Abstract
Mutations in the BCR-ABL1 kinase domain are an established mechanism of tyrosine kinase inhibitor (TKI) resistance in Philadelphia chromosome-positive leukemia, but fail to explain many cases of clinical TKI failure. In contrast, it is largely unknown why some patients fail TKI therapy despite continued suppression of BCR-ABL1 kinase activity, a situation termed BCR-ABL1 kinase-independent TKI resistance. Here, we identified activation of signal transducer and activator of transcription 3 (STAT3) by extrinsic or intrinsic mechanisms as an essential feature of BCR-ABL1 kinase-independent TKI resistance. By combining synthetic chemistry, in vitro reporter assays, and molecular dynamics-guided rational inhibitor design and high-throughput screening, we discovered BP-5-087, a potent and selective STAT3 SH2 domain inhibitor that reduces STAT3 phosphorylation and nuclear transactivation. Computational simulations, fluorescence polarization assays and hydrogen-deuterium exchange assays establish direct engagement of STAT3 by BP-5-087 and provide a high-resolution view of the STAT3 SH2 domain/BP-5-087 interface. In primary cells from chronic myeloid leukemia (CML) patients with BCR-ABL1 kinase-independent TKI resistance, BP-5-087 (1.0 μM) restored TKI sensitivity to therapy-resistant CML progenitor cells, including leukemic stem cells. Our findings implicate STAT3 as a critical signaling node in BCR-ABL1 kinase-independent TKI resistance, and suggest that BP-5-087 has clinical utility for treating malignancies characterized by STAT3 activation.
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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Aminosalicylic Acids / chemical synthesis
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Aminosalicylic Acids / chemistry
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Aminosalicylic Acids / pharmacology*
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Antineoplastic Agents / pharmacology
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Apoptosis / drug effects
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Benzamides / pharmacology
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Cell Line, Tumor
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Dasatinib
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Drug Discovery
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Drug Resistance, Neoplasm / drug effects
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Fusion Proteins, bcr-abl / antagonists & inhibitors
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Fusion Proteins, bcr-abl / genetics*
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Fusion Proteins, bcr-abl / metabolism
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Gene Expression Regulation, Leukemic*
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Genes, Reporter
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Humans
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Imatinib Mesylate
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / drug therapy
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / genetics
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / metabolism
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Leukemia, Myelogenous, Chronic, BCR-ABL Positive / pathology
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Leukocytes, Mononuclear / drug effects*
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Leukocytes, Mononuclear / metabolism
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Leukocytes, Mononuclear / pathology
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Luciferases / genetics
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Luciferases / metabolism
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Molecular Docking Simulation
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Neoplastic Stem Cells / drug effects*
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Neoplastic Stem Cells / metabolism
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Neoplastic Stem Cells / pathology
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Phosphorylation
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Piperazines / pharmacology
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Protein Kinase Inhibitors / pharmacology
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Protein Structure, Tertiary
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Pyrimidines / pharmacology
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STAT3 Transcription Factor / antagonists & inhibitors
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STAT3 Transcription Factor / chemistry
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STAT3 Transcription Factor / genetics*
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STAT3 Transcription Factor / metabolism
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Signal Transduction
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Small Molecule Libraries / chemical synthesis
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Small Molecule Libraries / chemistry
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Small Molecule Libraries / pharmacology*
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Sulfonamides / chemical synthesis
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Sulfonamides / chemistry
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Sulfonamides / pharmacology*
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Thiazoles / pharmacology
Substances
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Aminosalicylic Acids
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Antineoplastic Agents
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BCR-ABL1 fusion protein, human
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BP-5-087
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Benzamides
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Piperazines
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Protein Kinase Inhibitors
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Pyrimidines
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STAT3 Transcription Factor
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STAT3 protein, human
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Small Molecule Libraries
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Sulfonamides
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Thiazoles
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Imatinib Mesylate
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Luciferases
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Fusion Proteins, bcr-abl
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nilotinib
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Dasatinib