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)

Transient leukemia (TL) has been observed in approximately 10% of newborn infants with Down syndrome (DS). Although treatment with cytarabine is effective in high-risk TL cases, approximately 20% of severe patients still suffer early death. In this study, we demonstrate abundant KIT expression in all 13 patients with GATA1 mutations, although no significant difference in expression levels was observed between TL and acute myeloid leukemia. Stem cell factor (SCF) stimulated the proliferation of the TL cells from five patients and treatment with the tyrosine kinase inhibitor imatinib suppressed the proliferation effectively in vitro. To investigate the signal cascade, we established the first SCF-dependent, DS-related acute megakaryoblastic leukemia cell line, KPAM1. Withdrawal of SCF or treatment with imatinib induced apoptosis of KPAM1 cells. SCF activated the RAS/MAPK and PI3K/AKT pathways, followed by downregulation of the pro-apoptotic factor BIM and upregulation of the anti-apoptotic factor MCL1. Although we found novel missense mutations of KIT in 2 of 14 TL patients, neither mutation led to KIT activation and neither reduced the cytotoxic effects of imatinib. These results suggest the essential role of SCF/KIT signaling in the proliferation of DS-related leukemia and the possibility of therapeutic benefits of imatinib for TL patients.
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PMID:The key role of stem cell factor/KIT signaling in the proliferation of blast cells from Down syndrome-related leukemia. 1883 Feb 55

Dasatinib has been reported to potently inhibit juxtamembrane domain mutant KIT(D816V) autophosphorylation and KIT-dependent activation of down stream signaling important for cell growth and survival of neoplastic cells. Additionally, dasatinib induced apoptosis in mast cell and leukemia cell lines expressing KIT(D816V). Here, we present the first case report of long-term hematologic and molecular remission achieved with combined treatment with chemotherapy and dasatinib in a patient with systemic mastocytosis (SM) and acute myeloid leukemia (AML) with mutant KIT(D816V) expression. A 50-year-old male presented with pancytopenia, organomegaly, lymphadenopathy, and lytic bone lesions in the pelvis. The patient was found to have systemic mastocytosis (SM) and acute myelogeneous leukemia (AML) positive for KIT(D816V) and therefore diagnosed with SM with an associated clonal hematological non-mast cell lineage disease (SM-AHNMD). Both primary CD34+ cells containing myeloblasts and CD34- cells containing mastocytes obtained from the diagnostic BM lost viability markedly by in vitro dasatinib treatment. In addition, dasatinib diminished activity of STAT5, STAT3, AKT and ERK and attenuated the levels of c-KIT. The patient achieved a hematologic complete remission (HCR) by two induction chemotherapies with residual mastocytes. Dasatinib (70mg PO bid, days 1-4) was added to consolidation treatments composed of four cycles of high dose cytarabine and was then continued as maintenance therapy (50mg PO bid). Periodic bone marrow (BM) aspirate/biopsies (eight over 18 months) were performed. The patient remained in HCR, and the mastocyte burden decreased by 50%. The bone lytic lesions improved. The KIT(D816V)mutation progressively decreased and became undetectable in the last three BM analyses. This result was confirmed by an independent laboratory showing a lack of c-KIT mutation in both CD34+ cells and CD34- cells in the last BM. No significant adverse effects of dasatinib occurred. Dasatinib has in vitro and in vivo efficacy in SM-AML patients with KIT(D816V) mutation. Along with chemotherapy, dasatinib should be considered in these patients particularly if they cannot undergo allogeneic stem cell transplantation for this poor prognostic AML.
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PMID:Chemotherapy and dasatinib induce long-term hematologic and molecular remission in systemic mastocytosis with acute myeloid leukemia with KIT D816V. 1898 3

Acute myeloid leukemia (AML) is a malignant disease characterized by deregulated proliferation of immature myeloid cells. Constitutive activation of the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway is frequently detected in approximately 50-70% of AML patients. The gene INPP5D encodes the SH2-containing inositol 5-phosphatase 1 (SHIP1), which is a negative regulator of PI3K/AKT signaling. After lentiviral-mediated gene transfer of INPP5D into CD34(+) cells derived from AML patients (n=12) the granulocyte macrophage-colony stimulating factor (GM-CSF)-dependent proliferation was reduced in all samples analyzed (average 86%; range 72-93%). An enzymatically inactive form of SHIP1 (D672A) had no effect. In addition, SHIP1 reduced the autonomous proliferation of CD34(+) cells from a patient with a secondary AML who had a very high peripheral blast count (300 x 10(9) l(-1)). These data show that SHIP1 can effectively block GM-CSF-dependent and autonomous proliferation of AML cells.
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PMID:Reduced proliferation of CD34(+) cells from patients with acute myeloid leukemia after gene transfer of INPP5D. 1914 32

