A rational foundation for micheliolide-based combination strategy by targeting redox and metabolic circuit in cancer cells

Accumulating evidence has supported that targeting oxidative stress and metabolic alterations of cancer is an effective strategy to combat cancer. We previously reported that Dimethylaminomicheliolide (DMAMCL) and its active metabolite micheliolide (MCL) can cause oxidative stress and cell death in leukemia and glioblastoma. However, the detailed mechanism underlying MCL or DMAMCL triggered oxidative stress remains elusive. Herein, using leukemia HL60 cells and glioblastoma U118MG cells as models, we found that MCL-induced oxidative stress is mainly mediated by reduced glutathione (GSH). Overproduced reactive oxygen species (ROS) can lead to oxidative damage to mitochondrial, impairing the ability of the tricarboxylic acid (TCA) cycle and causing dysfunction of mitochondrial respiratory chain. On the other hand, the depletion of GSH activates GSH biosynthesis pathway and has possibility to give rise to more GSH to scavenge ROS in cancer cells. Targeting this redox and metabolic circuit, we identified L-buthionine sulfoximine (BSO), an inhibitor in GSH biosynthesis, as an agent that can enhance MCL regimen to inhibit GSH compensatory event and thereby further facilitate cancer cell oxidative stress. Together, these results illustrate that targeting redox and metabolic pathway by MCL/DMAMCL combination with BSO is a potent therapeutic intervention for the treatments of glioblastoma and acute-myelocytic leukemia.