Co-delivery of chitosan nanoparticles of 5-aminolevulinic acid and shGBAS for improving photodynamic therapy efficacy in oral squamous cell carcinomas

Background: The improvement of gene therapy provides hope for the treatment of cancer. However, malignant tumor is a multifactorial disease, which remains difficult to be cured with a single therapy. Our previous study reported that mitochondrial genes glioblastoma-amplified sequence (GBAS) plays a role in the development and treatment of oral squamous cell carcinoma (OSCC). The current study focused on building a mitochondrialtargeting drug co-delivery system for combined photodynamic therapy (PDT) and gene therapy. Methods: 5-aminolevulinic acid (ALA) photosensitizer loaded chitosan (CS) nanoparticles were prepared using ionic crosslinking method, and further synthesized with the GBAS gene plasmid DNA (shGBAS) by electrostatic attraction. We detected the effects of PDT using the co-delivery system (CS-ALA-shGBAS) on cell proliferation and mitochondrial injury by MTT and reactive oxygen species (ROS) assays, respectively. Additionally, a oral cancer Xenograft model of nude mice was built to test its inhibitive effect on the cancerous growth in vivo. Results: A novel nanocomposite, CS-ALA-shGBAS, was found to be spherical structures and had good dispersion, stability and hypotoxicity. Gel retardation assay showed that CS-ALA nanoparticle could synthesize shGBAS at and above Nanoparticle/Plasmid ratios of 1/2. Excitingly, the co-delivery system was suitable for transfected cells and displayed a superior mitochondrially targeted killing effect on OSCC in vitro and in vivo. Conclusion: Our study provides evidence that the chitosan-based co-delivery system of ALA-induced protoporphyrin IX (PpIX) photosensitizer and GBAS gene may be a novel mode of combined therapy for OSCC.