Sanguinarine Triggers Apoptosis and Ferroptosis Synchronously by Directly Binding BiP in Lung Squamous Cell Carcinoma

Lung squamous cell carcinoma (LUSC) is a prevalent and aggressive form of lung cancer with limited therapeutic options. Sanguinarine (SAG), a prominent benzophenanthridine alkaloid found in Chelidonium majus and known for its antitumour properties, was investigated to understand the molecular mechanisms of its anticancer effects on LUSC both in vitro and in vivo. This study utilized the MTT assay, colony formation assay, flow cytometry, transmission electron microscopy (TEM) and western blotting (WB) to evaluate cellular apoptosis and ferroptosis. Furthermore, drug affinity responsive target stability (DARTS) combined with liquid chromatography‒mass spectrometry (LC‒MS/MS), molecular docking (AutoDock), cellular thermal shift assay (CETSA), DARTS, and surface plasmon resonance (SPR) were employed to identify the targets of SAG and the interaction between SAG and its targets. Our findings revealed that SAG simultaneously induced apoptosis and ferroptosis in LUSC cells by directly binding to the ER chaperone BiP (binding immunoglobulin protein). The knockdown of BiP reversed the SAG-induced apoptosis and ferroptosis of LUSC cells. Mechanistically, SAG activated the PERK/eIF2α/chop/GADD34 pathway of ERS by upregulating BiP, ultimately leading to cell apoptosis and ferroptosis in vitro and in vivo.