Enhancing Tumor Therapy of Fe(III)-Shikonin Supramolecular Nanomedicine via Triple Ferroptosis Amplification.

Ferroptosis has been considered as a promising pathway to overcome apoptosis-induced tumor chemoresistance. However, the antitumor efficacy of ferroptosis-inducing agents is still limited because of the complexity and diversity of tumor microenvironments. Herein, we demonstrate a triple ferroptosis amplification strategy for tumor therapy by associating iron-based nanocarriers, ferroptosis molecular drugs, and HO-producing enzymes. Fe(III)-Shikonin (FeShik) metal-polyphenol-coordinated networks are employed to load a ferroptosis inducer of sorafenib (SRF) inside and glucose oxidase (GOx) outside, thus producing SRF@FeShik-GOx supramolecular nanomedicines (SNs). After delivering into glutathione (GSH)-overexpressed tumor cells, FeShik will disassemble and release Fe to induce cell death via ferroptosis. At the same time, GOx executes its catalytic activity to produce an acid environment and plenty of HO for stimulating OH generation via the Fenton reaction. Moreover, SRF will suppress the biosynthesis of GSH by inhibiting system Xc, further deactivating the enzymatic activity of glutathione peroxidase 4 (GPX4). Up-regulation of the oxidative stress level and down-regulation of GPX4 expression can dramatically accelerate the accumulation of lethal lipid peroxides, leading to ferroptosis amplification of tumor cells. The current strategy that utilizes ferroptosis-inducing agents as both nanocarriers and cargoes provides a pathway to enhance the efficacy of ferroptosis-based tumor therapy.