RESUMEN
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.
Asunto(s)
Ácidos Aminosalicílicos/farmacología , Proteínas de Fusión bcr-abl/genética , Regulación Leucémica de la Expresión Génica , Leucocitos Mononucleares/efectos de los fármacos , Células Madre Neoplásicas/efectos de los fármacos , Factor de Transcripción STAT3/genética , Bibliotecas de Moléculas Pequeñas/farmacología , Sulfonamidas/farmacología , Ácidos Aminosalicílicos/síntesis química , Ácidos Aminosalicílicos/química , Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Benzamidas/farmacología , Línea Celular Tumoral , Dasatinib , Descubrimiento de Drogas , Resistencia a Antineoplásicos/efectos de los fármacos , Proteínas de Fusión bcr-abl/antagonistas & inhibidores , Proteínas de Fusión bcr-abl/metabolismo , Genes Reporteros , Humanos , Mesilato de Imatinib , Leucemia Mielógena Crónica BCR-ABL Positiva/tratamiento farmacológico , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/metabolismo , Leucemia Mielógena Crónica BCR-ABL Positiva/patología , Leucocitos Mononucleares/metabolismo , Leucocitos Mononucleares/patología , Luciferasas/genética , Luciferasas/metabolismo , Simulación del Acoplamiento Molecular , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Fosforilación , Piperazinas/farmacología , Inhibidores de Proteínas Quinasas/farmacología , Estructura Terciaria de Proteína , Pirimidinas/farmacología , Factor de Transcripción STAT3/antagonistas & inhibidores , Factor de Transcripción STAT3/química , Factor de Transcripción STAT3/metabolismo , Transducción de Señal , Bibliotecas de Moléculas Pequeñas/síntesis química , Bibliotecas de Moléculas Pequeñas/química , Sulfonamidas/síntesis química , Sulfonamidas/química , Tiazoles/farmacologíaRESUMEN
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.
