MPEG-CS/Bmi-1RNAi Nanoparticles Synthesis and Its Targeted Inhibition Effect on CD133+ Laryngeal Stem Cells

Previous studies have confirmed that CD133(+) cells in laryngeal tumor tissue have the characteristics of cancer stem cells. Bmi-1 gene expression is central to the tumorigenicity of CD133(+) cells. In this study, we tried to develop a new siRNA carrier system using chitosan-methoxypolyethylene nanoparticles (CS-mPEG-NPs) that exhibit higher tumor-targeting ability and enhanced gene silencing efficacy in CD133(+) tumor stem cells. It is hoped to block the self-renewal and kill the stem cells of laryngeal carcinoma. The mPEG-CS-Bmi-1RNAi-NPs were synthesized and their characters were checked. The changes in invasion ability and sensitivity to radiotherapy and chemotherapy of CD133(+) Hep-2 tumor cells were observed after Bmi-1 gene silencing. The mPEG-CS-Bmi-1RNAi-NPs synthesized in this experiment have a regular spherical form, a mean size of 139.70 +/- 6.40 nm, an encapsulation efficiency of 85.21 +/- 1.94%, with drug loading capacity of 18.47 +/- 1.83%, as well as low cytotoxicity, providing good protection to the loaded gene, strong resistance to nuclease degradation and high gene transfection efficiency. After Bmi-1 gene silencing, the invasion ability of CD133(+) cells was weakened. Co-cultured with paclitaxel, the survival rates of CD133(+) Bmi-1RNAi cells were lower. After radiotherapy, the mean growth inhibition rate of CD133(+)/Bmi-1RNAi cells was significantly lower than CD133(+) cells. In conclusion, the mPEG-CS nano-carrier is an ideal vector in gene therapy, while silencing the Bmi-1 gene can enhance the sensitivity of CD133(+) tumor stem cells to chemoradiotherapy and abate their invasion ability.