Inhibition Of Histone Deacetylase Promoting Antitumor Immunotherapy&Case Report

Part one Study on histone deacetylase inhibition inducing tumor cell pyroptosisObjective:Studies have shown that histone deacetylase(HDAC)inhibition is a regulator related to tumor immunity,which can stimulate antitumor effects by inducing multiple programmed cell death modes.However,its ability to induce pyroptosis of tumor cells has not been fully explored.In this part,we explored the ability of HDAC inhibition in inducing pyroptosis of tumor cells.On that basis,to achieve tumor targeting release and reduce biotoxicity,we have designed tumor microenvironment-responsive nanoprodrug with HDAC inhibition to test its feasibility as a therapeutic target.Methods:We used LDH detection kit,Western blot assay and morphological observation to detect the ability of HDAC inhibition induced pyroptosis by testing the murine cell lines of oral squamous cell carcinoma,breast cancer and colon cancer.We rationally designed tumor microenvironment-responsive nanoprodrug LD NPs on the basis of HDAC inhibition.Transmission electron microscopy(TEM)imaging,cell fluorescence,flow cytometry(FCM),tumor multicellular spheroid(MCS),characterization test were used to analysis the environmental stability,biosafety,tumor targeting ability and pyroptosis-inducing ability of LD NPs.Results:We found that HDAC inhibition can induce typical morphological and functional changes of pyroptosis in murine oral squamous cell carcinoma,breast cancer and colon cancer cell lines.On this basis,we designed biomaterials LD NPs combining HDAC inhibition and chemotherapy drugs.It has been detected that the biomaterials have good functional stability,tumor environment targeting ability,and synergistic effect of inducing pyroptosis of tumor cells.Conclusions:HDAC inhibition can induce pyroptosis of tumor cells.The biomaterials combined with HDAC inhibition and chemotherapy could enhance tumor cell pyroptosis.Part two Study of improving tumor immune therapy by inhibiting histone deacetylaseObjective:Immunotherapy has great potential as a novel tumor therapy but the tumor immune therapy of oral squamous cell carcinoma(OSCC)still meet the dilemma of low response rate.To further explore the potential of HD AC inhibition combined with chemotherapy in tumor immunotherapy,we applied biomaterials LD NPs to the mouse model for treatment,and tested its feasibility of tumor targeting therapy and improving the response rate of immune checkpoint blockade.Methods:Firstly,we detected the biological biodistribution of this biomaterial in tumor-bearing mice to ensure the tumor targeting ability.On this basis,it was applied to the OSCC tumor-bearing mouse model for treatment.Information such as tumor sizes and weights was recorded and the therapeutic effect was analyzed.The enrichment of various immune cells in the immune system and tumor tissues of mice were detected by FCM and immunohistochemistry(IHC)to observe the effects on the immune system.Western blot assay was used to detect the pyroptosis-inducing ability.Then,the biomaterial was applied to the tumor bearing mouse model of breast cancer,and the feasibility of improving tumor immunotherapy and improving the response rate of PD-1 antibody treatment was tested in the same way.Finally,we tested its biosafety by hematological analysis,IHC and other methods.Results:We found that LD NPs,a biomaterial based on HDAC inhibition,could significantly enhance the antitumor effect and induce pyroptosis of tumor cells in tumor-bearing mouse model of oral squamous cell carcinoma.LD NPs significantly increased the number of tumor-infiltrating T cells and reduced myeloid suppressor cells(MDSCs)and regulatory T cells(Tregs)in the tumor environment.Then the treatment of breast cancer mice showed similar results.In addition,LD NPs significantly improved the response rate and survival time of mice treated with PD-1 antibody.At the same time,the biological safety was confirmed by hematological analysis and organ section observation of the treated mice.Conclusions:The results showed that LD NPs had good ability to induce tumor cell pyroptosis,improve tumor immunotherapy and enhance antitumor effect in vivo.LD NPs can significantly improve the response rate and survival time of PD-1 antibody therapy with good biosafety.Therefore,LD NPs has the potential in clinical application of tumor immune therapy and improving the response rate of immune checkpoint blockade.