Structure-Based Design and Characterization of the Highly Potent and Selective Covalent Inhibitors Targeting the Lysine Methyltransferases G9a/GLP

Abstract

Protein lysine methyltransferases G9a and GLP, which catalyze mono- and di-methylation of histone H3K9 and nonhistone proteins, play important roles in diverse cellular processes. Overexpression or dysregulation of G9a and GLP has been identified in various types of cancer. Here, we report the discovery of a highly potent and selective covalent inhibitor <b>27</b> of G9a/GLP via the structure-based drug design approach following structure-activity relationship exploration and cellular potency optimization. Mass spectrometry assays and washout experiments confirmed its covalent inhibition mechanism. Compound <b>27</b> displayed improved potency in inhibiting the proliferation and colony formation of PANC-1 and MDA-MB-231 cell lines and exhibited enhanced potency in reducing the levels of H3K9me2 in cells compared to noncovalent inhibitor <b>26</b>. <i>In vivo</i>, <b>27</b> showed significant antitumor efficacy in the PANC-1 xenograft model with good safety. These results clearly indicate that <b>27</b> is a highly potent and selective covalent inhibitor of G9a/GLP.