Enhanced anticancer effect of liposome encapsulated choline kinase-siRNA in mice

Abstract

The anticancer effect of choline kinase (ChK)-siRNA for breast cancer was evaluated using PEGylated liposomes both in vitro and in vivo. The optimal size and zeta-potential of siRNA/liposome complex were achieved using condensing agents of hyaluronic acid (HA) and protamine with weight ratios of (ChK-siRNA+HA+protamine): liposome between 0.05 and 0.0037. Suppression of the expression of ChK-mRNA and the resulting cell growth inhibition by the treatment with ChK-siRNA was the highest when using 2.5 and 5 mol% PEGylated liposomes. A pharmacokinetic study after intravenous injection into mice showed that the area under the curve (AUC) and blood half-life (t(1/2, alpha) and t(1/2, beta) ) of ChK-siRNA in 5 mol% PEGylated liposomes were 19 times and 2.2 to 10.5 times higher than that of naked siRNA, respectively. In vivo study showed that PEG-lipo with siRNA exhibited much better tumor growth inhibition and increased survival time than the free siRNA in an MDA-MB-231-bearing xenograft nude mouse model, presumably due to the increased half-life and the passive targeting effect mediated by the PEGylated liposome. The data clearly show that the PEGylated liposome, together with appropriate condensing agents, could serve as an effective delivery system for the ChK-siRNA therapeutics for breast cancer.