Glycolytic Reprogramming Mediated by the OTUD4-FXR1-HIF1A Axis Drives Gastric Cancer Progression

Ubiquitination and deubiquitination play critical roles in gastric cancer progression, yet systematic investigations of ubiquitin-regulating proteins in gastric cancer (GC) remain limited. To identify key regulators, we performed Ubiquitin-Focused CRISPR-Cas9 growth-based screening in GC cells and identified the deubiquitinase OTUD4 as a candidate gene promoting tumor growth. Functionally, OTUD4 was found to act as an oncogene by promoting the proliferation and metastasis of GC cell. Mechanistically, OTUD4 interacts with FXR1 through its N-terminal region (1-245 aa), and mutation of the catalytic cysteine residue (C45A) markedly impairs this interaction. OTUD4-mediated deubiquitination removes K48-linked polyubiquitin chains from FXR1, thereby protecting FXR1 from proteasomal degradation and increasing its stability. The resulting accumulation of FXR1 enhances HIF1A mRNA stability, leading to increased HIF1A expression. Consequently, HIF1A activates glycolytic programs and promotes the malignant progression of gastric cancer. Clinically, OTUD4 expression was significantly higher in tumor tissues, and higher OTUD4 levels were linked to decreased overall survival. Importantly, OTUD4 and FXR1 expression levels show a positive correlation in human GC samples. Collectively, these findings uncover an OTUD4-FXR1-HIF1A signaling axis that promotes glycolysis, which in turn functionally drives gastric cancer progression, and thereby provides a potential prognostic biomarker and therapeutic target.