Study Of Antitumor Activity Of Long-circulating Liposomes Loaded With Iridium(Ⅲ) Metal Complexes

Nowadays,with the rapid development of science and technology and the continuous improvement of medical science,cancer has become one of the most common life-threatening diseases,and the morbidity and mortality rates are both on the rise.Oncogenic diseases remain a great threat to human survival and an urgent worldwide problem for medical practitioners to solve.Therefore,it is essential to investigate an effective,less toxic and better tolerated therapeutic approach for the body.Notably,metal drugs have a tremendous impact on medical developments,especially in the treatment of cancer.Currently,cisplatin and its analogs are among the most effective chemotherapeutic agents in clinical practice.However,the low solubility of cisplatin in water,drug resistance,and high toxic side effects have limited clinical applications.Therefore,this has prompted scientific researchers to search and develop more efficient alternative transition metal complexes.In the last decades,a large number of metal complexes have been extensively studied in vitro and in vivo,and some are still in different stages of clinical studies.Among them,iridium（Ⅲ）-based complexes have shown high aggregation and anticancer activity.Also,some metal complexes showed low or no cytotoxic activity,but the cytotoxic activity in vitro and in vivo was significantly increased when the complexes were prepared as nanoparticles with liposomes as carriers.Apparently,liposomes as drug carriers can enhance the anticancer activity of metal complexes.In this thesis,we mainly synthesized and purified three series of three ligands and their iridium（Ⅲ）complexes.The synthesized complexes and loaded in the long-circulating liposomes were characterized by UV spectroscopy,IR spectroscopy,fluorescence spectroscopy,HR-MS,¹H NMR,¹³C NMR,nanoparticle size,zeta potential and the anti-tumor mechanism of the drugs was investigated thoroughly.The paper focuses on the antitumor activity of the complexes and loaded in the liposomes toward selected cancer cells and their mechanisms.Firstly,the cytotoxicity assay of the drug was performed by MTT methods,and the results revealed that the complexes and PEGylated liposomes had significant proliferation inhibitory effects on cancer cells.Subsequently,cellular uptake,high intracellular imaging system and ICP-MS assay revealed that the drug could effectively enter and accumulate in the cells.Flow cytometry and wound healing assays showed that drug entry into cells inhibited cell migration and cell cycle progression,which in turn induced apoptosis.Meanwhile,the analysis of reactive oxygen content levels,mitochondrial membrane potential changes and cellular autophagy in tumor cells by high-intensity imaging analysis system and flow cytometry showed that the ligands and PEGylated liposomes could reduce intracellular mitochondrial membrane potential and upregulate reactive oxygen species（ROS）levels.At the same time,the drugs also induced apoptosis through the occurrence of cellular autophagy.Finally,the effects of the complexes and PEGylated liposomes on the expression of related proteins in the apoptotic signaling pathway were investigated by Western blotting experiments,and significant changes in the expression of both PI3K/AKT and Bcl-2 family proteins were found.The results showed that the metal iridium（Ⅲ）complexes and long-circulating liposomes induced apoptosis and inhibited cell proliferation and migration in multiple ways.In addition,we selected a high active complex and liposome for in vivo antitumor activity studies.First,we performed subcutaneous tumor molds in nude mice using a xenograft,and then randomly grouped and administered the drug intraperitoneally to observe and record the tumor growth in the blank and drug-administered groups.Then,we observed the morphological changes of major organs and tumor tissues in mice by H&E staining and analyzed the positive expression levels ofγH2AX and c-Caspase 3 by immunohistochemistry.Finally,the damage of liposome on liver function was assessed by blood biochemical indexes ALT and AST.The experimental results showed that the complexes and liposomes also have good anti-tumor effects in vivo and good histocompatibility and biocompatibility.In conclusion,the novel complexes and liposomes were designed and synthesized with good antitumor effects in vivo and in vitro.