FBXW7/GSK3β-mediated proline-rich 11 degradation promotes oxidative DNA damage and inhibits tumor progression in renal cell carcinoma.

Rationale: Renal cell carcinoma (RCC) is a highly malignant and common urological tumor. In our previous study, we reported the upregulation of PRR11 in RCC, emphasizing its important role in cell cycle regulation and apoptosis. In this follow-up study, we aim to further investigate the carcinogenic mechanism of PRR11. Methods: Immunoprecipitation-mass spectrometry (IP-MS), ubiquitination assays, and in vitro phosphorylation assays were used to investigate the phosphorylation and ubiquitination-mediated degradation of PRR11 by FBXW7 and GSK3β. RNA-seq analysis of PRR11 knockdown RCC cells and cellular functional assays, including flow cytometry and comet assays, were performed to explore downstream signaling pathways and regulatory functions. Mouse subcutaneous tumor, tail vein lung metastasis, and popliteal lymph node metastasis models were established to validate PRR11's role in vivo. Results: Our results reveal that GSK3β recognizes and phosphorylates the CDC4 phosphodegron (CPD) consensus motif of PRR11, enabling FBXW7 to bind to PRR11 and catalyze its K48-linked ubiquitination and degradation. Moreover, PRR11 activates AKT signaling, which inhibits GSK3β activity. This inhibition prevents the phosphorylation of CPD motifs on PRR11, thereby obstructing FBXW7-mediated ubiquitination and degradation. The interaction between PRR11 and AKT creates a positive feedback loop that increases the level of both proteins, which ultimately accelerates RCC progression by inhibiting oxidative DNA damage. Conclusion: The FBXW7/GSK3β-PRR11-AKT axis plays a pivotal role in the development of RCC by regulating oxidative DNA damage. Targeting PRR11 may be a potential therapeutic strategy for RCC.