RESUMO
The epidermal growth factor receptor (EGFR)-directed tyrosine kinase inhibitors (TKIs) gefitinib, erlotinib and afatinib are approved treatments for non-small cell lung cancers harbouring activating mutations in the EGFR kinase, but resistance arises rapidly, most frequently owing to the secondary T790M mutation within the ATP site of the receptor. Recently developed mutant-selective irreversible inhibitors are highly active against the T790M mutant, but their efficacy can be compromised by acquired mutation of C797, the cysteine residue with which they form a key covalent bond. All current EGFR TKIs target the ATP-site of the kinase, highlighting the need for therapeutic agents with alternative mechanisms of action. Here we describe the rational discovery of EAI045, an allosteric inhibitor that targets selected drug-resistant EGFR mutants but spares the wild-type receptor. The crystal structure shows that the compound binds an allosteric site created by the displacement of the regulatory C-helix in an inactive conformation of the kinase. The compound inhibits L858R/T790M-mutant EGFR with low-nanomolar potency in biochemical assays. However, as a single agent it is not effective in blocking EGFR-driven proliferation in cells owing to differential potency on the two subunits of the dimeric receptor, which interact in an asymmetric manner in the active state. We observe marked synergy of EAI045 with cetuximab, an antibody therapeutic that blocks EGFR dimerization, rendering the kinase uniformly susceptible to the allosteric agent. EAI045 in combination with cetuximab is effective in mouse models of lung cancer driven by EGFR(L858R/T790M) and by EGFR(L858R/T790M/C797S), a mutant that is resistant to all currently available EGFR TKIs. More generally, our findings illustrate the utility of purposefully targeting allosteric sites to obtain mutant-selective inhibitors.
Assuntos
Antineoplásicos/farmacologia , Benzenoacetamidas/farmacologia , Resistencia a Medicamentos Antineoplásicos/genética , Receptores ErbB/genética , Proteínas Mutantes/antagonistas & inibidores , Inibidores de Proteínas Quinases/farmacologia , Tiazóis/farmacologia , Regulação Alostérica/efeitos dos fármacos , Sítio Alostérico/efeitos dos fármacos , Animais , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/enzimologia , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cetuximab/farmacologia , Modelos Animais de Doenças , Resistência a Múltiplos Medicamentos/efeitos dos fármacos , Resistência a Múltiplos Medicamentos/genética , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Sinergismo Farmacológico , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/química , Receptores ErbB/metabolismo , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/patologia , Camundongos , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Conformação Proteica/efeitos dos fármacos , Multimerização Proteica/efeitos dos fármacosRESUMO
Activated esters are widely used to label proteins at lysine side chains and Nâ termini. These reagents are useful for labeling virtually any protein, but robust reactivity toward primary amines generally precludes site-selective modification. In a unique case, fluorophenyl esters are shown to preferentially label human kappa antibodies at a single lysine (Lys188) within the light-chain constant domain. Neighboring residues His189 and Asp151 contribute to the accelerated rate of labeling at Lys188 relative to the ≈40 other lysine sites. Enriched Lys188 labeling can be enhanced from 50-70 % to >95 % by any of these approaches: lowering reaction temperature, applying flow chemistry, or mutagenesis of specific residues in the surrounding protein environment. Our results demonstrated that activated esters with fluoro-substituted aromatic leaving groups, including a fluoronaphthyl ester, can be generally useful reagents for site-selective lysine labeling of antibodies and other immunoglobulin-type proteins.
