Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.1 (ERK)
 95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bruton's tyrosine kinase (BTK) deficiency results in a differentiation block at the pre-B cell stage. Likewise, acute lymphoblastic leukemia cells are typically arrested at early stages of B cell development. We therefore investigated BTK function in B cell precursor leukemia cells carrying a BCR-ABL1, E2A-PBX1, MLL-AF4, TEL-AML1, or TEL-PDGFRB gene rearrangement. Although somatic mutations of the BTK gene are rare in B cell precursor leukemia cells, we identified kinase-deficient splice variants of BTK throughout all leukemia subtypes. Unlike infant leukemia cells carrying an MLL-AF4 gene rearrangement, where expression of full-length BTK was detectable in only four of eight primary cases, in leukemia cells harboring other fusion genes full-length BTK was typically coexpressed with kinase-deficient variants. As shown by overexpression experiments, kinase-deficient splice variants can act as a dominant-negative BTK in that they suppress BTK-dependent differentiation and pre-B cell receptor responsiveness of the leukemia cells. On the other hand, induced expression of full-length BTK rendered the leukemia cells particularly sensitive to apoptosis. Comparing BTK expression in surviving or preapoptotic leukemia cells after 10-Gy gamma radiation, we observed selective survival of leukemia cells that exhibit expression of dominant-negative BTK forms. These findings indicate that lack of BTK expression or expression of dominant-negative splice variants in B cell precursor leukemia cells can (i) inhibit differentiation beyond the pre-B cell stage and (ii) protect from radiation-induced apoptosis.
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PMID:Deficiency of Bruton's tyrosine kinase in B cell precursor leukemia cells. 1614 23

Chronic myeloproliferative diseases (CMPDs) are characterized by the abnormal proliferation and survival of one or more myeloid cell types. The archetype of this class of hematological diseases is chronic myeloid leukemia (CML), characterized by the presence of the Philadelphia (Ph) chromosome, the result of t(9;22)(q34;q11), and the associated BCR-ABL1 oncogene. Some of the Ph-negative myeloproliferative diseases are characterized by other chromosomal translocations involving a variety of tyrosine kinase genes, including ABL1, ABL2, PDGFRA, PDGFRB, FGFR1, and JAK2. The majority of Ph-negative CMPDs, however, such as chronic eosinophilic leukemia, polycythemia vera, essential thrombocythemia, and idiopathic myelofibrosis are not characterized by the presence of recurrent chromosomal abnormalities. Recent studies have identified the FIP1L1-PDGFRA fusion gene, generated due to a small cryptic deletion on chromosome 4q12, and the activating V617F mutation in JAK2 in a significant fraction of Ph-negative CMPDs. These results show that abnormalities in tyrosine kinase genes are central to the molecular pathogenesis of CMPDs. Genome-wide screenings to identify novel tyrosine kinase abnormalities in CMPDs may contribute to further improvement of the diagnosis and the treatment of these diseases.
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PMID:Chronic myeloproliferative disorders: a tyrosine kinase tale. 1634 Oct 34

We investigated genetically affected leukemic cells in FIP1L1-PDGFRA+ chronic eosinophilic leukemia (CEL) and in BCR-ABL1+ chronic myeloid leukemia (CML), two myeloproliferative disorders responsive to imatinib. Fluorescence in situ hybridization specific for BCR-ABL1 and for FIP1L1-PDGFRA was combined with cytomorphology or with lineage-restricted monoclonal antibodies and applied in CML and CEL, respectively. In CEL the amount of FIP1L1-PDGFRA+ cells among CD34+ and CD133+ cells, B and T lymphocytes, and megakaryocytes were within normal ranges. Positivity was found in eosinophils, granulo-monocytes and varying percentages of erythrocytes. In vitro assays with imatinib showed reduced survival of peripheral blood mononuclear cells but no reduction in colony-forming unit growth medium (CFU-GM) growth. In CML the BCR-ABL1 fusion gene was detected in CD34+/CD133+ cells, granulo-monocytes, eosinophils, erythrocytes, megakaryocytes and B-lymphocytes. Growth of both peripheral blood mononuclear cells and CFU-GM was inhibited by imatinib. This study provided evidence for marked differences in the leukemic masses which are targeted by imatinib in CEL or CML, as harboring FIP1L1-PDGFRA or BCR-ABL1.
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PMID:FIP1L1-PDGFRA in chronic eosinophilic leukemia and BCR-ABL1 in chronic myeloid leukemia affect different leukemic cells. 1721 55

