RESUMO
TP53 (which encodes p53 protein) is the most frequently mutated gene among all human cancers. Prevalent p53 missense mutations abrogate its tumour suppressive function and lead to a 'gain-of-function' (GOF) that promotes cancer. Here we show that p53 GOF mutants bind to and upregulate chromatin regulatory genes, including the methyltransferases MLL1 (also known as KMT2A), MLL2 (also known as KMT2D), and acetyltransferase MOZ (also known as KAT6A or MYST3), resulting in genome-wide increases of histone methylation and acetylation. Analysis of The Cancer Genome Atlas shows specific upregulation of MLL1, MLL2, and MOZ in p53 GOF patient-derived tumours, but not in wild-type p53 or p53 null tumours. Cancer cell proliferation is markedly lowered by genetic knockdown of MLL1 or by pharmacological inhibition of the MLL1 methyltransferase complex. Our study reveals a novel chromatin mechanism underlying the progression of tumours with GOF p53, and suggests new possibilities for designing combinatorial chromatin-based therapies for treating individual cancers driven by prevalent GOF p53 mutations.
Assuntos
Cromatina/genética , Cromatina/metabolismo , Mutação/genética , Neoplasias/genética , Neoplasias/patologia , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Acetilação , Animais , Linhagem Celular Tumoral , Proliferação de Células/genética , Cromatina/química , Feminino , Genes Supressores de Tumor , Genoma Humano/genética , Histona Acetiltransferases/metabolismo , Histona-Lisina N-Metiltransferase/metabolismo , Histonas/química , Histonas/metabolismo , Humanos , Masculino , Camundongos , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Proteína de Leucina Linfoide-Mieloide/metabolismo , Neoplasias/metabolismo , Fenótipo , Ligação Proteica , Processamento de Proteína Pós-TraducionalRESUMO
PIK-75 is a phosphoinositide-3-kinase (PI3K) α-isoform-selective inhibitor with high potency. Although published structure-activity relationship data show the importance of the NO2 and the Br substituents in PIK-75, none of the published studies could correctly determine the underlying reason for their importance. In this publication, we report the first X-ray crystal structure of PIK-75 in complex with the kinase GSK-3ß. The structure shows an unusual U-shaped conformation of PIK-75 within the active site of GSK-3ß that is likely stabilized by an atypical intramolecular Brâ â â NO2 halogen bond. NMR and MD simulations show that this conformation presumably also exists in solution and leads to a binding-competent preorganization of the PIK-75 molecule, thus explaining its high potency. We therefore suggest that the site-specific incorporation of halogen bonds could be generally used to design conformationally restricted bioactive substances with increased potencies.
RESUMO
The CEBPA gene is mutated in 9% of patients with acute myeloid leukemia (AML). Selective expression of a short (30-kDa) CCAAT-enhancer binding protein-α (C/EBPα) translational isoform, termed p30, represents the most common type of CEBPA mutation in AML. The molecular mechanisms underlying p30-mediated transformation remain incompletely understood. We show that C/EBPα p30, but not the normal p42 isoform, preferentially interacts with Wdr5, a key component of SET/MLL (SET-domain/mixed-lineage leukemia) histone-methyltransferase complexes. Accordingly, p30-bound genomic regions were enriched for MLL-dependent H3K4me3 marks. The p30-dependent increase in self-renewal and inhibition of myeloid differentiation required Wdr5, as downregulation of the latter inhibited proliferation and restored differentiation in p30-dependent AML models. OICR-9429 is a new small-molecule antagonist of the Wdr5-MLL interaction. This compound selectively inhibited proliferation and induced differentiation in p30-expressing human AML cells. Our data reveal the mechanism of p30-dependent transformation and establish the essential p30 cofactor Wdr5 as a therapeutic target in CEBPA-mutant AML.
