RIP3 mediates TCN-induced necroptosis through activating mitochondrial metabolism and ROS production in apoptosis-resistant cancer cells
Abstract Background: Resisting cell death is one of the hallmarks of cancer. Necroptosis is a form of non-caspase dependent necrotic cell death mediated by receptor-interacting protein kinase-1/3 (RIP1/3), which represents another mode of programmed cell death besides apoptosis. Growing evidence supports that RIP3 has emerged as a critical regulator of necroptosis and can be activated by several stimuli to trigger necroptotic cell death in a RIP1-independent manner. RIP3 also acts as an energy metabolism regulator associated with switching cell death from apoptosis to necroptosis. Natural products provide a unique source for the discovery of innovative leading compounds and drugs, which exhibits promising anticancer activities through inducing cell death and enhancing chemotherapeutic sensitivity. Trichothecin (TCN) is a sesquiterpenoid originating from an endophytic fungus of the herbal plant Maytenus hookeri Loes and shows potent anti-tumor bioactivity. However, the underlying mechanism is not fully understood.Methods: Cell permeability assay and transmission electron microscopy were applied to identify the death pattern induced by TCN in apoptotic-resistant cancer cells. We used Seahorse extracellular flux analyzer to examine the cellular oxygen consumption rate (OCR) and flow cytometry to detect mitochondrial reactive oxygen species (ROS) content. Xenograft animal experiment was performed to assess the effect of TCN synergized with cisplatin to enhance chemotherapeutic sensitivity of tumor cells. Results: Our current findings revealed that RIP3 mediated TCN-induced necroptosis through activating mitochondria energy metabolism and ROS production in apoptotic-resistant cancer cells. RIP3 might be involved in sensitizing tumor cells to chemotherapy induced by TCN. Conclusions: Activating RIP3 to induce necroptosis through reprogramming mitochondrial energy metabolism and ROS production contributes to the anti-tumor activity of TCN. Moreover, TCN could be exploited for therapeutic gain through up-regulating RIP3 to sensitize cancer chemotherapy.