Assuntos
Lisina/metabolismo , Proteínas/metabolismo , Cristalografia por Raios X , Teoria da Densidade Funcional , Humanos , Conformação Proteica , Proteínas/química , TermodinâmicaRESUMO
UNLABELLED: Bacterial pathogens Neisseria meningitidis and Brucella abortus pose threats to human and animal health worldwide, causing meningococcal disease and brucellosis, respectively. Mortality from acute N. meningitidis infections remains high despite antibiotics, and brucellosis presents alimentary and health consequences. Superoxide dismutases are master regulators of reactive oxygen and general pathogenicity factors and are therefore therapeutic targets. Cu,Zn superoxide dismutases (SODs) localized to the periplasm promote survival by detoxifying superoxide radicals generated by major host antimicrobial immune responses. We discovered that passive immunization with an antibody directed at N. meningitidis SOD (NmSOD) was protective in a mouse infection model. To define the relevant atomic details and solution assembly states of this important virulence factor, we report high-resolution and X-ray scattering analyses of NmSOD and of SOD from B. abortus (BaSOD). The NmSOD structures revealed an auxiliary tetrahedral Cu-binding site bridging the dimer interface; mutational analyses suggested that this metal site contributes to protein stability, with implications for bacterial defense mechanisms. Biochemical and structural analyses informed us about electrostatic substrate guidance, dimer assembly, and an exposed C-terminal epitope in the NmSOD dimer. In contrast, the monomeric BaSOD structure provided insights for extending immunogenic peptide epitopes derived from the protein. These collective results reveal unique contributions of SOD to pathogenic virulence, refine predictive motifs for distinguishing SOD classes, and suggest general targets for antibacterial immune responses. The identified functional contributions, motifs, and targets distinguishing bacterial and eukaryotic SOD assemblies presented here provide a foundation for efforts to develop SOD-specific inhibitors of or vaccines against these harmful pathogens. IMPORTANCE: By protecting microbes against reactive oxygen insults, SODs aid survival of many bacteria within their hosts. Despite the ubiquity and conservation of these key enzymes, notable species-specific differences relevant to pathogenesis remain undefined. To probe mechanisms that govern the functioning of Neisseria meningitidis and Brucella abortus SODs, we used X-ray structures, enzymology, modeling, and murine infection experiments. We identified virulence determinants common to the two homologs, assembly differences, and a unique metal reservoir within meningococcal SOD that stabilizes the enzyme and may provide a safeguard against copper toxicity. The insights reported here provide a rationale and a basis for SOD-specific drug design and an extension of immunogen design to target two important pathogens that continue to pose global health threats.
Assuntos
Complexo Antígeno-Anticorpo/ultraestrutura , Brucella abortus/imunologia , Neisseria meningitidis/imunologia , Superóxido Dismutase/imunologia , Superóxido Dismutase/ultraestrutura , Animais , Anticorpos/administração & dosagem , Anticorpos/imunologia , Sítios de Ligação de Anticorpos , Vacina contra Brucelose/imunologia , Brucella abortus/patogenicidade , Brucelose/imunologia , Brucelose/prevenção & controle , Cristalografia por Raios X , Modelos Animais de Doenças , Imunização Passiva/métodos , Meningite Meningocócica/imunologia , Meningite Meningocócica/prevenção & controle , Vacinas Meningocócicas/imunologia , Camundongos , Neisseria meningitidis/patogenicidade , Superóxido Dismutase/genética , Fatores de Virulência/imunologiaRESUMO
RNA-dependent RNA polymerases (RdRPs) from nonsegmented negative strand (NNS) RNA viruses perform both mRNA transcription and genome replication, and these activities are regulated by their interactions with RNA and other accessory proteins within the ribonucleoprotein (RNP) complex. Detailed biochemical characterization of these enzymatic activities and their regulation is essential for understanding the life cycles of many pathogenic RNA viruses and for antiviral drug discovery. We developed biochemical and biophysical kinetic methods to study the RNA synthesis and RNA binding activities of respiratory syncytial virus (RSV) L/P RdRP. We determined that the intact L protein is essential for RdRP activity, and in truncated L protein constructs, RdRP activity is abrogated due to their deficiency in RNA template binding. These results are in agreement with the observation of an RNA template-binding tunnel at the interface of RdRP and capping domains in RSV and vesicular stomatitis virus (VSV) L protein cryo-EM structures. We also describe nonradiometric assays for measuring RNA binding and RNA polymerization activity of RSV RdRP, which are amenable to compound screening and profiling.
Assuntos
RNA Polimerase Dependente de RNA , Vírus Sincicial Respiratório Humano , Antivirais , RNA Polimerase Dependente de RNA/genética , Vírus Sincicial Respiratório Humano/genética , Transcrição Gênica , Proteínas Virais/genéticaRESUMO
Autoimmune deficiency and destruction in either ß-cell mass or function can cause insufficient insulin levels and, as a result, hyperglycemia and diabetes. Thus, promoting ß-cell proliferation could be one approach toward diabetes intervention. In this report we describe the discovery of a potent and selective DYRK1A inhibitor GNF2133, which was identified through optimization of a 6-azaindole screening hit. In vitro, GNF2133 is able to proliferate both rodent and human ß-cells. In vivo, GNF2133 demonstrated significant dose-dependent glucose disposal capacity and insulin secretion in response to glucose-potentiated arginine-induced insulin secretion (GPAIS) challenge in rat insulin promoter and diphtheria toxin A (RIP-DTA) mice. The work described here provides new avenues to disease altering therapeutic interventions in the treatment of type 1 diabetes (T1D).
