Tellurium-Doped Bioactive Glassinduces Ferroptosis in Osteosarcoma Cells Regardless of FSP1

Human osteosarcoma (OS) is a rare tumor predominantly affecting long bones and characterized by a poor prognosis. Currently, the first line of intervention consists of surgical resection of primary tumors combined with radiotherapy and chemotherapy, with a profound impact on patient’s life. Since surgical removal of OS frequently results in large resection of bones the use of biomaterials to sustain the stability of remaining tissue and to stimulate bone regeneration is challenging. Moreover, residual neoplastic cells might be responsible for tumor recurrence. Here we explored the potential of doped-bioactive glass as novel therapeutic intervention to both eradicate residual malignant cells and promote bone regeneration. Bioactive glass (BAG) has been extensively studied and employed in the field of regenerative medicine, due to its osseointegration properties and ability to improve bone tissue regeneration. We found that the incorporation of tellurium in BAG selectively kills OS cells through ferroptosis while preserving the viability of hBMSCs, and stimulating their osteodifferentiation. Although the mechanism of Te toxicity is still unclear: i) Te-BAG generates lipid-ROS through LOXs activity but not iron overload; ii) Te-dependent ferroptosis is mediated by GPX4 down-regulation, and iv) abrogates the anti-ferroptotic activity of FSP1, which expression confers resistance of OS to canonical induction of ferroptosis.