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Reversal of Multidrug Resistance in Breast Cancer by MDR1 Gene SiRNA Cationic Liposomes

??OBJECTIVE To explore the feasibility of the reversal of multidrug resistance in breast cancer using vector-based small interference RNA(siRNA) and to solve the problems of siRNA transient expression and siRNA delivery in vivo. METHODS Based on the siRNA sequence which was screened in previous studies that could effectively inhibit the expression of MDR1 gene, the expression plasmid was constructed. The siRNA expression plasmid was then encapsulated in new nano-sized stealth cationic liposomes. Pharmacodynamic studies of the liposomes were carried out in vitro and in vivo. RESULTS The results showed that the cationic liposomes loaded with MDR1 siRNA expression plasmid could effectively inhibit the expression of MDR1 gene both in vitro and in vivo. CONCLUSION Multi-drug resistance of breast cancer cells is reversed to a great extent by this siRNA-containing cationic liposomes. Nano-sized cationic liposomes are ideal delivery vehicle of siRNA, which could protect the siRNA from degradation and deliver siRNA into the tumor region where it could exert functions.