Cyclic RGDyK conjugation facilitates intracellular drug delivery of polymeric micelles to integrin-overexpressing tumor cells and neovasculature.

摘要

On the basis of the fact of the overexpression of integrins in malignant tumor cells and neovasculature, and the advantage of polymeric micelles (PM) as the drug carriers, a cyclic RGD peptide (cRGDyK) was anchored on the surface of polyethylene glycol-b-poly(lactic-co-glycolic acid) (PEG-b-PLGA) micelles as a ligand of integrins in order to enhance the intracellular delivery of encapsulated hydrophobic drug into the tumor cells and its neovasculature. Toward this goal, PEG-b-PLGA micelles without or with cRGDyK conjugation loaded with paclitaxel (PTX) or DiI were prepared and characterized. The results revealed that drug-loaded micelles were stable in solution, with small diameters (<80 nm) and a low critical micelle concentration. Spectrophotofluorometry, confocal microscopy, and flow cytometry showed that cRGDyK-conjugated micelles (TPM) facilitated the cell-specific uptake of DiI into the murine melanoma B16-F10 cells and human umbilical vein endothelial cells (HUVEC) via integrin-mediated endocytosis compared with cRGDyK-free micelles (NPM), and the uptake was proportional to the ratio of cRGDyK modification in certain range. Meanwhile, PTX-loaded TPM displayed higher cytotoxicity and antiproliferation activities against both cells than PTX-loaded NPM. These results suggest that cRGDyK-coupled PEG-b-PLGA micelles may be the promising intracellular targeting carriers for efficient delivery of chemotherapeutic agents into tumor cells and neovasculature.