Discovery of a Novel G9a-Selective Inhibitor for Hepatocellular Carcinoma Treatment

Epigenetic dysregulation, particularly aberrant histone methylation orchestrated by histone methyltransferases (HMTs), is a fundamental driver of hepatocellular carcinoma (HCC). Among these HMTs, H3K9-specific methyltransferase G9a is markedly upregulated and promotes tumorigenesis. However, current G9a inhibitors lack sufficient selectivity and potency. Here, we identified compound 1071, a novel selective G9a inhibitor with a distinct chemical scaffold, which demonstrates superior cellular activity compared with the existing G9a inhibitor UNC0638. Mechanistically, compound 1071 reduces H3K9me2 levels and modulates the expression of key G9a targets, including p21, FOXO1, and PD-L1. Moreover, compound 1071 exhibits potent antitumor activity in both subcutaneous and c-Myc-driven HCC models, outperforming the first-line drug sorafenib without significant toxicity. This study establishes compound 1071 as a promising lead for G9a-targeted HCC therapy, advancing epigenetic drug discovery.