YULINK deficiency promotes cell death under glucose restriction in HCC cells in association with GLUT1-mediated glycolysis.

[BACKGROUND] Through evolutionary genomics analysis, we identified Yulink (MIOS, Entrez Gene: 54,468), a highly conserved gene encoding an 875 amino acid protein with diverse functions in humans. Given the importance of accelerated glycolysis in hepatocellular carcinoma (HCC), we explored the expression and function of Yulink in HCC cells and analyzed clinicopathological data to unveil its impact on patient survival.

[METHODS] Clinicopathological data from 184 patients with resectable HCC were mined to establish a correlation between Yulink expression and patient survival. We employed reverse transcription quantitative polymerase chain reaction (RT-qPCR) to assess Yulink expression in the tumor tissues. Various assays, including Western blotting, migration, MTT, cell cycle, immunofluorescence, oxidative stress, tumorigenesis, glucose uptake, glycolytic function, proximity ligation, and immunoprecipitation, were conducted on Huh7 cells to identify the regulatory mechanisms under glucose restriction.

[RESULTS] Comparative evolutionary genomics analysis revealed that patients with high Yulink expression had significantly shorter relapse-free survival (RFS) and overall survival (OS) (P < 0.0001 and = 0.0015, respectively). Multivariable Cox regression analysis identified Yulink expression as an independent unfavorable predictor of RFS (HR, 2.63; 95% CI, 1.58-4.38; P < 0.001) in HCC. Furthermore, Yulink expression positively correlated with Huh7 migration and survival, especially in response to glucose restriction. Yulink deficiency enhanced glucose restriction-induced cell death, likely due to increased reactive oxygen species (ROS) and DNA damage, with a failure of ATM-CHK2 activation. Huh7 xenografts with Yulink suppression exhibited delayed tumorigenesis in immunocompromised nude mice. Importantly, proximity Ligation assays and immunoprecipitation demonstrated that Yulink colocalized and interacted with glucose transporter 1 (GLUT1). Knockdown of Yulink not only suppressed GLUT1 expression, but also disrupted GLUT1 translocation from the cytosol to the cell membrane, resulting in downregulated glucose uptake and glycolysis.

[CONCLUSIONS] Our results underscore the protective role of Yulink in HCC survival under glucose restriction and its pivotal function in glucose metabolism, suggesting a mechanistic link between lower Yulink expression and higher survival in patients with HCC.