Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10721 (c-kit)
 6,575 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The c-kit receptor tyrosine kinase (KIT) is activated upon ligand binding, thereby leading to a variety of signaling events that play a fundamental role in hematopoiesis. In addition to ligand-dependent activation, we have previously shown that KIT is constitutively activated in a ligand-independent manner by two point mutations, Val-559-->Gly (G559) mutation in the juxtamembrane domain and Asp-814-->Val (V814) mutation in the phosphotransferase domain. To investigate the biochemical consequence and biologic significance of these mutations, retroviral vectors encoding KITG559 or KITV814 were introduced into murine pro-B-type Ba/F3 cells and myeloid FDC-P1 cells, both of which require interleukin-3 (IL-3) for their growth and survival. In the cells, KITG559 or KITV814 were found to be constitutively phophorylated on tyrosine in the absence of stem cell factor (SCF) that is a ligand for KIT. Chemical cross-linking analysis showed that a substantial fraction of the phosphorylated KITG559 underwent dimerization even in the absence of SCF, whereas the phosphorylated KITV814 did not, suggesting the distinct mechanisms underlying constitutive activation of KIT by G559 and V814 mutations. Furthermore, the cells expressing either KITG559 or KITV814 were found to show a factor-independent growth, whereas the cells expressing wild-type KIT (KITWT) proliferated in response to SCF as well as IL-3. Moreover, subcutaneous injection of Ba/F3 cells expressing KITG559 or KITV814 into nude mice resulted in production of large tumors at all sites of the injection within 2 weeks, and all nude mice quickly succumbed to leukemia and died. These results suggest that, although the mechanisms underlying constitutive activation of KITG559 or KITV814 may be different, both of the activating mutations have a function to induce a factor-independent and tumorigenic phenotype. Also, the data of this study raise the possibility that the constitutively activating mutations of c-kit may play a causal role in development of hematologic malignancies.
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PMID:Constitutively activating mutations of c-kit receptor tyrosine kinase confer factor-independent growth and tumorigenicity of factor-dependent hematopoietic cell lines. 753 May 9

Similar to two other hematopoietic growth factor receptors, the c-fms (macrophage colony-stimulating factor receptor) and the c-kit genes, c-mpl has been discovered through the study of oncogenic retroviruses. Unlike c-fms and c-kit, which both belong to a subgroup of tyrosine kinase receptors, the c-mpl proto-oncogene encodes a new member of the cytokine receptor superfamily. We have studied the expression of c-mpl in a series of 105 patients with hematologic malignancies using Northern blot analysis. The levels of c-mpl transcripts in lymphoid malignancies and in chronic myeloproliferative disorders were not significantly different from those found in normal bone marrow cells, in which c-mpl was barely detectable. In contrast, c-mpl expression was increased in 26 of 51 patients with acute myeloblastic leukemia (AML) and in 5 of 16 patients with myelodysplastic syndromes. Amplification of the c-mpl gene was detected in genomic DNA of one M4 AML patient. There was no significant correlation between c-mpl expression and the French-American-British classification of AML. Patients with high c-mpl expression appeared to belong to a subgroup of AML with a low rate of complete remission and a poor prognosis, including secondary leukemia and AML with unfavorable cytogenetic abnormalities.
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PMID:Expression of the c-mpl proto-oncogene in human hematologic malignancies. 839 55

The c-kit proto-oncogene encodes a receptor tyrosine kinase that is crucial to hematopoiesis, melanogenesis, and gametogeneis. Although the enzymatic activity of the c-kit product (KIT) is regulated by its ligand, both the Val559-->Gly (G559) mutation in the juxtamembrane domain and the Asp814-->Val (V814) mutation in the phosphotransferase domain lead to constitutive activation of KIT. By retroviral infection of hematopoietic progenitor cells with KIT(G559) or KIT(V814), KIT(G559) induced development of granulocyte/macrophage and mast-cell colonies in vitro without the addition of exogenous growth factors. KIT(V814) induced factor-independent growth of various types of hematopoietic progenitor cells, resulting in the development of mixed erythroid/myeloid colonies in addition to granulocyte/macrophage and mast-cell colonies. Furthermore, transplantation of KIT(G559) and KIT(V814)-infected bone marrow cells led to development of acute leukemia in one of 10 and six of 10 transplanted mice, respectively. No mice developed hematologic malignancies after transplantation of wild-type KIT-infected cells. Furthermore, transgenic mice expressing KIT(V814) developed acute leukemia or malignant lymphoma. These results demonstrate a direct role of the mutant KITs, particularly KIT(V814), in tumorigenesis of hematopoietic cells and suggest that similar mutations may contribute to the development of human hematologic malignancies.
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PMID:Neoplastic transformation of normal hematopoietic cells by constitutively activating mutations of c-kit receptor tyrosine kinase. 870 59

