Intravenous liposomal delivery of the short hairpin RNAs against Plk1 controls the growth of established human hepatocellular carcinoma

Polo-like kinase 1 (Plk1) is a key cell cycle regulator that is frequently overexpressed in human hepatocellular carcinomas. Blockade of the Plk1 pathway has been reported to be capable of inducing antitumor effect. Here, plasmids containing U6 promoter-driven shRNAs against human Plk1 were constructed and transfected in human hepatocellular carcinoma cell line HepG2. ShRNA targeting Plk1 almost completely reduced Plk1 expression in HepG2 hepatocellular carcinoma cells, as confirmed by RT-PCR and western blot. As a consequence, HepG2 cells exhibited reduced proliferation and enhanced apoptosis in vitro. Most importantly, treatment with Plk shRNA-DOTAP : Chol complex significantly suppressed the growth of HepG2 xenografts, accompanied with phenotypic changes in tumor cells, including proliferation inhibition and apoptosis induction. Our study suggested that shRNA-mediated silencing of Plk1 might be a novel therapeutic approach against human hepatocellular carcinoma by inhibiting tumor cells proliferation and inducing apoptosis.