RESUMO
Transcriptional deregulation is a hallmark of many cancers and is exemplified by genomic amplifications of the MYC family of oncogenes, which occur in at least 20% of all solid tumors in adults. Targeting of transcriptional cofactors and the transcriptional cyclin-dependent kinase (CDK9) has emerged as a therapeutic strategy to interdict deregulated transcriptional activity including oncogenic MYC. Here, we report the structural optimization of a small molecule microarray hit, prioritizing maintenance of CDK9 selectivity while improving on-target potency and overall physicochemical and pharmacokinetic (PK) properties. This led to the discovery of the potent, selective, orally bioavailable CDK9 inhibitor 28 (KB-0742). Compound 28 exhibits in vivo antitumor activity in mouse xenograft models and a projected human PK profile anticipated to enable efficacious oral dosing. Notably, 28 is currently being investigated in a phase 1/2 dose escalation and expansion clinical trial in patients with relapsed or refractory solid tumors.
Assuntos
Antineoplásicos , Neoplasias , Adulto , Humanos , Animais , Camundongos , Quinases Ciclina-Dependentes , Linhagem Celular Tumoral , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Antineoplásicos/química , Apoptose , Pontos de Checagem do Ciclo Celular , Modelos Animais de Doenças , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Inibidores de Proteínas Quinases/química , Quinase 9 Dependente de Ciclina , Neoplasias/tratamento farmacológicoRESUMO
Castration-resistant prostate cancers (CRPCs) lose sensitivity to androgen-deprivation therapies but frequently remain dependent on oncogenic transcription driven by the androgen receptor (AR) and its splice variants. To discover modulators of AR-variant activity, we used a lysate-based small-molecule microarray assay and identified KI-ARv-03 as an AR-variant complex binder that reduces AR-driven transcription and proliferation in prostate cancer cells. We deduced KI-ARv-03 to be a potent, selective inhibitor of CDK9, an important cofactor for AR, MYC, and other oncogenic transcription factors. Further optimization resulted in KB-0742, an orally bioavailable, selective CDK9 inhibitor with potent anti-tumor activity in CRPC models. In 22Rv1 cells, KB-0742 rapidly downregulates nascent transcription, preferentially depleting short half-life transcripts and AR-driven oncogenic programs. In vivo, oral administration of KB-0742 significantly reduced tumor growth in CRPC, supporting CDK9 inhibition as a promising therapeutic strategy to target AR dependence in CRPC.
Assuntos
Antagonistas de Receptores de Andrógenos/farmacologia , Quinase 9 Dependente de Ciclina/antagonistas & inibidores , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Inibidores de Proteínas Quinases/farmacologia , Receptores Androgênicos/genética , Transcrição Gênica/efeitos dos fármacos , Antagonistas de Receptores de Andrógenos/uso terapêutico , Animais , Linhagem Celular Tumoral , Quinase 9 Dependente de Ciclina/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Modelos Moleculares , Neoplasias de Próstata Resistentes à Castração/genética , Inibidores de Proteínas Quinases/uso terapêuticoRESUMO
The transcription factor Max is a basic-helix-loop-helix leucine zipper (bHLHLZ) protein that forms homodimers or interacts with other bHLHLZ proteins, including Myc and Mxd proteins. Among this dynamic network of interactions, the Myc/Max heterodimer has crucial roles in regulating normal cellular processes, but its transcriptional activity is deregulated in a majority of human cancers. Despite this significance, the arsenal of high-quality chemical probes to interrogate these proteins remains limited. We used small molecule microarrays to identify compounds that bind Max in a mechanistically unbiased manner. We discovered the asymmetric polycyclic lactam, KI-MS2-008, which stabilizes the Max homodimer while reducing Myc protein and Myc-regulated transcript levels. KI-MS2-008 also decreases viable cancer cell growth in a Myc-dependent manner and suppresses tumor growth in vivo. This approach demonstrates the feasibility of modulating Max with small molecules and supports altering Max dimerization as an alternative approach to targeting Myc.
Assuntos
Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/metabolismo , Lactamas/farmacologia , Compostos Policíclicos/farmacologia , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Repressoras/metabolismo , Bibliotecas de Moléculas Pequenas/farmacologia , Transcrição Gênica/efeitos dos fármacos , Animais , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/química , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Linhagem Celular , Dimerização , Modelos Animais de Doenças , Humanos , Lactamas/síntese química , Lactamas/uso terapêutico , Masculino , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Neoplasias/tratamento farmacológico , Compostos Policíclicos/síntese química , Compostos Policíclicos/uso terapêutico , Regiões Promotoras Genéticas , Ligação Proteica , Proteínas Proto-Oncogênicas c-myc/metabolismo , Ratos , Proteínas Repressoras/química , Proteínas Repressoras/genética , Bibliotecas de Moléculas Pequenas/uso terapêutico , Raios UltravioletaRESUMO
Unbiased binding assays involving small-molecule microarrays were used to identify compounds that display unique patterns of selectivity among members of the zinc-dependent histone deacetylase family of enzymes. A novel, hydroxyquinoline-containing compound, BRD4354, was shown to preferentially inhibit activity of HDAC5 and HDAC9 in vitro. Inhibition of deacetylase activity appears to be time-dependent and reversible. Mechanistic studies suggest that the compound undergoes zinc-catalyzed decomposition to an ortho-quinone methide, which covalently modifies nucleophilic cysteines within the proteins. The covalent nature of the compound-enzyme interaction has been demonstrated in experiments with biotinylated probe compound and with electrospray ionization-mass spectrometry.