Inhibition of the mutated fms-like tyrosine kinase 3 (FLT3) receptor tyrosine kinase is a promising therapeutic strategy in acute myeloid leukaemia (AML). However, development of resistance to FLT3 tyrosine kinase inhibitors (TKI), such as PKC412A, has been described recently. This observation may have an increasing impact on the duration of response and relapse rates in upcoming clinical trials employing FLT3-TKI. Herein we investigated two representatives of a novel class of FLT3-TKI: Bis(1H-indol-2-yl)methanones. Both compounds effectively induced apoptosis in FLT3-internal tandem duplicate (ITD)-transfected murine myeloid cells and in primary FLT3-ITD positive blasts. Combination of both compounds with chemotherapy revealed synergistic effects in apoptosis assays. The compounds did not show significant toxicity in human bone marrow cells derived from healthy donors. Compound102 overcame resistance to PKC412 within a non-myelotoxic dose-range. Western Blotting experiments of 32D-FLT3-ITD cells showed dose-dependent dephosphorylation of FLT3-ITD and of its downstream targets STAT5, AKT and ERK upon incubation with either compound. In conclusion, bis(1H-indol-2-yl)methanones overcome resistance mediated by FLT3-ITD mutations at position N676 and show strong efficacy in FLT3-ITD-positive cells alone as well as in combination with chemotherapy. We propose that further development of methanone compounds overcoming resistance to currently established FLT3-TKIs is an important step forward to an anticipated need within our future therapeutic algorithm in FLT3-ITD-positive AML.
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PMID:Bis(1H-indol-2-yl)methanones are effective inhibitors of FLT3-ITD tyrosine kinase and partially overcome resistance to PKC412A in vitro. 1918 86

The mechanism of cell transformation by Fms-like tyrosine kinase 3 (FLT3) in acute myeloid leukemia (AML) is incompletely understood. The most prevalent activated mutant FLT3 ITD exhibits an altered signaling quality, including strong activation of the STAT5 transcription factor. FLT3 ITD has also been found partially retained as a high-mannose precursor in an intracellular compartment. To analyze the role of intracellular retention of FLT3 for transformation, we have generated FLT3 versions that are anchored in the perinuclear endoplasmic reticulum (ER) by appending an ER retention sequence containing a RRR (R3) motif. ER retention of R3, but not of corresponding A3 FLT3 versions, is shown by biochemical, fluorescence-activated cell sorting, and immunocytochemical analyses. ER anchoring reduced global autophosphorylation and diminished constitutive activation of ERK1/2 and AKT of the constitutively active FLT3 versions. ER anchoring was, however, associated with elevated signaling to STAT3. Transforming activity of the FLT3 D835Y mutant was suppressed by ER anchoring. In contrast, ER-anchored FLT3 ITD retained STAT5-activating capacity and was transforming in vitro and in vivo. The findings highlight another aspect of the different signaling quality of FLT3 ITD: It can transform cells from an intracellular location.
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PMID:Anchoring of FLT3 in the endoplasmic reticulum alters signaling quality. 1920 27

The cyclic AMP-responsive element binding protein (CREB) is documented to be overexpressed in leukemia, but the underlying mechanism remains unknown. Here, microRNAs (miRNA), which act as negative regulators of gene expression principally through translational repression, are investigated for the mediation of high CREB protein levels. A series of miRNAs that target CREB were identified. Real-time quantitative PCR revealed that miR-34b was expressed significantly less in myeloid cell lines, previously known for high CREB protein levels. Exogenous miR-34b expression was induced, and results revealed a direct interaction with the CREB 3'-untranslated region, with the consequent reduction of the CREB protein levels in vitro. miR-34b restored expression caused cell cycle abnormalities, reduced anchorage-independent growth, and altered CREB target gene expression, suggesting its suppressor potential. Using reverse-phase protein array, CREB target proteins (BCL-2, cyclin A1, cyclin B1, cyclin D, nuclear factor-kappaB, Janus-activated kinase 1, and signal transducer and activator of transcription 3), as well as many downstream protein kinases and cell survival signaling pathways (AKT/mammalian target of rapamycin and extracellular signal-regulated kinase) usually elicited by CREB, were observed to have decreased. The miR-34b/miR-34c promoter was shown to be methylated in the leukemia cell lines used. This epigenetic regulation should control the observed miR-34b expression levels to maintain the CREB protein overexpressed. In addition, the inverse correlation between miR-34b and CREB expression was found in a cohort of 78 pediatric patients at diagnosis of acute myeloid leukemia, supporting this relationship in vivo. Our results identify a direct miR-34b target gene, provide a possible mechanism for CREB overexpression, and provide new information about myeloid transformation and therapeutic strategies.
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PMID:miR-34b targets cyclic AMP-responsive element binding protein in acute myeloid leukemia. 1925 99