Assuntos
Compostos Aza/química , Compostos Aza/farmacologia , Diabetes Mellitus Tipo 1/tratamento farmacológico , Hipoglicemiantes/química , Hipoglicemiantes/farmacologia , Indóis/química , Indóis/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/antagonistas & inibidores , Animais , Compostos Aza/farmacocinética , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Diabetes Mellitus Tipo 1/metabolismo , Humanos , Hipoglicemiantes/farmacocinética , Indóis/farmacocinética , Secreção de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Masculino , Camundongos , Simulação de Acoplamento Molecular , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Ratos , Ratos Sprague-Dawley , Ratos Wistar , Quinases DyrkRESUMO
Irreversible HER/erbB inhibitors selectively inhibit HER-family kinases by targeting a unique cysteine residue located within the ATP-binding pocket. Sequence alignment reveals that this rare cysteine is also present in ten other protein kinases including all five Tec-family members. We demonstrate that the Tec-family kinase Bmx is potently inhibited by irreversible modification at Cys496 by clinical stage EGFR inhibitors such as CI-1033. This cross-reactivity may have significant clinical implications.
Assuntos
Receptores ErbB/antagonistas & inibidores , Morfolinas/farmacologia , Proteínas Tirosina Quinases/antagonistas & inibidores , Quinazolinas/farmacologia , Animais , Cisteína/genética , Cisteína/metabolismo , Camundongos , Estrutura Molecular , Morfolinas/química , Quinazolinas/química , Homologia de Sequência de AminoácidosRESUMO
Glutathione S-transferases (GSTs) comprise a diverse superfamily of enzymes found in organisms from all kingdoms of life. GSTs are involved in diverse processes, notably small-molecule biosynthesis or detoxification, and are frequently also used in protein engineering studies or as biotechnology tools. Here, we report the high-resolution X-ray structure of Atu5508 from the pathogenic soil bacterium Agrobacterium tumefaciens (atGST1). Through use of comparative sequence and structural analysis of the GST superfamily, we identified local sequence and structural signatures, which allowed us to distinguish between different GST classes. This approach enables GST classification based on structure, without requiring additional biochemical or immunological data. Consequently, analysis of the atGST1 crystal structure suggests a new GST class, distinct from previously characterized GSTs, which would make it an attractive target for further biochemical studies.
Assuntos
Agrobacterium tumefaciens/enzimologia , Proteínas de Bactérias/química , Glutationa Transferase/química , Agrobacterium tumefaciens/química , Agrobacterium tumefaciens/citologia , Sequência de Aminoácidos , Proteínas de Bactérias/classificação , Cristalografia por Raios X , Dimerização , Glutationa Transferase/classificação , Modelos Moleculares , Dados de Sequência Molecular , Filogenia , Estrutura Secundária de ProteínaRESUMO
Non-small cell lung cancer patients carrying oncogenic EGFR mutations initially respond to EGFR-targeted therapy, but later elicit minimal response due to dose-limiting toxicities and acquired resistance. EGF816 is a novel, irreversible mutant-selective EGFR inhibitor that specifically targets EGFR-activating mutations arising de novo and upon resistance acquisition, while sparing wild-type (WT) EGFR. EGF816 potently inhibited the most common EGFR mutations L858R, Ex19del, and T790M in vitro, which translated into strong tumor regressions in vivo in several patient-derived xenograft models. Notably, EGF816 also demonstrated antitumor activity in an exon 20 insertion mutant model. At levels above efficacious doses, EGF816 treatment led to minimal inhibition of WT EGFR and was well tolerated. In single-dose studies, EGF816 provided sustained inhibition of EGFR phosphorylation, consistent with its ability for irreversible binding. Furthermore, combined treatment with EGF816 and INC280, a cMET inhibitor, resulted in durable antitumor efficacy in a xenograft model that initially developed resistance to first-generation EGFR inhibitors via cMET activation. Thus, we report the first preclinical characterization of EGF816 and provide the groundwork for its current evaluation in phase I/II clinical trials in patients harboring EGFR mutations, including T790M.
