Tumor suppressor protein-inspired peptide for siRNA delivery and synergistic cancer therapy

Small interfering RNA (siRNA) has shown promising therapeutic prospects in many major diseases. However, two main reasons limit the application of siRNA: poor endocytosis efficiency and weak endosomal escape ability. Therefore, the development of efficient and safe delivery vectors has always been an important study aspect of RNAi technology. Herein, we designed a self-assembled nanoparticle based on functionalized peptides to deliver siRNA to the down-regulated polo-like kinase 1 (PLK1) gene, which can inhibit tumor cells in the G2 phase. The functional polypeptide consists of cell membrane-penetrating peptide (CPP44) and p16 minimal inhibitory sequence (p16MIS). CPP44 can effectively mediate endocytosis, while p16MIS can inhibit tumor growth in the G1 phase and synergistically promote the apoptosis of tumor cells with siPLK1. <i>In vitro</i> and <i>in vivo</i> studies demonstrate that the developed nanoparticle exhibits high levels of silencing efficiency, antitumor activity, and therapeutic efficacy. Consequently, this study provides a novel approach to cancer treatment by simultaneously disrupting two stages of tumor cell division.