Novel non-covalent LSD1 inhibitors endowed with anticancer effects in leukemia and solid tumor cellular models

LSD1 is a histone lysine demethylase proposed as therapeutic target in cancer. Chemical modifications applied at C2, C4 and/or C7 positions of the quinazoline core of the previously reported dual LSD1/G9a inhibitor 1 led to a series of non-covalent, highly active, and selective LSD1 inhibitors (2-4 and 6-30) and to the dual LSD1/G9a inhibitor 5 that was more potent than 1 against LSD1. In THP-1 and MV4-11 leukemic cells, the most potent compounds (7, 8, and 29) showed antiproliferative effects at sub-micromolar level without significant toxicity at 1 μM in non-cancer AHH-1 cells. In MV4-11 cells, the new derivatives increased the levels of the LSD1 histone mark H3K4me2 and induced the re-expression of the CD86 gene silenced by LSD1, thereby confirming the inhibition of LSD1 at cellular level. In breast MDA-MB-231 as well as in rhabdomyosarcoma RD and RH30 cells, taken as examples of solid tumors, the same compounds displayed cell growth arrest in the same IC₅₀ range, highlighting a crucial anticancer role for LSD1 inhibition and suggesting no added value for the simultaneous G9a inhibition in these tumor cell lines.