Abstract
Fanconi anemia, complementation group C (FANCC)-deficient hematopoietic stem and progenitor cells are hypersensitive to a variety of inhibitory cytokines, one of which, TNFα, can induce BM failure and clonal evolution in Fancc-deficient mice. FANCC-deficient macrophages are also hypersensitive to TLR activation and produce TNFα in an unrestrained fashion. Reasoning that suppression of inhibitory cytokine production might enhance hematopoiesis, we screened small molecules using TLR agonist-stimulated FANCC- and Fanconi anemia, complementation group A (FANCA)-deficient macrophages containing an NF-κB/AP-1-responsive reporter gene (SEAP). Of the 75 small molecules screened, the p38 MAPK inhibitor BIRB 796 and dasatinib potently suppressed TLR8-dependent expression of the reporter gene. Fanconi anemia (FA) macrophages were hypersensitive to the TLR7/8 activator R848, overproducing SEAP and TNFα in response to all doses of the agonist. Low doses (50nM) of both agents inhibited p38 MAPK-dependent activation of MAPKAPK2 (MK2) and suppressed MK2-dependent TNFα production without substantially influencing TNFα gene transcription. Overproduction of TNFα by primary FA cells was likewise suppressed by these agents and involved inhibition of MK2 activation. Because MK2 is also known to influence production and/or sensitivity to 2 other suppressive factors (MIP-1α and IFNγ) to which FA hematopoietic progenitor cells are uniquely vulnerable, targeting of p38 MAPK in FA hematopoietic cells is a rational objective for preclinical evaluation.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Animals
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Cell Line
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Dasatinib
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Disease Models, Animal
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Enzyme Activation / drug effects
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Fanconi Anemia / genetics
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Fanconi Anemia / metabolism
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Fanconi Anemia Complementation Group A Protein / deficiency*
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Fanconi Anemia Complementation Group C Protein / deficiency*
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Gene Expression Regulation / drug effects
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Gene Knockout Techniques
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Humans
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Macrophages / drug effects
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Macrophages / metabolism
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Matrix Metalloproteinases / metabolism
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Mice
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Mice, Knockout
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Naphthalenes / pharmacology
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Phagocytes / drug effects
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Phagocytes / enzymology
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Phagocytes / metabolism*
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Phenotype
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Protein Kinase Inhibitors / pharmacology*
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Proto-Oncogene Proteins c-jun / metabolism
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Pyrazoles / pharmacology
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Pyrimidines / pharmacology
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RNA Processing, Post-Transcriptional / drug effects
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Small Molecule Libraries
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Thiazoles / pharmacology
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Toll-Like Receptors / metabolism*
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Transcription, Genetic / drug effects
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Tumor Necrosis Factor-alpha / antagonists & inhibitors
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Tumor Necrosis Factor-alpha / genetics
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p38 Mitogen-Activated Protein Kinases / antagonists & inhibitors*
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src-Family Kinases / antagonists & inhibitors
Substances
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Fanconi Anemia Complementation Group A Protein
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Fanconi Anemia Complementation Group C Protein
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Naphthalenes
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Protein Kinase Inhibitors
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Proto-Oncogene Proteins c-jun
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Pyrazoles
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Pyrimidines
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Small Molecule Libraries
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Thiazoles
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Toll-Like Receptors
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Tumor Necrosis Factor-alpha
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src-Family Kinases
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p38 Mitogen-Activated Protein Kinases
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Matrix Metalloproteinases
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doramapimod
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Dasatinib