Studies On The Anti-tumor Activity Of A New Type Of Iridium(Ⅲ)metal Complexes And Its Long-circulating Liposome

Cancer is a malignant disease that seriously endangers human health.Because of its characteristics of infinite proliferation,transformation,and easy dispersal and metastasis,it is clinically manifested as a high recurrence rate and mortality rate.Now it has become a medical problem that plagues the world.Since Rosenberg discovered cisplatin and which was applied to tumor treatment in the 1960s,platinum-based drugs such as carboplatin and oxaliplatin have been discovered one after another,and significant progress has been made in the clinical treatment for tumors.With the widespread use of platinum metal anti-tumor drugs,some of their shortcomings are gradually exposed,such as poor compliance,bone marrow suppression,severe neurotoxicity,nephrotoxicity,and acquired drug resistance severely restrict their clinical application.After years of development,researchers have discovered that complexes of platinum metals,such as palladium,osmium,ruthenium,iridium,and rhodium,also have good anti-tumor activity,and are expected to be further developed as substitutes for platinum metal.Therefore,based on the research of platinum metal anti-tumor drugs,improving the existing chemotherapy effects,and developing high-efficiency and low-toxic anti-tumor drugs has become a hot spot in drug development.In this thesis,three series of iridium（Ⅲ）metal complexes were synthesized and purified through the modification of 1,10-phenanthroline,and then the toxicity evaluation in vitro was carried out.It was found that the first series of iridium metal complexes containing amino groups are toxic to the selected cell lines,especially the most sensitive to mouse melanoma cell B16.The second and third series correspond to iridium metal complexes modified with halogen atoms-F and-Br,respectively.Due to the poor solubility of the obtained complexes,they are not cytotoxic in vitro.Therefore,we prepared it into liposomes with long circulation function and characterized its particle size and zeta potential.After liposome preparation,the solubility of iridium metal complexes encapsulated in the hydrophobic layer of liposomes is significantly increased,and the anti-tumor activity in vitro is also significantly enhanced.On this basis,the anti-tumor mechanism of iridium metal complexes has been deeply investigated.Then,through the qualitative detection of fluorescence microscope and the quantitative detection of ICP-MS,it was verified that the iridium metal complexes can be taken up by tumor cells.Flow cytometry was used to determine the effect of iridium complexes on cell apoptosis rate and cell cycle distribution.Western blot quantified the effects of iridium metal complexes on cycle control proteins,apoptosis-related proteins,autophagy proteins,and adhesion proteins.And under the fluorescence microscope,the changes of cell mitochondrial membrane potential,the accumulation of reactive oxygen species,the changes of Ca²⁺level,the release of cytochrome c,the polymerization of tubulin and the formation of autophagosomes were monitored.Finally,through mouse xenograft tumor model,the in vivo anti-tumor efficacy of iridium metal complexes was analyzed,and organ tissues were harvested for HE staining experiment to evaluate the safety of iridium metal complexes.The results show that the iridium metal complexes can regulate the upstream Bcl-2 family proteins to cause mitochondrial damage,and then the downstream Caspase is activated to trigger cell apoptosis.In addition,the iridium complexes regulate tumor cell proliferation by inhibiting the expression of cell cycle related proteins,affecting tubulin assembly,and blocking cells during a specific cell cycle.In vivo,iridium metal complexes can effectively slow down the tumor growth of xenograft mice,HE staining experiments also show that iridium metal complexes have no obvious toxicity to organs.In summary,the designed and synthesized iridium complexes（Ⅲ）have good anti-tumor activities in vivo and in vitro.