Enhanced docetaxel delivery using sterically stabilized RIPL peptide-conjugated nanostructured lipid carriers: In vitro and in vivo antitumor efficacy against SKOV3 ovarian cancer cells.

Docetaxel (DTX) has poor solubility, low specificity, and severe side effects. For efficient targeting of DTX to hepsin-overexpressing SKOV3 ovarian cancer cells, PEGylated and RIPL peptide (IPLVVPLRRRRRRRRC)-conjugated nanostructured lipid carriers (PEG-RIPL-NLCs) were examined for in vitro and in vivo antitumor efficacy. DTX-loaded plain NLCs (DTX-pNLCs), RIPL-NLCs (DTX-RIPL-NLCs), and PEG-RIPL-NLCs (DTX-PEG-RIPL-NLCs) were prepared using a solvent emulsification-evaporation technique. DTX was successfully loaded with high encapsulation efficiency (>93%), and all NLCs showed homogeneous dispersion with zeta potentials varying from -17 to 15 mV. Drug release was biphasic: initial rapid release, then gradual release. In vitro cytotoxicity was time- and dose-dependent: DTX-RIPL-NLCs and DTX-PEG-RIPL-NLCs exhibited greater cytotoxicity, enhanced cell apoptosis owing to the cell cycle arrest in the G2/M phase, and increased activation of the mitochondria-related intrinsic apoptosis pathway compared to DTX-pNLCs. Pharmacokinetic experiments in male Sprague-Dawley rats revealed that DTX-PEG-RIPL-NLCs increased the mean residence time of DTX but reduced total body clearance and volume of distribution. In a SKOV3-bearing xenograft Balb/c athymic mouse model, DTX-PEG-RIPL-NLCs suppressed tumors, evidenced by tumor volume change and histopathological examination. Thus, we conclude that PEG-RIPL-NLCs have an advantage of high payload of poorly water-soluble drugs and are a good candidate for drug targeting to SKOV3-derived ovarian cancer.