Assuntos
Antineoplásicos/farmacologia , Compostos de Bifenilo/farmacologia , Di-Hidropiridinas/farmacologia , Regulação Neoplásica da Expressão Gênica , Histona-Lisina N-Metiltransferase/antagonistas & inibidores , Leucemia Mieloide Aguda/metabolismo , Proteína de Leucina Linfoide-Mieloide/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/farmacologia , Sequência de Aminoácidos , Animais , Proteínas Estimuladoras de Ligação a CCAAT/genética , Proteínas Estimuladoras de Ligação a CCAAT/metabolismo , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Histona-Lisina N-Metiltransferase/genética , Histona-Lisina N-Metiltransferase/metabolismo , Histonas/genética , Histonas/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , Camundongos , Simulação de Acoplamento Molecular , Dados de Sequência Molecular , Terapia de Alvo Molecular , Mutação , Proteína de Leucina Linfoide-Mieloide/genética , Proteína de Leucina Linfoide-Mieloide/metabolismo , Ligação Proteica , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Estrutura Terciária de Proteína , Transdução de Sinais , Células Tumorais CultivadasRESUMO
The reaction of 3-halo-4-aminopyridines with acyl chlorides and triethylamine is described. The pyridin-4-yl α-substituted acetamide products were obtained in moderate to high yields. The presented rearrangement reaction, in which the presumed N-acylated intermediate reacts intramolecularly via nucleophilic aromatic substitution, results in a formal two-carbon insertion.
Assuntos
Acetamidas/síntese química , Hidrocarbonetos Clorados/química , Piridinas/química , Acetamidas/química , Cristalografia por Raios X , Etilaminas/química , Modelos Moleculares , Estrutura MolecularRESUMO
Abelson (Abl) tyrosine kinase is an important cellular enzyme that is rendered constitutively active in the breakpoint cluster region (BCR)-Abl fusion protein, contributing to several forms of leukemia. Although inhibiting BCR-Abl activity with imatinib shows great clinical success, many patients acquire secondary mutations that result in resistance to imatinib. Second-generation inhibitors such as dasatinib and nilotinib can overcome the majority of these mutations but fail to treat patients with an especially prevalent T315I mutation at the gatekeeper position of the kinase domain. However, a combination of nilotinib with an allosteric type IV inhibitor was recently shown to overcome this clinically relevant point mutation. In this study, we present the development of a direct binding assay that enables the straightforward detection of allosteric inhibitors which bind within the myristate pocket of Abl. The assay is amenable to high-throughput screening and exclusively detects the binding of ligands to this unique allosteric site.
Assuntos
Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-abl/antagonistas & inibidores , Modelos Moleculares , Estrutura Molecular , Inibidores de Proteínas Quinases/química , Proteínas Proto-Oncogênicas c-abl/metabolismo , Relação Estrutura-AtividadeRESUMO
In cancer, genetically activated proto-oncogenes often induce "upstream" dependency on the activity of the mutant oncoprotein. Therapeutic inhibition of these activated oncoproteins can induce massive apoptosis of tumor cells, leading to sometimes dramatic tumor regressions in patients. The PI3K and MAPK signaling pathways are central regulators of oncogenic transformation and tumor maintenance. We hypothesized that upstream dependency engages either one of these pathways preferentially to induce "downstream" dependency. Therefore, we analyzed whether downstream pathway dependency segregates by genetic aberrations upstream in lung cancer cell lines. Here, we show by systematically linking drug response to genomic aberrations in non-small-cell lung cancer, as well as in cell lines of other tumor types and in a series of in vivo cancer models, that tumors with genetically activated receptor tyrosine kinases depend on PI3K signaling, whereas tumors with mutations in the RAS/RAF axis depend on MAPK signaling. However, efficacy of downstream pathway inhibition was limited by release of negative feedback loops on the reciprocal pathway. By contrast, combined blockade of both pathways was able to overcome the reciprocal pathway activation induced by inhibitor-mediated release of negative feedback loops and resulted in a significant increase in apoptosis and tumor shrinkage. Thus, by using a systematic chemo-genomics approach, we identify genetic lesions connected to PI3K and MAPK pathway activation and provide a rationale for combined inhibition of both pathways. Our findings may have implications for patient stratification in clinical trials.
