Inhibitory effect of hybrid liposomes on the growth of liver cancer stem cells

Cancer stem cells (CSCs), also known as tumor-initiating cells, are involved in tumor progression, metastasis, and drug resistance. Hybrid liposomes (HLs) are nano-sized liposomal particles that can be easily prepared by ultrasonicating a mixture of vesicular and micellar molecules in buffer solutions. In this study, we investigated the inhibitory effects of HL on the growth of CSC subpopulations in liver cancer cells (HepG2) in vitro. HLs composed of 90 mol% L-α-dimyristoylphosphatidylcholine and 10 mol% polyoxyethylene(23) dodecyl ether were prepared by sonication. Cell viability was determined by the trypan blue exclusion assay. In liver cancer cells, CSCs were identified by the presence of the cell surface marker proteins CD133 and EpCAM by flow cytometry. A soft agar colony formation assay was performed using HepG2 cells pretreated with HLs. HLs selectively inhibited liver cancer cell growth without affecting normal hepatocytes. Additionally, HLs induced apoptosis of HepG2 cells by a"ctivating caspase-3. Notably, the CD133(+)/EpCAM(+) CSC sub-population of liver cancer cells treated with HLs was reduced. Furthermore, HLs markedly decreased the number of colony-forming cells. Finally, we confirmed the fusion and accumulation of HLs into the cell membranes of CSCs using a fluorescently labeled lipid (NBDPC). Significant accumulation of HL/NBDPC into the CSCs (particularly EpCAM(+) cells) occurred in a dose-dependent manner. These results suggest that HLs are a novel nanomedical therapeutic agent for targeting CSCs in liver cancer therapy. •Hybrid liposomes (HLs) consist of vesicular and micellar molecules.•HLs inhibited the growth of liver cancer cells without affecting normal cells.•HLs suppressed the colony-forming ability of liver cancer cells.•HLs selectively inhibited the growth of liver cancer stem cells (CD133(+)/EpCAM(+)).•HLs significantly accumulated in liver cancer stem cells (CD133(+)/EpCAM(+)).