SOX9 siRNA Loaded Lipid Nanoparticles Actively Targeted: Formulation, Delivery, and Antitumor Effect on Colorectal Cancer In Vitro and In Vivo

Small interfering RNA (siRNA)-based therapy, which silences disease-associated genes, has emerged as a potential therapeutic strategy for various disorders, including cancer. Lipid nanoparticles (LNPs) have become a leading platform for efficient siRNA delivery. SOX9, a family member of SRY-related high-mobility-group box (SOX) transcription factors, plays an important role in the pathogenesis and progression of colorectal cancer (CRC). Here, we developed cRGDfK peptide-modificed LNPs (R-LNPs) composed of DLin-MC3-DMA, DMG-PEG, DSPC, DSPE-PEG-cRGDfK, and cholesterol for the targeted delivery of SOX9 siRNA (siSOX9) in CRC treatment. The formulation, delivery, and antitumor effect on CRC in vitro and in vivo were explored. The optimized R-LNPs exhibited favorable physicochemical properties including a uniform particle size (159.6 ± 0.93 nm), low polydispersity index (PDI = 0.207 ± 0.016), near-neutral zeta potential (2.74 ± 0.35 mV), and high encapsulated efficiency (90.71 ± 1.63%). Additionally, R-LNPs demonstrated sustained and controlled in vitro release and good serum stability. The prepared R-LNPs were efficiently uptaken by HCT-116 via clathrin, lipid rafts, and caveolae dependent endocytosis and macropinocytosis. Subsequently, R-LNPs were colocalized with lysosomes before escaping into the cytoplasm, ensuring effective siRNA release. In vivo distribution studies confirmed tumor-specific accumulation for R-LNPs in HCT-116 xenograft models. Functionally, R-LNPs loading siSOX9 inhibited the proliferation, migration, and invasion of HCT-116 cells and Caco-2 cells ( P < 0.05 or 0.01) and inhibited tumor growth and proliferation in tumor-bearing mice ( P < 0.05 or 0.01). The antitumor effects were attributed to the silence of SOX9, which subsequently downregulated key oncogenic mediators, including β-catenin, cyclin D1, and c-Myc ( P < 0.05 or 0.01). Furthermore, R-LNPs demonstrated favorable safety in in vivo application. In conclusion, our cRGDfK-modified LNPs loading siSOX9 represent a promising targeted therapeutic strategy for CRC, offering both efficacy and biocompatibility.