Assuntos
Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Neoplasias/genética , Fosfatidilinositol 3-Quinases/genética , Inibidores de Proteínas Quinases/farmacologia , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Genótipo , Humanos , Neoplasias/enzimologia , Neoplasias/patologia , Inibidores de Fosfoinositídeo-3 QuinaseRESUMO
Targeting kinases outside the highly conserved ATP pocket is thought to be a promising strategy for overcoming bottlenecks in kinase inhibitor research, such as limited selectivity and drug resistance. Here we report the development and application of a direct binding assay to detect small molecules that stabilize the inactive conformation of the tyrosine kinase cSrc. Protein X-ray crystallography validated the assay results and confirmed an exclusively allosteric binding mode.
Assuntos
Regulação Alostérica , Proteínas Proto-Oncogênicas pp60(c-src)/antagonistas & inibidores , Trifosfato de Adenosina/metabolismo , Sítios de Ligação , Cristalografia por Raios X , Ligação de Hidrogênio , Proteínas Proto-Oncogênicas pp60(c-src)/metabolismoRESUMO
Targeting protein kinases with small organic molecules is a promising strategy to regulate unwanted kinase activity in both chemical biology and medicinal chemistry research. Traditionally, kinase inhibitors are identified in activity-based screening assays using enzymatically active kinase preparations to measure the perturbation of substrate phosphorylation, often resulting in the enrichment of classical ATP competitive (Type I) inhibitors. However, addressing enzymatically incompetent kinase conformations offers new opportunities for targeted therapies and is moving to the forefront of kinase inhibitor research. Here we report the development of a new FLiK (Fluorescent Labels in Kinases) binding assay to detect small molecules that induce changes in the conformation of the glycine-rich loop. Due to cross-talk between the glycine-rich loop and the activation loop in kinases, this alternative labeling approach can also detect ligands that stabilize inactive kinase conformations, including slow-binding Type II and Type III kinase inhibitors. Protein X-ray crystallography validated the assay results and identified a novel DFG-out binding mode for a quinazoline-based inhibitor in p38alpha kinase. We also detected the high-affinity binding of a clinically relevant and specific VEGFR2 inhibitor, and we provide structural details of its binding mode in p38alpha, in which it stabilizes the DFG-out conformation. Last, we demonstrate the power of this new FLiK labeling strategy to detect the binding of Type I ligands that induce conformational changes in the glycine-rich loop as a means of gaining affinity for the target kinase. This approach may be a useful alternative to develop direct binding assays for kinases that do not adopt the DFG-out conformation while also avoiding the use of expensive kits, detection reagents, or radioactivity frequently employed with activity-based assays.
Assuntos
Corantes Fluorescentes/química , Glicina/química , Inibidores de Proteínas Quinases , Cristalografia por Raios X , Glicina/antagonistas & inibidores , Glicina/metabolismo , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologiaRESUMO
The 512 protein kinases encoded by the human genome are a prime example of nature's ability to create diversity by introducing variations to a highly conserved theme. The activity of each kinase domain is controlled by layers of regulatory mechanisms involving different combinations of post-translational modifications, intramolecular contacts, and intermolecular interactions. Ultimately, they all achieve their effect by favoring particular conformations that promote or prevent the kinase domain from catalyzing protein phosphorylation. The central role of kinases in various diseases has encouraged extensive investigations of their biological function and three-dimensional structures, yielding a more detailed understanding of the mechanisms that regulate protein kinase activity by conformational changes. In the present review, we discuss these regulatory mechanisms and show how conformational changes can be exploited for the design of specific inhibitors that lock protein kinases in inactive conformations. In addition, we highlight recent developments to monitor ligand-induced structural changes in protein kinases and for screening and identifying inhibitors that stabilize enzymatically incompetent kinase conformations.