Assuntos
Antineoplásicos/farmacologia , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Receptores ErbB/metabolismo , Neoplasias Pulmonares/tratamento farmacológico , Mutação/efeitos dos fármacos , Animais , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Linhagem Celular Tumoral , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Neoplasias Pulmonares/metabolismo , Camundongos , Camundongos Nus , Fosforilação/efeitos dos fármacos , Ratos , Ensaios Antitumorais Modelo de Xenoenxerto/métodosRESUMO
Over the past decade, first and second generation EGFR inhibitors have significantly improved outcomes for lung cancer patients with activating mutations in EGFR. However, both resistance through a secondary T790M mutation at the gatekeeper residue and dose-limiting toxicities from wild-type (WT) EGFR inhibition ultimately limit the full potential of these therapies to control mutant EGFR-driven tumors and new therapies are urgently needed. Herein, we describe our approach toward the discovery of 47 (EGF816, nazartinib), a novel, covalent mutant-selective EGFR inhibitor with equipotent activity on both oncogenic and T790M-resistant EGFR mutations. Through molecular docking studies we converted a mutant-selective high-throughput screening hit (7) into a number of targeted covalent EGFR inhibitors with equipotent activity across mutants EGFR and good WT-EGFR selectivity. We used an abbreviated in vivo efficacy study for prioritizing compounds with good tolerability and efficacy that ultimately led to the selection of 47 as the clinical candidate.
Assuntos
Antineoplásicos/farmacologia , Benzimidazóis/farmacologia , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Descoberta de Drogas , Receptores ErbB/antagonistas & inibidores , Neoplasias Pulmonares/tratamento farmacológico , Nicotina/análogos & derivados , Inibidores de Proteínas Quinases/farmacologia , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Benzimidazóis/síntese química , Benzimidazóis/química , Carcinoma Pulmonar de Células não Pequenas/enzimologia , Carcinoma Pulmonar de Células não Pequenas/patologia , Proliferação de Células/efeitos dos fármacos , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Receptores ErbB/genética , Receptores ErbB/metabolismo , Humanos , Neoplasias Pulmonares/enzimologia , Neoplasias Pulmonares/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Modelos Moleculares , Conformação Molecular , Mutação , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/patologia , Nicotina/síntese química , Nicotina/química , Nicotina/farmacologia , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Ratos , Ratos Wistar , Relação Estrutura-AtividadeRESUMO
Mutations in human superoxide dismutase (HSOD) have been linked to the familial form of amyotrophic lateral sclerosis (FALS). Amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease) is one of the most common neurodegenerative disorders in humans. In ALS patients, selective killing of motor neurons leads to progressive paralysis and death within one to five years of onset. The most frequent FALS mutation in HSOD, Ala4-->Val, is associated with the most rapid disease progression. Here we identify and characterize key differences in the stability between the A4V mutant protein and its thermostable parent (HSOD-AS), in which free cysteine residues were mutated to eliminate interferences from cysteine oxidation. Denaturation studies reveal that A4V unfolds at a guanidine-HCl concentration 1M lower than HSOD-AS, revealing that A4V is significantly less stable than HSOD-AS. Determination and analysis of the crystallographic structures of A4V and HSOD-AS reveal structural features likely responsible for the loss of architectural stability of A4V observed in the denaturation experiments. The combined structural and biophysical results presented here argue that architectural destabilization of the HSOD protein may underlie the toxic function of the many HSOD FALS mutations.
Assuntos
Esclerose Lateral Amiotrófica/enzimologia , Superóxido Dismutase/química , Superóxido Dismutase/genética , Esclerose Lateral Amiotrófica/genética , Estabilidade Enzimática , Radicais Livres , Humanos , Cinética , Metais/química , Mutagênese Sítio-Dirigida , Mutação , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Superóxido Dismutase/metabolismoRESUMO
Many point mutations in human Cu,Zn superoxide dismutase (SOD) cause familial amyotrophic lateral sclerosis (FALS), a fatal neurodegenerative disorder in heterozygotes. Here we show that these mutations cluster in protein regions influencing architectural integrity. Furthermore, crystal structures of SOD wild-type and FALS mutant H43R proteins uncover resulting local framework defects. Characterizations of beta-barrel (H43R) and dimer interface (A4V) FALS mutants reveal reduced stability and drastically increased aggregation propensity. Moreover, electron and atomic force microscopy indicate that these defects promote the formation of filamentous aggregates. The filaments resemble those seen in neurons of FALS patients and bind both Congo red and thioflavin T, suggesting the presence of amyloid-like, stacked beta-sheet interactions. These results support free-cysteine-independent aggregation of FALS mutant SOD as an integral part of FALS pathology. They furthermore provide a molecular basis for the single FALS disease phenotype resulting from mutations of diverse side-chains throughout the protein: many FALS mutations reduce structural integrity, lowering the energy barrier for fibrous aggregation.
