Delivery Of Small Interfering RNA(siRNA) With Nanoparticular Systems For The Treatment Of Prostate Cancer

Cancer has become one of the main diseases that endanger human health and how to treat cancer effectively has become a worldwide problem.Since the phenomenon of RNA interference has been discovered,great progress has been made in the development of small interfering RNA(si RNA).si RNA could reverse the drug resistance of tumor cells,reduce the dosage of chemotherapeutic drugs and the toxic and side effects,which brings a new dawn to the treatment of cancer.However,as a nucleic acid biologic macromolecule,si RNA is difficulty to be absorbed by cells and is easily degraded by nuclease in vivo during delivery.Therefore,a safe and effective delivery carrier is needed to efficiently transport si RNA into tumor cells.Nanotechnology provides a new idea for the design of si RNA related antitumor drugs.As a delivery carrier of si RNA,nanoparticles could be enriched into tumor sites by enhanced pemeability and rentention effect(EPR),and efficiently deliver si RNA into tumor cells and inhibit the expression of the target gene.In the most widely used si RNA delivery vehicles,polymer nanoparticles have high structural integrity and stability,which could stably store drugs and control drug release,but could lead to non-specific adsorption.Lipid nanoparticles have good biocompatibility,but easy to be swallowed by reticuloendothelial system(RES).Meanwhile,the drug storage instability and other issues limit its clinical application.So si RNA delivery is the biggest challenge for clinical application of si RNA drugs.In this paper,two different nanomaterials for si RNA delivery have been constructed,which could efficiently deliver si RNA into tumor cells and inhibit tumor growth in vivo.The research work was divided into two parts.In the first part of this dissertation,in order to solve the shortcomings of polymer nanoparticles and liposomes,a lipid-polymer composite nanoparticle was designed,and the suitable lipid/polymer ratio was optimized for systematic administration of si RNA.By incorporation of the cationic lipid,the encapsulation efficiency of si RNA into the nanoparticles could be very high,while the diameter of the composite nanoparticle was around 120 nm.The composite nanoparticles could be effectively absorbed by DU145 cells,inhibit the expression of target gene Jnk-1 from m RNA and protein levels,and then induce apoptosis of tumor cells through the intrinsic pathway of mitochondrial/cytochrome C regulation.In vivo experiment,lipid-polymer composite nanoparticle PEG-LP/si Jnk-1 was injected by the caudal vein of mice.Then the tumor volume and weight of mice were measured.The results showed that PEG-LP/si Jnk-1 could inhibit the growth of the tumor in the nude mouse model of prostate cancer.The HE results showed that PEG-LP/si Jnk-1 did not have systemic toxicity and could be used for delivering si RNA in vivo.In the second part,we have developed dopamine coated iron oxide(Fe3O4).Then si RNA was loaded onto the surface of dopamine through ?-? stacking.Combined with cell membrane fusion technology,si RNA loaded Fe3O4@PDA nanoparticles were encapsulated by the mesenchymal stem cell membrane.As mesenchymal stem cells have the tumor tendency,the composites could not only be removed from the immune system but also have the ability to identify tumor targets.A series of characterizations of the synthesized nanoparticles were carried out by using the dynamic light scattering(DLS)and transmission electron microscopy(TEM).The experimental results showed that the prepared composite nanoparticles were spherical and the average hydrated size was about 109 nm.The stability experiments showed that the composite nanoparticles had good serum stability and long-term storage stability.The composite nanoparticles could be effectively absorbed by tumor cells,inhibit the expression of target gene Plk1 from m RNA and protein levels,and then induce apoptosis of tumor cells.The nanoparticles could inhibit the growth of the tumor in the nude mouse model of prostate cancer by the synergistic effect of photothermal therapy and gene therapy.The HE results showed that Fe3O4@PDAsi Plk1@MSCs nanoparticles did not have systemic toxicity and could be used for delivering si RNA in vivo.Therefore,the mesenchymal stem cells membrane derived composite nanomaterials will provide an effective strategy for tumor targeted therapy.