Inhibition of GRK2 mitigates cisplatin-induced acute and chronic nephrotoxicity by targeting the NADPH oxidase 4/oxidative stress axis.

BACKGROUND AND PURPOSE Cisplatin nephrotoxicity involves oxidative stress, with NADPH oxidase 4 (NOX4) in renal tubular epithelial cells (RTECs) as a potential source of key reactive oxygen species (ROS). Although G protein-coupled receptor kinase 2 (GRK2) contributes to tissue injury, its regulatory role in cisplatin nephrotoxicity via NOX4 remains undefined. We have investigated the underlying mechanisms of GRK2 in cisplatin-induced acute and chronic nephrotoxicity. EXPERIMENTAL APPROACH Hemizygous Grk2 knockout mice and homozygous Grk2 knockout RTECs were utilised. The GRK2-NOX4 interaction was investigated by co-immunoprecipitation or glutathione S-transferase pull-down. Kinase assays and ubiquitination experiments were performed to investigate the regulatory effect of GRK2 on the phosphorylation and ubiquitination of NOX4. Acute, sub-chronic and chronic cisplatin models, as well as syngeneic tumour models, evaluated the renoprotection afforded by the GRK2 inhibitor CP-25 and its impact on chemotherapy efficacy. KEY RESULTS Grk2 deficiency attenuated cisplatin-induced nephrotoxicity in vivo and reduced RTEC death and epithelial-mesenchymal transition (EMT) in vitro. Grk2 knockout or knockdown downregulated NOX4 expression, which repressed NOX4-mediated ROS release and oxidative stress, preventing cisplatin-induced RTEC death and EMT. GRK2 promoted NOX4 phosphorylation and suppressed ubiquitin-mediated degradation, thereby increasing NOX4 stability and ROS production. CP-25 effectively ameliorated cisplatin-induced nephrotoxicity, suppressed oxidative stress, and reduced renal apoptosis and EMT without compromising its anticancer efficacy. These protective effects also were observed in vitro. CONCLUSION AND IMPLICATIONS GRK2 plays a crucial role in cisplatin-induced nephrotoxicity by modulating NOX4, suggesting that targeting GRK2 is an effective renoprotective strategy for cisplatin-based cancer therapy.