Deubiquitination and stabilization of EIF4A3 by OTUB2 contributes to TPI1-mediated glycolysis and TNBC progression

Abstract Background Tumor cells rely on enhanced glycolytic capacity to facilitate cell growth and progression. However, the molecular mechanisms governing glycolysis in triple-negative breast cancer (TNBC) remain largely elusive. In this study, we elucidate the role of OTUB2 in regulating glycolysis in TNBC and delve into the mechanisms. Methods We utilized The Cancer Genome Atlas (TCGA) dataset to analyze the expressions of OTUB2, EIF4A3, and TPI1 in breast cancer tissues and specifically in triple-negative breast cancer (TNBC) tissues. qPCR and western blot experiments were performed to confirm the protein expressions of OTUB2, EIF4A3, and TPI1 in TNBC tissues and cell lines. Subsequently, overexpression and knockdown experiments followed by cell functional assays were conducted to elucidate the impact of OTUB2 on EIF4A3/TPI1-mediated TNBC malignant progression and related molecular mechanisms. Finally, a xenograft mouse model was established to verify the effect of OTUB2 in vivo. Results TCGA database indicated highly expressions of OTUB2, EIF4A3, and TPI1 in breast cancer tissues and TNBC tissues. Consistently, the mRNA and protein expressions of OTUB2, EIF4A3, and TPI1 were increased in TNBC tissues and cell lines, as compared to para-carcinoma tissues and MCF10A cells. OTUB2 knockdown inhibited cell proliferation, migration and invasion, and decreased glucose uptake, ATP level, lactate production, and ECAR, while the OTUB2 overexpression exhibited the opposite trends. Further data elucidated that OTUB2 stabilized the EIF4A3 protein via deubiquitination, and EIF4A3 interacted with TPI1 to stabilize its mRNA. Overexpression of EIF4A3 exacerbated TNBC malignant activities and glycolysis, while silencing TPI1 reversed these effects. In vivo, the knockdown of OTUB2 significantly inhibited tumor growth in a xenograft mouse model. Conclusions We conclude that OTUB2 deubiquitinates and stabilizes EIF4A3 to promote TNBC progression via TPI1-mediated glycolysis of tumor cells.