A novel chitosan-based nanomedicine for multi-drug resistant breast cancer therapy

In this study, a novel chitosan-based (CS) nanocarrier was developed for doxorubicin (DOX) and oleanolic acid (OA) codelivery. CS was first functionalized with folic acid to allow selective uptake by cancer cells, and then subsequently with OA. The resultant copolymer self-assembled into nanoparticles (NPs) upon addition to water. These FA-CS-g-OA@DOX nanoparticles (NPs) had appropriate size (180 nm) and size distribution (PDI < 0.45) for tumor therapy, as well as a high drug-loading efficiency (15.6% w/w DOX; 5.1% w/w OA) and pH-responsive release properties. In breast cancer MDA-MB-231 cells, more efficient uptake of FA-CS-g-OA@DOX NPs than of free DOX was observed by confocal laser scanning microscopy and flow cytometry. The in vitro cytotoxicity of FA-CS-g-OA@DOX NPs against MDA-MB-231 cells was higher than with free DOX and free OA, while the NPs were less harmful to healthy HUVEC cells. In vivo pharmacokinetic studies showed that FA-CS-g-OA@DOX NPs had a much longer circulation time than free DOX, while biodistribution results revealed that FA-CS-g-OA@DOX could actively target a MDA-MB-231 xenograft tumor in mice. The NPs are found to have apoptosis-enhancing and anti-proliferative capacities in vivo. The presence of OA in the formulation both sensitizes cancer cells to DOX and mitigates DOX-induced damage to healthy tissues. The FA-CS-g-OA@DOX NPs generated in this work hence have great potential for the treatment of multi-drug resistant breast cancers, and further offer a platform to target other cancers.