The clinical phenotype of myelofibrosis (MF) is recognized either de novo (primary) or in the setting of polycythemia vera (post-PV) or essential thrombocythemia (post-ET). Approximately one-third of patients with primary MF (PMF) present with cytogenetic abnormalities; the most frequent are del(20q), del(13q), trisomy 8 and 9, and abnormalities of chromosome 1 including duplication 1q. Other less frequent lesions include -7/del(7q), del(5q), del(12p), +21 and der(6)t(1;6)(q21;p21.3). In general, cytogenetic abnormalities are qualitatively similar among PMF, post-ET MF and post-PV MF although their individual frequencies may differ. Based on prognostic effect, cytogenetic findings in MF are classified as either 'favorable' or 'unfavorable'. The former include normal karyotype or isolated del(20q) or del(13q) and the latter all other abnormalities. Unfavorable cytogenetic profile in both PMF and post-PV/ET MF confers an independent adverse effect on survival; it is also associated with higher JAK2V617F mutational frequency. In addition to their prognostic value, cytogenetic studies in MF ensure diagnostic exclusion of other myeloid neoplasms that are sometimes associated with bone marrow fibrosis (e.g. BCR-ABL1-positive or PDGFRB-rearranged) and also assist in specific treatment selection (e.g. lenalidomide therapy is active in MF associated with del(5q).
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PMID:Conventional cytogenetics in myelofibrosis: literature review and discussion. 1914 Nov 19

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 (JAK2 V617F and other JAK2 mutations), essential thrombocythemia (JAK2V617F and MPL515 mutations), primary myelofibrosis (JAK2 V617F 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.
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PMID:Molecular drug targets in myeloproliferative neoplasms: mutant ABL1, JAK2, MPL, KIT, PDGFRA, PDGFRB and FGFR1. 1917 93

The 2008 WHO classification system for hematological malignancies is comprehensive and includes histology and genetic information. Myeloid neoplasms are now classified into five categories: acute myeloid leukemia, myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), MDS/MPN, and myeloid and/or lymphoid malignancies associated with eosinophilia and PDGFR or FGFR1 rearrangements. MPN are subclassified into eight separate entities: chronic myelogenous leukemia, polycythemia vera, essential thrombocythemia, primary myelofibrosis, systemic mastocytosis, chronic eosinophilic leukemia not otherwise specified, chronic neutrophilic leukemia, and unclassifiable MPN. The diagnosis of chronic myelogenous leukemia requires the presence of BCR-ABL1, while its absence is required for all other MPN. Additional MPN-associated molecular markers include mutations of JAK2, MPL, TET2 and KIT. JAK2 V617F is found in most patients with polycythemia vera, essential thrombocythemia, or primary myelofibrosis and is, therefore, useful as a clonal marker in those settings. The diagnostic utility of MPL and TET2 mutations is limited by low mutational frequency. In systemic mastocytosis, presence of KIT D816V is expected but not essential for diagnosis. Chronic eosinophilic leukemia not otherwise specified should be distinguished from both PDGFR-rearranged or FGFR1-rearranged neoplasms and hypereosinophilic syndrome. We discuss histologic, cytogenetic and molecular changes in MPN and illustrate their integration into practical diagnostic algorithms.
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PMID:Myeloproliferative neoplasms: contemporary diagnosis using histology and genetics. 1980 46

The acquired JAK2 V617F mutation is observed in the majority of patients with BCR-ABL1 negative chronic myeloproliferative neoplasms (MPN). BCR-ABL1 negative MPN displays myeloproliferation with an elevated leucocyte alkaline phosphatase (LAP) activity, a neutrophil activation marker. We tried to separate the downstream signalling of JAK2 V617F to stimulate myeloproliferation and LAP activity. NB4, a myeloid lineage cell line, was transduced with Jak2 V617F mutation or wild-type Jak2. We found that Jak2 V617F mutation, but not wild-type Jak2 enhanced LAP expression in NB4-derived neutrophils and proliferation of NB4 cells. JAK2 V617F induces constitutive phosphorylation of STAT3 and STAT5, and uses signalling targets such as Ras/MEK/ERK and PI3K/Akt pathways. By using MEK1/2 inhibitor U0126, PI3K inhibitor LY294002, and STAT3 or STAT5 siRNAs, JAK2 V617F was found to specifically use the STAT3 pathway to enhance LAP expression, while STAT5, Ras/MEK/ERK and PI3K/Akt, but not STAT3 pathways, were able to stimulate cell proliferation. These data strongly suggest that JAK2 V617F uses distinct signalling pathways to induce typical pathological features of MPN, such as high LAP activity and enhanced cell proliferation.
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PMID:JAK2 V617F uses distinct signalling pathways to induce cell proliferation and neutrophil activation. 2055 73

