Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023467 (acute myeloid leukemia)
 35,200 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Substitution of valine (Val) for aspartic acid (Asp) at codon 814 constitutively activates murine c-kit receptor tyrosine kinase (KIT), and Asp816Val mutation, corresponding to murine Asp814Val mutation, is found in patients with mastocytosis and acute myelocytic leukemia. However, the signal transduction pathways responsible for oncogenesis by the Asp814Val mutant (KIT(Val814)) are not fully understood. To examine the oncogenic signal transduction of KIT(Val814), we converted 20 tyrosine (Tyr) residues to phenylalanine (Phe) in the cytoplasmic domain of KIT(Val814) or deleted the C-terminal region containing 2 other tyrosine residues (Del). Among various KIT(Val814)- derived mutants, KIT(Val814-Tyr719Phe) and KIT(Val814-Del) severely impaired receptor tyrosine phosphorylation and association with the p85 subunit of phosphatidylinositol 3'-kinase (p85 (PI3-K)). Moreover, KIT(Val814-Tyr719Phe) and KIT(Val814-Del) failed to induce ligand-independent growth in Ba/F3 cells, indicating that Tyr719, the binding site for p85(PI3-K), and the C-terminal region are indispensable for factor-independent growth by KIT(Val814). Although the C-terminal region was also required for ligand-dependent growth by wild-type KIT (KIT(WT)), the Tyr719Phe substitution had negligible effects on ligand-dependent growth by KIT(WT). Furthermore, dominant-negative PI3-K significantly inhibited ligand-independent growth by KIT(Val814). These results demonstrate that Tyr719 is crucial for constitutive activation of KIT(Val814), but not for the ligand-induced activation of KIT(WT), and that the downstream signaling of PI3-K plays an important role in ligand-independent growth and tumorigenicity by KIT(Val814), thereby suggesting that KIT(Val814) is a unique activating mutation that leads to a distinguishable function from the effects of KIT(WT).
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PMID:Necessity of tyrosine 719 and phosphatidylinositol 3'-kinase-mediated signal pathway in constitutive activation and oncogenic potential of c-kit receptor tyrosine kinase with the Asp814Val mutation. 1239 43

The translocation (8;21), generating the AML1-ETO fusion protein, is one of the most frequent chromosomal abnormalities associated with acute myelogenous leukemia (AML). To elucidate its role in oncogenesis, bone marrow (BM) cells were infected with a retroviral vector carrying AML1-ETO and transplanted into mice. In contrast to previous transgenic mouse models, we show that AML1-ETO directly stimulates granulopoiesis, suppresses erythropoiesis, and impairs the maturation of myeloid, B, and T lymphoid cells in vivo. To determine the significance of earlier findings that expression of the tumor suppressor ICSBP is often downregulated in AML myeloblasts, AML1-ETO was introduced into BM cells derived from mice lacking the interferon regulatory factor ICSBP. Our findings demonstrate that AML1-ETO synergizes with an ICSBP deficiency to induce myeloblastic transformation in the BM, reminiscent of AML.
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PMID:AML1-ETO inhibits maturation of multiple lymphohematopoietic lineages and induces myeloblast transformation in synergy with ICSBP deficiency. 1241 32

Survivin is a member of the inhibitor of apoptosis protein (IAPs) family and considered to play a pivotal role in oncogenesis. We present the first report of survivin expression profile in myelodysplastic syndrome (MDS). Expression of survivin messenger RNA was evaluated by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) in patients with MDS and acute myeloid leukemia (AML). Eleven out of 12 patients with refractory anemia (RA) (91.6%), and all 3 patients with refractory anemia with excess blasts in transformation (RAEBt) (100%), were positive for survivin expression with the majority of cases showing abundant levels of the survivin transcript. On the other hand, expression of survivin was undetectable in the 4 patients with chronic myelomonocytic leukemia (CMMoL). The level and frequency of survivin expression in patients with refractory anemia were compared to those in patients with AML. Out of 12 patients with de novo AML, 5 patients (41.7%) showed detectable levels of survivin expression. Abundant survivin expression in RA was also confirmed by immunohistochemistry. In contrast, survivin was almost absent in two cases with aplastic anemia. We propose that high levels of survivin expression can serve as a reliable diagnostic marker of RA in MDS.
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PMID:Expression of the anti-apoptotic gene survivin in myelodysplastic syndrome. 1246 85

