Functionalized non-viral cationic vectors for effective siRNA induced cancer therapy

Poly(1-vinylimidazole) polyplexes as novel therapeutic gene carriers for lung cancer therapy

The present work explores the ability of poly(1-vinylimidazole) (PVI) to complex small interfering RNA (siRNA) silencing vascular endothelial growth factor (VEGF) and the in vitro efficiency of the formed complexes in A549 lung cancer cells. The polyplex formed was found to exhibit 66% complexation efficiency. The complexation was confirmed by gel retardation assays, FTIR and thermal analysis. The blank PVI polymer was not toxic to cells. The polyplex was found to exhibit excellent internalization and escaped the endosome effectively. The polyplex was more effective than free siRNA in silencing VEGF in lung cancer cells. The silencing of VEGF was quantified using Western blot and was also reflected in the depletion of HIF-1α levels in the cells treated with the polyplex. VEGF silencing by the polyplex was found to augment the cytotoxic effects of the chemotherapeutic agent 5-fluorouracil. Microarray analysis of the mRNA isolated from cells treated with free siRNA and the polyplex reveal that the VEGF silencing by the polyplex also altered the expression levels of several other genes that have been connected to the proliferation and invasion of lung cancer cells. These results indicate that the PVI complexes can be an effective agent to counter lung cancer.

Oligo-guanidyl targeted bioconjugates forming rod shaped polyplexes as a new nanoplatform for oligonucleotide delivery

Novel bioconjugates (Agm₆-M-PEG-FA) for active oligonucleotide (ON) delivery have been developed by conjugating a cationic oligo-guanidyl star-like shaped "head" (Agm₆-M) to a polymeric "tail" (PEG) terminating with folic acid (FA) as targeting agent or methoxy group (Agm₆-M-PEG-FA and Agm₆-M-PEG-OCH₃, respectively). Gel electrophoresis showed that the bioconjugates completely associated with ONs at 3 nitrogen/phosphate (N/P) ratio. Studies performed with folate receptor (FR)-overexpressing HeLa cells, showed that optimal cell up-take was obtained with the 75:25 w/w Agm₆-M-PEG-OCH₃:Agm₆-M-PEG-FA mixture. Dynamic light scattering and transmission electron microscopy showed that the polyplexes had size <80 nm with narrow polydispersity and rod-shaped morphology. The polyplexes were stable for several hours in plasma while ON was released in the presence of heparin concentration 16-times higher than the physiological one. The polyplexes displayed negligible cytotoxicity, hemolysis and low pro-inflammatory TNF-α release. Studies performed with FR-overexpressing HeLa and MDA-MB-231 cells using siRac1 revealed that the folated polyplexes caused significantly higher gene silencing (86.1 ± 9.6%) and inhibition of cell migration (40%) than the non-folated polyplexes obtained with Agm₆-M-PEG-OCH₃ only. Although cytofluorimetric analyses showed similar cell uptake for both folated and non-folated polyplexes, confocal, TEM and competition studies showed that the folated polyplexes were taken-up by lysosome escaping caveolin-mediated pathway with final polyplex localization within cytosol, while non-folated polyplexes were preferentially taken-up via clathrin-mediated pathway to localize in the lysosomes. Finally, preliminary in vivo studies carried out in mice revealed that the folated polyplexes dispose in the tumor mass.