ɑ1,3-mannosyltransferase promotes the malignant progression of bladder cancer through activating TNF signaling pathway.

BACKGROUND: Bladder cancer (BCa) is the most prevalent malignancy of the urinary system. Aberrant glycosylation, driven by specific glycosyltransferases (GTs), plays a pivotal role in various carcinogenic processes. However, the role of GTs-related glycobiomarkers and their underlying mechanisms in BCa remain poorly understood. METHODS: A diagnostic model based on GTs was constructed and validated using multiple bioinformatics tools. The diagnostic and prognostic value, biological functions and potential targeted drugs were assessed using R packages, K-M plotter and molecular docking. The functional impact and mechanism of ALG3 in BCa were investigated through functional assays, RNA sequencing, immunoprecipitation, and lectin pull down assays. RESULTS: A diagnostic model comprising six GTs (ALG3, POMT2, UGCG, XXYLT1, COLGALT1, and A4GALT) was established, demonstrating high diagnostic accuracy for BCa (AUC: 0.966; sensitivity: 88.5%; specificity: 92.6%), which was further validated. Among these, ALG3 and POMT2 belong to the mannosyltransferase family, with ALG3 identified as a more reliable diagnostic glycobiomarker than POMT2 for BCa detection. GSVA analysis revealed that ALG3 was significantly enriched in Umbrella cells, suggesting its potential role in influencing BCa cell fate. Overexpression of ALG3 promoted cell proliferation and metastasis by modulating CD44 N-glycosylation and activating the TNF signaling pathway, confirming its role as a tumor promoter and oncogene in BCa progression. Moreover, ALG3 was identified as a novel target of miR-142-5p. Four potential small molecule inhibitors of ALG3 were identified, with selumetinib emerging as a promising candidate. CONCLUSIONS: ALG3 contributed to BCa progression via CD44 N-glycosylation and TNF pathway, positioning it as a promising serum glycobiomarker, a feasible therapeutic target, and a valuable reference for personalized and precision medicine in BCa.