Identification of Selective, Cell Active Inhibitors of Protein Arginine Methyltransferase 5 through Structure-Based Virtual Screening and Biological Assays.

Protein arginine methyltransferase 5 (PRMT5), a type II PRMT enzyme, is reported as an important therapeutic target in leukemia and lymphoma. In the present study, based on the combination of virtual screening and biochemical validations, we discovered a series of small-molecule inhibitors targeting PRMT5. Among those, DC_Y134 exhibited the most potent activity with IC50 value of 1.7 µM and displayed good selectivity against other methyltransferases. Further treatment with DC_Y134 inhibited the proliferation of several hematological malignancy cell lines by causing cell cycle arrest and apoptosis. Western blot assays indicated that DC_Y134 reduced the cellular symmetrically dimethylated levels. In addition, we analyzed the binding mode of DC_Y134 through molecular docking, which revealed that DC_Y134 occupies the binding site of substrate arginine and explained the selectivity of this inhibitor. Taken together, compound DC_Y134 could be used to elucidate the biological roles of PRMT5 and serve as a lead compound for treatment of hematologic malignancies.