B3GNT5-associated glycosylation remodeling in tumor-associated macrophages supports TGF-β-related glioma progression.

Tumor-associated macrophages (TAMs) are abundant in the glioma microenvironment, but the glycosylation changes linked to their pro-tumorigenic functions remain unclear. β1,3-N-acetylglucosaminyltransferase 5 (B3GNT5), an enzyme involved in lacto/neolacto-series glycosphingolipid biosynthesis, has been associated with poor prognosis in glioma. Here, analyses of bulk transcriptomic, single-cell RNA-sequencing, and spatial transcriptomic datasets showed that B3GNT5 was enriched mainly in glioma-associated TAMs rather than in tumor cells. B3GNT5-high TAMs displayed M2-like features that were enriched at later stages of macrophage differentiation. In a macrophage-glioma coculture model, glioma-derived soluble signals increased B3GNT5 expression in macrophages. B3GNT5 silencing altered lectin-detectable cell-surface glycosylation and reduced macrophage-mediated glioma cell proliferation and invasion. B3GNT5 was associated with B4GALT1 expression, and co-immunoprecipitation and immunofluorescence assays indicated detectable B3GNT5-B4GALT1 association. Further experiments showed that B3GNT5 silencing reduced coculture-induced ITGB1/integrin β1 and TGF-β1 expression. Knockdown of TGFB1, ST6GAL1, or ITGB1 in macrophages attenuated TAM-induced Smad2 phosphorylation in glioma cells, while adenoviral ITGB1 overexpression partially restored TGF-β1 expression after B3GNT5 or ST6GAL1 depletion. These findings suggest that B3GNT5-associated glycosylation remodeling supports TAM-mediated, TGF-β-related glioma progression.