Inhibition of pulmonary cancer progression by epidermal growth factor receptor-targeted transfection with Bcl-2 and survivin siRNAs.

Clinical application of small interfering RNA (siRNA) in cancer therapy has been limited by the lack of an efficient systemic siRNA delivery system. In this report we describe an efficient siRNA delivery system directed to metastasized tumors, especially in the lungs. Anticancer siRNA was condensed in the presence of 9-arginine peptides (9Arg) and then complexed with cationic O,O'-dimyristyl-N-lysyl glutamate liposomes conjugated to antibodies against the epidermal growth factor receptor (EGFR). The ternary complex of optimized anti-EGFR-9Arg-lipoplexes exhibited efficient siRNA transfection of LS174T-Luc cancer cells grown in culture or orthotopically in mouse lungs. Anti-tumor Bcl-2/survivin siRNAs loaded in the anti-EGFR-9Arg-lipoplexes effectively suppressed transcription of their target genes, resulting in an efficient cancer cell death. Repeated intravenous administrations of the anti-EGFR-9Arg-lipoplexes effectively inhibited tumor growth in the mouse lungs and prolonged survival of the mice compared with nontargeted lipoplexes. These results suggest that the ternary complexes of anti-EGFR-9Arg-lipoplexes might have clinical applications in RNA interference cancer therapy.