Diacylglycerol in Cationic Nanoparticles Stimulates Oxidative Stress-Mediated Death of Cancer Cells.

Previous reports have suggested that cargo-free cationic nanoparticles (cNP) consisting of cationic monovalent lipids, such as 1,2-oleoyl-3-trimethylammonium-propane (DOTAP), induce reactive oxygen species (ROS) generation and toxicity in cells. In addition, cNP containing six lysine residues (6K) and cargo (6K-cNP) exerted synergistic effects on ROS production and cell death in cancer cells. In this study, we investigated the effect of diacylglycerol (DAG) derived from egg phosphatidylcholine in nanoparticles (NP) on ROS-mediated cellular toxicity. When DAG was incorporated into cNP (D-cNP) or 6K-cNP (6K-D-cNP) up to 7.8 mol% at the expense of DOTAP, and treated with cells, ROS generation in cancer cells increased further in a DAG concentration-dependent manner compared with those of both cNP without DAG. Concomitantly, cancer cell viability was more decreased upon the treatment with DAG-containing cNP. Moreover, D-cNP or 6K-D-cNP exhibited enhanced uptake into cells under endocytosis-inhibited conditions. Taken together, these results suggested that the presence of DAG in NP stimulated the interaction of NP with cancer cells and the resulting ROS-mediated cytotoxicity.