The PI3/AKT pathway is up-regulated in acute myeloid leukemia (AML), but its prognostic relevance in cytogenetically normal AML (CN-AML) is unclear. We evaluated RNA levels of AKT and two downstream substrates (FOXO3a-p27) in 110 de novo CN-AML, included in the Spanish PETHEMA therapeutic protocols. Patients with high FOXO3a gene expression displayed shorter OS (p=0.015) and RFS (p=0.048) than low FOXO3a expressers. Features selected in the multivariate analysis as having an independent prognostic value for a shorter survival were WBC>50x10(9)/L, age >65 years and high FOXO3a expression. We concluded that FOXO3a assessment could contribute to improve the molecular-based risk stratification in CN-AML.
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PMID:High FOXO3a expression is associated with a poorer prognosis in AML with normal cytogenetics. 1945 52

The PI3K/AKT and mTOR signaling pathways are activated in acute myeloid leukemia, including in the more immature leukemic populations. Constitutive PI3K activation is detectable in 50% of acute myeloid leukemia samples whereas mTORC1 is activated in all cases of this disease. In leukemic cells, the PI3K activity relates to the expression of the p110delta isoform of class IA PI3K. Constitutive PI3K activation is the result of autocrine IGF-1/IGF-1R signaling in 70% of acute myeloid leukemia samples but specific inhibition of this pathway does not induce apoptosis. Specific inhibition of PI3K/AKT or mTORC1 alone in vitro has anti-leukemic effects which are essentially exerted via the suppression of proliferation. However, as mTORC1 activation is independent of PI3K/AKT in acute myeloid leukemia, dual PI3K and mTOR inhibitors may induce apoptosis in blast cells. Moreover, mTORC1 inhibition using sirolimus overactivates PI3K/AKT via the upregulation of IRS2 expression and by favoring IGF-1/IGF-1R autocrine signaling. Recent data also indicate that mTORC1 does not control protein translation in acute myeloid leukemia. These results open the way for the design of direct inhibitors of protein synthesis as novel acute myeloid leukemia therapies and also for the development of second generation mTOR inhibitors (the TORKinhibs).
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PMID:Role of the PI3K/AKT and mTOR signaling pathways in acute myeloid leukemia. 1995 71

Human cancers, including acute myeloid leukemia (AML), commonly display constitutive phosphoinositide 3-kinase (PI3K) AKT signaling. However, the exact role of AKT activation in leukemia and its effects on hematopoietic stem cells (HSCs) are poorly understood. Several members of the PI3K pathway, phosphatase and tensin homolog (Pten), the forkhead box, subgroup O (FOXO) transcription factors, and TSC1, have demonstrated functions in normal and leukemic stem cells but are rarely mutated in leukemia. We developed an activated allele of AKT1 that models increased signaling in normal and leukemic stem cells. In our murine bone marrow transplantation model using a myristoylated AKT1 (myr-AKT), recipients develop myeloproliferative disease, T-cell lymphoma, or AML. Analysis of the HSCs in myr-AKT mice reveals transient expansion and increased cycling, associated with impaired engraftment. myr-AKT-expressing bone marrow cells are unable to form cobblestones in long-term cocultures. Rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR) rescues cobblestone formation in myr-AKT-expressing bone marrow cells and increases the survival of myr-AKT mice. This study demonstrates that enhanced AKT activation is an important mechanism of transformation in AML and that HSCs are highly sensitive to excess AKT/mTOR signaling.
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PMID:Constitutively active AKT depletes hematopoietic stem cells and induces leukemia in mice. 2000 87

Both arsenic trioxide (ATO) and bortezomib show separate antileukemic activity. With the purpose of evaluating whether the combination of ATO and bortezomib would be an option for patients with acute leukemia, we incubated HL60 leukemic cells with ATO alone and in combination with bortezomib. ATO and bortezomib cooperated to induce cell death and to inhibit proliferation and apoptosis in a synergistic way. The combined treatment resulted in a stronger activation of caspase 8 and 9, moderate activation of caspase 3, and increased expression of Fas and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-DR5 receptors. When bortezomib was added, some proapoptotic genes (CARD9, TRAIL) were upregulated, and some antiapoptotic genes (BCL2, BCL3, FLICE) were downregulated. When coincubated, approximately 80% of cells showed altered mitochondrial membrane permeability. Moreover, ATO alone and in combination with bortezomib abrogated DNA-binding activity of nuclear factor kappa beta (NF-kappaB). Gene expression assays showed that more deregulated genes were related to proliferation of leukocytes, tumorigenesis, control of cell cycle, hypoxia and oxidative stress, cytokines, PI3K-AKT, ERK-MAPK, EGF pathways, and ubiquitination. Finally, in three cases of acute myeloid leukemia, the addition of bortezomib to ATO significantly increased cytotoxicity. We conclude that the combination of bortezomib and ATO may be efficacious in the treatment of myeloid disorders.
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PMID:Synergistic antiproliferative effect of arsenic trioxide combined with bortezomib in HL60 cell line and primary blasts from patients affected by myeloproliferative disorders. 2047 14


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