Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Aberrant expression of FLT3 has been found in most cases of B-lineage ALL and AML, and subsets of T cell ALL, CML in blast crisis and CLL. In 20% of patients with AML the receptor has small internal tandem duplications of the juxtamembrane region which appear to contitutively activate the receptor. To investigate whether FLT3 activation could play a role in leukemia, we generated a constitutively activated FLT3 by fusing its cytoplasmic domain to the helix-loop-helix domain of TEL in analogy to the fusion that occurs with TEL-PDGFR in CMML. In vitro translation assays demonstrated oligomerization and intrinsic tyrosine kinase activity of the TEL-FLT3 chimeric receptor. Constitutively activated TEL-FLT3 conferred IL-3 independence and long-term proliferation to transfected Ba/F3 cells. Immunoblot analyses showed that JAK 2, STAT 3, STAT 5a, STAT 5b and CBL were tyrosine-phosphorylated in TEL-FLT3 expressing Ba/F3 cells in the absence of IL-3. These data suggest a possible role for the JAK/STAT pathway in FLT3 signaling. Transplantation of TEL-FLT3 expressing Ba/F3 cells into syngeneic mice caused mortality in all mice by 3 weeks after injection. Histopathologic analysis demonstrated a massive infiltration of mononuclear cells in the liver, spleen and bone marrow. The mimicking of naturally occurring TEL fusions provides an approach to assess aspects of the biology of activated FLT3, or other receptor-type tyrosine kinases (RTKs) in leukemic transformation.
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PMID:Constitutive activation of FLT3 stimulates multiple intracellular signal transducers and results in transformation. 1102 52

Rearrangements of 12p, resulting from deletions or translocations, are common findings in hematologic malignancies. In many cases, these rearrangements target the ETV6 gene (previously called TEL) located at 12p13. Various partner genes have been implicated in the formation of fusion genes with ETV6. These include PDGFRB, JAK2, NTRK3, ABL2, and ABL1, each of which encodes for proteins with tyrosine kinase activity. To date, ETV6/ABL1 transcripts have been detected in only four patients with a leukemic disorder. Here, we describe one adult with chronic myeloid leukemia and a child with T-cell acute lymphocytic leukemia with ETV6/ABL1. Molecular cytogenetic analysis confirmed that formation of an ETV6/ABL1 fusion in these patients required at least three chromosomal breaks and showed that each of these translocations is the result of a complex chromosomal rearrangement. Molecular analysis showed the presence of two fusion transcripts in both patients as the result of alternative splicing, questioning the suggested role of these transcripts in the lineage specificity. Clinical findings of these patients were compared to those of previously reported cases, and the possible clinical and biological similarities between ETV6/ABL1 and other fusion genes leading to increased tyrosine kinase activity are discussed.
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PMID:Molecular cytogenetic and clinical findings in ETV6/ABL1-positive leukemia. 1117 Feb 85

The tyrosine kinase inhibitor STI571 inhibits BCR/ABL and induces hematologic remission in most patients with chronic myeloid leukemia. In addition to BCR/ABL, STI571 also inhibits v-Abl, TEL/ABL, the native platelet-derived growth factor (PDGF)beta receptor, and c-KIT, but it does not inhibit SRC family kinases, c-FMS, FLT3, the epidermal growth factor receptor, or multiple other tyrosine kinases. ARG is a widely expressed tyrosine kinase that shares substantial sequence identity with c-ABL in the kinase domain and cooperates with ABL to regulate neurulation in the developing mouse embryo. As described here, ARG has recently been implicated in the pathogenesis of leukemia as a fusion partner of TEL. A TEL/ARG fusion was constructed to determine whether ARG can be inhibited by STI571. When expressed in the factor-dependent murine hematopoietic cell line Ba/F3, the TEL/ARG protein was heavily phosphorylated on tyrosine, increased tyrosine phosphorylation of multiple cellular proteins, and induced factor-independent proliferation. The effects of STI571 on Ba/F3 cells transformed with BCR/ABL, TEL/ABL, TEL/PDGFbetaR, or TEL/ARG were then compared. STI571 inhibited tyrosine phosphorylation and cell growth of Ba/F3 cells expressing BCR/ABL, TEL/ABL, TEL/PDGFbetaR, and TEL/ARG with an IC(50) of approximately 0.5 microM in each case, but it had no effect on untransformed Ba/F3 cells growing in IL-3 or on Ba/F3 cells transformed by TEL/JAK2. Culture of TEL/ARG-transfected Ba/F3 cells with IL-3 completely prevented STI571-induced apoptosis in these cells, similar to what has been observed with BCR/ABL- or TEL/ABL-transformed cells. These results indicate that ARG is a target of the small molecule, tyrosine kinase inhibitor STI571.
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PMID:ARG tyrosine kinase activity is inhibited by STI571. 1129 Jun 9