An association between mediastinal germ cell tumors (MGCT) and hematological malignancies (e.g. acute leukemia, malignant histiocytosis) has been recognized since 1984. A rare case of mediastinal mature teratoma with angiosarcoma, a hematopoietic region and granulocytic sarcoma is reported in a 29-year-old male. The resected tumor was 9.0 x 6.5 cm, weighed 65 g and showed extensive necrosis, forming a cyst. The histological features of the tumor showed a mature teratoma, which contained a large gland lined by ciliated epithelium, hyalinous cartilage, a paraganglion-like structure, well-differentiated angiosarcoma with atypical hematopoiesis composed of CD34-positive cells, and malignant round cells. The malignant round cells did not stain for CD34 but were positive for leukocyte common antigen (LCA) and c-kit product. From these findings, the round cells were diagnosed as granulocytic sarcoma. The patient died of metastasis of the granulocytic sarcoma in the tonsils and cervical lymph nodes 8 months after surgery. A leukemic condition was not present throughout the clinical course. The association between MGCT and hematological malignancy is a distinctive syndrome. However, its pathogenesis is still obscure and the origin of the hematopoietic malignancy has not been fully elucidated. In this particular case, it is suggested that the granulocytic sarcoma might have arisen from the abnormal hematopoietic area in the mediastinal teratoma.
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PMID:Mediastinal mature teratoma with coexistence of angiosarcoma, granulocytic sarcoma and a hematopoietic region in the tumor: a rare case of association between hematological malignancy and mediastinal germ cell tumor. 977 15

The association of mast cell diseases and some hematologic malignancies, usually myeloproliferative disorders, myelodysplastic syndromes, and acute leukemia is well recognized. We report the case of a patient with telangiectasia macularis eruptiva perstans, a rare form of cutaneous mastocytosis, and multiple myeloma, an association that has been described only twice in the literature. Parallel improvement of both conditions was observed under chemotherapy regimens for multiple myeloma. Pathogenesis remains unclear, although the abnormalities in the c-kit pathway may play a role in the proliferation of cells from both lineages.
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PMID:Telangiectasia macularis eruptiva perstans and multiple myeloma. 1104 37

Mast cell disease (MCD), a proliferation of mast cells (MC), is occasionally associated with hematologic malignancies. Neoplastic MC have activating c-kit mutations. c-kit is a receptor tyrosine kinase required for the development, proliferation, and survival of MC. Interaction of c-kit with its ligand stem cell factor induces dimerization, receptor phosphorylation, and signal transduction. The most common c-kit mutation detected in neoplastic MCD is Asp816Val, which results in ligand-independent autophosphorylation of the receptor leading to MC proliferation. We describe the rare occurrence of MCD associated with acute myeloid leukemia, report a novel c-kit mutation Asp816 His, and discuss the pathogenesis of MCD associated with hematologic malignancies.
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PMID:Mast cell disease associated with acute myeloid leukemia: detection of a new c-kit mutation Asp816His. 1107 60

