Biomimetic Metal-organic Nanoframework For Synergistic Antitumor Therapy Via Metabolism Intervention

The complexity and heterogeneity of malignant tumors are the main challenges of conventional cancer treatment modalities in clinics.The rapid development of nanomedicine and molecular biology of tumors have brought new hope for achieving efficient,less toxic and minimally invasive tumor therapy.Compared to normal cells,tumor cells have significantly different metabolic characteristics.Targeting the metabolic needs of cancer cells to achieve enhanced therapeutics is an emerging approach for cancer treatment.Zeolitic imidazolate frameworks（ZIFs）,a class of porous metal-organic frameworks composed of metal ions and imidazole linkers,particularly,ZIF-8 consisting of Zn²⁺and dimethylimidazole are widely used in biomedical fields because of their high specific surface area,easy functionalization and excellent chemical stability.However,these exogenous metallic nanodrugs usually accumulate passively at tumor sites through enhanced permeability and retention（EPR）effects,facing challenges such as limited tumor-specific targeting ability,short circulation time and easy clearance by mononuclear phagocyte system.By replicating the physical properties and biological functions of the source cells,the bionanosystem can be disguised as endogenous substances to actively target the tumor site and evade the recognition and clearance by the immune system.Based on these backgrouds,intergrating different metabolic intervention strategies,this thesis established two kinds of biomimetic ZIF-8 based nanodrug systems in which the p H-responsive ZIF-8 were utilized as core and coated with mouse breast cancer cell（4T1）tumor cell membrane,and further explored the targeted synergistic antitumor efficiency and mechanism towards the breast cancer both in vivo and in vitro.A homologous targeting cascade ZIF-8 nanoplatform based on autophagic flux interference(denoted as CQ/Cu Z@M_4T1-G)was developed for the autophagy inhibition amplified enzymic-Fenton like catalytic therapy.CQ/Cu Z@M_4T1-G was constructed by wearing Cu²⁺-doped and chloroquine（CQ）loaded ZIF-8 with glucose oxidase（GOx）anchored tumor cell membrane.The GOx-driven glycolysis effectively cut off glucose supply for starvation therapy,which also provided abundant H₂O₂ and decreased p H.Meanwhile,the released Cu²⁺was reduced to Cu⁺by glutathione and converted the elevated H₂O₂ into highly toxic·OH via a Cu⁺-mediated Fenton-like reaction in the tumor.More importantly,autophagy inhibitor CQ was applied to block downstream autophagic flux and hinder the self-protection pathway.Thus,the tumor succumbed to the severe stress of an enzymatic-Fenton like cascading reaction,yielding a remarkable therapeutic effect as demonstrated by both in vitro and in vivo results.Our study provides a promising regimen of inhibiting cancer cellular intrinsic autophagy resistance to amplify cascade catalytic therapy for a new type of oncotherapy in the future.The CQ/Cu Z@M_4T1-G system has a relative complex composition and achieves cascade antitumor effects in tumor cells through multiple pathways.However,in addition to tumor cells,there are also a large number of immune cells in the tumor tissue.In view of the unique constitutive properties of ZIF-8 and the complexity of the immunosuppressive microenvironment,this thesis further investigated the biological effects of ZIF-8 and extended the therapeutic approach from focusing on tumor cells to focusing on the tumor microenvironment to overcome immune"cold"tumors,induce sufficient immunogenic death and activate systemic antitumor immune effects in solid tumors.Therefore,a NIR-II photosensitive and biomimetic ZIF-8 nanoplatform(CuS/Z@M_4T1)was detailed by integrating Zn²⁺-enriched ZIF-8,photothermal agent CuS nanodots and 4T1 cell membrane cloaking for Zn²⁺metabolic intereference amplified photothermal immunostimulatory.CuS/Z@M_RBC was prepared using red blood cell membrane（RBC）as a control,and the excellent 4T1 homologous targeting performance of CuS/Z@M_4T1was confirmed.Under NIR-II laser irradiation and weakly acidic microenvironment,CuS/Z@M_4T1 could accelerate release of excessive Zn²⁺,causing intracellular Zn²⁺overload in 4T1 cells.Metabolomics showed that excess Zn²⁺could interfere with multiple metabolic pathways in tumor cells,leading to tumor metabolic disorders,causing multi-level cellular energy loss,reducing ATP synthesis,thereby hindering the production of heat shock proteins,inhibiting the cellular intrinsic thermal resistance,and augmenting the effect of CuS nanodot-mediated photothermal therapy（PTT）.In vitro and in vivo experiments showed that the enhanced PTT induced an immune cascade in tumor cells and promoted the conversion of immune"cold"tumors into immune"hot"tumors.Combining CuS/Z@M_4T1 with a PD-1 treatment recruited more cytotoxic T lymphocytes and reduced regulatory T cell activity,thereby eliminating tumors in situ and suppressing distal tumors and lung metastases.The work firstly provides a new approach of ionic interference mediated metabolic modulation to explore the potential therapeutic effects of high concentrations ZIF-8 on tumors and overcome the intrinsic thermoresistance of tumor cells.Also,it provides a new strategy to enhance phoththermal immunotherapy and greatly contributes to the further development of Zn²⁺nanomodulators.In summary,this thesis successfully constructed two biomimetic nanoplatforms based on ZIF-8(CQ/Cu Z@M_4T1-G and CuS/Z@M_4T1)and demonstrated their excellent anti-tumor therapeutic effects in vitro and in vivo.The construction of these two nanotherapeutic systems provides new ideas and insights into the use of ZIF-8-based nanopharmaceutical platforms for overcoming intrinsic tumor resistance by metabolic modulation for amplified tumor synergistic therapy.