Paeoniflorigenone triggers TRIM28 phosphorylation-dependent ferroptosis and immune activation to suppress intrahepatic cholangiocarcinoma.

Intrahepatic cholangiocarcinoma is a highly lethal malignancy characterized by a rising incidence and a dismal 5-year survival rate of < 10%. While targeted therapies and immunotherapies have expanded treatment paradigms, their clinical efficacy remains hampered by modest patient response rates. Here, we identify total glucosides of paeony and its principal bioactive monomer, paeoniflorigenone (PFG), as potential effective therapeutic agents against ICC, demonstrating potent suppression of malignant phenotypes across multi-dimensional ICC models. Transcriptomic profiling identified ferroptosis as the primary mechanism driving PFG-induced ICC cell death, which is hallmarked by intracellular Fe²⁺ overload, robust ROS generation, and lipid peroxidation. Mechanistically, PFG directly binds to TRIM28, triggering its phosphorylation at Ser824. This modification alleviates repressive H3K9me3 occupancy at the HMOX1 promoter, thereby unlocking local chromatin accessibility to drive HMOX1 transcription and culminate in ferroptosis. Notably, PFG-induced ferroptosis not only curbs ICC cell proliferation and migration but also activates antigen presentation and reshapes a tumoricidal immune microenvironment, characterized by enhanced infiltration and activation of CD8⁺ cytotoxic T cells. In summary, this study unveils a previously unrecognized ferroptosis regulatory pathway-the TRIM28/H3K9me3/HMOX1 axis-and demonstrates that PFG may represent a potential natural small-molecule candidate for ICC treatment.