RESUMEN
Targeting subunits of BAF/PBAF chromatin remodeling complexes has been proposed as an approach to exploit cancer vulnerabilities. Here, we develop proteolysis targeting chimera (PROTAC) degraders of the BAF ATPase subunits SMARCA2 and SMARCA4 using a bromodomain ligand and recruitment of the E3 ubiquitin ligase VHL. High-resolution ternary complex crystal structures and biophysical investigation guided rational and efficient optimization toward ACBI1, a potent and cooperative degrader of SMARCA2, SMARCA4 and PBRM1. ACBI1 induced anti-proliferative effects and cell death caused by SMARCA2 depletion in SMARCA4 mutant cancer cells, and in acute myeloid leukemia cells dependent on SMARCA4 ATPase activity. These findings exemplify a successful biophysics- and structure-based PROTAC design approach to degrade high profile drug targets, and pave the way toward new therapeutics for the treatment of tumors sensitive to the loss of BAF complex ATPases.
Asunto(s)
Ensamble y Desensamble de Cromatina/genética , Proteínas de Unión al ADN/genética , Leucemia Mieloide Aguda/genética , Proteínas Nucleares/genética , Proliferación Celular , Células Cultivadas , Proteínas de Unión al ADN/metabolismo , Humanos , Leucemia Mieloide Aguda/metabolismo , Estructura Molecular , Proteínas Nucleares/metabolismoRESUMEN
In the version of this article originally published, several lines of text in the last paragraph of the right column on page 1 of the PDF were transposed into the bottom paragraph of the left column. The affected text of the left column should read "The ATP-dependent activities of the BAF (SWI/SNF) chromatin remodeling complexes affect the positioning of nucleosomes on DNA and thereby many cellular processes related to chromatin structure, including transcription, DNA repair and decatenation of chromosomes during mitosis12,13." The affected text of the right column should read "SMARCA2/4BD inhibitors are thus precluded from use for the treatment of SMARCA4 mutant cancers but could provide attractive ligands for PROTAC conjugation. Small molecules binding to other bromodomains have been successfully converted into PROTACs by conjugating them with structures capable of binding to the E3 ligases von Hippel-Lindau (VHL) or cereblon5,6,10,11,25,26,27." The errors have been corrected in the PDF version of the paper.
RESUMEN
Site-selective ruthenium(II)-catalyzed direct arylation of amides was achieved through CH cleavages with modular auxiliaries, derived from easily accessible 1,2,3-triazoles. The triazolyldimethylmethyl (TAM) bidentate directing group was prepared in a highly modular fashion through copper(I)-catalyzed 1,3-dipolar cycloaddition and allowed for ruthenium-catalyzed CH arylations on arenes and heteroarenes, as well as alkenes, by using easy-to-handle aryl bromides as the arylating reagents. The triazole-assisted CH activation strategy was found to be widely applicable, to occur under mild reaction conditions, and the catalytic system was tolerant of important electrophilic functionalities. Notably, the flexible triazole-based auxiliary proved to be a more potent directing group for the optimized ruthenium(II)-catalyzed direct arylations, compared with pyridyl-substituted amides or substrates derived from 8-aminoquinoline.
RESUMEN
Modular 1,2,3-triazoles enabled iron-catalyzed CH arylations with broad scope. The novel triazole-based bidentate auxiliary is easily accessible in a highly modular fashion and allowed for user-friendly iron-catalyzed C(sp(2) )H functionalizations of arenes and alkenes with excellent chemo- and diastereoselectivities. The versatile iron catalyst also proved applicable for challenging C(sp(3) )H functionalizations, and proceeds by an organometallic mode of action. The triazole-assisted CH activation strategy occurred under remarkably mild reaction conditions, and the auxiliary was easily removed in a traceless fashion. Intriguingly, the triazole group proved superior to previously used auxiliaries.
Asunto(s)
Hierro/química , Triazoles/química , CatálisisRESUMEN
Targeted protein degradation has recently emerged as a novel option in drug discovery. Natural protein half-life is expected to affect the efficacy of degrading agents, but to what extent it influences target protein degradation has not been systematically explored. Using simple mathematical modeling of protein degradation, we find that the natural half-life of a target protein has a dramatic effect on the level of protein degradation induced by a degrader agent which can pose significant hurdles to screening efforts. Moreover, we show that upon screening for degraders of short-lived proteins, agents that stall protein synthesis, such as GSPT1 degraders and generally cytotoxic compounds, deceptively appear as protein-degrading agents. This is exemplified by the disappearance of short-lived proteins such as MCL1 and MDM2 upon GSPT1 degradation and upon treatment with cytotoxic agents such as doxorubicin. These findings have implications for target selection as well as for the type of control experiments required to conclude that a novel agent works as a bona fide targeted protein degrader.
