Novel acridine-based LSD1 inhibitors enhance immune response in gastric cancer

Recently, histone lysine specific demethylase 1 (LSD1) has become an emerging and promising target for cancer immunotherapy. Herein, based on our previously reported LSD1 inhibitor DXJ-1 (also called 6x ), a series of novel acridine-based LSD1 inhibitors were identified via structure optimizations. Among them, compound 5ac demonstrated significantly enhanced inhibitory activity against LSD1 with an IC 50 value of 13 nM, about 4.6-fold more potent than DXJ-1 (IC 50  = 73 nM). Molecular docking studies revealed that compound 5ac could dock well into the active site of LSD1. Further mechanism studies showed that compound 5ac inhibited the stemness and migration of gastric cancer cells, and reduced the expression of PD-L1 in BGC-823 and MFC cells. More importantly, BGC-823 cells were more sensitive to T cell killing when treated with compound 5ac . Besides, the tumor growth was also suppressed by compound 5ac in mice. Together, 5ac could serve as a promising candidate to enhance immune response in gastric cancer.