GALNT6 coordinates glycolysis and α-KG-dependent DNA methylation to promote TNBC progression.

As the most aggressive form of breast cancer, triple-negative breast cancer (TNBC) is associated with poor prognosis and a lack of effective therapeutic options. Glycosylation has been linked to metabolic reprogramming in various cancers, and therapies targeting glycosylation-mediated metabolic reprogramming have been found to be effective. However, the role of the glycosyltransferase GALNT6 in TNBC metabolic reprogramming has not been examined. Our approach involved analyzing clinical data to assess the association between GALNT6 levels and patient outcomes. We employed gene knockdown techniques to silence GALNT6 expression in TNBC models. To investigate the underlying mechanisms, we utilized methods to measure glycolytic activity, metabolite levels, protein stability assays, transcriptional analysis, and assessment of DNA methylation status. Our results revealed that high level of GALNT6 were associated with poor clinical outcomes in TNBC. GALNT6 knockdown inhibited glycolytic and enhanced α-KG accumulation. Mechanistically, GALNT6 stabilizes HIF-1α through O-glycosylation, thereby enhancing the transcriptional levels of glycolytic enzymes. Meanwhile, GALNT6 stabilizes PFKM and PKM2 via O-glycosylation to protect them from proteasomal degradation. In parallel, GALNT6 promotes α-KG depletion by upregulating IDH2 and α-KGDH while suppressing GPT2. This depletion inhibits TET3-mediated DNA demethylation, thereby elevating 5mC levels, which in turn activates genes such as KIF14 to promote TNBC progression. Notably, silencing glycosylation-dependent glycolytic pathways or inhibiting α-KG-dependent processes markedly suppressed TNBC proliferation. Our study uncovers GALNT6 as a key regulator of metabolic reprogramming (glycolysis/TCA cycle) and epigenetic remodeling (5mC/TET3) to accelerate TNBC progression, suggesting that targeting the GALNT6-mediated metabolic-epigenetic axis may provide a novel therapeutic strategy for TNBC.