ABSTRACT
In this study, we prepared small interfering RNA (siRNA)/cationic liposome complexes (lipoplexes) modified with folate (FA)-polyethylene glycol (PEG, MW 2000, 3400 or 5000)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) to facilitate their uptake into tumor cells via folate receptor (FR), and with PEG1600-cholesterol (PEG1600-Chol) or PEG2000-chondroitin sulfate conjugate (PEG2000-CS), to enhance their systemic stability. Among the FA-PEG-modified siRNA lipoplexes, 0.5 mol% FA-PEG5000-DSPE-modified lipoplexes with 2.5 mol% PEG2000-CS or PEG1600-Chol (LP-0.5F5/2.5P2-CS and LP-0.5F5/2.5P1.6-CL, respectively) exhibited selective growth inhibition of human nasopharyngeal carcinoma KB cells through transduction with polo-like kinase 1 (PLK1) siRNA. Furthermore, the LP-0.5F5/2.5P2-CS and LP-0.5F5/2.5P1.6-CL lipoplexes exhibited decreased agglutination with erythrocytes through PEGylation, and markedly decreased the accumulation of siRNA in murine lungs after systemic injection. Finally, systemic injection of LP-0.5F5/2.5P2-CS and LP-0.5F5/2.5P1.6-CL lipoplexes resulted in accumulation of siRNA in KB tumor xenografts. These findings suggest that PEGylation of FA-PEG5000-DSPE-modified siRNA lipoplexes with PEG2000-CS or PEG1600-Chol might improve their systemic stability without the loss of selective transfection activity in tumor cells.
Subject(s)
Liposomes , Neoplasms , Humans , Animals , Mice , RNA, Small Interfering , Folic Acid , Polyethylene Glycols , Transfection , Neoplasms/drug therapy , Cell Line, TumorABSTRACT
Polyethylene glycol (PEG)modifications (PEGylations) of cationic liposome/small interfering RNA complexes (siRNA lipoplexes) can enhance their systemic stability. The present study determined the effects of PEG anchors in PEGylated siRNA lipoplexes on in vitro genesilencing effects and siRNA biodistribution after intravenous injection. Three types of dialkyl or trialkyl cationic lipids were used in the current study for the preparation of cationic liposomes. Additionally, various PEGylated siRNA lipoplexes that contained PEG1,2distearoylsn-glycero-3phosphoethanolamine (DSPE), PEG1,2distearoylracglycero3-methylpolyoxyethylene (DSG), PEGcholesterol (PEGChol) and PEGchondroitin sulfate conjugate (PEGCS) were prepared. The results revealed that PEGylation of siRNA lipoplexes with PEGDSPE strongly decreased genesilencing effects in cells. In contrast, those with PEGDSG, PEGChol and PEGCS did not largely decrease gene-silencing effects. However, regardless of the PEGderivative type, PEGylation of siRNA lipoplexes decreased their agglutination with erythrocytes. Furthermore, intravenous injection of PEGylated siRNA lipoplexes markedly decreased the accumulation of siRNA in the lungs, regardless of the type of PEGderivative. However, nonPEGylated siRNA lipoplexes accumulated mainly in the lungs regardless of the siRNA lipoplex cationic lipid type. The results indicated that PEGylation of siRNA lipoplexes with PEGDSG, PEGChol and PEGCS may improve systemic stability without losing transfection activity by PEGylation.