Covalent inhibitors of EZH2: Design, synthesis and evaluation

The histone lysine methyltransferase EZH2 has been implicated as a key component in cancer development. Up to date, there are only a few EZH2 covalent inhibitors. In this study, a new series of 3-acrylamido-2-methyl-N-((2-oxo-1,2-dihydropyridin-3-yl) methyl) benzamide derivatives were designed, synthesized, and demonstrated to act as EZH2 covalent inhibitors, among which SKLB-03176 was the most potent compound. SAM competition experiments, mass spectrometry, and washing-out assays proved that SKLB-03176 could covalently bind to the SAM pocket of EZH2. Remarkably, SKLB-03176 exhibited weak activity against other targets, such as 5 histone methyltransferases and more than 30 kinases. Besides, it could inhibit the activity of a variety of EZH2 mutants and significantly inhibit the expression of H3K27Me3 in cells. Furthermore, SKLB-03176 showed no cytotoxicity to normal cells. Our data suggested that SKLB-03176 could be used as a promising lead compound for the development of new EZH2 covalent inhibitors and a valuable chemical tool to study the biological functions of EZH2 or PRC2.