Viscosalactone B, a natural LSD1 inhibitor, inhibits proliferation in vitro and in vivo against prostate cancer cells.

Lysine-specific demethylase 1 (LSD1) has been a promising target to treat prostate cancer, and discovery of novel LSD1 inhibitors would have great clinical significance. In this work, viscosalactone B was first identified as a novel LSD1 inhibitor. Viscosalactone B isolated from Withania Somnifera displayed antiproliferative activity against PC3, DU145, C42B, PC3/MDVR, DU145/MDVR, and C42B/MDVR cells with IC values of 1.17, 0.72, 3.86, 2.06, 0.96 and 1.15 μM, respectively. In comparison, it was a selective LSD1 inhibitor with an IC value of 970.27 nM and could induce a significant accumulation of LSD1 substrates H3K9me1, H3K9me2, and H3K4me1 in a concentration-dependent manner in DU145 cells. According to docking studies, it formed hydrogen bonds with the Thr11, Lys14, and Arg8 residues of LSD1. Importantly, while it displayed potent antitumor efficacy in vivo, it did not show obvious cytotoxicity on the major organs of nude mice. Therefore, viscosalactone B, as a novel LSD1 inhibitor, is a potential candidate that can be used for the treatment of prostate cancer in clinics.