Induction of apoptosis by chitosan/HPV16 E7 siRNA complexes in cervical cancer cells

Consecutive expression of the high‑risk human papillomavirus (HPV) oncoproteins, E6 and E7, is pivotal for malignant transformation and maintenance of the malignant phenotype. These oncogenes may be potential targets of gene silencing‑based molecular therapies for human cervical cancer. The aim of the present study was to evaluate the efficacy of chitosan‑based HPV16 E7 siRNA delivery and the chitosan/HPV16 E7 siRNA complex in the induction of apoptosis in CaSki cells constitutively expressing HPV16 E6 and E7. Chitosan/siRNA nanoparticles were prepared by adding a chitosan solution drop‑wise to an equal volume of siRNA solution. Formation of the chitosan/siRNA complex was verified by gel retardation assays and the entry of siRNA into the cells was confirmed by fluorescence microscopy. Expression of HPV16 E7 was examined by western blot analysis and apoptotic cells were detected by TUNEL staining. Chitosan formed complexes with HPV16 E7 siRNA. The chitosan/siRNA nanoparticles were efficiently delivered into CaSki cells and were observed to induce apoptosis. In conclusion, chitosan is suitable for use as a carrier for delivery of siRNA into cancer cells. The delivery of chitosan/HPV16 E7 siRNA nanoparticles in vivo may serve as a promising therapy for cervical cancer.