Discovery of Reversible DNA Methyltransferase and Lysine Methyltransferase G9a Inhibitors with Antitumoral in Vivo Efficacy
Obdulia Rabal, Edurne San José-Enériz, Xabier Agirre, Juan Antonio Sánchez-Arias, Amaia Vilas-Zornoza, Ana Ugarte, Irene de Miguel, Estíbaliz Miranda, Leire Garate, Mario Fraga, Pablo Santamarina, Raul Fernandez Perez, Raquel Ordoñez, Elena Sáez, Sergio Roa, María José García-Barchino, José Angel Martínez-Climent, Yingying Liu, Wei Wu, Musheng Xu, Felipe Prosper, Julen Oyarzabal
Using knowledge- and structure-based approaches, we designed and synthesized reversible chemical probes that simultaneously inhibit the activity of two epigenetic targets, histone 3 lysine 9 methyltransferase (G9a) and DNA methyltransferases (DNMT), at nanomolar ranges. Enzymatic competition assays confirmed our design strategy: substrate competitive inhibitors. Next, an initial exploration around our hit 11 was pursued to identify an adequate tool compound for in vivo testing.
In vitro treatment of different hematological neoplasia cell lines led to the identification of molecules with clear antiproliferative efficacies (GI50 values in the nanomolar range). On the basis of epigenetic functional cellular responses (levels of lysine 9 methylation and 5-methylcytosine), an acceptable therapeutic window (around 1 log unit) and a suitable pharmacokinetic profile, 12 was selected for in vivo proof-of-concept ( Nat. Commun. 2017 , 8 , 15424 ). Herein, 12 achieved a significant in vivo efficacy: 70% overall tumor growth inhibition of a human acute myeloid leukemia (AML) xenograft in a mouse model.