Angiogenesis plays a critical role in the growth and metastasis of solid and hematologic malignancies. This complex and highly regulated process involves numerous different cell types and mediators. Vascular endothelial growth factor, basic fibroblast growth factor, and platelet-derived growth factor are among the soluble factors that stimulate this process. They are ligands for specific tyrosine kinase receptors that are important in transduction of intracellular signals and induction of angiogenesis. SU6668 is a novel molecule that competitively inhibits the tyrosine kinase of the receptors for vascular endothelial growth factor, basic fibroblast growth factor, platelet-derived growth factor, and c-kit. In vitro studies have confirmed that SU6668 inhibits growth factor-stimulated tyrosine phosphorylation. SU6668 also has significant antitumor activity against many types of tumor xenograft explants in athymic mice. SU6668 inhibits angiogenesis through several mechanisms, including the induction of apoptosis in vascular endothelial cells and tumor cells. Currently, Phase 1 studies are being initiated to evaluate the potential of SU6668 as an anticancer agent for humans.
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PMID:SU6668, a multitargeted angiogenesis inhibitor. 1177 84

Neovascularization is increasingly recognized as an important factor in the pathogenesis of hematologic malignancies as well as solid tumors. The complex interactions between several cell types and numerous cytokine mediators suggest the involvement of autocrine and paracrine signaling mechanisms. Vascular endothelial growth factor (VEGF) in particular is critical to both stimulation of leukemic growth and proliferation of endothelial cells. Tyrosine kinase receptors specific for certain growth factors represent attractive target molecules for anticancer therapy. SU5416 is a competitive inhibitor of VEGF receptor subtypes VEGFR-1 and VEGFR-2 and stem cell factor receptor c-kit. Preclinical evidence shows that SU5416 effectively inhibits VEGF-induced endothelial cell proliferation and slows growth of subcutaneous solid tumor xenografts. This agent is in late-stage clinical trials in patients with solid tumors, and a Phase 2 study was recently initiated to evaluate its utility in the treatment of acute myeloid leukemia. In this Phase 2 study, investigators are seeking to determine the response rate to the antiangiogenic agent SU5416. Translational research in this study is intended to aid our understanding of the precise mechanisms by which SU5416 affects acute myeloid leukemia cells and the bone marrow microenvironment.
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PMID:Role of angiogenesis inhibitors in acute myeloid leukemia. 1177 83

Stem cell factor is a haemopoietic growth factor that interacts with the c-kit-encoded transmembrane tyrosine kinase receptor during signal transduction in haemopoietic progenitor stem cells. We have screened 127 Chinese patients with myelodysplastic syndromes or acute myeloid leukaemia for structural rearrangements in the stem cell factor and c-kit genes using Southern blot analysis. No structural rearrangements were detected in any of the bone marrow samples that were tested. It seems that structural rearrangements in the stem cell factor and c-kit genes are rare in Hong Kong patients who have a haematological malignancy.
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PMID:Lack of structural rearrangement in c-kit and stem cell factor genes in Hong Kong Chinese patients with myelodysplastic syndromes or acute myeloid leukaemia. 1183 49

Angiogenesis is an important component of the pathogenesis of hematologic malignancies. A negative prognostic implication of increased angiogenesis has been established for acute and chronic myeloid and lymphocytic leukemias, myeloproliferative diseases, multiple myeloma, non-Hodgkin's lymphoma (NHL), and hairy cell leukemia. An association between the return of increased marrow vascularity to normal levels and durability of response has been established in some of these diseases. Elevated levels ofproangiogenic factors have been associated with a poor prognosis in the acute and chronic leukemias, multiple myeloma, and NHL. These data lend support to the reduction of activity of proangiogenic factors as a therapeutic modality. Vascular endothelial growth factor (VEGF) has been implicated as the major proangiogenic factor that regulates multiple endothelial cell functions, including mitogenesis. A direct relationship between VEGF and leukemic blasts and malignant plasma cells has been established, but VEGF may have a function distinct from its role in angiogenesis. Current protocols with anti- VEGF agents in patients with hematologic malignancies involve the use of monoclonal antibody, blockers of the VEGF-receptor tyrosine kinase pathway, thalidomide (Thalomid) and its analogs, and cyclooxygenase inhibitors. The receptor tyrosine kinase inhibitors also affect platelet-derived growthfactor, c-kit, and Flt-3 to varying degrees, considerably broadening their potential efficacy. This review will summarize several angiogenesis inhibitors in clinical development.
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PMID:The emerging role of angiogenesis inhibitors in hematologic malignancies. 1210 77


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