Assuntos
Proteínas Quinases/química , Proteínas Quinases/metabolismo , Processamento de Proteína Pós-Traducional , Regulação Alostérica , Animais , Domínio Catalítico , Estabilidade Enzimática , Humanos , Ligantes , Modelos Moleculares , Estrutura Molecular , Mutagênese Sítio-Dirigida , Fosforilação , Conformação Proteica , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Proteínas Quinases/genética , Estrutura Terciária de Proteína , Relação Estrutura-AtividadeRESUMO
Kinase disregulation disrupts the intricate network of intracellular signaling pathways and contributes to the onset of diseases such as cancer. Although several kinase inhibitors are on the market, inhibitor selectivity and drug resistance mutations persist as fundamental challenges in the development of effective long-term treatments. Chemical entities binding to less conserved allosteric sites would be expected to offer new opportunities for scaffold development. Because no high-throughput method was previously available, we developed a fluorescence-based kinase binding assay for identifying and characterizing ligands which stabilize the inactive kinase conformation. Here, we present a description of the development and validation of this assay using the serine/threonine kinase p38alpha. By covalently attaching fluorophores to the activation loop of the kinase, we were able to detect conformational changes and measure the K(d), k(on), and k(off) associated with the binding and dissociation of ligands to the allosteric pocket. We report the SAR of a synthesized focused library of pyrazolourea derivatives, a scaffold known to bind with high affinity to the allosteric pocket of p38alpha. Additionally, we used protein X-ray crystallography together with our assay to examine the binding and dissociation kinetics to characterize potent quinazoline- and quinoline-based type II inhibitors, which also utilize this binding pocket in p38alpha. Last, we identified the b-Raf inhibitor sorafenib as a potent low nanomolar inhibitor of p38alpha and used protein X-ray crystallography to confirm a unique binding mode to the inactive kinase conformation.
Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Corantes Fluorescentes/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Trifosfato de Adenosina/metabolismo , Regulação Alostérica , Sequência de Aminoácidos , Benzenossulfonatos/farmacologia , Ligação Competitiva , Domínio Catalítico , Cristalografia por Raios X , Ativação Enzimática , Estabilidade Enzimática , Humanos , Cinética , Modelos Moleculares , Dados de Sequência Molecular , Niacinamida/análogos & derivados , Compostos de Fenilureia , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/metabolismo , Pirazóis/química , Pirazóis/metabolismo , Pirazóis/farmacologia , Piridinas/farmacologia , Reprodutibilidade dos Testes , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/metabolismo , Bibliotecas de Moléculas Pequenas/farmacologia , Sorafenibe , Relação Estrutura-Atividade , Proteínas Quinases p38 Ativadas por Mitógeno/química , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Kinase inhibitors represent the backbone of targeted cancer therapy, yet only a limited number of oncogenic drivers are directly druggable. By interrogating the activity of 1,505 kinase inhibitors, we found that BRD4-NUT-rearranged NUT midline carcinoma (NMC) cells are specifically killed by CDK9 inhibition (CDK9i) and depend on CDK9 and Cyclin-T1 expression. We show that CDK9i leads to robust induction of apoptosis and of markers of DNA damage response in NMC cells. While both CDK9i and bromodomain inhibition over time result in reduced Myc protein expression, only bromodomain inhibition induces cell differentiation and a p21-induced cell-cycle arrest in these cells. Finally, RNA-seq and ChIP-based analyses reveal a BRD4-NUT-specific CDK9i-induced perturbation of transcriptional elongation. Thus, our data provide a mechanistic basis for the genotype-dependent vulnerability of NMC cells to CDK9i that may be of relevance for the development of targeted therapies for NMC patients.
