Self-catalyzed nitric oxide nanocomplexes induce ferroptosis for cancer immunotherapy.

Ferroptosis, triggered by membrane lipid peroxidation (LPO) and diminished antioxidants, can be induced by intracellular iron (II, Fe). However, the role of nitric oxide (NO) in causing Fe overload for ferroptosis remains uncertain. This study reveals that NO can stimulate endogenous Fe release by upregulating heme oxygenase 1 (HMOX1) expression. Here, ferritin heavy chain (FHC) siRNA and hyaluronic acid (HA)-modified Arg-stabilized zinc peroxide (AZOSH), a non-ferrous-based nanoagent, is synthesized to trigger ferroptosis by inducing intracellular Fe overload. AZOSH, a self-catalyzed NO nanocomplex, effectively generates NO through a reaction of self-supplied Arginine (Arg) and hydrogen peroxide (HO), which promotes glutathione (GSH) consumption to downregulate glutathione peroxidase 4 (GPX4) expression and produces peroxynitrite (ONOO) to enhance LPO. Meanwhile, NO promotes endo/lysosomal escape of siRNA by damaging membrane structures. Moreover, AZOSH significantly triggers Fe overload through the synergistic effects of NO-activated HMOX1 expression and FHC siRNA-mediated ferritin sequestration. Additionally, the released Zn from AZOSH induces oxidative stress by inhibiting mitochondrial function, further promoting ferroptosis. Consequently, AZOSH-mediated ferroptosis exhibits a strong cellular immunogenic response for T-cell activation and infiltration. Importantly, the integration of AZOSH with an anti-PD-1 antibody results in notable antitumor efficacy in vivo. Therefore, this study provides a novel concept of NO-induced ferroptosis, highlighting its role in enhancing PD-1-based immunotherapeutic efficacy.