Objective To explore whether stimulator of interferon genes(STING)agonist ADU-S100 could enhance the antitumor immune response of a chitosan(CS)nanoparticle-mediated DNA vaccine containing a tumor-specific antigen Dickkopf-related protein 1(DKK1)in multiple myeloma(MM).Methods CS-DNA nanoparticles were prepared by using the compound coprecipitation method.The particle sizes and Zeta potential of the CS-DNA nanoparticles were measured by using the Zetasizer Nano-ZS laser particle size analyzer.The DNA protection effect and in vivo DNA expression efficiency of the CS-DNA nanoparticles were assessed by using gel retardation assay and Western blot,respectively.The lentiviruses expressing human DKK1(hDKK1)genes were used to establish MPC-11 cells(MPC-11-hDKK1)which stably expressed hDKK1,and the MPC-11-hDKK1 cells were subcutaneously given to mice to construct tumor models.The tumor-bearing mice were randomly divided into a control group(intramuscular injection of CS-pcDNA3.1),an ADU-S100 immunization group(subcutaneous injection of ADU-S100),a CS-pDKK1 immunization group(intramuscular injection of CS-pDKK1)and an ADU-S1OO/CS-pDKK1 co-immunization group(intramuscular injection of CS-pDKK1+subcutaneous injection of ADU-S100),with 5 mice in each group.The tumor-bearing mice in each group were immunized 3 times at 10-day intervals according to the corresponding immunization schedule.The size of tumor was measured every week.On day 42 after MPC-11-hDKK1 cell inoculation,the tumor weight of mice in each immunization group was measured;the percentages of CD11c+dendritic cell(DC),CD8+CD11c+DC and major histocompatibility complex class Ⅱ(MHCII)+CD11c+DC subsets in the spleen of mice in each immunization group were detected by using flow cytometry.The splenocytes of mice in each group were stimulated with recombinant hDKK-1 protein in vitro,the percentage of EdU+cells in CD8+T lymphocytes in each immunization group was detected by using flow cytometry,and the killing effect of cytotoxic T lymphocyte(CTL)in each group was assessed by using the lactate dehydrogenase(LDH)cytotoxicity assay kit.Results The particle size and Zeta potential of the CS-DNA nanoparticles were(204.3±2.31)nm and(15.47±1.01)mV,respectively.Gel retardation assay showed that DNA enveloped in CS nanoparticles could be completely retarded.Western blot analysis indicated that CS-DNA nanoparticles could be effectively expressed in vivo.The relative expression of DKK1 protein was significantly higher in MPC-11-hDKK1 cells than in MPC-11-Ctrl cells(P＜0.05).On days 7 and 14 after MPC-11-hDKK1 cell inoculation,there was no significant difference in tumor volume of mice between the ADU-S100 immunization group,CS-pDKK1 immunization group,ADU-S100/CS-pDKK1 co-immunization group and the control group(P＞0.05);on days 21,28,35 and 42 after MPC-11-hDKK1 cell inoculation,the tumor volumes of mice in the ADU-S100 immunization group,CS-pDKK1 immunization group and ADU-S100/CS-pDKK1 co-immunization group were significantly lower than those in the control group(P＜0.05);the tumor volume of mice in the ADU-S100/CS-pDKK1 co-immunization group was significantly lower than that in the ADU-S100 immunization group and CS-pDKK1 immunization group(P＜0.05).On day 42 after MPC-11-hDKK1 cell inoculation,the tumor weight of mice in the ADU-S100 immunization group,CS-pDKK1 immunization group and ADU-S1 OO/CS-pDKK1 co-immunization group was significantly lower than that in the control group(P＜0.05);the tumor weight of mice in the ADU-S100/CS-pDKK1 co-immunization group was significantly lower than that in the ADU-S100 immunization group and CS-pDKK1 immunization group(P＜0.05).The proportions of CD11c+DC,CD8+CD11c+DC and MHCII+CD11c+DC subsets in the spleen of mice in the ADU-S100 immunization group,CS-pDKK1 immunization group and ADU-S100/CS-pDKK1 co-immunization group were significantly higher than those in the control group(P＜0.05).The proportions of CD11c+DC,CD8+CD11c+DC and MHCII+CD11c+DC subsets in the spleen of mice in the ADU-S100/CS-pDKK1 co-immunization group were significantly higher than those in the ADU-S100 immunization group and CS-pDKK1 immunization group(P＜0.05).The CTL killing effect and the proportion of EdU+cells in CD8+T lymphocytes in the ADU-S100 immunization group,CS-pDKK1 immunization group and ADU-S1OO/CS-pDKK1 co-immunization group were significantly higher than those in the control group(P＜0.05);the CTL killing effect and the proportion of EdU+cells in CD8+T lymphocytes in the ADU-S100/CS-pDKK1 co-immunization group were significantly higher than those in the ADU-S100 immunization group and CS-pDKK1 immunization group(P＜0.05).Conclusion STING agonist ADU-S100 can significantly improve the antitumor immunity of the CS-pDKK1 nanoparticle vaccine in MM,and this vaccine strategy provides a potential treatment approach for MM.
stimulator of interferon genes agonistchitosan nanoparticleDNA vaccineantitumor immunitymultiple myeloma
维普
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