Construction Of Small Molecule Self-assembled Ferroptosis Prodrug Delivery System And Its Application In Tumor Differentiation Therap

Cancer stem cells（CSCs）,considered to be the driving source of cell heterogeneity,can regulate tumor metastasis,recurrence,aggressiveness,and resistance to conventional chemotherapy,and play a key role in tumor recurrence and proliferation.Therefore,effective killing or even eradication of CSCs is the key to tumor stem cell therapy.In this study,we successfully designed and prepared a small molecule self-assembly nano prodrug delivery system that can be used for the combined treatment of triple-negative breast cancer stem cells,and cleverly utilized the strategy of small molecule self-assembly and combination therapy.It achieves responsive release and precisely targeted co-delivery of ferroptosis drug ferrocentene（Fc）,differentiation-inducing agent all-trans retinoic acid（ATRA）and chemotherapeutics doxorubicin（DOX）,effectively overcoming the chemotherapy resistance,easy distal metastasis and high recurrence in the treatment of triple-negative breast cancer（TNBC）.Firstly,the small molecule compound Fc-SS-ATRA with nano self-assembly function was synthesized successfully.In the process of self-assembly,it could efficiently load the chemotherapeutics DOX and construct the nano-prodrug DOX@Fc-SS-ATRA NPs.In order to increase stability and tumor targeting,DSPE-PEG-HA was coated on the surface to obtain nano-prodrug HA/DOX@Fc-SS-ATRA NPs with targeting capacity.HA/DOX@Fc-SS-ATRA NPs has the characteristics of good stability,high drug loading and tumor targeting,which effectively improves its accuracy and safety for cancer stem cell therapy.Secondly,HA/DOX@Fc-SS-ATRA NPs can depolymerize under the action of overexpressed GSH in tumor microenvironment,and effectively releases three therapeutic drugs to achieve ferroptosis,differentiation therapy and chemotherapy.The released DOX can not only be used as chemotherapy drugs to promote the apoptosis of TNBC cells,but also can increase the concentration of H₂O₂through the regulation of intracellular NOX4,and then promotes the intracellular Fenton reaction to enhance ferroptosis.The combination of ferroptosis-differentiation therapy-chemotherapy has achieved high efficiency and safety in the treatment of cancer cells and cancer stem cells.Finally,HA/DOX@Fc-SS-ATRA NPs can be proved that effectively enriched in tumor tissue through drug distribution experiments.HA/DOX@Fc-SS-ATRA NPs showed good tumor inhibition and good biological safety in 4T1 subcutaneous tumor bearing model.In addition,in TNBC orthotopic spontaneous lung metastasis model,HA/DOX@Fc-SS-ATRA NPs not only showed a good effect of inhibiting tumor growth in situ,but also demonstrated a good effect of inhibiting distal lung metastasis.At the same time,no obvious organ damage was caused during the treatment,and the survival time of mice was significantly prolonged.It shows the safety,high efficiency and specificity of the nano-drug in the treatment of cancer stem cells.