An ATF ₂₄ peptide-functionalized β-elemene-nanostructured lipid carrier combined with cisplatin for bladder cancer treatment

Objective: In this study, we aimed to develop an amino-terminal fragment (ATF) peptide-targeted liposome carrying β-elemene (ATF₂₄-PEG-Lipo-β-E) for targeted delivery into urokinase plasminogen activator receptor-overexpressing bladder cancer cells combined with cisplatin (DDP) for bladder cancer treatment. Methods: The liposomes were prepared by ethanol injection and high-pressure microjet homogenization. The liposomes were characterized, and the drug content, entrapment efficiency, and in vitro release were studied. The targeting efficiency was investigated using confocal microscopy, ultra-fast liquid chromatography, and an orthotopic bladder cancer model. The effects of ATF₂₄-PEG-Lipo-β-E combined with DDP on cell viability and proliferation were evaluated by a Cell Counting Kit-8 (CCK-8) assay, a colony formation assay, and cell apoptosis and cell cycle analyses. The anticancer effects were evaluated in a KU-19-19 bladder cancer xenograft model. Results: ATF₂₄-PEG-Lipo-β-E had small and uniform sizes (˜79 nm), high drug loading capacity (˜5.24 mg/mL), high entrapment efficiency (98.37 ± 0.95%), and exhibited sustained drug release behavior. ATF₂₄-PEG-Lipo-β-E had better targeting efficiency and higher cytotoxicity than polyethylene glycol (PEG)ylated β-elemene liposomes (PEG-Lipo-β-E). DDP, combined with ATF₂₄-PEG-Lipo-β-E, exerted a synergistic effect on cellular apoptosis and cell arrest at the G2/M phase, and these effects were dependent on the caspase-dependent pathway and Cdc25C/Cdc2/cyclin B1 pathways. Furthermore, the in vivo antitumor activity showed that the targeted liposomes effectively inhibited the growth of tumors, using the combined strategy. Conclusions: The present study provided an effective strategy for the targeted delivery of β-elemene (β-E) to bladder cancer, and a combined strategy for bladder cancer treatment.

Keywords: DDP; active targeting liposome; bladder cancer; uPAR; β-elemene.