Asunto(s)
Proteolisis , Humanos , Proteínas Proto-Oncogénicas c-mdm2/metabolismo , Semivida , Doxorrubicina/farmacología , Doxorrubicina/metabolismo , Proteína 1 de la Secuencia de Leucemia de Células Mieloides/metabolismo , Proteínas/metabolismo , Proteínas/químicaRESUMEN
Targeted protein degradation offers an alternative modality to classical inhibition and holds the promise of addressing previously undruggable targets to provide novel therapeutic options for patients. Heterobifunctional molecules co-recruit a target protein and an E3 ligase, resulting in ubiquitylation and proteosome-dependent degradation of the target. In the clinic, the oral route of administration is the option of choice but has only been achieved so far by CRBN- recruiting bifunctional degrader molecules. We aimed to achieve orally bioavailable molecules that selectively degrade the BAF Chromatin Remodelling complex ATPase SMARCA2 over its closely related paralogue SMARCA4, to allow in vivo evaluation of the synthetic lethality concept of SMARCA2 dependency in SMARCA4-deficient cancers. Here we outline structure- and property-guided approaches that led to orally bioavailable VHL-recruiting degraders. Our tool compound, ACBI2, shows selective degradation of SMARCA2 over SMARCA4 in ex vivo human whole blood assays and in vivo efficacy in SMARCA4-deficient cancer models. This study demonstrates the feasibility for broadening the E3 ligase and physicochemical space that can be utilised for achieving oral efficacy with bifunctional molecules.
Asunto(s)
Adenosina Trifosfatasas , Factores de Transcripción , Adenosina Trifosfatasas/genética , Adenosina Trifosfatasas/metabolismo , ADN Helicasas/genética , ADN Helicasas/metabolismo , Humanos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteolisis , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismo , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/genética , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/metabolismoRESUMEN
Receptor type protein tyrosine phosphatase-sigma (PTPσ) is primarily expressed by adult neurons and regulates neural regeneration. We recently discovered that PTPσ is also expressed by hematopoietic stem cells (HSCs). Here, we describe small molecule inhibitors of PTPσ that promote HSC regeneration in vivo. Systemic administration of the PTPσ inhibitor, DJ001, or its analog, to irradiated mice promotes HSC regeneration, accelerates hematologic recovery, and improves survival. Similarly, DJ001 administration accelerates hematologic recovery in mice treated with 5-fluorouracil chemotherapy. DJ001 displays high specificity for PTPσ and antagonizes PTPσ via unique non-competitive, allosteric binding. Mechanistically, DJ001 suppresses radiation-induced HSC apoptosis via activation of the RhoGTPase, RAC1, and induction of BCL-XL. Furthermore, treatment of irradiated human HSCs with DJ001 promotes the regeneration of human HSCs capable of multilineage in vivo repopulation. These studies demonstrate the therapeutic potential of selective, small-molecule PTPσ inhibitors for human hematopoietic regeneration.
Asunto(s)
Apoptosis/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Células Madre Hematopoyéticas/efectos de los fármacos , Proteínas Tirosina Fosfatasas Clase 2 Similares a Receptores/antagonistas & inhibidores , Regeneración/efectos de los fármacos , Regulación Alostérica , Animales , Antimetabolitos Antineoplásicos/farmacología , Apoptosis/efectos de la radiación , Fluorouracilo/farmacología , Células Madre Hematopoyéticas/efectos de la radiación , Humanos , Ratones , Radiación , Regeneración/efectos de la radiación , Proteína bcl-X/efectos de los fármacos , Proteína bcl-X/metabolismo , Proteína de Unión al GTP rac1/efectos de los fármacos , Proteína de Unión al GTP rac1/metabolismo , Proteínas de Unión al GTP rho/efectos de los fármacos , Proteínas de Unión al GTP rho/metabolismoRESUMEN
Ruthenium-catalyzed direct arylations of phenols bearing removable directing groups were accomplished through carboxylate assistance via six-membered ruthenacycles as key intermediates.