Assuntos
Esclerose Lateral Amiotrófica/genética , Mutação , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismo , Esclerose Lateral Amiotrófica/patologia , Sítios de Ligação , Cobre/metabolismo , Cristalografia por Raios X , Cisteína/química , Dimerização , Estabilidade Enzimática , Humanos , Interações Hidrofóbicas e Hidrofílicas , Substâncias Macromoleculares , Microscopia de Força Atômica , Microscopia Eletrônica , Modelos Moleculares , Conformação Proteica , Superóxido Dismutase/química , Zinco/metabolismoRESUMO
Insufficient pancreatic ß-cell mass or function results in diabetes mellitus. While significant progress has been made in regulating insulin secretion from ß-cells in diabetic patients, no pharmacological agents have been described that increase ß-cell replication in humans. Here we report aminopyrazine compounds that stimulate robust ß-cell proliferation in adult primary islets, most likely as a result of combined inhibition of DYRK1A and GSK3B. Aminopyrazine-treated human islets retain functionality in vitro and after transplantation into diabetic mice. Oral dosing of these compounds in diabetic mice induces ß-cell proliferation, increases ß-cell mass and insulin content, and improves glycaemic control. Biochemical, genetic and cell biology data point to Dyrk1a as the key molecular target. This study supports the feasibility of treating diabetes with an oral therapy to restore ß-cell mass, and highlights a tractable pathway for future drug discovery efforts.
Assuntos
Proliferação de Células , Quinase 3 da Glicogênio Sintase/genética , Células Secretoras de Insulina/citologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Tirosina Quinases/genética , Animais , Divisão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/fisiopatologia , Regulação para Baixo/efeitos dos fármacos , Quinase 3 da Glicogênio Sintase/metabolismo , Glicogênio Sintase Quinase 3 beta , Humanos , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/enzimologia , Masculino , Camundongos , Camundongos Transgênicos , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Piridazinas/farmacologia , Quinases DyrkAssuntos
Fatores de Ribosilação do ADP/química , Proteínas de Bactérias/química , Citidina Desaminase/química , Dobramento de Proteína , Proteínas Ribossômicas/química , Thermotoga maritima/química , Fatores de Ribosilação do ADP/genética , Fatores de Ribosilação do ADP/fisiologia , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Proteínas de Bactérias/fisiologia , Cristalografia por Raios X , Citidina Desaminase/fisiologia , Dados de Sequência Molecular , Estrutura Terciária de Proteína , Proteínas Ribossômicas/genética , Proteínas Ribossômicas/fisiologia , Thermotoga maritima/fisiologiaRESUMO
Type-1 diabetes (T1D) is an autoimmune disease targeting insulin-producing beta cells, resulting in dependence on exogenous insulin. To date, significant efforts have been invested to develop immune-modulatory therapies for T1D treatment. Previously, IL-2 immunotherapy was demonstrated to prevent and reverse T1D at onset in the non-obese diabetic (NOD) mouse model, revealing potential as a therapy in early disease stage in humans. In the NOD model, IL-2 deficiency contributes to a loss of regulatory T cell function. This deficiency can be augmented with IL-2 or antibody bound to IL-2 (Ab/IL-2) therapy, resulting in regulatory T cell expansion and potentiation. However, an understanding of the mechanism by which reconstituted regulatory T cell function allows for reversal of diabetes after onset is not clearly understood. Here, we describe that Ab/IL-2 immunotherapy treatment, given at the time of diabetes onset in NOD mice, not only correlated with reversal of diabetes and expansion of Treg cells, but also demonstrated the ability to significantly increase beta cell proliferation. Proliferation appeared specific to Ab/IL-2 immunotherapy, as anti-CD3 therapy did not have a similar effect. Furthermore, to assess the effect of Ab/IL-2 immunotherapy well after the development of diabetes, we tested the effect of delaying treatment for 4 weeks after diabetes onset, when beta cells were virtually absent. At this late stage after diabetes onset, Ab/IL-2 treatment was not sufficient to reverse hyperglycemia. However, it did promote survival in the absence of exogenous insulin. Proliferation of beta cells could not account for this improvement as few beta cells remained. Rather, abnormal insulin and glucagon dual-expressing cells were the only insulin-expressing cells observed in islets from mice with established disease. Thus, these data suggest that in diabetic NOD mice, beta cells have an innate capacity for regeneration both early and late in disease, which is revealed through IL-2 immunotherapy.