Skin Cancer’s Personalized Topical Gene Therapy by Non-Viral Q-Starch/siRNA Nano-complexes
Skin cancers are currently treated mostly by infiltrative surgical methods, radiation and chemotherapy. Multiple tumor promoting pathways involved in melanoma and non-melanoma skin cancers, require invoking other strategies to detect prominent oncogenes of the diseases. RNA interference (RNAi) has the potential to serve as a therapeutic tool for treating skin cancer, but delivering functional RNAs to skin cells is challenging mainly due to the stratum corneum`s barrier properties. We therefore aim to exploit RNAi therapy, using ultrasound as a skin penetration enhancer, and modified polysaccharide/siRNA nano-complexes as a non-invasive, non-viral RNAi delivery system, that consequently downregulate specific oncogenes detected in melanoma and non-melanoma skin cancers, resulting in personalized gene therapy. Biocompatible and biodegradable potato starch was modified with positively charged quaternary amine groups (Q-starch) and electrostatically self-assembled with negatively charged siRNA to form complexes, that were characterized by gel electrophoresis, Zeta potential analyzer, DLS and FTIR. Q-starch/siRNA complexes were found to be ~80 nm in diameter with positive zeta potential, demonstrating nano-sized complexes capable of penetrating the cells` membrane, and indication of possible electrostatic interactions between the complexes and the negatively charged cell`s membrane. In vitro transfection and cellular uptake experiments on Basal Cell Carcinoma cell line (TE 354.T) and Melanoma cell line (a-375) measured by flow cytometry methods using fluorescently labeled complexes, demonstrated an efficient uptake of Q-starch/siRNACy5 complexes in various concentrations and their accumulation in the cytoplasm of the cells. RT-PCR demonstrated gene silencing in all concentrations, up to 70%, after 72 hours with Q-starch/siRNA nano-complexes.