Targeting oxeiptosis-mediated tumor suppression: a novel approach to treat colorectal cancers by sanguinarine.

Oxeiptosis is a recently identified reactive oxygen species (ROS)-sensitive, caspase independent, non-inflammatory regulated cell death pathway. The activation of Kelch-like ECH-associated protein 1-Phosphoglycerate mutase 5-Apoptosis inducing factor mitochondria associated 1 (KEAP1-PGAM5-AIFM1) pathway is the key signaling event in the execution of oxeiptosis. In the present study, we demonstrate that sanguinarine (SNG), a quaternary benzophenanthridine alkaloid, induces oxeiptosis in human colorectal cancer (CRC) cells via ROS, specifically hydrogen peroxide (HO)-dependent activation of KEAP1-PGAM5-AIFM1 signaling axis. Whilst, knockdown of KEAP1, PGAM5, and AIFM1 largely abolishes SNG-induced oxeiptosis, hence reinforcing the importance of the role of this pathway in the SNG-mediated cytotoxicity. Moreover, extracellular addition of HO sensitizes SNG-induced oxeiptosis in CRC cells, while removal of intracellular ROS by ROS scavengers, not only alleviated the overproduction of ROS caused by SNG, but also reversed the biochemical events associated with oxeiptosis. Finally, in vivo study demonstrates that SNG effectively reduces the tumor growth in HT-29 xenograft mouse model through features associated with oxeiptosis. This study highlights oxeiptosis as a novel tumor suppressive mechanism and further investigation of the role of oxeiptosis in cancer treatment is warranted.