RESUMO
Despite a series of persuasive experimental evidence for the involvement of eyes absent protein tyrosine phosphatases in various human cancers, no small-molecule inhibitor has been reported so far. We have identified seven novel inhibitors of eyes absent homologue 2 (Eya2) with IC(50) values ranging from 1 to 70 µm by the virtual screening with docking simulations and enzyme inhibition assay. Atomic charges of the active-site Mg(2+) ion complex are calculated to enhance the accuracy of docking simulations. The newly discovered inhibitors are structurally diverse and have various chelating groups for the Mg(2+) ion. The interactions with the amino acid residues responsible for the stabilizations of the inhibitors in the active site of Eya2 are addressed in detail.
Assuntos
Quelantes/química , Quelantes/farmacologia , Desenho de Fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Proteínas Nucleares/antagonistas & inibidores , Proteínas Tirosina Fosfatases/antagonistas & inibidores , Domínio Catalítico , Concentração Inibidora 50 , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Modelos Moleculares , Proteínas Nucleares/metabolismo , Ligação Proteica , Proteínas Tirosina Fosfatases/metabolismo , Relação Estrutura-AtividadeRESUMO
EGCG and quercetin are known as beneficial dietary flavonoid for various diseases including diabetes mellitus. But it is not certain whether they could protect pancreatic beta cell directly. We performed this study to test both EGCG and quercetin could directly protect beta cell line under oxidative stress, and verify the action mechanisms. The protective effect of quercetin on INS-1 cells against oxidative stress was concentration dependent, but EGCG showed specific concentration zone for the protection. The protective effect of EGCG was more pronounced in pre-treatment before oxidative stress, while quercetin showed dramatic improvement of viability in simultaneous incubation with H2O2. In EGCG pre-treatment, antioxidant enzymes and activity were decreased, but the phosphorylated PI3K and Akt were significantly increased. PI3K inhibitor significantly reduced cell viability in EGCG pre-treatment. In conclusion, EGCG and quercetin have protective effect on INS-1 cells against oxidative stress through both antioxidant effect and anti-apoptosis signaling. In EGCG, pre-treatment make its effect better by the enhancement of anti-apoptosis signaling. Quercetin protected INS-1 cells more in simultaneous incubation via strong antioxidant defense.