br The gene silencing and cell death
The gene silencing and cell death mediating MDEA/DOPE nano-particles described in this study could potentially be used to treat non-resectable solid tumors, for example, by intra-tumoral injections. The siRNA could be directed towards cancer oncogenes and/or drug re-sistance genes like MDR1. The penetration of our rather large nano-particles through a dense solid tumor would need to be studied how-ever.
The cationic lipid MDEA forms nanoparticles when combined with siRNA and these induce sequence specific gene silencing in cancer cells. The addition of DOPE increases transfection efficiency to a maximum of 93% which was achieved at a DOPE to MDEA to ratio of 3 and an N:P ratio of 6. Experiments with the model drug Nile red shows that small molecular weight drugs can be stably encapsulated in the particles and be co-delivered along siRNA to the cytoplasm of cells. Sufficient eto-poside could also be included in the nanoparticles to give effective well concentrations of over 10 μM while still achieving 83% and 77% gene silencing, respectively. Etoposide inclusion induced cell death in the lung cancer and oral cancer cell lines H1299 and Cal27, respectively. In conclusion, a novel drug delivery system for co-delivery of siRNA and chemotherapeutics was developed; the system may hold value in the treatment of non-resectable chemotherapy resistant tumors.
The authors would like to thank Jørgen Kjems and Anne Chauchereau who provided the H1299 and Cal27 L-Glutamine and the tech-nical staff from the University of Southern Denmark. We would also like to thank Aleksandra Rojek for help with transmission electron micro-scopy, The Danish Molecular Biomedical Imaging Center (DaMBIC) for use of Confocal Microscopy and the Carlsberg Foundation for funding (Carlsberg start up grant to EAC).
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