Endocytosis Pathway Self-Regulation for Precise Image-Guided Therapy through an Enzyme-Responsive Modular Peptide Probe

Before arriving at the intracellular destinations, probes might be trapped in the lysosomes, reducing the amount of cargos, which compromises the therapeutic outcomes. The current methods are based on the fact that probes enter the lysosomes and then escape from them, which do not fundamentally solve the degradation by lysosomal hydrolases. Here, an enzyme-responsive modular peptide probe named PKP that can be divided into two parts, Pal-part and KP-part, by matrix metalloproteinase-2 (MMP-2) overexpressed in tumor microenvironments is designed. Pal-part quickly enters the cells and forms nanofibers in the lysosomes, decreasing protein phosphatase 2A (PP2A), which transforms the endocytic pathway of KP-part from clathrin-mediated endocytosis (CME) into caveolae-mediated endocytosis (CvME) and allows KP-part to directly reach the mitochondria sites without passing through the lysosomes. Finally, through self-regulating intracellular delivery pathways, the mitochondrial delivery efficiency of KP-part is greatly improved, leading to an optimized image-guided therapeutic efficiency. Furthermore, this system also shows great potential for the delivery of siRNA and doxorubicin to achieve precise cancer image-guided therapy, which is expected to significantly expand its application and facilitate the development of personalized therapy.