The AML1 (CBFA2) gene is the most frequent target of chromosomal rearrangements observed in human acute leukemia. These rearrangements include the commonly reported t(8;21)(q22;q22) or AML1/ETO fusion in AML-M2, the t(3;21)(q26;q22) or AML1 fusion with one of three genes, MDS1, EAP or EVI1, in therapy-related AML and MDS, as well as in blast crisis in CML and the t(12;21)(p13;q22) or TEL/AML1 fusion in B-cell ALL. In addition to the t(3;21), other AML1 translocations have also been reported in therapy-related MDS and AML, particularly after treatment with topoisomerase II inhibitors. AML1 gene rearrangements have also been observed less frequently with numerous other chromosomal partners. Here, we describe a patient with AML-M4 and a previously unreported rearrangement involving the AML1 locus and an unknown locus on the short arm of chromosome 1 at 1p32.
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PMID:A unique AML1 (CBF2A) rearrangement, t(1;21)(p32;q22), observed in a patient with acute myelomonocytic leukemia. 1156 47

The t(3;12)(q26;p13) translocation is a recurrent chromosomal aberration observed in myeloid malignancies. It has been shown that the translocation results in the fusion of the TEL (ETV6) gene at 12p13 and the EV11 gene at 3q26. We report the first case with Philadelphia (Ph)-positive chronic myelogenous leukemia (CML) expressing the TEL/EVI1 fusion transcript. A 26-year-old man was initially diagnosed as having the chronic phase of Ph-positive CML. The t(3;12)(q26;p13) emerged 16 months prior to the myeloid blastic crisis. Reverse transcriptase-polymerase chain reaction detected the TEL/EVI1 transcript without the intervening 5' non-coding exon of EVI1, suggesting that inappropriate expression of the EVI1 protein driven by the TEL promotor could play a critical role in progression to the blast crisis of CML.
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PMID:Expression of the TEL/EVI1 fusion transcript in a patient with chronic myelogenous leukemia with t(3;12)(q26;p13). 1183 39

Constitutive activation of tyrosine kinases, such as the BCR/ABL fusion associated with t(9;22)(q34;q22), is a hallmark of chronic myeloid leukemia (CML) syndromes in humans. Expression of BCR/ABL is both necessary and sufficient to cause a chronic myeloproliferative syndrome in murine bone marrow transplantation models, and absolutely depends on kinase activity. Progression of CML to acute leukemia (blast crisis) in humans has been associated with acquisition of secondary chromosomal translocations, including the t(7;11)(p15;p15) resulting in the NUP98/HOXA9 fusion protein. We demonstrate that BCR/ABL cooperates with NUP98/HOXA9 to cause blast crisis in a murine model. The phenotype depends both on expression of BCR/ABL and NUP98/HOXA9, but tumors retain sensitivity to the ABL inhibitor STI571 in vitro and in vivo. This paradigm is applicable to other constitutively activated tyrosine kinases such as TEL/PDGFbetaR. These experiments document cooperative effects between constitutively activated tyrosine kinases, which confer proliferative and survival properties to hematopoietic cells, with mutations that impair differentiation, such as the NUP98/HOXA9, giving rise to the acute myeloid leukemia (AML) phenotype. Furthermore, these data indicate that despite acquisition of additional mutations, CML blast crisis cells retain their dependence on BCR/ABL for proliferation and survival.
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PMID:A murine model of CML blast crisis induced by cooperation between BCR/ABL and NUP98/HOXA9. 1203 33

Several patients with clinical features of chronic myeloid leukemia (CML) have fusion of the TEL (ETV6) gene on 12p13 with ABL on 9q34 and express a chimeric Tel-Abl protein that contains the same portion of the Abl tyrosine kinase fused to Tel, an Ets family transcription factor, rather than Bcr. In a murine retroviral bone marrow transduction-transplantation model, a Tel (exon 1-5)-Abl fusion protein induced 2 distinct illnesses: a CML-like myeloproliferative disease very similar to that induced by Bcr-Abl but with increased latency and a novel syndrome characterized by small-bowel myeloid cell infiltration and necrosis, increased circulating endotoxin and tumor necrosis factor alpha levels, and fulminant hepatic and renal failure. Induction of both diseases required the Tel pointed homology oligomerization domain and Abl tyrosine kinase activity. Myeloid cells from mice with both diseases expressed Tel-Abl protein. CML-like disease induced by Tel-Abl and Bcr-Abl was polyclonal and originated from cells with multilineage (myeloid, erythroid, and B- and T-lymphoid) repopulating ability and the capacity to generate day-12 spleen colonies in secondary transplantations. In contrast to findings with Bcr-Abl, however, neither Tel-Abl-induced disease could be adoptively transferred to irradiated secondary recipient syngeneic mice. These results show that Tel-Abl has leukemogenic properties from distinct from those of Bcr-Abl and may act in a different bone marrow progenitor.
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PMID:The Tel-Abl (ETV6-Abl) tyrosine kinase, product of complex (9;12) translocations in human leukemia, induces distinct myeloproliferative disease in mice. 1203 90