Assuntos
Terapia de Alvo Molecular , Neoplasias/enzimologia , Neoplasias/patologia , Inibidores de Proteínas Quinases/farmacologia , Proteínas de Ciclo Celular , Linhagem Celular Tumoral , Ciclina T/metabolismo , Quinase 9 Dependente de Ciclina/antagonistas & inibidores , Quinase 9 Dependente de Ciclina/metabolismo , Células HEK293 , Ensaios de Triagem em Larga Escala , Humanos , Neoplasias/genética , Proteínas Nucleares/antagonistas & inibidores , Proteínas Nucleares/metabolismo , Inibidores de Proteínas Quinases/química , RNA Polimerase II/metabolismo , Elongação da Transcrição Genética/efeitos dos fármacos , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/metabolismo , Transcrição Gênica/efeitos dos fármacosRESUMO
WD repeat-containing protein 5 (WDR5) is an important component of the multiprotein complex essential for activating mixed-lineage leukemia 1 (MLL1). Rearrangement of the MLL1 gene is associated with onset and progression of acute myeloid and lymphoblastic leukemias, and targeting the WDR5-MLL1 interaction may result in new cancer therapeutics. Our previous work showed that binding of small molecule ligands to WDR5 can modulate its interaction with MLL1, suppressing MLL1 methyltransferase activity. Initial structure-activity relationship studies identified N-(2-(4-methylpiperazin-1-yl)-5-substituted-phenyl) benzamides as potent and selective antagonists of this protein-protein interaction. Guided by crystal structure data and supported by in silico library design, we optimized the scaffold by varying the C-1 benzamide and C-5 substituents. This allowed us to develop the first highly potent (Kdisp < 100 nM) small molecule antagonists of the WDR5-MLL1 interaction and demonstrate that N-(4-(4-methylpiperazin-1-yl)-3'-(morpholinomethyl)-[1,1'-biphenyl]-3-yl)-6-oxo-4-(trifluoromethyl)-1,6-dihydropyridine-3-carboxamide 16d (OICR-9429) is a potent and selective chemical probe suitable to help dissect the biological role of WDR5.
Assuntos
Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Compostos de Bifenilo/síntese química , Compostos de Bifenilo/farmacologia , Di-Hidropiridinas/síntese química , Di-Hidropiridinas/farmacologia , Histona-Lisina N-Metiltransferase/antagonistas & inibidores , Histona-Lisina N-Metiltransferase/efeitos dos fármacos , Leucemia/tratamento farmacológico , Proteína de Leucina Linfoide-Mieloide/antagonistas & inibidores , Animais , Antineoplásicos/farmacocinética , Linhagem Celular Tumoral , Desenho de Fármacos , Feminino , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , Camundongos SCID , Modelos Moleculares , Simulação de Acoplamento Molecular , Bibliotecas de Moléculas Pequenas , Relação Estrutura-Atividade , Difração de Raios XRESUMO
Receptor tyrosine kinases represent one of the prime targets in cancer therapy, as the dysregulation of these elementary transducers of extracellular signals, like the epidermal growth factor receptor (EGFR), contributes to the onset of cancer, such as non-small cell lung cancer (NSCLC). Strong efforts were directed to the development of irreversible inhibitors and led to compound CO-1686, which takes advantage of increased residence time at EGFR by alkylating Cys797 and thereby preventing toxic effects. Here, we present a structure-based approach, rationalized by subsequent computational analysis of conformational ligand ensembles in solution, to design novel and irreversible EGFR inhibitors based on a screening hit that was identified in a phenotype screen of 80 NSCLC cell lines against approximately 1500 compounds. Using protein X-ray crystallography, we deciphered the binding mode in engineered cSrc (T338M/S345C), a validated model system for EGFR-T790M, which constituted the basis for further rational design approaches. Chemical synthesis led to further compound collections that revealed increased biochemical potency and, in part, selectivity toward mutated (L858R and L858R/T790M) vs nonmutated EGFR. Further cell-based and kinetic studies were performed to substantiate our initial findings. Utilizing proteolytic digestion and nano-LC-MS/MS analysis, we confirmed the alkylation of Cys797.
