Asiaticoside promoted ferroptosis and suppressed immune escape in gastric cancer cells by downregulating the Wnt/ß-catenin pathway.

ABSTRACT

BACKGROUND: Our previous study has revealed that asiaticoside (AC) promotes endoplasmic reticulum stress and antagonizes proliferation and migration of gastric cancer (GC) via miR-635/HMGA1 axis. However, the effect and mechanism of AC on other progressions of GC, such as ferroptosis and immune escape, are still unknown. METHODS: AGS and HGC27 cells were incubated with 1, 2 and 4 µM of AC for 24 h. Mice xenografted with AGS cells were intragastrically injected with AC. The effect and mechanism of AC on GC were determined by the measurement of the ferrous iron level, the ROS level and the glutathione peroxidase (GSH) content, flow cytometry, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry and western blotting assays. RESULTS: AC increased the Fe2+ level and the ROS level, but decreased the expression of GPX4 and SLC7A11 and the GSH level. Besides, AC enhanced the percent of CD8+ T cells and the IFN-γ concentration, but reduced the PD-L1 expression and the IL-10 level. Mechanically, AC downregulated the relative levels of ß-catenin, active-ß-catenin, p-GSK3ß/GSK3ß, cyclin D1 and c-Myc in GC cells, which were rescued with the application of LiCl (an activator of Wnt/ß-catenin pathway) in AGS cells. Moreover, activation of Wnt/ß-catenin pathway by LiCl or the ß-catenin overexpression inverted the effect of AC on ferroptosis and immune escape in GC cells. In vivo, AC treatment declined the tumor size and weight, the level of GPX4, SLC7A11, PD-L1 and IFN-γ, and the expression of Wnt/ß-catenin pathway. CONCLUSION: AC enhanced ferroptosis and repressed immune escape by downregulating the Wnt/ß-catenin signaling in GC.