Mutations in signal transduction molecules, which regulate cell differentiation and proliferation, are involved in the development of leukemia. Aberrations of receptor type tyrosine kinases are known to arise from FLT3 mutations in acute myeloid leukemia (AML) and myelodysplastic syndrome, and c-Kit mutations in mast cell tumors. BCR/ABL found in chronic myelogenous leukemia (CML) is a hallmark of the constitutively active forms of cytoplasmic tyrosine kinases. Downstream of the tyrosine kinase is the RAS GTP-binding protein, and genetic mutations related to this protein have been found in a wide variety of malignant tumors including hematopoietic tumors. In the nucleus, transcription factor-encoding genes are frequently detected as the targets of chromosomal translocations found in specific types of leukemias. For instance, the AML1 gene generates AML1/MTG8 chimera by t (8;21) translocation in AML (M2), AML1/EVI-1 chimera by t (3;21) translocation in blastic crisis of CML, and TEL/AML1 chimera in t (12;21) translocation (pre-B cell type acute lymphoblastic leukemia). Another example of abnormal transcription factors is PML/RAR alpha generated by t (15;17) translocation found in acute promyelocytic leukemia. Mutations or deletions of tumor suppressor genes are frequently found in cell cycle regulators such as p53, RB and p16 genes. Therefore, mutations of any molecules involved in the signal transduction pathways from growth factor receptors to inside the nucleus are thought to contribute to neoplastic transformation of hematopoietic cells.
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PMID:[Molecular mechanisms in leukemogenesis]. 1214 88

A certain number of pediatric cancer patients still succumb to relapse following conventional treatment of their malignancies. One of the mechanisms of relapse is escape from immunity. Adoptive cellular immunotherapy with effector cells has the potential to overcome this escape. In adults, the CD3+ CD56+ cell, a cytokine-induced killer (CIK) cell, appears to be a promising effector cell type with the greatest cytotoxicity. This effector cell type may work in children as well. No similar studies with children have been published. We speculated that expanded CD3+ CD56+ cells obtained from pediatric cancer patients during remission would act similarly against various pediatric tumor cell lines; therefore, we undertook the present study to find support for our speculation. This study was undertaken to generate and expand CD3+ CD56+ CIK cells from normal peripheral blood mononuclear cells (PBL) obtained from 6 children with cancer (2 with acute lymphoblastic leukemia, 2 with large cell lymphoma, and 2 with osteosarcoma) in remission after intensive chemotherapy and to study the cytotoxic activities of these cells against chronic myeloid leukemia cell line K562 t(9;22), 4 pediatric tumor cell lines [infant acute lymphoblastic leukemia RS4 t(4;11), TEL/AML acute lymphoblastic leukemia REH t(12;21), alveolar rhabdomyosarcoma Rh-Cr t(2;13), and Ewing sarcoma EW-Le t(11;22)], and 2 pediatric glioblastoma multiforme cultured cell lines (G74 and G77). CIK cells were generated and expanded in culture medium to which interferon gamma, monoclonal antibody against CD3, and interleukin 2 were added at appropriate times. Cells were counted by flow cytometry. Net lactate dehydrogenase release from target cells incubated with CIK cells was used as an index of CIK cell cytotoxicity against various pediatric tumor cell lines. The results show that after 21 days in culture CD3+ CD56+ CIK cells derived from the 6 pediatric patients accounted for a median of 28.3% of the entire culture (range, 10.7%-36.4%). Before expansion no such cells were found in any of the 6 children. Median lytic activity rates of CIK cells were 45.5% to 64.5%, rates that contrasted drastically to the lytic activity rates of PBL, which were only 8% to 12%. The findings of the present study are encouraging. They provide information for developing adoptive immunotherapy for future clinical trials with pediatric cancer patients, particularly those patients with minimal residual disease after intensive chemotherapy or stem cell transplantation (especially nonmyeloablative transplantation procedures).
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PMID:Generation of CD3+ CD56+ cytokine-induced killer cells and their in vitro cytotoxicity against pediatric cancer cells. 1262 54

Functional roles of several Ets transcription factors in megakaryocytic and erythroid differentiation of the human chronic myelogenous leukemia cell line K562 was investigated. When K562 cells were induced to differentiate into the megakaryocyte lineage by treatment with TPA, the expression of the c-ets-1, Fli-1 and TEL2 genes was increased, and that of the TEL gene was decreased at the onset of differentiation. When the cells were induced to differentiate into the erythroid lineage by treatment with Hemin, expression of the c-ets-1 gene was increased, and that of the Fli-1 and TEL genes was decreased. To investigate the role of TEL in the growth and differentiation of K562 cells, we introduced an expression plasmid containing the TEL gene into the cells. Overexpression of TEL in K562 cells leads to inhibition of the endogenous expression of megakaryocyte-specific GPIIb and GPIbalpha genes, and inhibition of cell growth. DNA array analysis revealed that expression of genes such as the RhoG and D4-GDI genes was down-regulated in TEL-overexpressing cells, while that of the representative growth-related genes such as the c-myc, c-fos and c-jun genes was not remarkably changed. These results suggest that several Ets family transcription factors are implicated in megakaryocytic and erythroid differentiation of K562 cells and TEL inhibits the expression of some megakaryocyte-specific genes and growth in K562 cells.
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PMID:Effects of overexpression of the Ets family transcription factor TEL on cell growth and differentiation of K562 cells. 1273 1


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