RESUMO
In order to promote siRNA transfer in tumour cells, we used an original cationic lipid, synthesized in our laboratory, dimethyl-hydroxyethyl-aminopropane-carbamoyl-cholesterol (DMHAPC-Chol). Liposomes were prepared from this lipid and dioleoylphosphatidylethanolamine (DOPE) in equimolar proportion. Its transfecting capacity was evaluated using ELISA, cell cytometry, and RT-PCR in estimating the silencing effect of VEGF siRNA. This liposome efficiently delivered VEGF siRNA in two human cancer cell lines abundantly secreting VEGF, A431 and MDA-MB-231. Results showed that 50 nM of VEGF siRNA carried by DMHAPC-Chol/DOPE liposomes already silenced more than 90% of VEGF in these cells. A comparative study with two commercial carriers indicated that the inhibition induced by VEGF siRNA transported by cationic DMHAPC-Chol/DOPE liposomes was comparable to that induced by INTERFERin and better than lipofectamine 2000. Moreover, a transfection by a GFP plasmid followed by a GFP siRNA showed that DMHAPC-Chol/DOPE liposomes compared to lipofectamine were less efficient for plasmid but better for siRNA transport. Following one of our previous works concerning cell delivery of plasmid ( Percot et al., 2004 ), the main interest of results presented here resides in the double potential of DMHAPC-Chol/DOPE liposomes to deliver little-sized siRNA as well as large nucleic acids in cells.
