Awakening p53 in vivo by D-peptides-functionalized ultra-small nanoparticles: Overcoming biological barriers to D-peptide drug delivery

Peptides are a rapidly growing class of therapeutics with many advantages over conventional small molecule drugs. Dextrorotary (D)-peptides, with increased enzymatic stability and prolonged plasma half-life in comparison with natural L-peptides, are considered to have great potential as recognition molecules and therapeutic agents. However, the in vivo efficacy of current therapeutic D-peptides is hindered by their inefficient cellular uptake in diseased tissues. Methods: To overcome physiological and cellular barriers to D-peptides, we designed a gold-based ultra-small nanocarrier coupled with polylysine (PLL) and a receptor-targeted peptide to deliver therapeutic D-peptides. Using a D-peptide p53 activator (DPA) as a proof of concept, we synthesized, functionalized and characterized gold- and DPA-based nanoparticles termed AuNP-DPA. Results: AuNP-DPA were effectively enriched in tumor sites and subsequently internalized by cancer cells, thereby suppressing tumor growth via reactivating p53 signaling. More importantly, through a series of in vivo experiments, AuNP-DPA showed excellent biosafety without the common side effects that hinder p53 therapies in clinic trials. Conclusion: The present study not only sheds light on the development of AuNP-DPA as a novel class of antitumor agents for drugging the p53 pathway in vivo, but also supplies a new strategy to use D-peptides as intracellular PPI inhibitors for cancer-targeted therapy.