Protein-based drug carrier specific for HER2-positive breast cancer cells

The aim of this study was to design a protein-based single chain vehicle that be able to recognize and enter HER2-overexpressing cancer cells and subsequently enter their nuclei. To this end, we conjugated VH domain of an anti-HER2 antibody (Herceptin) as HER2 targeting element, nine arginine residues (summarily called 9R) as cell penetrating peptide (CPP), and nuclear localization signals (NLSs) of TUS and c-Myc proteins as nuclear delivery mediators. The recombinant construct was labeled with FITC fluorescent dye to trace within the cells. Fluorescent imaging revealed that the construct was able to specifically recognize HER2-overexpressing cells and enter their nuclei.