STING signaling contributes to methotrexate-induced liver injury by regulating ferroptosis in mice.

Methotrexate (MTX), an anti-metabolite agent, is a widely used chemotherapeutic anticancer drug, but its hepatotoxicity severely limits its clinical application. Nevertheless, the precise mechanisms of MTX-caused liver damage are extremely intricate and still need to be fully clarified. In the current study, we investigated the role of the STING-ERS-ferroptosis axis in MTX-triggered hepatic toxicity in vivo and in vitro models. Male C57BL/6 J mice exposed to a single dose of MTX (0, 2, 5, and 20 mg/kg) for 3 days exhibited severe liver damage and overactivated STING signaling. Moreover, we found that ferroptosis was also involved in MTX-mediated liver damage. Interestingly, STING deficiency alleviated liver damage, inhibited liver inflammation, as well as suppressed hepatic lipid peroxidation and ferroptosis in MTX-treated mice. Consistently, STING inhibitor (C-176) pretreatment also alleviated MTX-induced STING signaling activation, ROS overproduction and ferroptosis in AML12 cells. Finally, we verified that ER stress was responsible for the MTX-induced liver injury and ferroptosis caused by STING activation. Taken together, our study uncovered a novel link between STING signaling and ferroptosis in MTX-triggered hepatic damages, and suggested that targeting the STING-ER stress-ferroptosis axis might be a promising and effective therapeutic approach against MTX-induced liver damage.