RACK1 promotes NF-κB pathway activation and glioma cell proliferation by inhibiting RPS2 ubiquitination.

BACKGROUND

Gliomas are aggressive brain tumors with poor prognosis. Receptor for Activated C Kinase 1 (RACK1) and Ribosomal Protein S2 (RPS2) are linked to tumor progression, but their combined roles in glioblastoma remain unclear.

METHODS

Differentially expressed genes (DEGs) from GSE41031 and the Cancer Genome Atlas (TCGA)-glioma datasets were identified and intersected, and protein-protein interaction (PPI) network analysis was performed using multiple algorithms. The expression and function of RACK1 and RPS2 were analyzed in vitro. Co-immunoprecipitation (Co-IP) and ubiquitination experiments analyzed the physical interaction and protein stability of RACK1 and RPS2. NF-κB pathway activity was examined using Western blot and luciferase reporter assays.

RESULTS

Bioinformatics analysis revealed that RACK1 and RPS2 were hub genes significantly upregulated in glioma. RACK1 expression was significantly increased in glioma cell lines and promoted cell proliferation, migration and invasion. RACK1 knockdown induced G2/M phase cell arrest by downregulating cyclin B1 and CDK1. Silencing RPS2 also inhibited glioma cell proliferation and colony formation. Mechanistically, RACK1 stabilized RPS2 by inhibiting ubiquitin-mediated RPS2 degradation. RACK1 knockdown accelerated RPS2 degradation and increased its ubiquitination, while MG132 reversed this effect. Both RACK1 and RPS2 positively regulated the NF-κB pathway, and RPS2 overexpression partially rescued the inhibitory effects of RACK1 knockdown on NF-κB pathway and cell growth.

CONCLUSION

Our results suggest that RACK1 promotes glioma cell proliferation by promoting NF-κB pathway activation by inhibiting RPS2 ubiquitination, and may serve as a potential biomarker and therapeutic target for glioma progression.