Jolkinolide B Inhibits Gastric Cancer Growth by Targeting the PANoptosis Molecular Switch Caspase-8.

Background: To elucidate the mechanisms by which Jolkinolide B (JB), derived from Euphorbia fischeriana, suppresses gastric cancer (GC) development, given its known potent antitumor effects and the lack of detailed understanding of its impact and molecular processes in GC. Methods: The study utilized both cellular and animal models to investigate the effects of JB on GC. The GC cell lines AGS and MKN45 were used to assess JB's impact on cell growth, proliferation, migration, and invasion. Molecular techniques, including molecular docking and dynamics simulations, were employed to explore the binding interactions between JB and caspase-8. The inhibitor Z-IETD-FMK was used to examine the role of caspase-8 in JB-mediated PANoptosis. Xenograft tumor transplantation experiments were conducted to evaluate JB's effect on tumor growth and biotoxicity in vivo. Results: JB markedly inhibited the growth, proliferation, migration, and invasion of the AGS and MKN45 GC cell lines. It induced PANoptosis in GC cells by activating caspase-8, leading to increased expression of cleaved caspase-3/7 (apoptosis), GSDMD-N (pyroptosis), and p-RIPK1 and p-MLKL (necroptosis). Molecular docking and dynamics simulations revealed that JB binds effectively to caspase-8 with a binding free energy (ΔTotal) of -34.41 kcal/mol, suggesting specific binding-induced caspase-8 activation. The inhibition of caspase-8 by Z-IETD-FMK prevented JB-mediated PANoptosis. Additionally, JB significantly reduced tumor growth in xenograft models without causing biotoxicity. Conclusion: JB is a promising bioactive agent that inhibits gastric cancer growth through the activation of the PANoptosis pathway. This study highlights JB's potential as an effective therapeutic option for GC, underlining the importance of its binding interaction with caspase-8 and subsequent activation of apoptotic, pyroptotic, and necroptotic pathways.