Piperlongumine inhibits esophageal squamous cell carcinoma in vitro and in vivo by triggering NRF2/ROS/TXNIP/NLRP3-dependent pyroptosis

Pyroptosis, a type of programmed cell death, is characterized by cell swelling with bubbles, and the release of inflammatory cell cytokines. Piperlongumine (PL) is a natural bioactive product extracted from Piper longum L, which can effectively exert anti-tumor activities in cancer. However, the effects and the exact molecular mechanisms of PL in esophageal squamous cell carcinoma (ESCC) remain unclear. This research aimed to investigate the role and mechanism of PL on ESCC in vitro and in vivo. In vitro, the MTT results showed that the IC50 of PL in ESCC cells was 28.55 μM. Moreover, PL significantly suppressed malignant behavior by promoting pyroptosis of ESCC cells by inhibiting proliferation, migration, invasion, and colony formation of KYSE-30 cells, up-regulating expressions of ASC, Cleaved-caspase-1, NLRP3, and GSDMD, while inducing the generation of ROS. Further, NRF2 knockdown promoted TXNIP expression, while overexpression of NRF2 inhibited TXNIP expression. However, after PL treatment, this effect was reversed. In addition, PL significantly inhibited the malignant behavior of ESCC cells while the inhibitory effects were reversed by DMF (NRF2 activator) or NAC (ROS eliminator) treatment. Finally, PL markedly increased expressions of ASC, Cleaved-caspase-1, NLRP3, GSDMD, and the generation of ROS while the effects were reversed by TXNIP knockdown or RUS (TXNIP inhibitor) treatment. In vivo, the KYSE-30 xenograft model confirmed that PL inhibited the growth of ESCC transplanted tumors by promoting cell pyroptosis. In conclusion, the results suggested that PL inhibited the malignant behavior of ESCC cells in vitro and tumorigenesis of ESCC in vivo by inhibiting NRF2 and promoting ROS-TXNIP-NLRP3-mediated pyroptosis.