Effect Of Arginine On Endocytosis And Its Application In Cancer Therapy

Gene/drug therapy has shown great application potential in the field of cancer treatment.Gene/drug therapy relies on ideal gene/drug carriers to deliver cargoes for therapy.An ideal delivery vector needs to exhibit excellent biocompatibility,be able to protect genes/drugs from being degraded by the complex enzyme system in the body fluid environment,and efficiently enter tumor cells across various barriers.Among various barriers,endocytosis is a key factor that affects the therapeutic effect.Effective cellular uptake is the prerequisite for genes/drugs to exert therapeutic effects.The application of most traditional delivery vectors was restricted due to their low endocytosis efficiency.In recent years,cell penetrating peptides have attracted numerous attention of researchers because of their good cell compatibility and excellent cell membrane penetrating ability.The introduction of cell penetrating peptides into the delivery system can effectively improve the cellular uptake efficiency of the system and significantly improve the therapeutic effect.In this paper,we designed and prepared a series of polyarginine-based gene/drug delivery vectors,and systematically studied their cellular uptake efficiency and tumor therapeutic effect.The specific research results are as follows:(1)A three-component functional peptide was designed and synthesized to solve the barriers encountered during the gene delivery process.Among these three components,GE11 efficiently binds to the over-expressed EGFR on the surface of tumor cells,giving the system tumor targeting ability and reducing the system's impact on normal cells and tissues.Octa-arginine improves the cellular uptake efficiency;polyhistidine helps the system complete endosomal escape via the proton sponge effect,and improves the therapeutic effect.At the same time,in order to improve the complexing ability of the peptide to the plasmid,we covalently connect the functional peptide to the surface of the gold nanoparticle through the gold-sulfur bond.Polypeptide gold nanoparticles can be tightly complexed with polypeptides to form particles with a particle size of 60-70 nm,and nanoparticles in this range can accumulate in the tumor site through the EPR effect.We changed the number of histidines and the combination manner of the three components,and studied their performance in endocytosis and tumor treatment respectively.The experimental results show that when GE11 is connected with arginine polymer,it can show 1+1>2 synergy effect.GE11 and arginine polymer can jointly promote the combination of the system and tumor cells,showing excellent endocytosis ability.(2)We designed a novel peptide with sequence RHRHRHRHRHRHR-NH2 and covalently connect perfluorooctyl amide at its two ends.This triblock polymer can self-assemble into a new type of nanovesicles in aqueous solution and the hydrophilic segment would form arch bridge structure.Compared with the traditional linear flexible arginine segment,this arch bridge structure maximizes the efficiency of interaction with various groups on the cell surface,so that fewer arginine residues can achieve excellent.The cell membrane penetration efficiency and the separation of arginine and histidine further increase the area of action of arginine.The superhydrophobic properties of the fluorine chains at both ends can be in close contact with each other to form a "fluorine phase",which makes the nanovesicles have excellent stability.At the same time,the fluorine chains are also oleophobic,which reduces the interaction between the system and organics such as protein lipid,Extend the circulation time in the body.In both in vitro and in vivo tumor treatment experiments,NPT has shown excellent effects,which is significantly higher than the NPD of nanovesicles formed by traditional diblock polymers.(3)On the basis of the preliminary work,the cavity of NPT is used to carry the anticancer drug Dox·HCl.The experimental results show that NPT has excellent DLC and DLE.Its excellent stability enables NPT to encapsulate drugs in normal environment for a long time.A leak has occurred.At the same time,histidine is protonated in the unique slightly acidic environment of the tumor,and the repulsion between the charges causes gaps in the NPT,and the drug in the lumen flows out to achieve the purpose of pH-responsive release.In the cell endocytosis test,NPT-Dox still showed excellent results,and obvious cell internalization could be observed within 15 minutes.Because of the presence of pH-responsive release,NPT-Dox showed a strong killing effect on tumor cells 4T1 cells,while normal cells NIH3T3 showed a higher survival rate.Because of its excellent properties,NPT has shown great application potential as a drug delivery vehicle.