Isoquercitrin Inhibits Lung Cancer Cell Growth Through Triggering Pyroptosis and Ferroptosis

Isoquercitrin possesses anti-tumor activity in several types of cancers, however, its effects and underlying mechanisms on lung cancer have not been reported. Human lung cancer cell lines as well as normal lung epithelial BEAS-2B cells were treated with isoquercitrin. The influences of isoquercitrin in vitro were evaluated by determining cell viability, apoptosis, pyroptosis, and ferroptosis. Additionally, A549 tumor-bearing mice were generated to explore the anti-cancer effect of isoquercitrin in vivo. We found that isoquercitrin dose-dependently reduced lung cancer cells' viability, with no toxicity against BEAS-2B cells. Isoquercitrin at 40 μM and 80 μM was used in vitro. Isoquercitrin increased apoptosis, elevated NLRP3 inflammasome activation-mediated pyroptosis, and promoted ferroptosis in lung cancer cells. NLRP3 knockdown and caspase-1 selective inhibitor VX-765 attenuated isoquercitrin-induced pyroptosis and ferroptosis, but not apoptosis. Furthermore, isoquercitrin accelerated ROS generation, while ROS inhibitor N-acetylcysteine abrogated isoquercitrin-induced apoptosis, NLRP3 related-pyroptosis and ferroptosis. In vivo, isoquercitrin (1 mg/kg and 5 mg/kg) inhibited tumor growth, increased apoptosis, NLRP3-related pyroptosis, ferroptosis and ROS generation in tumors. Taken together, isoquercitrin inhibits lung cancer growth by triggering ROS/NLRP3-mediated pyroptosis and ferroptosis, with ROS also directly inducing apoptosis. This suggests that isoquercitrin might be a potential therapeutic agent for lung cancer.