Preliminary Study On The Combined Application Of Metabolic Regulation Of Tumor And Chemotherapy And Immunotherapy

Cancer, caused by environmental and hereditary factors, display uncontrolled cell growth, invasion that intrudes and destroys adjacent tissues, and sometimes metastasis, or spreading to other locations in the body via lymph or blood. Cancer brings serious harm to human health, which is the secondary cause of death worldwide. And the number of cancer deaths is increasing. Currently, there are two main strategies of cancer treatment:one is to bring damage on tumor cells directly; the second is to improve the body’s immunity and wipe out tumor cells indirectly. Conventional cancer treatments include chemotherapy, radiotherapy and surgery. Now, other treatments are also rapidly developing, such as immune therapy, metabolic therapy and gene therapy. But because of the strong adaptability of tumor, single treatment or single drug is proved hard to completely defeat cancer. Combined therapy now trends in cancer treatment. In this thesis, we study the anti-tumor effect of a first-line chemotherapy drug combined with tumor metabolic regulation, immunotherapy combined with tumor metabolic regulation, and screen a series of triazoles as inhibitors of immunosuppressive enzyme indoleamine 2,3-dioxygenase (IDO).In the first chapter, we focus on the anti-tumor activity of DCA as a metabolic treatment drug in combination with capecitabine which is commonly used as an oral chemotherapy drug. Firstly, assay on mice melanoma B16 isograft indicated a synergistic inhibition activity on B16 growth between DCA and capecitabine. Through immunohistochemisty assay, it was observed that combination of DCA and capecitabine accelerated the apoptosis of B16, and capecitabine could also inhibit proliferation of B16 while DCA showed little impact. Subsequently, assay on human lung adenocarcinoma A549 xenograft showed an obvious inhibition activity of single use of capecitabine, however, high dose of capecitabine caused toxicity.Then we found that DCA could enhance inhibition activity of different doses of capecitabine by promoting the apoptosis of tumor cell and reducing the amount of tumor stem cell. By realtime PCR and RNAi assay, it was also observed that DCA showed little impact on expression of capecitabine metabolic enzyme thymidine phosphorylase (TP) and other enzymes related. Therefore, it would not affect the cytotoxicity of capecitabine against tumor cell. Further cell-based study indicated that DCA showed synergistic effect with 5-deoxyuridine, metabolic intermediate of capecitabine, but antagonistic effect with 5-fluorouracil either in normoxia or hypoxia condition in vitro. By comparison with documents reported, we believe that the micro-environment and metabolic way of tumor cell are the key factors contributed to DCA’s treatment efficacy, and in vitro assay should not be the only evaluation standard for DCA’s treatment efficacy.Our colleague had demonsated that lycopene and quercetin could synergeticly raise NK cell’s activity when administrated orally to mice. In the second chapter, we studied the anti-tumor capacity of DCA combined with lycopene and quercetin. And elucidated the possible anti-tumor mechanism of the three was that DCA cooperates with quercetin and lycopene promoting tumor cells apoptosis. DCA activates the mitochondrial apoptosis pathway in tumor cells, making tumor cells more sensitive to the lycopene and quercetin-activated NK cells.In the third chapter, we screened a series of 1,2,3-Triazoles derivatives as IDO inhibitors, which plays an important role in tumor immune suppression. We indentified three potent IDO inhibitors,4-Phenyl-lH-1,2,3-triazole,4-(2-Bromo-phenyl)-1H-1,2,3-triazole and 4-(2-Chlorophenyl)-1H-1,2,3-triazole with Ki value 22、18 and 14.5 μM respectively, which are better than the commonly used IDO inhibitor 1-MT. Using purified recombined human IDO and more physiologically relevant cell-based activity assay we identified their inhibition type and ki value. We also tested their influence on T cell proliferation to prepare for further in vivo experiment.In summary, this thesis preliminary explored three cancer treatment methods, including changing tumor cell’s metabolism, up-regulating innate immunity by natural products and releasing tumor immune suppression. We also discussed the possibility of combination therapy of these three methods, which has some clinical value.