CPPs-modified chitosan as permeability-enhancing chemotherapeutic combined with gene therapy nanosystem by thermosensitive hydrogel for the treatment of osteosarcoma

Chemotherapy resistance of osteosarcoma (OS) is still the crux of poor clinical curative effect.E3 ubiquitin-protein ligase Rad18 (Rad18) contributed to doxorubicin resistance in OS, which ultimately mediated DNA damage tolerance and led to a poor prognosis and chemotherapy response in patients.In this study, doxorubicin was loaded in the process of Fe2+ and siRad18 forming nanoparticles(FSD) through coordination, chitosan modified with cell penetrating peptide (H6R6) was synthesized and coated on the surface of the NPs(FSD-CHR). FSD-CHR was then dispersed in thermosensitive hydrogel(PPP) for peritumoral injection of osteosarcoma in situ. Subsequently, the physicochemical properties and molecular biological characteristics of the drug delivery system were characterized. Finally, an osteosarcoma model was established to study the anti-tumor effects of multifunctional nanoparticles and the immunotherapy effect combined with αPD-L1.FSD-CHR has enhanced tumor tissue permeability, siRad18 can significantly reduce Dox-mediated DNA damage tolerance and enhance anti-tumor effects, and iron-based NPs show enhanced ROS upregulation. FSD-CHR@PPP showed significant inhibition of osteosarcoma growth in vivo and a reduced incidence of lung metastasis. In addition, siRad18 was unexpectedly found to enhance Dox-mediated immunogenic cell death (ICD).FSD-CHR@PPP combined with PD-L1 blocking significantly enhanced anti-tumor effects due to decreased PD-L1 enrichment.Hydrogel encapsulation of permeable nanoparticles provides an effective strategy for doxorubicin-resistant OS, showing that gene therapy blocking DNA damage tolerance can enhance treatment response to chemotherapy and appears to enhance the effect of ICD inducers to activate the immune system.