GSH/pH Dual Activatable Cross-linked and Fluorinated PEI for Cancer Gene Therapy Through Endogenous Iron De-Hijacking and in Situ ROS Amplification

Ferroptosis-related cancer therapy is limited by insufficient Fe2+/Fe3+ redox pair and hydrogen peroxide (H2O2) for producing lethal hydroxyl radicals (center dot OH). Although exogenous iron or ROS-producing drugs can enhance ferroptosis, exploiting endogenous iron (labile iron pool, LIP) stored in ferritin and promoting ROS generation may be safer. Herein, a metal/drug-free nanomedicine is developed for responsive LIP release and H2O2 generation on the mitochondria membranes, amplifying hydroxyl radical production to enhance ferroptosis-mediated antitumor effects. A glutathione(GSH)/pH dual activatable fluorinated and cross-linked polyethyleneimine (PEI) with dialdehyde polyethylene glycol layer nanocomplex loaded with MTS-KR-SOD (Mitochondria-targeting-sequence-KillerRed-Superoxide Dismutase) and CRISPR/Cas9-CA IX (Carbonic anhydrase IX (CA IX)) plasmids (FP@MC) are developed for enhanced ferroptosis through endogenous iron de-hijacking and in situ ROS amplification. Two plasmids are constructed to knockdown CA IX and translate KillerRed-SOD recombinant protein specifically on mitochondria membranes, respectively. The CA IX knockdown acidifies the intracellular environment, leading the release of LIP from ferritin as a "flare" to initiate endogenous chemodynamic therapy. Meanwhile, MTS-KR-SOD generates H2O2 when irradiated by a 590 nm laser to assist chemodynamic therapy, leading to ROS amplification for mitochondria damage and lipid peroxide accumulation. The combined therapeutic effects aggravate cancer ferroptosis and suppress tumor growth, providing a new paradigm for amplifying ROS and iron ions to promote ferroptosis-related cancer therapy. The GSH/pH dual activatable fluorinated PEI system is used to transfect MTS-KR-SOD and Cas-CA IX plasmids into B16-F10 cancer cells in vitr and in vivo. Decreased intracellular pH caused by the knockdown of CA IX de-hijacked Fe2+ from ferritin, ignited H2O2 fuel triggered by laser irradiated MTS-KillerRed-SOD for enhanced ferroptosis. Thus, achieving cascade-amplify ROS cytotoxicity by photodynamic-assisted endogenous chemodynamic therapy.image