Proteolysis-triggered RNA Interference for Mitochondrial Iron Dyshomeostasis to Activate Antitumor Immunity in...

Although the disturbance of iron metabolism holds significant promise for antitumor therapy, the specific regulation of the precise acting site remains challenging. Here, a self-triggering proteolysis RNA interference system (cRGD-VFs) is elaborately constructed to precisely disturb mitochondrial iron homeostasis, the core hub of cellular iron regulation, for evoking antitumor immunity. Specifically, ferritin is conjugated with E3 ligase ligand VH032 and tumor-targeting cRGD peptide through click chemistry, and further loaded with ENO1-targeted siRNA to prepare cRGD-VFs. Following the targeted uptake by tumor cells, cRGD-VFs recruits E3 ligase to initiate the ubiquitination process to trigger the proteolysis of ferritin, resulting in the release of abundant Fe²⁺ and the loaded siRNA. siRNA-mediated ENO1-targeted knockdown would upregulate the mitochondrial iron transport channel through the ENO1-IRP1-Mfrn1 pathway, which subsequently leads to mitochondrial iron overload and the increase of detrimental mitochondrial reactive oxygen species (ROS), thereby triggering severe mitochondria destruction and causing mass death of tumor cells. Noteworthily, it is found that cRGD-VFs-mediated mitochondrial iron overload can activate powerful antitumor immunity by upregulating immune-related pathways to eliminate tumors, achieving notable tumor suppression in multiple murine liver cancer models, which represents a promising strategy of disturbing mitochondrial iron homeostasis for potentiating antitumor immunotherapy.