ROS-Activatable siRNA-Engineered Polyplex for NIR-Triggered Synergistic Cancer Treatment.

Small interfering RNA (siRNA) shows excellent pharmaceutical prospects in treating diverse life-threatening diseases. Photodynamic therapy (PDT) is a clinically employed noninvasive treatment method that can trigger selective damage toward targeted tissue and cells. However, insufficient delivery of siRNA and photosensitizer to cancer cells remarkably hindered the application of siRNA and PDT in the treatment of cancer. In this study, a unique reactive oxygen species (ROS)-activatable polyplex, which consists of the PEGylated cationic polymer, ROS-cleavable linker, photosensitizer Ce6, and RRM2-against siRNA, termed PPTC/siRNA, was engineered. Upon irradiation of near-infrared (NIR) light, the polyplex efficiently generated ROS, which triggered degradation of the ROS-sensitive linker, disassembling the complex, destabilization of the cell membrane, and significantly accelerated cellular entry and endosomal escape of siRNA. Besides achieving effective siRNA internalization and gene silence in cancer cells in vitro, PPTC/siRNA synergistically inhibited tumor growth in both cell line-derived xenograft and patient-derived xenograft hepatocellular carcinoma murine models by repressing the RRM2 expression (reducing cell proliferation) and triggering photodynamic killing (enhancing cell apoptosis). The proposed polyplex also showed ideal safety profiles both in cell line and in animal. It provides a novel strategy for NIR-triggered RNAi and PDT combinational cancer treatment.