection of three driver mutations (in Janus kinase 2, calreticulin and myeloproliferative leukemia virus oncogene genes) in 289 cases of essential thrombocythemia and 99 cases of primary myelofibrosis. In essential thrombocythemia, 154 (53%) Janus kinase 2 V617F, 96 (33%) calreticulin, 9 (3%) myeloproliferative leukemia virus oncogene gene mutation-positive and 30 triple-negative (11%) cases were identified, while in primary myelofibrosis 56 (57%) Janus kinase 2 V617F, 25 (25%) calreticulin, 7 (7%) myeloproliferative leukemia virus oncogene gene mutation-positive and 11 (11%) triple-negative cases were identified. Patients positive for the calreticulin mutation were younger and had higher platelet counts compared to Janus kinase 2 mutation-positive counterparts. Calreticulin mutation-positive patients with essential thrombocythemia showed a lower risk of developing venous thrombosis, but no difference in overall survival. Calreticulin mutation-positive patients with primary myelofibrosis had a better overall survival compared to that of the Janus kinase 2 mutation-positive (P=0.04) or triple-negative cases (P=0.01). Type 2 calreticulin mutation occurred more frequently in essential thrombocythemia than in primary myelofibrosis (P=0.049). In essential thrombocythemia, the calreticulin mutational load was higher than the Janus kinase 2 mutational load (P<0.001), and increased gradually in advanced stages. Calreticulin mutational load influenced blood counts even at the time point of diagnosis in essential thrombocythemia. We confirm that calreticulin mutation is associated with distinct clinical characteristics and explored relationships between mutation type, load and clinical outcome.
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PMID:Distinct clinical characteristics of myeloproliferative neoplasms with calreticulin mutations. 2489 36

Myeloproliferative neoplasms (MPNs) are often characterized by JAK2 or calreticulin (CALR) mutations, indicating aberrant trafficking in pathogenesis. This study focuses on Mpl trafficking and Jak2 association using two model systems: human erythroleukemia cells (HEL; JAK2V617F) and K562 myeloid leukemia cells (JAK2WT). Consistent with a putative chaperone role for Jak2, Mpl and Jak2 associate on both intracellular and plasma membranes (shown by proximity ligation assay) and siRNA-mediated knockdown of Jak2 led to Mpl trapping in the endoplasmic reticulum (ER). Even in Jak2 sufficient cells, Mpl accumulates in punctate structures that partially colocalize with ER-tracker, the ER exit site marker (ERES) Sec31a, the autophagy marker LC3 and LAMP1. Mpl was fused to miniSOG, a genetically encoded tag for correlated light and electron microscopy. Results suggest that a fraction of Mpl is taken up into autophagic structures from the ER and routed to autolyososomes. Surface biotinylation shows that both immature and mature Mpl reach the cell surface; in K562 cells Mpl is also released in exosomes. Both forms rapidly internalize upon ligand addition, while recovery is primarily attributed to immature Mpl. Mpl appears to reach the plasma membrane via both conventional ER-Golgi and autolysosome secretory pathways, as well as recycling.
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PMID:Mpl traffics to the cell surface through conventional and unconventional routes. 2493 76

We studied the impact of driver mutations of JAK2, CALR, (calreticulin gene) or MPL on clinical course, leukemic transformation, and survival of patients with primary myelofibrosis (PMF). Of the 617 subjects studied, 399 (64.7%) carried JAK2 (V617F), 140 (22.7%) had a CALR exon 9 indel, 25 (4.0%) carried an MPL (W515) mutation, and 53 (8.6%) had nonmutated JAK2, CALR, and MPL (so-called triple-negative PMF). Patients with CALR mutation had a lower risk of developing anemia, thrombocytopenia, and marked leukocytosis compared with other subtypes. They also had a lower risk of thrombosis compared with patients carrying JAK2 (V617F). At the opposite, triple-negative patients had higher incidence of leukemic transformation compared with either CALR-mutant or JAK2-mutant patients. Median overall survival was 17.7 years in CALR-mutant, 9.2 years in JAK2-mutant, 9.1 years in MPL-mutant, and 3.2 years in triple-negative patients. In multivariate analysis corrected for age, CALR-mutant patients had better overall survival than either JAK2-mutant or triple-negative patients. The impact of genetic lesions on survival was independent of current prognostic scoring systems. These observations indicate that driver mutations define distinct disease entities within PMF. Accounting for them is not only relevant to clinical decision-making, but should also be considered in designing clinical trials.
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PMID:Clinical effect of driver mutations of JAK2, CALR, or MPL in primary myelofibrosis. 2498 90

