• C1GalT1 expression is elevated in bladder cancer and is modified by O-GlcNAcylation, which stabilizes the protein and enhances its interaction with the chaperone Cosmc.
• Mutations at Thr229 or Thr233 of C1GalT1 reduce its stability and promote proteasomal degradation, highlighting specific O-GlcNAc sites as critical regulators.
• Downregulation of C1GalT1 suppresses glycolysis and inhibits the pro-tumorigenic phenotype of bladder cancer cells, suggesting a metabolic link.
• This study reveals a novel crosstalk between O-GlcNAc and O-GalNAc glycosylation pathways, offering potential therapeutic targets for bladder cancer.