Targeting ST3GAL1 to downregulate ligands for the glycoimmune checkpoint Siglec-7 and reverse immune escape in hepatocellular carcinoma.

Sorafenib is the first-line therapy for advanced hepatocellular carcinoma (HCC). However, acquired resistance to sorafenib remains a significant challenge. Previous studies have shown that sorafenib treatment induces the formation of truncated O-glycans in HCC cells, but the relationship between sorafenib-induced glycosylation changes and acquired therapy resistance remains unclear. Primary natural killer (NK) cells, freshly isolated from peripheral blood or following culture and expansion, expressed the glycoimmune checkpoints Siglec-7 and Siglec-9. HCC cells exhibited varying levels of Siglec-7/9 ligands on their surface. Sorafenib-resistant liver cancer cells displayed hypersialylation, leading to increased expression of surface Siglec-7/9 ligands, which conferred protection against NK cell-mediated cytotoxicity. Silencing ST3GAL1 significantly reduced Siglec-7 ligand expression on liver cancer cells, enhancing their susceptibility to NK-mediated cytotoxicity and cetuximab-induced antibody-dependent cellular cytotoxicity (ADCC) in epidermal growth factor receptor (EGFR)-expressing tumor cells. Furthermore, high ST3GAL1 expression correlated with poor clinical outcomes in patients with stage 1-2 HCC. This study highlights the critical role of ST3GAL1 in regulating Siglec-7 ligands to facilitate immune escape from NK cell cytotoxicity. Moreover, its elevated expression is associated with adverse clinical outcomes in HCC. Targeting ST3GAL1 may represent a promising strategy to enhance NK cell-mediated anti-tumor immunity in HCC.