Calreticulin, an endoplasmic reticulum protein with multiple functions involving chaperone activity and calcium homeostasis, plays an important role in cellular proliferation and differentiation. Calreticulin dysfunction is known to be associated with different cancers. Very recently, calreticulin mutations have been identified in myeloproliferative neoplasms (MPNs), with a particularly high frequency in MPNs without Janus kinase 2 (JAK2) mutations, which exhibit clinical characteristics different from those with mutant JAK2. Here, we focus on the structure, function and carcinogenicity of calreticulin, as well as its relationship with MPNs not involving JAK2 mutations.
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PMID:Calreticulin gene mutations in myeloproliferative neoplasms without Janus kinase 2 mutations. 2537 10

The Polycythemia Vera Study Group (PVSG) and WHO classifications distinguished the Philadelphia (Ph(1)) chromosome-positive chronic myeloid leukemia from the Ph(1)-negative myeloproliferative neoplasms (MPN) essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (MF) or primary megakaryocytic granulocytic myeloproliferation (PMGM). Half of PVSG/WHO-defined ET patients show low serum erythropoietin levels and carry the JAK2(V617F) mutation, indicating prodromal PV. The positive predictive value of a JAK2(V617F) PCR test is 95% for the diagnosis of PV, and about 50% for ET and MF. The WHO-defined JAK2(V617F)-positive ET comprises three ET phenotypes at clinical and bone marrow level when the integrated WHO and European Clinical, Molecular and Pathological (ECMP) criteria are applied: normocellular ET (WHO-ET), hypercellular ET due to increased erythropoiesis (prodromal PV) and hypercellular ET associated with megakaryocytic granulocytic myeloproliferation (EMGM). Four main molecular types of clonal MPN can be distinguished: JAK2(V617F)-positive ET and PV; JAK2 wild-type ET carrying the MPL(515); mutations in the calreticulin (CALR) gene in JAK2/MPL wild-type ET and MF, and a small proportion of JAK2/MPL/CALR wild-type ET and MF patients. The JAK2(V617F) mutation load is low in heterozygous normocellular WHO-ET. The JAK2(V617F) mutation load in hetero-/homozygous PV and EMGM is clearly related to MPN disease burden in terms of splenomegaly, constitutional symptoms and fibrosis. The JAK2 wild-type ET carrying the MPL(515) mutation is featured by clustered small and giant megakaryocytes with hyperlobulated stag-horn-like nuclei, in a normocellular bone marrow (WHO-ET), and lacks features of PV. JAK2/MPL wild-type, CALR mutated hypercellular ET associated with PMGM is featured by dense clustered large immature dysmorphic megakaryocytes and bulky (cloud-like) hyperchromatic nuclei, which are never seen in WHO-ECMP-defined JAK2(V617F) mutated ET, EMGM and PV, and neither in JAK2 wild-type ET carrying the MPL(515) mutation. Two thirds of JAK2/MPL wild-type ET and MF patients carry one of the CALR mutations as the cause of the third distinct MPN entity. WHO-ECMP criteria are recommended to diagnose, classify and stage the broad spectrum of MPN of various molecular etiologies.
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PMID:Changing concepts of diagnostic criteria of myeloproliferative disorders and the molecular etiology and classification of myeloproliferative neoplasms: from Dameshek 1950 to Vainchenker 2005 and beyond. 2511 92

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.
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PMID:JAK2 inhibitors do not affect stem cells present in the spleens of patients with myelofibrosis. 2537 58

In 2013, Nangalia et al. and Klampfl et al. found a recurrent and abundant mutation in the calreticulin gene (CALR), mutually exclusive with JAK2 and MPL alterations. At present, the data concerning the new mutation, i.e. its prevalence, allele burden and clinical significance, are scarce. We report the incidence and molecular characteristics of CALR mutations in a group of 184 Polish patients with myeloproliferative neoplasms (MPNs). Clinical data analysis revealed significant differences between JAK2 V617F-mutated and CALR-mutated groups. In essential thrombocythemia patients, hemoglobin levels and leukocyte counts were significantly higher in JAK2-positive than in CALR-positive patients (p = 0.023 and p = 0.017, respectively), but the CALR-positive patients had significantly higher platelet counts (p = 0.022). Patients harboring CALR mutations were also younger at the time of diagnosis (p = 0.039). In primary myelofibrosis patients, the degree of anemia was less severe in those who were CALR exon 9 mutation-positive than in those who were JAK2 V617F-positive (p = 0.048).
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PMID:Frequency and molecular characteristics of calreticulin gene (CALR) mutations in patients with JAK2 -negative myeloproliferative neoplasms. 2532 79

