Discovery of alkyl bis(oxy)dibenzimidamide derivatives as novel protein arginine methyltransferase 1 (PRMT1) inhibitors

Protein arginine methylation, a post-translational modification critical for a variety of biological processes, is catalyzed by protein arginine N-methyltransferases (PRMTs). In particular, PRMT1 is responsible for over 85% of the arginine methylation in mammalian cells. Dysregulation of PRMT1 is involved in diverse pathological diseases including cancers. However, most current PRMT1inhibitors are lack of specificity, efficacy, and bioavailability. Herein, a series of alkyl bis(oxy)dibenzimidamide derivatives were identified as selective PRMT1 inhibitors. Amongst them, the most potent compound corresponds to hexamidine (IC50 = 5.9 ± 1.7 μM), which is an antimicrobial agent. The binding between hexamidine and PRMT1 was further validated by thermal shift assays and nuclear magnetic resonance (NMR) experiments. Molecular docking and NMR assays indicated that hexamidine occupied the substrate binding pocket. Furthermore, hexamidine effectively blocked cell proliferation in cancer cell lines related to PRMT1 overexpression. Taken together, this study has provided a druggable scaffold targeting PRMT1 as well as a new way to repurpose old drugs which is a complementary tool for the discovery of new lead compounds. This article is protected by copyright. All rights reserved.