Tempol Mitigates Methotrexate-Induced Osteotoxicity via Oxidative Stress Modulation and MAPK Pathway Inhibition.

Purpose: Osteotoxicity, a common consequence of Methotrexate (MTX) therapy, significantly compromises bone health by inducing oxidative stress and disrupting bone remodeling. This study examines the protective effects of Tempol, a nitroxide compound with antioxidant properties, against MTX-induced osteotoxicity. Methods: Osteocyte-like MLO-Y4 cells were cultured and treated with Tempol and MTX to evaluate changes in apoptotic mediators, MAPK signaling pathways, and oxidative stress parameters. Results: MTX treatment significantly increased caspase-3 activity and Bax expression while decreasing Bcl-2 levels, thereby creating a pro-apoptotic environment. It also activated stress-related pathways by elevating JNK and ERK activities. Conversely, Tempol effectively countered these effects by restoring the balance of apoptotic mediators, downregulating MAPK activation, and enhancing Total Antioxidant Status (TAS). Additionally, Tempol reduced Total Oxidant Status (TOS) and improved the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Conclusion: These findings highlight Tempol's potential to mitigate oxidative stress and apoptosis linked to MTX therapy, supporting its use as an adjunctive treatment to protect bone health in patients undergoing MTX therapy. Emphasizing Tempol's clinical implications as a protective agent reinforces the urgency for further research into its long-term effects on cellular viability and bone integrity in the context of chemotherapy.