Cell Surface Nucleolin as a Promising Receptor for Effective AS1411 Aptamer-Mediated Targeted Drug Delivery into Cancer Cells

Background: One of the major abundant proteins in the nucleous is nucleolin that overexpressed on the cytoplasmic membrane of malignant and endothelial cells and makes it as a promising condidate for targeted drug delivery. Objectives: In this study, doxorubicin (Dox) as a chemotherapy drug was entrapped into the Poly lacticco- glycolic acid (PLGA)-based nanoparticles (NPs). Then, the targeting ability of anti nucleolin AS1411 aptamer-targeted Dox-encapsulated PLGA-based NPs (AS1411-NPs) was investigated in high nucleolin-expressing C26 colon carcinoma and rat C6 glioma cell lines compared with low nucleolinexpressing mouse L929 cell line. Methods: We recently first assessed the existence of cell surface nucleolin of these three different cell lines by immunocytochemistry method. We found that a large amount of nucleolin was localized in the cytoplasmic membrane of C26 and C6 cell lines, with a very smaller amount on the surface of L929 cell line. Results: As a result, more rapidly internalization of AS1411-NPs into the C26 and C6 cells compared with L929 cells was verified. Conclusion: We think that AS1411-NPs, as a ligand, first bind to nucleolin, as a receptor, and then the receptor-ligand complex is more efficiently incorporated into the high nucleolin-expressing cell lines through receptor-mediated endocytosis pathway.