RESUMO
Preventing histone recognition by bromodomains emerges as an attractive therapeutic approach in cancer. Overexpression of ATAD2 (ATPase family AAA domain-containing 2 isoform A) in cancer cells is associated with poor prognosis making the bromodomain of ATAD2 a promising epigenetic therapeutic target. In the development of an in vitro assay and identification of small molecule ligands, we conducted structure-guided studies which revealed a conformationally flexible ATAD2 bromodomain. Structural studies on apo-, peptide-and small molecule-ATAD2 complexes (by co-crystallization) revealed that the bromodomain adopts a 'closed', histone-compatible conformation and a more 'open' ligand-compatible conformation of the binding site respectively. An unexpected conformational change of the conserved asparagine residue plays an important role in driving the peptide-binding conformation remodelling. We also identified dimethylisoxazole-containing ligands as ATAD2 binders which aided in the validation of the in vitro screen and in the analysis of these conformational studies.
Assuntos
Adenosina Trifosfatases/química , Proteínas de Ligação a DNA/química , Desenho de Fármacos , Inibidores Enzimáticos/química , Histonas/química , Isoxazóis/química , Fragmentos de Peptídeos/química , Processamento de Proteína Pós-Traducional , ATPases Associadas a Diversas Atividades Celulares , Adenosina Trifosfatases/antagonistas & inibidores , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/metabolismo , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Sítios de Ligação , Biotinilação , Proteínas de Ligação a DNA/antagonistas & inibidores , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Histonas/antagonistas & inibidores , Histonas/metabolismo , Humanos , Isoxazóis/síntese química , Isoxazóis/farmacologia , Cinética , Ligantes , Proteínas Mutantes/antagonistas & inibidores , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Fragmentos de Peptídeos/antagonistas & inibidores , Fragmentos de Peptídeos/metabolismo , Maleabilidade , Conformação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Sulfonamidas/síntese química , Sulfonamidas/química , Sulfonamidas/farmacologia , meta-Aminobenzoatos/síntese química , meta-Aminobenzoatos/química , meta-Aminobenzoatos/farmacologiaRESUMO
The tyrosine kinase p56lck (lck) is essential for T cell activation; thus, inhibitors of lck have potential utility as autoimmune agents. Our initial disclosure of a new class of lck inhibitors based on the phenylaminoimidazoisoquinolin-9-one showed reasonable cellular activity but did not work in vivo upon oral administration. Our current work highlights the further use of rational drug design and molecular modeling to produce a series of lck inhibitors that demonstrate cellular activity below 100 nM and are as efficacious as cyclosporin A in an in vivo mouse model of anti-CD3-induced IL-2 production.
Assuntos
Benzimidazóis/síntese química , Inibidores Enzimáticos/síntese química , Imunossupressores/síntese química , Isoquinolinas/síntese química , Proteína Tirosina Quinase p56(lck) Linfócito-Específica/antagonistas & inibidores , Administração Oral , Animais , Anticorpos Monoclonais/farmacologia , Benzimidazóis/química , Benzimidazóis/farmacologia , Complexo CD3/imunologia , Cristalografia por Raios X , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Feminino , Humanos , Imunossupressores/química , Imunossupressores/farmacologia , Interleucina-2/antagonistas & inibidores , Interleucina-2/biossíntese , Interleucina-2/sangue , Isoquinolinas/química , Isoquinolinas/farmacologia , Células Jurkat , Camundongos , Camundongos Endogâmicos BALB C , Modelos Moleculares , Conformação Molecular , Ligação Proteica , Relação Estrutura-AtividadeRESUMO
An imidazo[4,5-h]isoquinolin-7,9-dione (1) was identified as an adenosine 5'-triphosphate competitive inhibitor of lck by high throughput screening. Initial structure-activity relationship studies identified the dichlorophenyl ring and the imide NH as important pharmacophores. A binding model was constructed to understand how 1 binds to a related kinase, hck. These results suggested that removing the gem-dimethyl group and flattening the ring would enhance activity. This was realized by converting 1 to the imidazo[4,5-h]isoquinolin-9-one (20), resulting in an 18-fold improvement in potency against lck and a 50-fold increase in potency in a cellular assay.