GTPBP4 promotes colorectal cancer cell proliferation by positively regulating MYC-driven glycolytic metabolism.

Colorectal cancer remains a leading cause of cancer death globally, creating an urgent need for novel therapeutic targets. Here, we investigate the expression, function, and regulatory mechanism of GTP-binding protein 4 (GTPBP4) in colorectal cancer. Analysis of The Cancer Genome Atlas (TCGA) colon adenocarcinoma (COAD) dataset showed that GTPBP4 is upregulated in colorectal tumors relative to normal mucosa, and high GTPBP4 expression correlates significantly with reduced overall survival. We observed a strong positive correlation between GTPBP4 and MYC expression across the cohort, leading us to generate stable GTPBP4-knockdown HCT116 and SW620 cells, as well as isogenic rescue lines overexpressing MYC. GTPBP4 depletion markedly suppressed cell proliferation, as determined by Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU) incorporation, and clonogenic assays. Mechanistically, GTPBP4 knockdown reduced both MYC mRNA and protein levels, accelerated MYC protein turnover, and increased MYC ubiquitination (all P < 0.05), indicating dual transcriptional and post-translational regulation. Concurrently, GTPBP4 silencing downregulated key glycolytic enzymes and decreased glycolytic flux, effects that were fully reversed by ectopic MYC expression (P < 0.05). In a subcutaneous xenograft model, GTPBP4 knockdown significantly inhibited tumor growth, reduced MYC and Ki-67 proliferation antigen (Ki-67) expression, and blunted glycolytic metabolism (P < 0.01 or P < 0.05). Co-expression of MYC restored all these parameters and reversed the enhanced MYC ubiquitination (P < 0.05). Collectively, our data demonstrate that GTPBP4 sustains MYC expression through dual mechanisms to drive glycolytic reprogramming and colorectal cancer growth, identifying the GTPBP4/MYC/glycolysis axis as a promising therapeutic target.