Characterization of hydrophobic anti-cancer drug-loaded amphiphilic peptides as a gene carrier.

An amphiphilic peptide with a 3-arginine stretch and a 6-valine stretch was evaluated as a gene carrier. The short amphiphilic peptide, R3V6, not only formed micelles in aqueous solution, but was also able to deliver plasmid DNA (pDNA) into cells without toxicity. In this research, various amphiphilic peptides were synthesized with a 3-arginine stretch and a 6-valine, -alanine, -leucine, or -phenylalanine stretch. In vitro transfection assays in human embryonic kidney 293 cells showed that R3V6 and R3L6 peptides had higher transfection efficiencies than R3A6, R3F6, and poly-L-lysine (PLL). Since the peptide micelles had hydrophobic cores, a hydrophobic anti-cancer drug, bis-chloronitrosourea (BCNU),was able to be loaded into the cores of the micelles. The incorporation of the hydrophobic drug into the cores of the peptide micelles may stabilize the micelle structure and increase the transfection efficiency. The in vitro transfection assay with BCNU-loaded R3V6 (R3V6-BCNU) or R3L6 (R3L6-BCNU) showed that the BCNU-loaded peptide micelles had a higher transfection efficiency than the peptide micelles without BCNU. R3V6-BCNU and R3L6-BCNU had the highest transfection at a 0.8:1 weight ratio (BCNU:R3V6) and a 1.2:1 weight ratio (BCNU:R3L6), respectively. Furthermore, compared to simple diffusion, a more efficient delivery of the drug into cells may be facilitated by endocytosis of the micelles. R3L6-BCNU and R3V6-BCNU had higher cell toxicity to cells than BCNU alone. Therefore, the R3V6- and R3L6-BCNU may be useful for drug and gene combination cancer therapy.