Assuntos
Antineoplásicos/química , Resistencia a Medicamentos Antineoplásicos , Receptores ErbB/antagonistas & inibidores , Antineoplásicos/farmacologia , Carcinoma Pulmonar de Células não Pequenas , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular , Cristalografia por Raios X , Bases de Dados de Compostos Químicos , Desenho de Fármacos , Receptores ErbB/genética , Humanos , Cinética , Neoplasias Pulmonares , Modelos Moleculares , Conformação Molecular , Mutação , Pirazóis/química , Pirazóis/farmacologia , Pirimidinas/química , Pirimidinas/farmacologia , Quinazolinas/química , Quinazolinas/farmacologia , Bibliotecas de Moléculas Pequenas , Solubilidade , Relação Estrutura-Atividade , Quinases da Família src/química , Quinases da Família src/genéticaRESUMO
Mutations in the catalytic domain at the gatekeeper position represent the most prominent drug-resistant variants of kinases and significantly impair the efficacy of targeted cancer therapies. Understanding the mechanisms of drug resistance at the molecular and atomic levels will aid in the design and development of inhibitors that have the potential to overcome these resistance mutations. Herein, by introducing adaptive elements into the inhibitor core structure, we undertake the structure-based development of type II hybrid inhibitors to overcome gatekeeper drug-resistant mutations in cSrc-T338M, as well as clinically relevant tyrosine kinase KIT-T670I and Abl-T315I variants, as essential targets in gastrointestinal stromal tumors (GISTs) and chronic myelogenous leukemia (CML). Using protein X-ray crystallography, we confirm the anticipated binding mode in cSrc, which proved to be essential for overcoming the respective resistances. More importantly, the novel compounds effectively inhibit clinically relevant gatekeeper mutants of KIT and Abl in biochemical and cellular studies.
Assuntos
Inibidores de Proteínas Quinases/síntese química , Proteínas Proto-Oncogênicas c-abl/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-kit/antagonistas & inibidores , Linhagem Celular Tumoral , Cristalografia por Raios X , Desenho de Fármacos , Resistencia a Medicamentos Antineoplásicos , Humanos , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Mutação , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas c-abl/genética , Proteínas Proto-Oncogênicas c-kit/genética , Relação Estrutura-AtividadeRESUMO
The WD40-repeat protein WDR5 plays a critical role in maintaining the integrity of MLL complexes and fully activating their methyltransferase function. MLL complexes, the trithorax-like family of SET1 methyltransferases, catalyze trimethylation of lysine 4 on histone 3, and they have been widely implicated in various cancers. Antagonism of WDR5 and MLL subunit interaction by small molecules has recently been presented as a practical way to inhibit activity of the MLL1 complex, and N-(2-(4-methylpiperazin-1-yl)-5-substituted-phenyl) benzamides were reported as potent and selective antagonists of such an interaction. Here, we describe the protein crystal structure guided optimization of prototypic compound 2 (K dis = 7 µM), leading to identification of more potent antagonist 47 (K dis = 0.3 µM).
RESUMO
The vast majority of small molecules known to modulate kinase activity, target the highly conserved ATP-pocket. Consequently, such ligands are often less specific and in case of inhibitors, this leads to the inhibition of multiple kinases. Thus, selective modulation of kinase function remains a major hurdle. One of the next great challenges in kinase research is the identification of ligands which bind to less conserved sites and target the non-catalytic functions of protein kinases. However, approaches that allow for the unambiguous identification of molecules that bind to these less conserved sites are few in number. We have previously reported the use of fluorescent labels in kinases (FLiK) to develop direct kinase binding assays that exclusively detect ligands which stabilize inactive (DFG-out) kinase conformations. Here, we present the successful application of the FLiK approach to develop a high-throughput binding assay capable of directly monitoring ligand binding to a remote site within the MAPK insert of p38α mitogen-activated protein kinase (MAPK). Guided by the crystal structure of an initially identified hit molecule in complex with p38α, we developed a tight binding ligand which may serve as an ideal starting point for further investigations of the biological function of the MAPK insert in regulating the p38α signaling pathway.