With the discovery of the JAK2V617F mutation in patients with Philadelphia chromosome-negative (Ph(-)) myeloproliferative neoplasms (MPNs) in 2005, major advances have been made in the diagnosis of MPNs, in understanding of their pathogenesis involving the JAK/STAT pathway, and finally in the development of novel therapies targeting this pathway. Nevertheless, it remains unknown which mutations exist in approximately one-third of patients with non-mutated JAK2 or MPL essential thrombocythemia (ET) and primary myelofibrosis (PMF). At the end of 2013, two studies identified recurrent mutations in the gene encoding calreticulin (CALR) using whole-exome sequencing. These mutations were revealed in the majority of ET and PMF patients with non-mutated JAK2 or MPL but not in polycythemia vera patients. Somatic 52-bp deletions (type 1 mutations) and recurrent 5-bp insertions (type 2 mutations) in exon 9 of the CALR gene (the last exon encoding the C-terminal amino acids of the protein calreticulin) were detected and found always to generate frameshift mutations. All detected mutant calreticulin proteins shared a novel amino acid sequence at the C-terminal. Mutations in CALR are acquired early in the clonal history of the disease, and they cause activation of JAK/STAT signaling. The CALR mutations are the second most frequent mutations in Ph(-) MPN patients after the JAK2V617F mutation, and their detection has significantly improved the diagnostic approach for ET and PMF. The characteristics of the CALR mutations as well as their diagnostic, clinical, and pathogenesis implications are discussed in this review.
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PMID:Calreticulin mutations in myeloproliferative neoplasms. 2538 51

The discovery of the JAK2V617F mutation followed by the discovery of other genetic abnormalities allowed important progress in the understanding of the pathogenesis and management of myeloproliferative neoplasms (MPN)s. Classical Breakpoint cluster region-Abelson (BCR-ABL)-negative neoplasms include 3 main disorders: essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF). Genomic studies have shown that these disorders are more heterogeneous than previously thought with 3 main entities corresponding to different gene mutations: the JAK2 disorder, essentially due to JAK2V617F mutation, which includes nearly all PVs and a majority of ETs and PMFs with a continuum between these diseases and the myeloproliferative leukemia (MPL) and calreticulin (CALR) disorders, which include a fraction of ET and PMF. All of these mutations lead to a JAK2 constitutive activation. Murine models either with JAK2V617F or MPLW515L, but also with JAK2 or MPL germ line mutations found in hereditary thrombocytosis, have demonstrated that they are drivers of myeloproliferation. However, the myeloproliferative driver mutation is still unknown in approximately 15% of ET and PMF, but appears to also target the JAK/Signal Transducer and Activator of Transcription (STAT) pathway. However, other mutations in genes involved in epigenetics or splicing also can be present and can predate or follow mutations in signaling. They are involved either in clonal dominance or in phenotypic changes, more particularly in PMF. They can be associated with leukemic progression and might have an important prognostic value such as additional sex comb-like 1 mutations. Despite this heterogeneity, it is tempting to target JAK2 and its signaling for therapy. However in PMF, Adenosine Tri-Phosphate (ATP)-competitive JAK2 inhibitors have shown their interest, but also their important limitations. Thus, other approaches are required, which are discussed in this review.
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PMID:Myeloproliferative neoplasms: JAK2 signaling pathway as a central target for therapy. 2548 52

Tumor angiogenesis has been identified to play a critical role in tumor growth and tumor progression, and is regulated by a balance of angiogenic and antiangiogenic cytokines. This has been documented for solid tumors, and there is emerging evidence suggesting that tumor progression of hematological malignancies also depends on the induction of new blood vessel formation. Data on angiogenesis in the bone marrow of BCR-ABL1-negative myeloproliferative neoplasm patients suggest an increase of the microvessel density and vascular endothelial growth factor (VEGF) expression, and there is a relation to the JAK2-V617F status. The most important proangiogenic agent is VEGF, activating VEGF receptors 1 and 2. Inhibition of VEGF signaling by monoclonal antibodies or small molecules (kinase inhibitors) has already been successfully established for the treatment of different cancer entities, and multiple new drugs are being tested in clinical trials. Most patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF) that was not associated with a JAK2 or MPL alteration carried a somatic mutation in calreticulin (CALR). Thus, CALR mutations should be included in the next classification system for ET/PMF. This review summarizes recent advances in the basic understanding of the role of angiogenesis in myeloproliferative neoplasms and the translation of such basic findings into clinical studies.
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PMID:Angiogenesis in myeloproliferative neoplasms, new markers and future directions. 2554 63


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