ST8SIA4-mediated N-glycosylation of hENT1 suppresses gemcitabine resistance in pancreatic cancer

Gemcitabine (GEM) serves as a first-line chemotherapeutic agent for pancreatic cancer (PC), but its clinical efficacy is significantly limited by the emergence of drug resistance, necessitating in-depth exploration of the underlying molecular mechanisms. This study employed the TCGA database to analyze ST8SIA4 expression, revealing consistent downregulation in PC tumor tissues compared to matched normal adjacent tissues. A GEM-resistant cell model (SW1990/GEM) was generated from SW1990 cells through incremental dose induction to further investigate resistance pathways. Experimental analyses included qPCR and Western blotting for gene and protein expression, CHX chase assays for protein stability, CO-IP for protein-protein interactions, CCK-8 tests for cellular proliferation, and flow cytometry for apoptotic rates. Results demonstrated that ST8SIA4 downregulation was prevalent in both PC tissues and the SW1990/GEM model. Overexpression of ST8SIA4 suppressed GEM resistance in SW1990/GEM cells and upregulated hENT1 protein expression; however, this effect was attenuated by an N-linked glycosylation inhibitor. Crucially, silencing hENT1 counteracted the resistance inhibition induced by ST8SIA4 overexpression. Collectively, these findings indicate that ST8SIA4 regulates N-linked glycosylation of hENT1, thereby stabilizing hENT1 protein expression and reversing GEM resistance in PC, offering a potential therapeutic target for overcoming chemotherapy resistance.