Enhanced antitumor efficacy by cyclic RGDyK-conjugated and paclitaxel-loaded pH-responsive polymeric micelles

Cyclic RGDyK (cRGDyK)-conjugated pH-sensitive polymeric micelles were fabricated for targeted delivery of paclitaxel to prostate cancer cells based on pH-sensitive copolymer poly(2-ethyl-2-oxazoline)-poly(d,l-lactide) (PEOz-PLA) and cRGDyK-PEOz-PLA to enhance antitumor efficacy. The prepared micelles with an average diameter of about 28 nm exhibited rapid release behavior at endo/lysosome pH, effectively enhanced the cytotoxicity of paclitaxel to PC-3 cells by increasing the cellular uptake, which was correlated with integrin αvβ3 expression in tumor cells. The active targeting activity of the micelles was further confirmed by in vivo real time near-infrared fluorescence imaging in PC-3 tumor-bearing nude mice. Moreover, the active targeting and pH-sensitivity endowed cRGDyK-conjugated micelles with a higher antitumor effect in PC-3 xenograft-bearing nude mice compared with unmodified micelles and Taxol with negligible systemic toxicity. Therefore, these results suggested that cRGDyK-conjugated pH-sensitive polymeric micelles may be a promising delivery system for efficient delivery of anticancer drugs to treat integrin αvβ3-rich prostate cancers.