Abstract
Helicobacter pylori (H. pylori) infection is a well-established risk factor for gastric cancer, primarily due to its virulence factor, cytotoxin-associated gene A (CagA). Although PD-L1/PD-1-mediated immune evasion is critical in cancer development, the impact of CagA on PD-L1 regulation remains unclear. This study revealed that H. pylori CagA upregulated squalene epoxidase (SQLE) expression, a key enzyme in the cholesterol biosynthesis pathway. Elevated SQLE activity increased cellular palmitoyl-CoA levels, enhancing PD-L1 palmitoylation while decreasing its ubiquitination. This ultimately increases PD-L1 stability, suppressing T cell activity and facilitating immune evasion in gastric cancer. In summary, our findings highlight the crucial role of the CagA-SQLE-PD-L1 axis in gastric cancer progression, suggesting potential therapeutic strategies for targeting CagA-positive gastric cancer.