Necroptosis signaling and mitochondrial dysfunction cross-talking facilitate cell death mediated by chelerythrine in glioma

Glioma is the most common primary malignant brain tumor with poor survival and limited therapeutic options. Chelerythrine (CHE), a natural benzophenanthridine alkaloid, has been reported to exhibit the anti-tumor effects in a variety of cancer cells. However, the molecular target and the signaling process of CHE in glioma remain elusive. Here we investigated the underlying mechanisms of CHE in glioma cell lines and glioma xenograft mice model. Our results found that CHE-induced cell death is associated with RIP1/RIP3-dependent necroptosis rather than apoptotic cell death in glioma cells at the early time. Mechanism investigation revealed the cross-talking between necroptosis and mitochondria dysfunction that CHE triggered generation of mitochondrial ROS, mitochondrial depolarization, reduction of ATP level and mitochondrial fragmentation, which was the important trigger for RIP1-dependent necroptosis activation. Meanwhile, PINK1 and parkin-dependent mitophagy promoted clearance of impaired mitochondria in CHE-incubated glioma cells, and inhibition of mitophagy with CQ selectively enhanced CHE-induced necroptosis. Furthermore, early cytosolic calcium from the influx of extracellular Ca2+ induced by CHE acted as important "priming signals" for impairment of mitochondrial dysfunction and necroptosis. Suppression of mitochondrial ROS contributed to interrupting positive feedback between mitochondrial damage and RIPK1/RIPK3 necrosome. Lastly, subcutaneous tumor growth in U87 xenograft was suppressed by CHE without significant body weight loss and multi-organ toxicities. In summary, the present study helped to elucidate necroptosis was induced by CHE via mtROS-mediated formation of the RIP1-RIP3-Drp1 complex that promoted Drp1 mitochondrial translocation to enhance necroptosis. Our findings indicated that CHE could potentially be further developed as a novel therapeutic strategy for treatment of glioma.