Menin-MLL inhibitors induce ferroptosis and enhance the anti-proliferative activity of auranofin in several types of cancer cells

Abstract

Menin-mixed-lineage leukemia (MLL) inhibitors have potential for use as therapeutic agents for MLL-rearranged leukemia. They are also effective against solid cancers, such as breast cancer. The present study demonstrated that menin-MLL inhibitors, such as MI-463, unexpectedly induced the ferroptotic cell death of several cancer cell lines. MI-463 at a double-digit nM concentration markedly decreased the viable number of OVCAR-8 ovarian cancer cells for 3 days. Ferrostatin-1 (a ferroptosis inhibitor) almost completely abrogated the MI-463-induced decrease in viable cell numbers. Furthermore, the cancer cell-killing activity was inhibited by N-acetylcysteine [a scavenger of reactive oxygen species (ROS)], deferoxamine (DFO, an iron chelator), PD146176 (a specific inhibitor of arachidonate 15-lipoxygenase), idebenone (a membrane-permeable analog of CoQ10) and oleic acid [a monounsaturated fatty acid and one of the end products of stearoyl-CoA desaturase 1 (SCD1)], whereas Z-VAD-FMK (an apoptosis inhibitor) had a negligible effect on cell death. It was also found that MI-463 in combination with auranofin (a thioredoxin reductase inhibitor) synergistically increased cancer the death of breast, ovarian, pancreatic and lung cancer cell lines (88%, 14/16 cell lines). The synergistic induction of cell death was abrogated by ferroptosis inhibitor and DFO. Inhibitors of SCD1, similar to MI-463, also enhanced cancer cell death synergistically with auranofin, while inhibitors of SCD1 and MI-463 did not additively induce cell death. Treatment with zinc protoporphyrin-9, a specific inhibitor of heme oxygenase-1 (HO-1), markedly attenuated the cell death induced by MI-463 plus auranofin. On the whole, these results suggest that the MI-463-induced decrease in cell viability may be at least partly associated with the inhibition of SCD1 activity. In addition, the potent induction of HO-1 contributed to the synergistic effects of MI-463 plus auranofin. Therefore, menin-MLL inhibitors, such as MI-463, in combination with auranofin represent an effective therapeutic approach for several types of cancer via the induction of ferroptosis.