Abstract
High levels of cytokines are associated with a poor prognosis in acute myeloid leukemia (AML). However, cytokines may induce, on one hand, survival factor expression and cell proliferation and, on the other hand, expression of inhibitory signals such as up-regulation of suppressors of cytokine signaling (SOCS) and induce apoptotic cell death. Because blasts from patients with AML express high procaspase protein levels, we asked whether granulocyte-macrophage colony-stimulating factor (GM-CSF) enhances procaspase protein production in AML cells. In the GM-CSF-responsive OCIM2 AML cell line, GM-CSF induced signal transducer and activator of transcription 5 (Stat 5) phosphorylation, up-regulated cyclin D2, and stimulated cell cycle progression. Concurrently, GM-CSF stimulated expression of SOCS-2 and -3 and of procaspases 2 and 3 and induced caspase 3 activation, poly(ADP[adenosine 5'-diphosphate]-ribose) polymerase (PARP) cleavage, and apoptotic cell death. The Janus kinase (Jak)-Stat inhibitor AG490 abrogated GM-CSF-induced expression of procaspase 3 and activation of caspase 3. Under the same conditions GM-CSF up-regulated production of BAX as well as Bcl-2, Bcl-XL, survivin, and XIAP. GM-CSF also increased procaspase 3 protein levels in OCI/AML3 and Mo7e cells, suggesting that this phenomenon is not restricted to a single leukemia cell line. Our data suggest that GM-CSF exerts a dual effect: it stimulates cell division but contemporaneously up-regulates Jak-Stat-dependent proapoptotic proteins. Up-regulation of procaspase levels in AML is thus a beacon for an ongoing growth-stimulatory signal.
Publication types
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Comparative Study
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Acute Disease
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Apoptosis / drug effects*
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Caspases / biosynthesis
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Caspases / genetics
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Cell Division / drug effects
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DNA-Binding Proteins*
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Enzyme Induction / drug effects
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Enzyme Inhibitors / pharmacology
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Enzyme Precursors / biosynthesis
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Enzyme Precursors / genetics
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Gene Expression Regulation, Neoplastic / drug effects
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Genes, bcl-2
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Granulocyte-Macrophage Colony-Stimulating Factor / pharmacology*
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Humans
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Inhibitor of Apoptosis Proteins
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Leukemia, Erythroblastic, Acute / pathology
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Leukemia, Myeloid / pathology*
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Microtubule-Associated Proteins / biosynthesis
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Microtubule-Associated Proteins / genetics
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Neoplasm Proteins / biosynthesis
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Neoplasm Proteins / genetics
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Poly(ADP-ribose) Polymerases / metabolism
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Protein Biosynthesis
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Proteins / genetics
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Proto-Oncogene Proteins / biosynthesis
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins c-bcl-2 / biosynthesis
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Proto-Oncogene Proteins c-bcl-2 / genetics
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Recombinant Proteins / pharmacology
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Repressor Proteins*
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Signal Transduction / drug effects
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Suppressor of Cytokine Signaling 3 Protein
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Suppressor of Cytokine Signaling Proteins
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Survivin
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Trans-Activators*
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Transcription Factors*
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Tumor Cells, Cultured / cytology
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Tumor Cells, Cultured / drug effects
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Tumor Stem Cell Assay
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Tyrphostins / pharmacology
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X-Linked Inhibitor of Apoptosis Protein
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bcl-2-Associated X Protein
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bcl-X Protein
Substances
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BAX protein, human
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BCL2L1 protein, human
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BIRC5 protein, human
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DNA-Binding Proteins
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Enzyme Inhibitors
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Enzyme Precursors
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Inhibitor of Apoptosis Proteins
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Microtubule-Associated Proteins
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Neoplasm Proteins
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Proteins
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Proto-Oncogene Proteins
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Proto-Oncogene Proteins c-bcl-2
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Recombinant Proteins
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Repressor Proteins
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SOCS2 protein, human
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SOCS3 protein, human
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Suppressor of Cytokine Signaling 3 Protein
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Suppressor of Cytokine Signaling Proteins
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Survivin
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Trans-Activators
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Transcription Factors
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Tyrphostins
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X-Linked Inhibitor of Apoptosis Protein
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XIAP protein, human
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alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide
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bcl-2-Associated X Protein
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bcl-X Protein
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Granulocyte-Macrophage Colony-Stimulating Factor
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Poly(ADP-ribose) Polymerases
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Caspases