Application of Coiled Coil Peptides in Liposomal Anticancer Drug Delivery Using a Zebrafish Xenograft Model

摘要

The complementary coiled coil forming peptides E-4 [(EIAALEK)(4)] and K-4 [(KIAALKE)(4)] are known to trigger liposomal membrane fusion when tethered to lipid vesicles in the form of lipopeptides. In this study, we examined whether these coiled coil forming peptides can be used for drug delivery applications. First, we prepared E-4 peptide modified liposomes containing the far-red fluorescent dye TO-PRO-3 iodide (E-4-Lipo-TP3) and confirmed that E-4-liposomes could deliver TP3 into HeLa cells expressing K-4 peptide on the membrane (HeLa-K) under cell culture conditions in a selective manner. Next, we prepared doxorubicin-containing E-4-liposomes (E-4-Lipo-DOX) and confirmed that E4-liposomes could also deliver DOX into HeLa-K cells. Moreover, E-4-Lipo-DOX showed enhanced cytotoxicity toward HeLa-K cells compared to free doxorubicin. To prove the suitability of E-4/K-4 coiled coil formation for in vivo drug delivery, we injected E-4-Lipo-TP3 or E-4-Lipo-DOX into zebrafish xenografts of HeLa-K. As a result, E-4-liposomes delivered TP3 to the implanted HeLa-K cells, and E-4-Lipo-DOX could suppress cancer proliferation in the xenograft when compared to nontargeted conditions (i.e., zebrafish xenograft with free DOX injection). These. data demonstrate that coiled coil formation enables drug selectivity and efficacy in vivo. It is envisaged that these findings are a step forward toward biorthogonal targeting systems as a tool for clinical drug delivery.