| Objective To explore the antitumor effects of redox-responsive nanoparticles containing platinum(Ⅳ)—NP@Pt(Ⅳ)in ovarian cancer.Methods Redox-responsive polymer carriers were synthesized.Polymer carriers and platinum(Ⅳ)—Pt(Ⅳ)can self-assemble into NP@Pt(Ⅳ).Inductively coupled plasma mass spectrometiy was performed to detect the platinum release from NP@Pt(Ⅳ)in reducing environment and the platinum content in ovarian cancer cells ES2 treated with cisplatin,Pt(Ⅳ)and NP@Pt(Ⅳ).The proliferation ability of the ovarian cancer cells were detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay.Cellular apoptosis was assessed by Flow cytometry.The high-grade serous ovarian cancer patient-derived xenograft(PDX)mice were intravenously injected with Cy7.5 labeled NP@Pt(Ⅳ)followed by In Vivo Imaging System.Mice were treated with PBS,cisplatin and NP@Pt(Ⅳ).Tumor volume and weight were measured in each group.Necrosis,apoptosis and cell proliferation of tumor tissues were detected by hematoxylin-eosin(H&E)staining,TUNEL fluorescence staining and Ki67 immunohistochemistry staining.Body weight and H&E staining of heart,liver,spleen,lung and kidney of mice in each group were measured.Results The platinum release of NP@Pt(Ⅳ)after 48 h in reducing environment was 76.29%,which was significantly higher than that of 26.82%in non-reducing environment(P<0.001).The platinum content in ES2 cells after 1 h,4 h,and 7 h of treatment with NP@Pt(Ⅳ)were significantly higher than that of Pt(Ⅳ)(P<0.05).The half maximal inhibitory concentration of NP@Pt(Ⅳ)in ovarian cancer cells ES2,A2780,A2780DDP was 1.39 μM,1.42 μM and 4.62.M,respectively,which were lower than that of Pt(Ⅳ)(2.89 μM,7.27 μM,and 16.74 pM)and cisplatin(5.21 μM,11.85 μM,and 71.98 μM).The apoptosis rate of ES2 cells treated with NP@Pt(Ⅳ)was(33.91 ±3.80)%,which was significantly higher than that of Pt(Ⅳ)[(16.28±2.41)%,P=0.010]and cisplatin[(15.01 ± 1.17)%,P=0.017].In high-grade serous ovarian cancer PDX model,targeted accumulation of Cy7.5 labeled NP@Pt(Ⅳ)at tumor tissue could be observed.After the treatment,the tumor volume of mice in NP@Pt(Ⅳ)group was 130±98 mm3,which was significantly lower than that in control group(1349±161 mm3,P<0.001)and cisplatin group(715±293 mm3,P=0.020).The tumor weight of mice in NP@Pt(Ⅳ)group was 0.17±0.09 g,which was significantly lower than that in control group(1.55±0.11 g;P<0.001)and cisplatin group(0.82±0.38 g,P=0.029).The areas of tumor necrosis and apoptosis in mice treated with NP@Pt(Ⅳ)were higher than that in mice treated with cisplatin.Immunohistochemical staining revealed that there were low expressions of Ki67 at tumor tissues of mice treated with NP@Pt(Ⅳ)compared with cisplatin.The change in body weight of mice in NP@Pt(Ⅳ)group was not significantly different from that of the control group(20.87±0.79 g vs.18.56±2.04 g,P=0.063).Moreover,the major organs of the heart,liver,spleen,lung,and kidney were also normal by H&E staining.Conclusion Redox-responsive NP@Pt(Ⅳ),produced in this study can enhance the accumulation of cisplatin in ovarian cancer cells and improve the efficacy of ovarian cancer chemotherapy.Objective To construct a novel platinum(Ⅳ)nanodrug that can initiate platinum polymerization and to investigate its potentiation of chemotherapy as well as immunotherapy for ovarian cancer.Methods In this study,a platinum(Ⅳ)prodrug IM-Pt(Ⅳ)with polymerization function was prepared by oxidative denaturation,and a thermosensitive polymer P1 containing an azo bond was synthesized to wrap IM-Pt(Ⅳ)and photothermal agent P2 to form a new nanoparticle NPPt/Azo/PTT.NPPt/Azo/PTT+L can undergo polymerization reaction.The ability of NPPVAzo/PTT+L to undergo polymerization was verified at the cellular level.The proliferation inhibitory ability and pro-apoptotic effect of NPPt/Azo/PTT+L ovarian cancer cells were detected by tetramethylazole blue(MTT),Annexin V-FITC/PI double staining and flow cytometry.To detect the induction of immunogenic cell death of ovarian cancer cells by NPPt/Azo/PTT+L.In vivo imaging system was performed to observe the biodistribution of Cyanine 7.5(Cy7.5)-labeled NP@Pt(Ⅳ)in high-grade plasmacytoid ovarian cancer human-derived tumor xenografts(PDX)mice.To detect the tumor suppressive effect of NPPt/Azo/PTT+L in PDX mice.Flow cytometry was performed to detect the number of relevant immune cells in lymph,spleen and tumor tissues of mice.Results(1)A novel drug delivery system with platinum(Ⅳ)prodrug NPPt/Azo/PT,which integrates the polymerizable platinum(Ⅳ)prodrug(IM-Pt(Ⅳ)),the azo bond-containing thermosensitive polymer P1,and the photothermal agent P2,was successfully constructed.(2)Test tube level verified that NPPt/Azo/PTT has good photothermal properties under 1064 nm light,P2 cleaves,generates carbon radicals and releases IM-Pt(Ⅳ)under thermal conditions,and IM-Pt(Ⅳ)can further undergo polymerization reaction.(3)Cellular level verified that NPPt/Azo/PTT can polymerize intracellularly under 1064 nm light,reduce platinum efflux in ovarian cancer cells,increase platinum content in ES2 cells,and increase y-H2AX expression.MTT assay Annexin V-FITC/PI double-staining assay and flow cytometry results suggest that NPPt/Azo/PTT+L can effectively inhibit the proliferation and promote the apoptosis of many ovarian cancer cells;(4)NPPt/Azo/PTT+L can promote the release of calreticulin(CRT),high mobility group protein B1(HMGB1),adenosine triphosphate(ATP)and induce immunogenic cell death(ICD)effect in ES2 cells;and promote the maturation of mouse bone marrow-derived dendritic cells(BMDCs).(5)NPPt/Azo/PTT+L effectively inhibits tumor growth in ovarian cancer PDX mice.(6)NPPt/Azo/PTT+L altered the immune microenvironment of ovarian cancer tumors,promoting the maturation of dendritic cells(DCs)and CD8+T cell expression,and suppressing the immunosuppressive cell phenotype of tumor-associated macrophages,regulatory T cells,and myeloid-derived suppressor cells.(7)The combination of NPPt/Azo/PTT+L with anti-PD-L1 monoclonal antibody further promoted the infiltration of CD8+T cells in tumor tissues.Conclusion In this study,we successfully designed NPPt/Azo/PTT that can polymerize in ovarian cancer cells under NIR light,which can enhance the efficacy of platinum drug chemotherapy by reducing the cellular efflux of platinum and promoting DNA damage.It also activated the ICD effect,reshaped the immune microenvironment of ovarian cancer,and enhanced the immunotherapeutic effect of anti-PD-L1 monoclonal antibody. |
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