Investigation Of Thymidine Nucleoside Derivatives For Tumor Immunotherapy

As cancer has become the major cause of death in human diseases,the traditional cancer therapies,including surgery,radiotherapy and chemotherapy,etc.,have achieved significant success,but these methods also have many potential side effects and limitations.Recently,tumor immunotherapy has been regarded as a major breakthrough for cancer treatment because of its superiorities such as cancer broad-spectrum,long duration and little side effects.Specifically,traditional anthracycline-based anticancer chemical drugs can activate antitumor immune response by immunogenic cell death(ICD)mechanism,but the efficacy of immunogenicity is low due to limited potency of ICD inducers.Thymidine nucleoside derivatives are a new calss of organic chemical entity with photosensitive toxicity and have similar chemical structures to anthracycline drugs.But their poor solubility and the UVA excitation wavelength which is difficult to penetrate limit the application in biology.There have been many reported nano co-delivery systems combined with chemotherapy,photodynamic therapy,photothermal therapy used to strengthen the cancer treatment through ICD mechanism.In addition,vaccine adjuvants also have shown their unique advantages to enhance the antitumor immune effect in vivo.In this study,the potential of thymidine nucleoside derivatives as ICD inducers were studied,and their applications in cancer immunotherapy were investigated with nano liposome systems and vaccine adjuvants.The main research contents and results are as follows:(1)A liposomal drug delivery system of thymidine quinoxaline dichloroides with the size about 100 nm was prepared which showed good stability.Tumor active targeting function was achieved through surface modification with c RGD functional groups.The biological activities of liposomal drug delivery systems on different cells were determined.The results showed that high number of nanoparticles and high level of c RGD concentration could promote the uptake of conjugates by tumor cells.Also,the cytotoxicity of liposomal drug delivery systems had a linear correlation with the accumulation of intracellular drug at low concentration.In addition,the empty liposomes had low cytotoxicity to normal liver cells with good biological safety.More importantly,the burst release of ATP and high-mobility group box 1(HMGB1)and the calreticulin exposure by tumor cells after treatment indicated that liposomal formulation could accelerate the induction of ICD after UVA irradiation compared with free thymidine quinoxaline dichloroides compound.Futher animal study demonstrated that cancer cell vaccines prepared by this c RGD liposomal drug delivery system with UVA irradiation had effective prophylactic antitumor immune activity,suggesting a promising prospect in cancer vaccines.(2)The therapeutic potential of cancer vaccines was investigated using another thymidine nucleoside derivative,thymidine quinoxaline naphthalene with a much higher potent cytotoxicity.The study included the preparation of liposomal drug delivery systems,chemophysical characterization,stability study,the effect on human hepatoma cell line Bel7402 and mouse hepatoma cell line H22 and the feasibility of the cancer vaccine prepared by such liposomal drug delivery system in cancer treatment.The results showed that the liposomal system had similar physical properties and stability to the liposomal thymidine quinoxaline dichloride system.Compared with the anthracycline drug mitoxantrone(positive control),both free compound and liposomal system could effectively promote the explosive release of ICD markers and enhance the killing of tumor cells.Animal experiment study indicated that cancer cell vaccines based on this liposomal system are more effective than cancer cell vaccines based on mitoxantrone in cancer treatment.After that,the efficacy in tumor therapy by cancer cell vaccines treated with thymidine quinoxaline naphthalene was investigated with adjuvants.The mixed lymphocyte experiment in vitro and antitumor experiment in vivo showed that compared with aluminum salt adjuvant and poly(I:C)adjuvant,the addition of Cp G adjuvant in cancer cell vaccines had specific enhancement effect on the immune responses against tumor,which was achieved through promoted infiltration of T lymphocytes in tumor tissues,induced maturation of dendritic cells and stimulated activation of tumor specific CD8+ T cells to strengthen cytotoxicity against tumor cells.All these results demonstrated that cancer cell vaccines produced by themidine quinoxaline derivatives plus UVA irradiation could be an effective immunotherapeutic strategy for cancer treatment in combination with liposomal delivery systems or Cp G vaccine adjuvant.The research in this paper provided a new idea for cancer therapy of thymidine nucleoside derivatives,and provided a basis for the development of personalized and specific whole cancer cell vaccines using these derivatives as ICD inducers.