Discovery of thiosemicarbazone-containing compounds with potent anti-proliferation activity against drug-resistant K562/A02 cells.

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) is a major obstacle to successful chemotherapy for leukemia. In this study, a series of thiosemicarbazone-containing compounds (4a-b, 7a-q) were synthesized. Biological evaluation showed that the most active compound 7e displayed potent anti-leukemia activity against P-gp overexpressing drug-resistant K562/A02 cells, with an IC value of 0.44 μM. Notably, compound 7e exhibited a selective killing effect on K562/A02 cells by dose-dependently increasing the intracellular levels of reactive oxygen species (ROS), thus exerting a potential collateral sensitivity (CS)-promoting effect in vitro. Moreover, compound 7e could inhibit HDAC1 and HDAC6, and induce the apoptosis of K562/A02 cells by increasing the expression of Bax, decreasing Bcl-2 protein level, and promoting the cleavage of caspase-3 and PARP, respectively. Overall, 7e may be a potential anti-cancer agent against drug-resistant myelogenous leukemia.