Background: Targeted delivery of small interfering RNA (siRNA) to the specific tumor tissues and
cells is the key challenge in the development of RNA interference as a therapeutic application.
Methods: To target breast cancer, we developed a cationic nanoparticle as a therapeutic delivery system. The
successful synthesis of the magnetic nanoparticles modified by polyaspartate (PAA) and polyethyleneimine (PEI)
was confirmed using fourier transform infrared (FT-IR) measurements. The designed nanoparticle has been characterized
evaluating its size and charge before and after nanoplex formation with siRNA.
Results: The designed nanoparticle could effectively form nanoplex with siRNA in 2:1 w/w ratio. Survivin
siRNA was used to suppress the antiapoptotic gene, survivin, in MCF-7 cells. According to the importance of
combinational therapy, Mitoxantrone (MTX) was used as a chemotherapeutic agent as well. The multifunctional
nanoparticles have been successfully entered into about 63% of the MCF-7 cells shown via microscopic and
flowcytometric methods. This effective cellular uptake led to the cell apoptosis. Down regulation of survivin was
determined in mRNA and protein levels using Real Time PCR and western blotting, respectively.
Conclusion: Gathering all obtained data, it was concluded that Fe3O4-PAA-PEI nanoparticles can deliver siRNA
effectively into the cytoplasm of the MCF-7 breast cancer cells and induce apoptosis.