Heat induces pyroptosis in human normal lung epithelial cells and lung cancer cells via caspase-3/GSDME activation

Background: Hyperthermia (including thermal ablation and whole-body hyperthermia) is one of the methods to treat lung tumor. The primary mechanism underlying this method involves causing tumor cell necrosis, apoptosis, and pyroptosis. Pyroptosis can trigger a series of inflammatory reactions and serves as a contributing factor to lung injury. The objective of this study was to investigate whether hyperthermia can induce pyroptosis of normal lung epithelial cells, while concurrently triggering pyroptosis of lung tumor cells. Materials and Methods: The cell lines PC-9 and BEAS-2B used in this study represent lung tumor cells and normal lung epithelial cells, respectively. PC-9 and BEAS-2B cells was simulated with a 45°C thermostatic water bath in vitro . Cell morphological characteristics were observed using microscopy. Gene expressions were evaluated by quantitative real-time PCR and protein expressions were assessed using Western blotting. Results: Heat stress induced morphological features of pyroptosis in BEAS-2B and PC-9 cells and upregulated pyroptosis-related gene expressions ( GSDMD, GSDME, caspase-1, caspase-3, IL-1β , and IL-18 ) in both cells. Also, heat stress resulted in an upregulation of cleaved GSDME but not cleaved GSDMD in BEAS-2B and PC-9 cells and increased cleaved GSDME can be efficiently abrogated by inhibition of caspase-3. Conclusion: Heat induces pyroptosis in BEAS-2B and PC-9 cells, and the mechanism of pyroptosis induction is realized through the GSDME/caspase-3 pathway. The results showed hyperthermia can induce pyroptosis of lung cancer cells as well as normal lung epithelial cells at the same time. This might provide a potential target for prevention and treatment of lung injury after hyperthermia.