The activation of the NF-kappaB family of transcription factors plays a crucial role in oncogenesis. The IkappaB family has the ability to retain the NF-kappaB in an inactive complex in the cytoplasm. Recently, mutations of the IkappaBalpha gene were found in Hodgkin's lymphoma, which allows NF-kappaB proteins to translocate into the nucleus in an active form. In this report, we describe a mutational analysis of IkappaBalpha for primary tumor cells obtained from patients with a variety of hematologic malignancies (acute myelogenous leukemia, chronic myelogenous leukemia, myelodysplastic syndrome, hairy cell leukemia, adult T-cell leukemia, and mantle cell lymphoma) as well as 15 leukemia, lymphoma, and myeloma cell lines (HL60, U937, HEL, K562, NALM1, Jurkat, JM, MOLT4, Raji, KS1, OKM2T, OKM3T, F6T, Su9T01, and C2-2). RT-PCR, followed by direct sequencing, was performed and all samples expressed IkappaBalpha. One missense mutation was identified in a primary effusion lymphoma cell line, KS1. However, NF-kappaB (p65) protein was absent from the nucleus of KS1 immunohistochemically, suggesting that the mutation did not alter the function of IkappaBalpha in this case. Taken together, although it is not clear whether normal IkappaBalpha protein was expressed in hematologic malignancies, mutations of IkappaBalpha could be rare events in these diseases, except for Hodgkin's lymphoma. Alterations of other members of NF-kappaB/ IkappaB family proteins might act on the development of hematologic malignancies.
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PMID:Mutational analysis of IkappaBalpha in hematologic malignancies. 1252 85

Cyclin A1 is a tissue-specific A-type cyclin that is essential for spermatogenesis. Overexpression of cyclin A1 was found in acute myeloid leukemia and cyclin A1 induced leukemia in a transgenic mouse model. We used quantitative real-time reverse transcription-polymerase chain reaction to analyze cyclin A1 expression in solid tumors. Cyclin A1 expression was very low in breast cancer, non-small cell lung cancer and in cervical carcinoma. However, substantial expression of cyclin A1 was found in testicular and ovarian cancer and in endometrial cancer. In testis specimens, cyclin A1 expression was much higher in testicular tumors compared to Sertoli cell only syndrome that lacks spermatogenesis. Compared to normal spermatogenesis, testicular cancers expressed on average lower levels of cyclin A1. Among the different histological subtypes of testicular tumors, embryonal cell carcinomas and immature teratomas expressed the highest levels of cyclin A1. The cyclin A1 levels in these tumors were similar to those seen in normal testis. Seminomas and yolk sac tumors expressed intermediate levels, whereas cyclin A1 expression was very low in mature teratomas. These findings indicate that cyclin A1 is expressed in selected solid tumors. Its known oncogenic function and the high expression levels in aggressive testicular tumors suggest a role for cyclin A1 in germ cell tumorigenesis.
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PMID:Cyclin A1 is highly expressed in aggressive testicular germ cell tumors. 1253 81

Ewing's tumors are rare pediatric neoplasms that are characterized by specific chromosomal translocations and gene rearrangements. All of the fusion genes reported to date in Ewing's tumors juxtapose the EWS gene at 22q12 to an ETS-related gene, the most common of which are FLI1 at 11q24 and ERG at 21q22. We present here four cases of Ewing's tumor, which showed no evidence of a EWS gene rearrangement, but instead contained translocations involving 16p11 and 21q22. A rearrangement involving the same chromosome bands, t(16;21)(p11;q22), is found in rare cases of acute myeloid leukemia and fuses the FUS gene at 16p11 to the ERG gene at 21q22. In two of our Ewing's tumor cases, we were able to show at the sequence level that the translocation between chromosomes 16 and 21 similarly results in a FUS/ERG fusion. In one case, exons 1-5 and most of exon 6 of FUS were fused in-frame to exon 9 of ERG; in the other case, FUS exons 1-7 were fused in-frame to ERG exons 8-9. The functional fusion transcript is expected to be expressed from the der(21)t(16;21) derivative. In the two other t(16;21)-positive Ewing's cases, we performed bacterial artificial chromosome fluorescence in situ hybridization analysis on metaphases and interphase nuclei to demonstrate colocalization of bacterial artificial chromosomes containing FUS and ERG genes, also highly suggestive of fusion gene formation. These represent the first four cases where FUS, rather than EWS, is rearranged with an ETS-family transcription factor in Ewing's tumors. Our data provide additional evidence that the transactivation domains of the TET family of RNA-binding proteins (such as EWS and FUS) are interchangeable, and suggests a novel mechanism of oncogenesis in Ewing's tumors.
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PMID:FUS/ERG gene fusions in Ewing's tumors. 1290 33

