A Possible Mechanism of Cisplatin-Induced Tumor Necrosis Factor (TNF)-α Production in Murine Macrophages

Abstract

Cisplatin has been used for the treatment of various solid cancers or sarcomas; however, it can induce severe adverse effects. Among these adverse effects, nephrotoxicity, which has the potential to be a dose-limiting factor of this agent, develops due to the secretion of tumor necrosis factor-α (TNF-α) from macrophages; however, the precise mechanisms are still unclear. To elucidate possible mechanisms, we investigated the involvement of mitogen-activated protein kinases (MAPK) and reactive oxygen species (ROS) in cisplatin-induced TNF-α mRNA expression and protein produc- tion in the mouse macrophage-like cell line, RAW 264. Cisplatin (1 μM) significantly increased TNF-α mRNA expres- sion and protein production. Extracellular-regulated kinase (ERK) and p38 MAPK, but not c-Jun N-terminal kinase (JNK), phosphorylation increased in response to cisplatin. Although an ERK inhibitor (PD98059) suppressed both cis- platin-induced TNF-α mRNA expression and its protein production, a p38 MAPK inhibitor (SB203580) decreased TNF-α protein production only. A JNK inhibitor (SP600125) had no effect on cisplatin-induced TNF-α mRNA expres- sion. Furthermore, a scavenger of ROS, N,N’-dimethylthiourea, suppressed both ERK activation and TNF-α mRNA expression. These results suggest that the phosphorylation of ERK by ROS is involved in cisplatin-induced TNF-α mRNA expression and that the signaling pathway of p38 MAPK is related to TNF-α protein production.