RESUMEN
Lysine specific demethylase 1 KDM1A (LSD1) regulates histone methylation and it is increasingly recognized as a potential therapeutic target in oncology. We report on a high-throughput screening campaign performed on KDM1A/CoREST, using a time-resolved fluorescence resonance energy transfer (TR-FRET) technology, to identify reversible inhibitors. The screening led to 115 hits for which we determined biochemical IC50, thus identifying four chemical series. After data analysis, we have prioritized the chemical series of N-phenyl-4H-thieno[3, 2-b]pyrrole-5-carboxamide for which we obtained X-ray structures of the most potent hit (compound 19, IC50 = 2.9 µM) in complex with the enzyme. Initial expansion of this chemical class, both modifying core structure and decorating benzamide moiety, was directed toward the definition of the moieties responsible for the interaction with the enzyme. Preliminary optimization led to compound 90, which inhibited the enzyme with a submicromolar IC50 (0.162 µM), capable of inhibiting the target in cells.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Histona Demetilasas/antagonistas & inhibidores , Pirroles/farmacología , Línea Celular Tumoral , Cristalografía por Rayos X , Diseño de Fármacos , Ensayos Analíticos de Alto Rendimiento , Humanos , Espectroscopía de Protones por Resonancia Magnética , Pirroles/química , Espectrometría de Masa por Ionización de Electrospray , Relación Estructura-ActividadRESUMEN
The balance of methylation levels at histone H3 lysine 4 (H3K4) is regulated by KDM1A (LSD1). KDM1A is overexpressed in several tumor types, thus representing an emerging target for the development of novel cancer therapeutics. We have previously described ( Part 1, DOI 10.1021.acs.jmedchem.6b01018 ) the identification of thieno[3,2-b]pyrrole-5-carboxamides as novel reversible inhibitors of KDM1A, whose preliminary exploration resulted in compound 2 with biochemical IC50 = 160 nM. We now report the structure-guided optimization of this chemical series based on multiple ligand/KDM1A-CoRest cocrystal structures, which led to several extremely potent inhibitors. In particular, compounds 46, 49, and 50 showed single-digit nanomolar IC50 values for in vitro inhibition of KDM1A, with high selectivity in secondary assays. In THP-1 cells, these compounds transcriptionally affected the expression of genes regulated by KDM1A such as CD14, CD11b, and CD86. Moreover, 49 and 50 showed a remarkable anticlonogenic cell growth effect on MLL-AF9 human leukemia cells.