| Celastrol,an active compound isolated from the root extract of Tripterygium wilfordii used as a Chinese herbal medicine,exhibits broad anticancer activities and it has great potential for transformation as an anti-cancer drug.However,its poor water stability,narrow therapeutic window,and numerous adverse effects greatly limit its in vivo application.To overcome these limitations,we innovatively used the coordination of CEL and Fe（III）,and based on the dual response of reactive oxygen species（ROS）and adenosine triphosphate（ATP）in tumor microenvironment,designed an intelligent responsive delivery system for celastrol.The main research findings are as follows:First,we synthesized a CEL-Fe（III）chelate that can be dissociated by ATP as a detoxification core,and the formation and dissociation of its coordination structure were fully verified.Subsequently,CEL-Fe was encapsulated in the hydrophobic core of a ROS-responsive polymer by nanoprecipitation to form an intelligent responsive delivery system,CEL-Fe NPs.The morphology,particle size and zeta potential characterization demonstrated that the CEL-Fe NPs had uniform particle size of about 86 nm and a surface charge of about-20m V,and were stable in aqueous solution and buffer.Meanwhile,CEL-Fe NPs exhibited the ability of ATP-induced coordination disintegration and Fe（III）-enhanced ROS responsive drug release behavior,and a 24 h release rate of 83%was achieved in mild acid and H2O2-containing release media.Second,through in vitro cell toxicity testing and computer simulation molecular docking,we verified the cytotoxicity reduction of CEL-Fe and the recovery of cytotoxicity after ATP treated,as well as its inherent mechanism.Relevant studies on the nanoparticle encapsulation system confirmed the effective cellular uptake of the drug.Moreover,western blot,detection of caspase 3 activity and apoptosis level demonstrated that the specific mechanisms of cytotoxicity changes were related to the expression level of the Hsp90-Cdc37 client protein,as well as the impact on cell proliferation and apoptosis.Finally,the acute hemolysis tests,biosafety tests,live mouse imaging,and in vivo anti-tumor experiments proved that CEL-Fe NPs had significantly improved biosafety,and no obvious tissue toxicity was observed at high doses.In addition,we established a patient-derived xenograft tumor model to evaluate the therapeutic effect of CEL-Fe NPs in vivo,and the experimental results proved that nanoparticles can effectively accumulate in tumors,and,based on their responsive release and drug efficacy reactivation,CEL-Fe NPs have stronger anti-tumor efficacy than free drug and uncoordinated CEL NPs,and Their tumor volume was less than 1/10 of the PBS-treated group.In summary,the intelligent responsive delivery system CEL-Fe NPs we synthesized has the following characteristics:In normal physiological tissues,the hydrophilic polyethylene glycol（PEG）terminal in the polymer maintained the in vivo circulation stability of CEL-Fe NPs,while CEL-Fe maintained its coordination state to ensure high biosafety and reduced systemic toxicity.In the tumor microenvironment rich in ATP and ROS,ROS triggered and enhanced drug release behavior,followed by competitive binding with ATP,leading to the destruction of the coordination bond of CEL-Fe and the reactivation of the anticancer efficacy of CEL.Our research provides innovative ideas for the development of coordination-based CEL derivatives and drug detoxification systems. |
