Self-amplified ROS production from fatty acid oxidation enhanced tumor immunotherapy by atorvastatin/PD-L1 siRNA lipopeptide nanoplexes

Abstract

Despite the important role of reactive oxygen species (ROS) in battling cancer, ROS production with current approaches has been severely limited by the deficiency of oxy-substrates in tumor microenvironment. Herein, an atorvastatin (Ato)-catalytic self-amplified approach was utilized for sustainable ROS production and enhancing anti-tumor efficacy of PD-L1 silencing. A C18-pArg8-ss-pHis10 lipopeptide based self-assembled nanoplexes was developed to co-encapsulate AMP-activated protein kinase (AMPK) activator of Ato and PD-L1 siRNA. Efficient delivery of payloads was achieved because of the acidic pH triggered the protonation of pHis10, disulfide-bond exposure for cleavage and subsequent cytosolic translocation. Ato was found to activate AMPK, boosting the highly restrained mitochondrial fatty acid oxidation (FAO) in cancer cells for ROS production. The ROS derived from FAO further activated AMPK, creating a positive-feedback mechanism of sustainable ROS production. The self-amplified ROS production from cellular mitochondrial FAO was maintained by the sufficient intracellular fatty acid substrates arising from the dysregulated lipid metabolism and Ato inhibited triglyceride synthesis in cancer cells. The excessive ROS level was found to successfully induce immunogenic cell death effect, boosting the anti-tumor efficacy of PD-L1 silencing. Overall, the Ato catalyzed self-amplified ROS production has been demonstrated as a promising alternative for cancer therapy.