Effective suppression of the Kirsten rat sarcoma viral oncogene in pancreatic tumor cells via targeted small interfering RNA delivery using nanoparticles.

The objective of this study was to establish an efficient carrier for small interfering RNA (siRNA) delivery targeting pancreatic tumor cells. A copolymer consisting of a single-chain variable fragment targeted to human CD44 variant 6 (scFv(CD44v6)) functional group conjugated to polyethylene glycol-poly-L-lysine was synthesized and assembled into micelles encapsulating the siRNAs. Flow cytometry and Western blot assays were performed to evaluate the transfection efficiency and gene-silencing effect of the siRNAs. Afterward, (4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, Transwell, soft agar colony formation, and enzyme-linked immunosorbent assays were performed to evaluate the biological functions of PANC-1 cells after Kirsten rat sarcoma viral oncogene knockdown. In vivo assays were performed using a BALB/c (nu/nu) mouse model subcutaneously injected with PANC-1 xenografts. Real-time in vivo fluorescence imaging was used to monitor the tumor homing of the nanoparticles. The scFv(CD44v6) enabled more efficient delivery of siRNAs and exhibited enhanced gene silencing compared with nontargeted nanoparticles. Furthermore, targeted delivery of the siRNAs induced a potent inhibitory effect on cell proliferation, colony formation, invasion, and vascular endothelial growth factor production. The animal assays revealed that single-chain variable fragment nanoparticles accumulated in the tumor tissue and enhanced the inhibition of tumor growth in vivo. The scFv(CD44v6)-conjugated nanocarriers provide a highly efficient and safe platform for systemic gene therapy for pancreatic cancer.