Iron oxide nanoparticles loaded with paclitaxel inhibits glioblastoma by enhancing autophagy-dependent ferroptosis pathway

Objective: To explore inhibitory effect of iron oxide nanoparticles loaded with paclitaxel (IONP@PTX) on glioblastoma (GBM) and its potential mechanism.

Methods: IONP@PTX was synthesized and the characteristics were assessed by chemico-physical analysis and observed directly under transmission electron microscope. U251 cells and HMC3 cells were separately incubated with IONP@PTX and PTX, and then cell viability was detected by Cell Counting Kit-8. The capacity of cell invasive and migration was verified by Scratch wound healing and Transwell migration and invasion assays. Expressions levels of Autophagy and Ferroptosis biomarkers were demonstrated by Western blotting assay. Intracellular Reactive Oxygen Species (ROS) and lipid peroxidation were detected with DCFH-DA and C11-BODIPY staining, respectively. Intracellular concentration of iron ions was quantified spectrophotometrically. Moreover, inhibitory effect of IONP@PTX on GBM was evaluated by monitoring tumor growth and the toxicity of IONP@PTX was evaluated by measuring the body weight and index of liver and spleen in the mice bearing GBM xenograft.

Results: The successfully synthesized IONP@PTX possesses a hydrate diameter about 36 nm and a core diameter around 10 nm. IONP@PTX exerted an inhibitory effect on U251 cells, but had little effect on HMC3 cells compared with PTX alone. In addition, IONP@PTX inhibited the capacity of cell migration and invasion, increased the levels of iron ions, ROS and lipid peroxidation, enhanced the expression of autophagy-related protein Beclin1 and LC3II, and suppressed the expression of p62 and ferroptosis-related protein GPX4 in vitro compared with control group. Moreover, administration of IONP@PTX suppressed tumor volume of GBM xenografts and decreased the expression level of GPX4 protein in tumor tissues in comparison with control group (All P < 0.05). Intriguingly, the effect of IONP@PTX on GBM could be weakened by additional 3-MA or enhanced by additional rapamycin in vitro and in vivo (P < 0.05). More importantly, IONP@PTX had no obvious toxic effect on mice bearing GBM xenograft.

Conclusion: IONP@PTX inhibits GBM growth by enhancing autophagy-dependent Ferroptosis pathway, thus it might become a potential ferroptosis-inducing agent for ferroptosis-based tumor therapy.