Assuntos
Inibidores de Histona Desacetilases/farmacologia , Histona Desacetilases/metabolismo , Animais , Linhagem Celular , HumanosRESUMO
High throughput screening (HTS) has historically been used for drug discovery almost exclusively by the pharmaceutical industry. Due to a significant decrease in costs associated with establishing a high throughput facility and an exponential interest in discovering probes of development and disease associated biomolecules, HTS core facilities have become an integral part of most academic and non-profit research institutions over the past decade. This major shift has led to the development of new HTS methodologies extending beyond the capabilities and target classes used in classical drug discovery approaches such as traditional enzymatic activity-based screens. In this brief review we describe some of the most interesting developments in HTS technologies and methods for chemical probe discovery.
Assuntos
Descoberta de Drogas/métodos , Sondas Moleculares/química , Proteínas/química , Proteínas/metabolismo , Bibliotecas de Moléculas Pequenas/química , Humanos , FenótipoRESUMO
The technique of small-molecule microarray (SMM) screening is based on the ability of small molecules to bind to various soluble proteins. This type of interaction is easily detected by the presence of a fluorescence signal produced by labeled antibodies that specifically recognize a unique sequence (tag) present on the target protein. The fluorescent signal intensity values are determined based on signal-to-noise ratios (SNRs). SMM screening is a high-throughput, unbiased method that can rapidly identify novel direct ligands for various protein targets. This binding-based assay format is generally applicable to most proteins, but it is especially useful for protein targets that do not possess an enzymatic activity. SMMs enable screening a protein in a purified form or in the context of a cellular lysate, likely providing a more physiologically relevant screening environment.
Assuntos
Extratos Celulares/química , Proteínas/química , Bibliotecas de Moléculas Pequenas/química , Imunofluorescência/métodos , Humanos , Ligantes , Análise Serial de Proteínas/métodos , Ligação Proteica , Proteínas/isolamento & purificaçãoRESUMO
Members of the ETS transcription factor family have been implicated in several cancers, where they are often dysregulated by genomic derangement. ETS variant 1 (ETV1) is an ETS factor gene that undergoes chromosomal translocation in prostate cancers and Ewing sarcomas, amplification in melanomas, and lineage dysregulation in gastrointestinal stromal tumors. Pharmacologic perturbation of ETV1 would be appealing in these cancers; however, oncogenic transcription factors are often deemed "undruggable" by conventional methods. Here, we used small-molecule microarray screens to identify and characterize drug-like compounds that modulate the biologic function of ETV1. We identified the 1,3,5-triazine small molecule BRD32048 as a top candidate ETV1 perturbagen. BRD32048 binds ETV1 directly, modulating both ETV1-mediated transcriptional activity and invasion of ETV1-driven cancer cells. Moreover, BRD32048 inhibits p300-dependent acetylation of ETV1, thereby promoting its degradation. These results point to a new avenue for pharmacologic ETV1 inhibition and may inform a general means to discover small molecule perturbagens of transcription factor oncoproteins.
Assuntos
Compostos de Anilina/administração & dosagem , Proteínas de Ligação a DNA/metabolismo , Terapia de Alvo Molecular , Neoplasias/tratamento farmacológico , Neoplasias da Próstata/tratamento farmacológico , Fatores de Transcrição/metabolismo , Triazinas/administração & dosagem , Linhagem Celular Tumoral , Proteínas de Ligação a DNA/antagonistas & inibidores , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Masculino , Neoplasias/metabolismo , Regiões Promotoras Genéticas , Neoplasias da Próstata/patologia , Bibliotecas de Moléculas Pequenas , Ressonância de Plasmônio de Superfície , Fatores de Transcrição/antagonistas & inibidoresRESUMO
p300 and CREB-binding protein (CBP) act as multifunctional regulators of p53 via acetylase and polyubiquitin ligase (E4) activities. Prior work in vitro has shown that the N-terminal 595 aa of p300 encode both generic ubiquitin ligase (E3) and p53-directed E4 functions. Analysis of p300 or CBP-deficient cells revealed that both coactivators were required for endogenous p53 polyubiquitination and the normally rapid turnover of p53 in unstressed cells. Unexpectedly, p300/CBP ubiquitin ligase activities were absent in nuclear extracts and exclusively cytoplasmic. Consistent with the cytoplasmic localization of its E3/E4 activity, CBP deficiency specifically stabilized cytoplasmic, but not nuclear p53. The N-terminal 616 aa of CBP, which includes the conserved Zn(2+)-binding C/H1-TAZ1 domain, was the minimal domain sufficient to destabilize p53 in vivo, and it included within an intrinsic E3 autoubiquitination activity and, in a two-step E4 assay, exhibited robust E4 activity for p53. Cytoplasmic compartmentalization of p300/CBP's ubiquitination function reconciles seemingly opposed functions and explains how a futile cycle is avoided-cytoplasmic p300/CBP E4 activities ubiquitinate and destabilize p53, while physically separate nuclear p300/CBP activities, such as p53 acetylation, activate p53.