Dysregulation of cell cycle is important in oncogenesis. We analyzed the inactivation of the INK4 family CKI/CDK/RB pathway by gene promoter hypermethylation in leukemogenesis. The methylation-specific polymerase chain reaction (MSP) with primers for methylated (M-MSP) and unmethylated (U-MSP) alleles of the p15, p16, p18, and RB genes was used to study five leukemic cell lines, 50 acute myeloid leukemia (AML) and 25 acute lymphoblastic leukemia (ALL) samples. None of the leukemic cell lines showed p18 and RB methylation. p15 was methylated in Raji, while p16 was methylated in U937 and Raji. In NB4 and Jurkat, both alleles of p15 and p16 appeared to be deleted. At diagnosis, p15 methylation occurred in 29 (58%) AML patients, and 10 (40.0%) ALL patients. p16 methylation occurred in two (4%) AML and two (8%) ALL patients. Only one each of AML and ALL patients had concurrent p15 and p16 methylation. None of the patients had methylation of p18 or RB. In AML, p15 methylation was associated with M2 subtype ( p=0.018). Patients with and without p15 methylation had similar complete remission (CR) rates and projected 5-year overall survival (OS) or disease-free survival (DFS). Therefore, methylation inactivation of the INK4/CDK/RB pathway in leukemia involved primarily p15 and occasionally p16, but not p18 or RB. In AML, p15 gene methylation was associated with the M2 subtype, but was not prognostic for CR, OS, or DFS.
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PMID:Epigenetic inactivation of INK4/CDK/RB cell cycle pathway in acute leukemias. 1451 84

Mutations in the proto-oncogene c-kit cause constitutive kinase activity of its product, KIT protein, and are associated with human mastocytosis and gastrointestinal stromal tumors (GISTs). Although currently available tyrosine kinase inhibitors are effective in the treatment of GISTs, there has been limited success in the treatment of mastocytosis. 17-Allylamino-17-demethoxygeldanamycin (17-AAG), a benzoquinoid ansamycin antibiotic, which binds to heat shock protein 90 (hsp90) causes destabilization of various hsp90-dependent kinases important in oncogenesis. Treatment with 17-AAG of the mast cell line HMC-1.2, harboring the Asp816Val and Val560Gly KIT mutations, and the cell line HMC-1.1, harboring a single Val560Gly mutation, causes both the level and activity of KIT and downstream signaling molecules AKT and STAT3 to be down-regulated following drug exposure. These data were validated using Cos-7 cells transfected with wild-type and mutated KIT. 17-AAG promotes cell death of both HMC mast cell lines. In addition, neoplastic mast cells isolated from patients with mastocytosis, incubated with 17-AAG ex vivo, are selectively sensitive to the drug compared to the mononuclear fraction. These data provide compelling evidence that 17-AAG may be effective in the treatment of c-kit-related diseases including mastocytosis, GISTs, mast cell leukemia, subtypes of acute myelogenous leukemia, and testicular cancer.
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PMID:17-Allylamino-17-demethoxygeldanamycin (17-AAG) is effective in down-regulating mutated, constitutively activated KIT protein in human mast cells. 1455 Nov 38

Gene expression analysis of human leukemias has provided insight into disease classification and mechanisms of oncogenesis. Its success is particularly evident for acute leukemias with rearrangement of the mixed lineage leukemia (MLL) gene on chromosome 11q23. Unlike most other recurrent translocations, MLL rearrangements are found in leukemias classified as acute myelogenous leukemia (AML) or acute lymphoblastic leukemia (ALL). In addition, MLL-rearranged leukemias often express both myeloid- and lymphoid-associated genes. These unusual characteristics have generated much interest in the cell of origin and the mechanism of transformation by MLL rearrangements. Here we review insights gained from characterization of MLL-rearranged human leukemias by genome-wide expression profiling and compare these to data from model systems.
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PMID:MLL-rearranged leukemias: insights from gene expression profiling. 1458 77

Basic fibroblast growth factor (bFGF) is known to play a critical role in tumorigenesis of solid tumors. The importance of bFGF in hematological malignancies such as acute myeloid leukemia (AML) remains to be elucidated. Therefore, we determined bFGF protein expression by immunohistochemical analyses in bone marrow biopsies of patients with newly diagnosed, untreated AML. The expression of bFGF was significantly increased in AML patients [n = 81; median, 3.0 (interquartile range, 1.8-3.9) arbitrary units (AU)] as compared with controls [n = 18; 1.9 (1.5-2.3) AU]. The degree of bFGF expression did not correlate with microvessel density. bFGF/FGF receptor mRNA and bFGF protein were detected in different AML cell lines. To study autocrine growth stimulation of AML blasts, the AML cell lines HL-60, M-07e, and KG-1 were incubated with bFGF. A significant dose-dependent increase in proliferation and colony formation was observed. These effects were abrogated by the addition of a polyclonal anti-bFGF antibody. In conclusion, increased expression of bFGF in the bone marrow of AML patients seems to play an important role in the pathophysiology of AML by promoting autocrine growth stimulation of leukemic blasts.
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PMID:Overexpression of basic fibroblast growth factor and autocrine stimulation in acute myeloid leukemia. 1461 19


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