| ObjectiveChemotherapy has become a major treatment when prostate cancer progresses to a hormone-resistant prostate cancer stage.However,due to the lack of targeting,chemotherapeutic drugs often cause serious side effects,which greatly limits their application.In recent years,with the rapid development of nanotechnology,nano drug-loading systems have been extensively studied in enhancing the chemotherapy effect of tumors.However,due to the heterogeneity of the tumor,it is difficult to eliminate the tumor by a single chemotherapy method.One solution is to combine treatments with several different mechanisms of action.Photodynamic therapy(PDT),as an important clinically approved non-invasive treatment,has been extensively studied in cancer therapy.In addition,in order to further improve the circulation time of the nano drug-loading system in the body,many research teams have proposed the application of biofilm systems to construct biomimetic drug delivery systems in recent years,and achieved good results.Based on the above research background,this project designed and prepared a bilayer biomimetic drug-loading system with the function of targeting prostate cancer cells,and achieved effective treatment of prostate cancer through synergistic photodynamic therapy and chemotherapy,providing a theoretical and research basis for clinical treatment of prostate cancer.MethodsThis topic is divided into two experimental parts:(1)We designed and prepared a polyglutamate-phenylalanine-cystine nanogel(PLG–(PLP-co-PLC))loaded with the chemotherapy drug 10-hydroxycamptothecin(HCPT)as the inner core and coated with erythrocyte membrane(RV)as the external shell,as a bilayer biomimetic nano drug-loading system.Luteinizing hormone-releasing hormone(LHRH)having a function of targeting prostate cancer cells was embedded on the surface of the erythrocyte membrane,and the drug-loading system(LHRH-RV-NG/HCPT)achieved the targeted delivery of chemotherapeutic drugs while prolonging the blood circulation time of the nanocarriers,thereby achieving the purpose of effectively inhibiting the progression of prostate cancer.The therapeutic effect of drug-loaded systems in the treatment of prostate cancer was evaluated by in vitro characterization(particle size,stability,drug release),in vitro cell assay(endocytosis,cell growth inhibition),and in vivo animal experiments(pharmacokinetic experiments,drug tissue distribution,in vivo antitumor experiments).(2)Based on the previous experiment,we loaded the photosensitizer chlorin E6(Ce6)into the phospholipid bilayer of the erythrocyte membrane to construct a multifunctional nano drug-loading system(LHRH-RV/Ce6-NG/HCPT)to achieve synergistic treatment of prostate cancer with photodynamic therapy and chemotherapy.The therapeutic effect of drug-loaded system in the treatment of prostate cancer was evaluated by in vitro characterization(particle size,stability,drug release),in vitro cell assay(endocytosis,ROS production assay,cell growth inhibition)and in vivo animal experiments(pharmacokinetic experiments,drug tissue distribution,in vivo inhibition).ResultsThe first experimental results showed that the bilayer biomimetic nanocarrier LHRH-RV-NG/HCPT had a typical two-layer structure with a size of about 100 nm.The outer erythrocyte membrane retained its own protein component,effectively reducing the clearance of nanocarriers by macrophages.In addition,the polyamino acid nanogel could respond to the tumor reducing environment,thereby increasing the release rate of the loaded drug.The results of cell uptake experiments showed that the modification of LHRH effectively enhanced the endocytosis of the nanocarriers by the tumor cells,and thusshowed good tumor cell growth inhibition effect in vitro.In vivo animal experiments showed that erythrocyte membrane modification significantly prolonged the in vivo circulation time of LHRH-RV-NG/HCPT and effectively increased the accumulation of HCPT in tumor tissues.In vivo anti-tumor experiments showed that LHRH-RV-NG/HCPT exhibited stronger inhibition of tumor growth and anti-metastasis than RV-NG/HCPT,NG/HCPT and free HCPT.Histological and immunohistochemical results confirmed LHRH-RV-NG/HCPT could induce apoptosis of tumor cells more effectively.In addition,the bilayer nanocarrier did not cause significant tissue organ toxicity and showed good in vivo safety.The second experimental results showed that in addition to the advantages of LHRH-RV-NG/HCPT,LHRH-RV/Ce6-NG/HCPT could effectively produce ROS under the irradiation of 670 nm near-infrared light,which could affect the fluidity and permeability of cell membrane phospholipid bilayer.On the one hand,destroy the outsourced erythrocyte membrane,further accelerated the release of HCPT in the nanogel;on the other hand,further increase the uptake of LHRH-RV/Ce6-NG/HCPT by tumor cells.In vitro cell experiments verified that the synergy of photodynamic therapy and chemotherapy showed stronger tumor growth inhibition than single treatment.In vivo anti-tumor experiments had further demonstrated that the synergistic treatment of photodynamic therapy and chemotherapy was more effective in inhibiting the growth and metastasis of prostate cancer.ConclusionThis study successfully designed and prepared a bilayer biomimetic nano drug-loading system with targeting effect.This drug-loading system could exert excellent anti-tumor effect through passive targeting and active targeting dual targeting to prostate cancer cells.In addition,we further introduced photodynamic therapy based on the drug-loading system,and explored the advantages of synergy between photodynamic therapy and chemotherapy in the treatment of prostate cancer.The results of the study demonstrated that the synergy between photodynamic therapy and chemotherapy exhibited superior prostate cancertreatment compared with the single treatment,and could more effectively inhibit the growth and metastasis of prostate cancer.Therefor,this study provides a new research direction for the treatment of prostate cancer,especially advanced prostate cancer. |
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