Advancing 599 Peptide siRNA-Carrier Designs For Treatment Of Oral Cancer

Objectives: The objective of this study was to examine chemical variants of the 599 peptide carrier and their ability to deliver bioactive small interfering RNAs (siRNAs) into oral cancer cells to induce silencing of the targeted oncoprotein, CIP2A.
Methods: The 599 peptide was chemically modified to generate 8 different variants. Gel-shift assays were used to analyze both the binding and stability of siRNAs in complex with the 599 peptide carrier variants. Moreover, fluorescence microscopy, qPCR, and western blot analyses were used to assess the siRNA uptake into oral cancer cells and the gene silencing efficiencies mediated by the 599 peptide carrier variants.
Results: Gel-shift assays demonstrated that specific chemical modifications of the 599 peptide carrier can either increase or decrease their ability to bind siRNAs or protect them from nuclease-mediated degradation. Moreover, fluorescence microscopy analysis suggested that variants of the 599 peptide carrier can affect the degree of cellular uptake and intracellular localization pattern of the siRNA cargo. qPCR studies demonstrated that chemical variations in the 599 peptide carrier design could both increase and decrease the efficacy of gene silencing of CIP2A. Subsequent western blot analyses further corroborated that several variants of the 599 peptide carrier were able to more efficiently induce CIP2A knockdown than others.
Conclusions: Together, these data demonstrate the utility of specific chemical modifications in advancing the 599 peptide carrier design in its ability to more effectively target and deliver bioactive siRNAs to oral cancer cells.