Cuproptosis Contributes to Cisplatin-Induced Nephrotoxicity: Insights into Thymol's Potential Inhibitory and Protective Effects.

Background: Cisplatin is a powerful treatment for cancer; however, its clinical application is compromised due to its potential for nephrotoxicity. The development of nephroprotective agents is hindered mainly due to the lack of understanding of the exact underlying mechanism. Additionally, the identification of safe nephroprotective agents that can be used as an adjunct to cisplatin is necessary. Methods: Rats were pretreated with thymol (60 mg/kg, orally) daily for two weeks and received a single cisplatin injection (8 mg/kg, i.p.) on the seventh day to induce nephrotoxicity. Results: Thymol prevented cisplatin-induced renal injury and restored serum creatinine and blood urea nitrogen. The renoprotective activity of thymol was further validated by histopathological studies, as demonstrated by the preserved architectures of the glomeruli, proximal, and distal convoluted tubules. Oxidative stress plays an important role in the pathophysiology of nephrotoxicity. Herein, cisplatin administration increased lipid peroxides and depleted the cellular antioxidant defense mechanisms (GSH, SOD, Nrf2, and HO-1). Interestingly, thymol remarkably ameliorated these alterations and restored oxidative status. We further examined the impact of cisplatin and/or thymol on cuproptosis, a distinct type of cell death associated with the excess intracellular accumulation of copper which is aggravated by oxidative stress. Pretreatment with thymol blunted the cisplatin-induced upregulation of genes associated with cuproptosis, including SLC31A1, DLAT, FDX1, LIAS, and ATP7A, as well as FDX1 protein expression. Furthermore, the molecular docking studies of thymol demonstrated favorable fitting and interactions with the conservative amino acids of FDX-1, DLAT, and ATP7A. This further supports the inhibitory effect of thymol on cuproptosis, which underlies its protective properties. Conclusions: This study illustrates that cuproptosis and oxidative stress play crucial roles in the development and progression of cisplatin-induced nephrotoxicity, and the protective activity of thymol is attributed, at least in part, to blunting these mechanisms.