Delivery Of SiRNA With Nanoparticles For Cancer Therapy

siRNA,as a kind of nucleic drugs rising in recent years,has brought new opportunities for cancer therapy.However,significant barriers still exist on the road to clinical applications of siRNA drugs.Successful siRNA drugs need suitable tumor disease targets and effective drug delivery systems.Although a lot of siRNA targetable molecules have been identified through tumor genome sequencing and diverse siRNA delivery systems have been developed,the optimal therapeutic targets still need careful selection,and current delivery systems also need optimization.In our project,we found GLUT3 and Plk1 as two safe and effective siRNA targets after thoroughly comparing cancer cells and normal tissue cells.Besides,we synthesized a new tumor pH-sensitive polymer,and used it to encapsulate siRNA into nanoparticles.With the new designed nanoparticle,we can deliver siRNA into cancer cells effectively by overcoming multiple barriers in drug delivery.The two main contents of our project are described as follows:1.We chose glucose transporters 3(GLUT3),which is highly expressed in gloma cells and gloma stem cells in low glucose tumor environment,as the therapeutic target.We screened an effective GLUT3 siRNA,and encapsulated it into cationic lipid(BHEM-Chol)assisted PEG-b-PLA polymer nanoparticle.In cellular level,we proved that this nanoparticle can deliver siRNA into gloma cells and gloma stem cells effectively.With GLUT3 siRNA delivery,the expression of GLUT3 was significantly silenced in gloma cells and gloma stem cells.Subsequently,the glucose uptake and lactate production of gloma cells were inhibited due to GLUT3 knockdown.Finally,we injected GLUT3 siRNA-encapsulated nanoparticle into gloma-bearing mice for cancer therapy,the growth of gloma was significantly inhibited and the percentage of gloma stem cells was down-regulated due to GLUT3 knockdown induced metabolism inhibition.2.Considering the shortages of cationic lipid assisted PEG-b-PLA polymer nanoparticle in tumor cell uptake and intracellular siRNA release,we synthesized a tumor pH-labile linkage-bridged block copolymer of poly(ethylene glycol)with poly(lacide-co-glycolide)(PEG-Dlinkm-PLGA).This polymer only changed the bridged linkage between PEG and PLGA,hence it is as biocompatible and safe as the FDA approved PEG-PLGA.The obtained siRNA-encapsulating PEG-Dlinkm-PLGA nanoparticle gained efficiently prolonged circulation in the blood and preferential accumulation in tumor sites via the PEGylation.Furthermore,the PEG surface layer was detached in response to the tumor acidity microenvironment to facilitate cellular uptake,and the siRNA was rapidly released within tumor cells due to the hydrophobic PLGA layer.Hence,this nanoparticle enhanced the overall effects of gene silencing and tumor therapy.In cellular level and animal level,we proved this nanoparticle can shelled the PEG layer in tumor acidic environment.Besides,we demonstrated accelerated intracellular siRNA release of this nanoparticle with "Black Hole Quenching" assay.In tumor therapy,we injected Plkl siRNA-encapsulating nanoparticle into MDA-MB-231 xenograft tumor model,and displayed this nanoparticle can achieve better tumor growth inhibition with lower siRNA dose.