Non-receptor protein tyrosine kinases are responsible for signal transduction during many physiologic cellular processes, including cell growth and proliferation, apoptosis, differentiation, regulation of actin cytoskeleton, cell shape, adhesion, motility and migration. Aberrant activity of protein tyrosine kinases (acquired as a result of chromosomal translocation or point mutation) has been implicated in the stimulation of cancer growth and progression, the induction of drug-resistance, tumour neovascularization, tissue invasion, extravasation and the formation of metastases. Small molecule tyrosine kinase inhibitors interfere with these pathophysiological circuits by blocking the signalling cascades triggered by the aberrantly activated protein tyrosine kinases (e.g. BCR-ABL1, FIP1L1-PDGFRA or ETV6-PDGFRB).Tyrosine kinase inhibitors (imatinib, nilotinib, dasatinib) now belong to established anti-cancer agents with clinical activity in patients with CML, Ph+ ALL, and myeloid neoplasms with overexpression of PDGFRA, PDGFRB and wild-type KIT. New generation tyrosine kinase inhibitors (e.g. dasatinib) with extended activity against SRC and EPH kinases belong to promising anti-cancer agents with documented preclinical activity in several solid tumours (e.g. prostate cancer).
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PMID:[ABL1, SRC and other non-receptor protein tyrosine kinases as new targets for specific anticancer therapy]. 2080 17

Genetic instability due to increased DNA damage and altered DNA repair is of central significance in the initiation and progression of inherited and sporadic human leukemias. Although very rare, some inherited DNA repair insufficiency syndromes (e.g., Fanconi anemia, Bloom's syndrome) have added substantially to our understanding of crucial mechanisms of leukemogenesis in recent years. Conversely, sporadic leukemias account for the main proportion of leukemias and here DNA damaging reactive oxygen species (ROS) play a central role. Although the exact mechanisms of increased ROS production remain largely unknown and no single pathway has been detected thus far, some oncogenic proteins (e.g., the activated tyrosine kinases BCR-ABL1 and FLT3-ITD) seem to play a key role in driving genetic instability by increased ROS generation which influences the disease course (e.g., blast crisis in chronic myeloid leukemia or relapse in FLT3-ITD positive acute myeloid leukemia). Of course other mechanisms, which promote genetic instability in leukemia also exist. A newly emerging mechanism is the genome-wide alteration of epigenetic marks (e.g., hypomethylation of histone H3K79), which promotes chromosomal instability. Taken together genetic instability plays a critical role both in inherited and sporadic leukemias and emerges as a common theme in both inherited and sporadic leukemias. Beyond its theoretical impact, the analysis of genetic instability may lead the way to the development of innovative therapy strategies.
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PMID:Genetic instability in inherited and sporadic leukemias. 2084 30

The hypereosinophilic syndromes (HES) include a group of heterogeneous diseases characterized by the persistent increase of the number of eosinophils in blood and bone marrow. Few cases of paediatric hypereosinophilia (pHES) have been described in the literature. Early identification of pHES that may evolve towards a lymphomyeloproliferative disease is relevant in light of prognostic and therapeutic implications. Molecular features of 10 pHES patients were analysed at presentation and during their clinical course, including analysis of BCR-ABL1 and FIP1L1/PDGFRA fusion genes, quantitation of WT1 gene copy number and clonality of T-cell receptor (TCR) and immunoglobulin heavy chain (IGH). All patients had normal karyotype and germline TCR configuration. Five children showed IGH clonality at presentation: of these, two developed a B non-Hodgkin lymphoma and a B-lineage acute lymphocytic leukaemia at six and 12 months respectively, two spontaneously reverted to a polyclonal IGH profile during the follow-up, and the last one persisted with pHES without B-clonal evolution after 19 months. One patient had a PDGFRA/FIP1L1 fusion and achieved hematologic and molecular remission after imatinib therapy. IGH rearrangement was observed to be a frequent molecular feature of pHES and may precede B-cell clonal expansion and evolution into B-cell malignancies in children.
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PMID:Molecular characterization of paediatric idiopathic hypereosinophilia. 2095 1


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