Tumor-targeting Magnetic Lipoplex Delivery Of ShRNA Suppresses IGF-1R Overexpression Of Lung Cancer A549Cells In Vitro And In Vivo

Objective:to evaluate the effect of shRNA mediated by magnetic liposome on inhibition the growth of non-small cell lung cancer (NSCLC) under the interference of magnetic field in vitro and in vivo. Method:to construct plasmid expressing GFP and shRNA against IGF-1R (pGFPshIGF-1R); superparamagnetic iron oxide nanoparticles (SPIONs) and cationic liposome comprised the magnetic liposome. In our study, magnetofection is a process in which pGFPshIGF-IRs are associated with magnetic liposome to form magnetic lipoplexes. These complexes are then concentrated onto the surface of targeted cells under the influence of a magnetic field. pGFPshIGF-1R was transferred into A549cells by magnetofection under a series of interaction time and strength of external magnetic fields. pGFPshIGF-1R was delivered into A549cells in vitro and injected intravenously into the tumor-bearing mice every48h for four doses in vivo by way of lipofection or magnetofection. The magnetofection efficiency was analyzed by cytometry and the potency of IGF-1R knockdown was analyzed by western blot technology. Three weeks after the4th injection the mice were killed and the tumors were removed and weighed. The tumor inhibition rate was calculated and the toxicity of the magnetic nanoparticles vectors was evaluated. Result:Interaction time and strength of magnetic field could influence the magnetofection efficiency. When the strength and interaction time of magnetic field was250mT and15min, the highest transfection efficiency was acquired. In vitro, IGF-1R specific-shRNA transfected by lipofection inhibited IGF-1R protein by56.1±6%and by liposomal magnetofection by85.1±3%. At the end of experiment, the animal tumor weight from PBS, lipofection and magnetofection group was0.46±0.12g,0.27±0.05g,0.16±0.04g. pGFPshIGF-1R delivered by both lipofection and magnetofection significantly inhibited the growth of tumor by41.3%(P<0.01)and65.2%(P<0.001), compared with PBS group. In vivo IGF-IR specific-shRNA by lipofection inhibited IGF-IR protein by an average of43.8±5.3%; that by liposomal magnetofection inhibited IGF-1R protein by43.4±5.7%,56.3±9.6%, and72.2±6.8%, at24,48, and72h, respectively, after pGFPshIGF-1R injection. Conclusion:Our findings indicate that magnetofection based on magnetic liposome as gene vectors may be a promising method that allows the targeting of gene therapy to lung cancer.