Doxorubicin and erastin co-loaded hydroxyethyl starch-polycaprolactone nanoparticles for synergistic cancer therapy

Cancer stem cells (CSCs), enabled to self-renew, differentiate, and initiate the bulk tumor, are recognized as the culprit of treatment resistance, metastasis, and recurrence. Simultaneously eradicating CSCs and bulk cancer cells is crucial for successful cancer therapy. Herein, we reported that doxorubicin (Dox) and erastin co-loaded hydroxyethyl starch-polycaprolactone nanoparticles (DEPH NPs) eliminated CSCs and cancer cells by regulating redox status. We found that an excellently synergistic effect existed when Dox and erastin were co-delivered by DEPH NPs. Specifically, erastin could deplete intracellular glutathione (GSH), thereby inhibiting the efflux of intracellular Dox and boosting Dox-induced reactive oxygen species (ROS) to amplify redox imbalance and oxidative stress. The high ROS levels restrained CSCs self-renewal via downregulating Hedgehog pathways, promoted CSCs differentiation, and rendered differentiated cancer cells vulnerable to apoptosis. As such, DEPH NPs significantly eliminated not only cancer cells but more importantly CSCs, contributing to suppressed tumor growth, tumor-initiating capacity, and metastasis, in various tumor models of triple negative breast cancer. This study demonstrates that the combination of Dox and erastin is potent in elimination of both cancer cells and CSCs, and that DEPH NPs represent a promising treatment against CSCs-rich solid tumors.