Abstract
Presence of the activating length mutation (LM) in the juxtamembrane domain or point mutation in the kinase domain of FMS-like tyrosine kinase-3 (FLT-3) mediates ligand-independent progrowth and prosurvival signaling in approximately one-third of acute myelogenous leukemia (AML). PKC412, an inhibitor of FLT-3 kinase activity, is being clinically evaluated in AML. Present studies demonstrate that treatment of human acute leukemia MV4-11 cells (containing a FLT-3 LM) with the heat shock protein 90 inhibitor 17-allylamino-demethoxy geldanamycin (17-AAG) attenuated the levels of FLT-3 by inhibiting its chaperone association with heat shock protein 90, which induced the poly-ubiquitylation and proteasomal degradation of FLT-3. Treatment with 17-AAG induced cell cycle G(1) phase accumulation and apoptosis of MV4-11 cells. 17-AAG-mediated attenuation of FLT-3 and p-FLT-3 in MV4-11 cells was associated with decrease in the levels of p-AKT, p-ERK1/2, and p-STAT5, as well as attenuation of the DNA binding activity of STAT-5. Treatment with 17-AAG, downstream of STAT5, reduced the levels of c-Myc and oncostatin M, which are transactivated by STAT5. Cotreatment with 17-AAG and PKC412 markedly down-regulated the levels of FLT-3, p-FLT-3, p-AKT, p-ERK1/2, and p-STAT5, as well as induced more apoptosis of MV4-11 cells than either agent alone. Furthermore, the combination of 17-AAG and PKC412 exerted synergistic cytotoxic effects against MV4-11 cells. Importantly, 17-AAG and PKC412 induced more loss of cell viability of primary AML blasts containing FLT-3 LM, as compared with those that contained wild-type FLT-3. Collectively, these in vitro findings indicate that the combination of 17-AAG and PKC412 has high level of activity against AML cells with FLT-3 mutations.
MeSH terms
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Antineoplastic Combined Chemotherapy Protocols / pharmacology*
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Apoptosis / drug effects
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Benzoquinones
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Cysteine Endopeptidases / metabolism
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DNA, Neoplasm / metabolism
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DNA-Binding Proteins / metabolism
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Drug Synergism
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Enzyme Inhibitors / administration & dosage
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Enzyme Inhibitors / pharmacology
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G1 Phase / drug effects
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HSP90 Heat-Shock Proteins / metabolism
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Humans
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Lactams, Macrocyclic
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Leukemia, Myeloid, Acute / drug therapy*
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Leukemia, Myeloid, Acute / enzymology
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Leukemia, Myeloid, Acute / genetics
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Leukemia, Myeloid, Acute / pathology
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Milk Proteins*
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Mitogen-Activated Protein Kinase 1 / metabolism
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinases / metabolism
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Multienzyme Complexes / metabolism
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Proteasome Endopeptidase Complex
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Protein Serine-Threonine Kinases / metabolism
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Proto-Oncogene Proteins / genetics*
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins c-akt
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Receptor Protein-Tyrosine Kinases / genetics*
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Receptor Protein-Tyrosine Kinases / metabolism
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Rifabutin / administration & dosage
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Rifabutin / analogs & derivatives*
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Rifabutin / pharmacology*
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STAT5 Transcription Factor
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Signal Transduction / drug effects
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Staurosporine / administration & dosage
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Staurosporine / analogs & derivatives*
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Staurosporine / pharmacology*
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Trans-Activators / metabolism
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Ubiquitin / metabolism
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fms-Like Tyrosine Kinase 3
Substances
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Benzoquinones
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DNA, Neoplasm
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DNA-Binding Proteins
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Enzyme Inhibitors
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HSP90 Heat-Shock Proteins
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Lactams, Macrocyclic
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Milk Proteins
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Multienzyme Complexes
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Proto-Oncogene Proteins
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STAT5 Transcription Factor
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Trans-Activators
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Ubiquitin
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Rifabutin
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tanespimycin
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FLT3 protein, human
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Receptor Protein-Tyrosine Kinases
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fms-Like Tyrosine Kinase 3
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AKT1 protein, human
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Protein Serine-Threonine Kinases
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Proto-Oncogene Proteins c-akt
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Mitogen-Activated Protein Kinase 1
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinases
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Cysteine Endopeptidases
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Proteasome Endopeptidase Complex
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Staurosporine
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midostaurin