Decitabine-Loaded Gold Nanocages For Photothermal Cancer Therapy

Background:Cancer is one of the major threats to human health.China has the highest incidence of cancer and the highest mortality rate in the world.Given the high risk of cancer and mortality,researchers around the world have been working to develop more accurate,rapid and effective treatments to overcome this major cancer challenge.Traditional cancer therapies,including surgery,radiotherapy and chemotherapy,have some limitations such as severe side effects and drug-resistant relapse,so it is important to find new therapies and develop more effective treatment strategies to address cancer's ills.Nanomedicine has been a darling of the scientific community for many cutting-edge studies.Nanomedic-based photothermy Therapy(PTT)is a highly effective treatment that is less traumatic,controllable and can selectively kill tumor cells through thermotherapy,based on differences in heat tolerance between normal and tumor cells.It has great potential for synergizing multiple therapies,especially in combination with chemotherapy,to improve chemotherapies and reduce adverse reactions.However,free anti-tumor drugs given directly to patients show unsatisfactory therapeutic effects and often have harmful side effects on normal tissues.In order to overcome these shortcomings,the most attractive and promising strategy is to construct an anti-tumor drug delivery system that achieves effective targeted delivery and precise control of drug release,thereby improving treatment outcomes and minimizing adverse reactions.Therefore,a combination of chemotherapy and thermotherapy has been successfully used to improve therapeutic efficacy.Gold nanocages(Au NCs)are excellent nanoparticles for photothermal conversion agents and drug delivery due to their hollow nano-structures,high photothermal conversion efficiency and surface modification of ultrathin porous walls.DNA methylation(DNMT)is a DNA methylation “writer” enzymes,and DNMT1,a member of the family,is highly expressed in cancer stem cells and plays an important role in stem cell stemness maintenance,making it a therapeutic target for cancer.Decitabine is a DNMT1 inhibitor that blends DNA and forms an irreversible covalent adduct with DNA methyltransferase.At low concentrations,Decitabine induces DNA hypomethylation to play its anticancer role.Purpose:By designing and synthesizing a gold nanocages nanoparticle(Au@Dec@T7)loaded with the DNMT1 inhibitor Decitabine and surface-modified with a targeted small molecule peptide(DSPEPEG-T7),as well as studying its chemistry,in vitro function and in vivo therapeutic efficacy,preliminary confirmation of the nanoparticle's tumor inhibition in photothermal therapy provides a theoretical and experimental basis for clinical cancer treatment.Methods:(1)Au@Dec@T7 was prepared and its morphology,particle size,potential,stability,dispersion,photothermal conversion ability,photothermal stability,drug loading and release were studied.(2)Through cell experiments(Intracellular uptake,CCK-8,Calcein-AM/PI live cell staining,colonyformation assay,cell migration assay,Western blot,Dot Blot)we studied the targeting ability,cytotoxicity,cell killing ability,photothermal treatment effect,synergistic treatment effectand underlying molecular mechanism of Au@Dec@T7 NPs.(3)Through the establishment of H22 tumor-bearing mouse liver cancer model,we studied the biosafety,biodistribution,tumor growth inhibition,effect of photothermal therapy and synergistic treatment with chemotherapy of Au@Dec@T7 NPs.Result:(1)We have successfully synthesized Au@Dec@T7 nanomedicines with a unique hollowed-out porous wall nano-structure of ? 50 nm with a negative surface charge of-15.8 m V,stable presence in PBS,fetal bovine serum,and medium,and good dispersion of PDI = 0.3.The Au@Dec@T7 solution showed a photothermal conversion efficiency of 38.9% and a drug load of 32.8% under 808 nm laser exposure.The increasing temperature trend was Au@Dec@T7concentration dependent and 808 nm laser light intensity dependent,with a strong near infrared absorption capacity and demonstrated good photothermal stability,enabling drug loading and biomodification.(2)Cell uptake and ICP assays demonstrated good targeting of tumor cells by Au@Dec@T7,CCK-8,live cell staining,clonogenic and cell migration assays demonstrated Au@Dec@T7's superior killing ability against tumor cells,and Au@Dec@T7+NIR had photoheat-enhanced tumor suppressor effects,Western blot,Dot Blot and RT-q PCR explored Au@Dec@T7's ability to shed light on tumor cell proliferation and migration,and further modulating the expression in cancer cells.(3)A H22 hepatocellular carcinoma(HCC)model was established in Balb/c mice and after 60 days of treatment,the Au@Dec@T7+NIR photothermal treatment group showed excellent tumor suppression,tumor size and weight,and longest survival(approximately 15 days longer than the control group,with a 40% survival rate)compared to all other light and non-light groups.Tissue biopsy staining of vital tissue organs revealed that Au@Dec@T7+NIR had the best tumor suppressor effect.Tissue RT-q PCR revealed molecular mechanisms in mice,activated P15 and E-cadherin expression,and inhibited DNA methyltransferase activity.Au@Dec@T7+NIR showed "1 + 1 > 2" favorable efficacy compared to single drug or photothermal therapy.Moreover,blood tests,biochemical markers,and pathology tests showed that Au@Dec@T7 nanomedicines is well biosecure.These results further demonstrate the efficacy and significance of our Au@Dec@T7 system for synergistic phototherapies and pharmacotherapy.Conclusion:In summary,DNMT1 inhibitor-mediated chemotherapy and Au NCs-mediated PTT have a synergistic effect,significantly reducingthe proliferation of tumour cell.The conceptual model of DNMT1 inhibitor combined with Au NCs-mediated PTT of tumour cell proposed in this experiment has the potential for future clinical translational applications.