Effects of O-GlcNAc glycosylated modified transferase on prognosis of diffuse large B-cell lymphoma and analysis of downstream targets.

Diffuse large B-cell lymphoma (DLBCL) is a clinically and biologically heterogeneous malignancy, but the prognostic and biological significance of O-linked β-N-acetylglucosamine (O-GlcNAc) modification remains incompletely understood. We analyzed three microarray-based DLBCL cohorts obtained from the Gene Expression Omnibus (GSE87371, GSE117556, and GSE181063; total n = 2,090). Consensus clustering was used to characterize the expression patterns of glycosylation-related genes. The associations of these expression patterns and O-GlcNAc transferase (OGT) expression with overall survival were evaluated using Kaplan-Meier analysis and Cox regression. Differential expression, pathway enrichment, single-sample gene set enrichment, and correlation analyses were performed to characterize biological features associated with OGT expression. We also used OCI-LY3 and SU-DHL-4 cell lines to investigate the effects of OGT overexpression, shRNA-mediated knockdown, and pharmacological inhibition on cell proliferation and apoptosis. Co-immunoprecipitation and immunoblotting were performed to assess protein O-GlcNAcylation and phosphorylation, together with selected signaling proteins, anti-apoptotic factors, and epigenetic regulators. In result, Glycosylation-related genes displayed heterogeneous expression patterns across DLBCL samples that were associated with survival, with OGT emerging as a key prognostic candidate. High OGT expression was associated with shorter survival in all three cohorts, and patients with OGT overexpression and high International Prognostic Index scores had particularly poor outcomes. Increased levels of OGT expression co-varied with PI3K-AKT-MTOR signaling, MYC target signaling, and selected anti-apoptotic and epigenetic features. In both cell lines, OGT overexpression promoted proliferation and was accompanied by increased O-GlcNAcylation and activation-associated phosphorylation of PI3K, AKT, and Myc, together with increased protein levels of Bcl-2, Mcl-1, EZH2, and KMT2D. OGT knockdown or pharmacological inhibition produced opposite changes and increased apoptosis. These findings indicate that elevated OGT expression is associated with unfavorable survival and adverse signaling features in DLBCL. Further studies are required to establish the direct causal relationships and therapeutic significance of OGT-associated O-GlcNAcylation.