Notably, pharmacological demethylation of HGC-27 cells with 5-aza-CdR restored ARID1A expression while suppressing PD-L1 (Figs. 10D–10F).These findings suggest an inverse regulatory relationship between ARID1A and PD-L1 in the studied models, implying that ARID1A loss-of-function may reprogram immune checkpoint signaling in gastric cancer. This evidence concerns the gene ARID1A and gastric cancer.