OGT-mediated O-GlcNAcylation of BICD2 drives gemcitabine resistance in pancreatic cancer via accelerating G2/M cell cycle progression.

Gemcitabine resistance remains a major obstacle in pancreatic cancer therapy. We herein report that O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) and its catalytic enzyme, O-GlcNAc transferase (OGT), are markedly upregulated in gemcitabine-resistant (Gem-R) pancreatic cancer cells, driven by hyperactivated glycolysis. Mechanistically, OGT interacts with and catalyzes the O-GlcNAcylation of BICD2 at serine 192 (S192), which further promotes BICD2 phosphorylation. This dual post-translational modification enhances BICD2 binding to RanBP2 and dynactin (DCTN1) during the G2/M phase, thereby accelerating cell cycle progression and gemcitabine resistance. Genetic depletion of OGT or pharmacological inhibition (OSMI-1) restores gemcitabine sensitivity, whereas the overexpression of OGT or stabilization of O-GlcNAcylation (PugNAc) exacerbates resistance and tumor aggressiveness. In the KPC genetically engineered mouse model of spontaneous pancreatic cancer, the combination of gemcitabine and OSMI-1 exerts an additive effect. Clinically, elevated levels of O-GlcNAcylation, OGT, and O-GlcNAcylated BICD2 correlate with a poor prognosis in patients with pancreatic cancer. Our study unveils the OGT-BICD2 (O-GlcNAcylation/phosphorylation)-RanBP2/DCTN1 axis as a pivotal regulator of gemcitabine resistance and suggests targeting O-GlcNAcylation as a promising therapeutic strategy to overcome chemoresistance in pancreatic cancer.