Nanoparticles-encapsulated doxorubicin alleviates drug resistance of osteosarcoma via inducing ferroptosis.

To determine the effects of polymeric nanoparticle for doxorubicin (Dox) delivery and treatment of drug-resistant Osteosarcoma (OS) cells. Methoxy-polyethylene glycol amino (mPEG-NH2) and platinum bio-mimetic polycaprolactone-cysteine (PtBMLC) were crosslinked to obtain glutathione (GSH)-responsive mPEG-NH2-PtBMLC polymer to encapsulate Dox (named as Nano-Dox). The particle size and zeta potential of the nanoparticles were measured, and internalization of Dox by OS cells was observed. After treatment with Nano-Dox, cell proliferation was determined by cell counting kit 8 (CCK-8) and colony formation assay. Cell migration and invasion were determined by Transwell assay. Cell cycle arrest was assessed by flow cytometry. The induction of ferroptosis was analyzed by abnormal accumulation of total iron, Fe2+. Nano-Dox exhibited a stronger localization in OS cells (p < 0.01). Nano-Dox induced more significant suppression of drug-resistant OS cell growth (p < 0.01), migration (p < 0.01), and invasion (p < 0.01), compared with the single Dox treatment group, along with decreased expression of N-cadherin, Snail, and Vimentin, suggesting impaired cancer migration and invasion. The treatment with Nano-Dox induced notable cell cycle arrest at G0/G1 phase (p < 0.01) and accumulation of iron, Fe2+, and MDA (p < 0.01), as well as suppressed the protein levels of glutathione peroxidase 4 (GPX4) and SLC7A11. Administration of ferroptosis inhibitor (Fer-1) reversed the anti-proliferation effects of Nano-Dox (p < 0.01). The Dox delivered by the polymeric nanoparticle system notably enhanced its effects on suppressing the growth, migration, and invasion of drug-resistant OS cells via inducing ferroptosis. The application of environment response polymer enhanced the delivery of Dox and the therapeutic effects on OS.