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 derived from Zanthoxylum nitidum (Roxb.) DC, exhibits established anti-tumor activity; however, its molecular mechanisms in LUSC remain incompletely defined. In this study, the anti-cancer effects and underlying mechanisms of SAG were systematically investigated in vitro and in vivo. Cell viability and death were evaluated using methyl thiazolyl tetrazolium (MTT) assays, colony formation assays, flow cytometry, transmission electron microscopy (TEM), and Western blotting (WB). Drug affinity responsive target stability (DARTS) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS), molecular docking, cellular thermal shift assay (CETSA), and surface plasmon resonance (SPR) were employed to identify and validate molecular targets of SAG. The results demonstrated that SAG simultaneously induces apoptosis and ferroptosis in LUSC cells by directly targeting the endoplasmic reticulum (ER) chaperone binding immunoglobulin protein (BiP). Silencing of BiP markedly attenuated SAG-induced apoptosis and ferroptosis, confirming its essential role in this process. Mechanistically, SAG up-regulates BiP expression and activates the protein kinase R-like endoplasmic reticulum kinase (PERK)/eIF2α/C/EBP homologous protein (CHOP)/GADD34 signaling axis of ER stress (ERS), ultimately leading to dual induction of apoptosis and ferroptosis in vitro and in vivo.