RESUMO
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.
Assuntos
Ácidos Aminossalicílicos/farmacologia , Proteínas de Fusão bcr-abl/genética , Regulação Leucêmica da Expressão Gênica , Leucócitos Mononucleares/efeitos dos fármacos , Células-Tronco Neoplásicas/efeitos dos fármacos , Fator de Transcrição STAT3/genética , Bibliotecas de Moléculas Pequenas/farmacologia , Sulfonamidas/farmacologia , Ácidos Aminossalicílicos/síntese química , Ácidos Aminossalicílicos/química , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Benzamidas/farmacologia , Linhagem Celular Tumoral , Dasatinibe , Descoberta de Drogas , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Proteínas de Fusão bcr-abl/antagonistas & inibidores , Proteínas de Fusão bcr-abl/metabolismo , Genes Reporter , Humanos , Mesilato de Imatinib , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Leucócitos Mononucleares/metabolismo , Leucócitos Mononucleares/patologia , Luciferases/genética , Luciferases/metabolismo , Simulação de Acoplamento Molecular , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Fosforilação , Piperazinas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Estrutura Terciária de Proteína , Pirimidinas/farmacologia , Fator de Transcrição STAT3/antagonistas & inibidores , Fator de Transcrição STAT3/química , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais , Bibliotecas de Moléculas Pequenas/síntese química , Bibliotecas de Moléculas Pequenas/química , Sulfonamidas/síntese química , Sulfonamidas/química , Tiazóis/farmacologiaRESUMO
We herein report the design and synthesis of the first nanomolar binding inhibitor of STAT5 protein. Lead compound 13a, possessing a phosphotyrosyl-mimicking salicylic acid group, potently and selectively binds to STAT5 over STAT3, inhibits STAT5-SH2 domain complexation events in vitro, silences activated STAT5 in leukemic cells, as well as STAT5's downstream transcriptional targets, including MYC and MCL1, and, as a result, leads to apoptosis. We believe 13a represents a useful probe for interrogating STAT5 function in cells as well as being a potential candidate for advanced preclinical trials.