Glycosylation changes are pivotal in colorectal cancer (CRC) development. The role of bisecting GlcNAc, a specific N-glycosylation type catalyzed by glycosyltransferase MGAT3, in CRC progression remains elusive. Previous studies indicated that dietary interventions can be beneficial for patients with certain congenital disorders of glycosylation. However, the impact of dietary fatty acids, such as palmitic acid (PA), on glycosylation regulation remains largely unclear. Here, we observed markedly decreased levels of bisecting GlcNAc and MGAT3 in colonic tissues of CRC patients. Downregulation of bisecting GlcNAc in CRC cells increased cell proliferation, migration, and invasion, while decreasing apoptosis. Moreover, a PA-rich diet inhibited CRC carcinogenesis in azoxymethane/dextran sodium sulfate-induced CRC mice by elevating bisecting GlcNAc levels. However, in Mgat3fl/fl Villin-Cre mice the inhibitory effects of the PA-rich diet were abolished. Intact glycopeptide analysis revealed that PA enhanced the bisecting GlcNAc modification on desmoglein 2 (DSG2). Additionally, DSG2 was identified to inhibit CRC carcinogenesis through the EGFR/AKT signaling pathway. In conclusion, dietary PA suppresses CRC carcinogenesis by regulating bisecting GlcNAc modification on DSG2, providing a direct mechanistic link between dietary fatty acids and CRC.
Lei et al. (Mon,) studied this question.