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Effect And Mechanism Of Clustered Cobaltous Oxide Nanoparticles Initiate Ferroptosis By Regulating KEAP1/NRF2/HMOX1 Pathway For Radiotherapy Sensitization

Posted on:2024-03-21Degree:MasterType:Thesis
Country:ChinaCandidate:J Q ZhaoFull Text:PDF
GTID:2544307175976599Subject:Public health
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Radiotherapy,a treatment based on the cytotoxic effect of irradiation(IR),is one of the most effective methods for the clinical treatment of tumors.The difference in sensitivity of different cells to irradiation is the basis for the application of radiotherapy.Since the damage effect of irradiation on cells is a deterministic effect,increasing the irradiation dose can improve the therapeutic effect of tumors with poor sensitivity,but it also makes the surrounding normal tissues receive too much irradiation and causes serious side effects.Clinically,the side effects of radiotherapy can be reduced by strictly controlling the dose of irradiation.However,the radioresistance of cancer cells often leads to poor efficacy of radiotherapy.By improving the radiosensitivity of cancer cells,it can effectively kill cancer cells and protect the surrounding normal tissues without increasing the dose of irradiation.Therefore,the research and development of radiosensitizers is a hotspot in the field of irradiation medicine.Ferroptosis,a new type of regulated cell death,is also an important mechanism of radiotherapy to kill cancer cells.Studies have found that irradiation can not only directly destroy nucleic acids of target cells,causing base damage and single-or double-strand breaks,but also produces reactive oxygen species(ROS)and excessive lipid peroxidation,which promotes the occurrence of ferroptosis.Therefore,it is an effective strategy to regulate the radiosensitivity of cancer cells by promoting ferroptosis.In recent years,the rapid development of nanotechnology has provided new strategies for cancer treatment.Nanomaterials have the characteristics of small particle size,long circulation time in vivo,easy manual modification,and can be used for targeted drug release.Integrating the advantages of ferroptosis and nanotechnology,developing the nanomaterials with tumor targeting and ferroptosis inducing ability,has attracted much attention in the field of radiotherapy sensitization.Cobalt(Co)is an essential trace element that plays a biologically crucial role in our bodies as a constituent of vitamin B12.Recently,a high intratumoral Co content was found to be a good prognostic indicator after surgery.Since Co and iron belong to the same group VIII element,ferroptosis induced by Co overload may be the underlying cause of this clinical finding.Inspired by this,we propose a therapeutic scheme using Co-based nanomaterials with good biosafety to increase the intratumoral Co content,and explore the possibility of using them as ferroptosis inducers to achieve radiotherapy sensitization.Therefore,based on the biomineralization strategy,bovine serum albumin(BSA)was used as a template and reducing agent,clustered cobaltous oxide nanoparticles were successfully prepared by the modification of tumor targeting peptide i RGD and the loading of Dendritic mesoporous silica nanoparticles(DMSNs).It has been confirmed that iCoDMSNs have a good radiosensitizing ability by combinedly using cells and tumor-bearing mice radiotherapy models.To further probe the radiosensitization mechanism of iCoDMSNs,we carried out a proteomics study and found that heme oxygenase-1(HMOX1),a key molecule in the ferroptosis pathway,was significantly up-regulated.By using Western blot,q-PCR and immunofluorescence staining,we identified the mechanism by which iCoDMSNs up-regulate HMOX1 and induce ferroptosis.Key findings and conclusions were as follows:1.Based on the principle of biomineralization,cobaltous oxide nanodots Co O@BSA NDs(Co NDs)were successfully prepared using BSA and cobalt chloride(Co Cl2).Subsequently,the tumor penetrating peptide i RGD was successfully ligated to obtain peptide-modified nanodots i RGD-Co O@BSA(i Co NDs).In order to enhance the tumor targeting ability of nanodots,i Co NDs were further loaded into DMSNS to prepare clustered cobaltous oxide nanoparticles(iCoDMSNs).The nanoparticles are stable in alkaline and neutral solutions,but depolymerize in acidic media,which allows the ability of controlled release of iCoDMSNs in the acidic environment of tumors.2.iCoDMSNs exhibit low cytotoxicity and good blood compatibility in vitro.When the nanoparticles were injected into the mice through the tail vein,there was no significant effect on the blood routine,blood biochemical indexes and important organs of the mice,showing good biological safety.3.The penetration ability of iCoDMSNs was confirmed by 3D tumor cell spheroid penetration assay.After injection of the nanoparticles into the tumor-bearing mouse model through the tail vein,in vivo and photoacoustic imaging showed that iCoDMSNs could target the tumor tissue and accumulate in the tumor site for a long time,showing good tumor targeting and tumor penetration ability.4.iCoDMSNs have inhibitory effects on a variety of tumor cells.Proteomic studies showed that the changes of ferroptosis pathway were abnormal after the treatments with iCoDMSNs,and the key protein of ferroptosis signaling pathway,HMOX1,was significantly up-regulated.Cell experiments confirmed that iCoDMSNs could significantly increase the levels of intracellular Fe2+and lipid peroxidation,while ferroptosis inhibitor Ferrostatin-1(Fer-1)could reverse the above abnormal changes and restore the survival rate of target cells,indicating that iCoDMSNs could exert anti-tumor effect by inducing ferroptosis.5.Clonogenic survival assay confirmed that iCoDMSNs had a good radiosensitization effect,with a sensitization enhancement ratio(SER)of 1.7.In the tumor-bearing mouse model,on the basis of RT,the combined use of iCoDMSNs can significantly aggravate the tumor tissue damage,reduce the tumor volume and weight,and prolong the survival time of mice.6.iCoDMSNs produce hydroxyl radicals(·OH)through the Fenton-like reaction in cancer cells,affecting Kelch-like epichlorohydrin-related protein 1(KEAP1)regeneration and up-regulating nuclear erythrocyte 2-related factor 2(NRF2)and downstream HMOX1,resulting in the increase of transferrin receptor(TFR)and the decrease of solute carrier family40 member 1(SLC40A1),and expanding the labile iron pool in cells.Induction of ferroptosis in cancer cells.7.Clonogenic survival assay and tumor-bearing mouse models confirmed that iCoDMSNs activated the KEAP1/NRF2/HMOX1 ferroptosis pathway,resulting in increased iron content and lipid peroxidation,thereby triggering ferroptosis to enhance radiosensitivity.In summary,this study designed,prepared and evaluated a novel radiosensitizing agent iCoDMSNs with simple synthesis,good biosafety and tumor penetration ability,and identified the molecular mechanism by which cobaltin-based nanomaterials induce ferroptosis to regulate cell radiosensitivity,which may provide a new strategy for clinical radiosensitization.
Keywords/Search Tags:cobaltous oxide, ferroptosis, heme oxygenase 1, radiotherapy sensitizers
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