Ferroptosis inhibits biological behaviors of glioma cells by downregulating Galectin-9 transcriptional level via extracellular Acetyl-HMGB1.

Ferroptosis, the most common programmed cell death process, and immune checkpoints play increasingly prominent roles in glioma. However, the effects of ferroptosis on immune checkpoints on glioma remain unclear. The intracellular ROS levels of ferroptotic glioma cells were observed via fluorescence microscopy. The extracellular Acetyl-HMGB1 content of ferroptotic glioma cells was detected via an ELISA kit. Transwell chambers (8.0 μm) were used to detect the invasion ability of ferroptotic glioma cells. The ability of ferroptotic glioma cells to proliferate was detected via the CCK-8 reagent. The apoptosis of ferroptotic glioma cells was detected via an Annexin V-FITC apoptosis kit. The transcriptional levels of four immune checkpoints (CD80, CD155, HMGB1, and galectin-9) in ferroptotic glioma cells were detected via RT-PCR. Ferroptosis in glioma cells promotes the release of acetyl-HMGB1 and autophagy is involved in this process. Inhibiting extracellular acetyl-HMGB1 while inducing ferroptosis promoted the invasion and proliferation of glioma cells and inhibited apoptosis. Ferroptosis downregulated the transcription of CD155 and galectin-9 in glioma cells, but inhibition of extracellular acetyl-HMGB1 reversed the effect of ferroptosis on the downregulation of galectin-9 transcription. In conclusion, ferroptosis downregulates galectin-9 transcription via extracellular acetyl-HMGB1, thereby inhibiting the biological behavior of glioma cells.