Assuntos
Bioensaio/métodos , Proteína Quinase 14 Ativada por Mitógeno/química , Sítios de Ligação , Corantes Fluorescentes , Humanos , Ligantes , Sistema de Sinalização das MAP Quinases , Proteína Quinase 14 Ativada por Mitógeno/genética , Proteína Quinase 14 Ativada por Mitógeno/metabolismo , Estrutura Terciária de ProteínaRESUMO
In this paper, we present the structure-based design, synthesis and biological activity of N-pyrazole, N'-thiazole-ureas as potent inhibitors of p38α mitogen-activated protein kinase (p38α MAPK). Guided by complex crystal structures, we employed the initially identified N-aryl, N'-thiazole urea scaffold and introduced key structural elements that allowed the formation of novel hydrogen bonding interactions within the allosteric site of p38α, resulting in potent type III inhibitors. [4-(3-tert-Butyl-5-{[(1,3-thiazol-2-ylamino)carbonyl]amino}-1H-pyrazol-1-yl)-phenyl]acetic acid 18c was found to be the most potent compound within this series and inhibited p38α activity with an IC(50) of 135 ± 21 nM. Its closest analog, ethyl [4-(3-tert-butyl-5-{[(1,3-thiazol-2-ylamino)carbonyl]amino}-1H-pyrazol-1-yl)phenyl]acetate 18b, effectively inhibited p38α mediated phosphorylation of the mitogen activated protein kinase activated protein kinase 2 (MK2) in HeLa cells.
Assuntos
Proteína Quinase 14 Ativada por Mitógeno/metabolismo , Inibidores de Proteínas Quinases/síntese química , Pirazóis/síntese química , Tiazóis/síntese química , Ureia/análogos & derivados , Humanos , Concentração Inibidora 50 , Espectroscopia de Ressonância Magnética , Proteína Quinase 14 Ativada por Mitógeno/antagonistas & inibidores , Modelos Moleculares , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Pirazóis/química , Pirazóis/farmacologia , Espectrometria de Massas por Ionização por Electrospray , Relação Estrutura-Atividade , Tiazóis/química , Tiazóis/farmacologia , Ureia/síntese química , Ureia/química , Ureia/farmacologia , Difração de Raios XRESUMO
Protein kinases are key enzymes in the complex regulation of cellular processes in almost all living organisms. For this reason, protein kinases represent attractive targets to stop the growth of eukaryotic pathogens such as protozoa and fungi. However, using kinase inhibitors to fight against these organisms bears several challenges since most of them are unselective and will also affect crucial host kinases. Here we present the X-ray structure of glycogen synthase kinase 3 from the fungal plant pathogen Ustilago maydis (UmGSK3) and its inhibition by type-II kinase inhibitors. Despite the high sequence homology between the human and the fungal variant of this vital kinase, we found substantial differences in the conformational plasticity of their active sites. Compounds that induced such conformational changes could be used to selectively inhibit the fungal kinase. This study serves as an example of how species-specific selectivity of inhibitors can be achieved by identifying and addressing the inactive state of a protein kinase. In addition to this, our study gives interesting insights into the molecular plasticity of UmGSK3 by revealing a previously unknown inactive conformation of this important kinase family.
Assuntos
Antifúngicos/administração & dosagem , Sistemas de Liberação de Medicamentos/métodos , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Inibidores de Proteínas Quinases/administração & dosagem , Ustilago/enzimologia , Sequência de Aminoácidos , Cristalografia por Raios X , Quinase 3 da Glicogênio Sintase/química , Quinase 3 da Glicogênio Sintase/metabolismo , Humanos , Dados de Sequência Molecular , Ustilago/efeitos dos fármacosRESUMO
Structural simplification of an antimitotic natural product podophyllotoxin with mimetic heterocyclic scaffolds constructed using multicomponent reactions led to the identification of compounds exhibiting low nanomolar antiproliferative and apoptosis-inducing properties. The most potent compounds were found in the dihydropyridopyrazole, dihydropyridonaphthalene, dihydropyridoindole, and dihydropyridopyrimidine scaffold series. Biochemical mechanistic studies performed with dihydropyridopyrazole compounds showed that these heterocycles inhibit in vitro tubulin polymerization and disrupt the formation of mitotic spindles in dividing cells at low nanomolar concentrations, in a manner similar to podophyllotoxin itself. Separation of a racemic dihydropyridonaphthalene into individual enantiomers demonstrated that only the optical antipode matching the absolute configuration of podophyllotoxin possessed potent anticancer activity. Computer modeling, performed using the podophyllotoxin binding site on ß-tubulin, provided a theoretical understanding of these successful experimental findings.