Up-Regulation of FBXO17 Promotes Ferroptosis and Suppresses the Stemness of Prostate Cancer Cells Through Wnt/β-Catenin Pathway.

Abstract

As a critical component of E3 ubiquitin ligase complexes, FBXO17 exhibits either tumor-promoting or tumor-suppressing in a variety of tumors, but its biological function and molecular mechanism in prostate cancer (PCa) are still unclear. FBXO17 expression in PCa cell lines and normal prostate epithelial cells (RWPE-1) was assessed using Western blot. The malignant biological behavior of the cells was evaluated using EdU staining, Transwell assay, and flow cytometry. The proportion of CD44+CD133+ stem cell subsets was determined via flow cytometry, and the stemness of PCa cells was evaluated using the sphere formation assay. FerroOrange staining, transmission electron microscopy, and the C11 BODIPY kit were used to detect ferroptosis-related indicators. The subcutaneous tumor model of nude mice was constructed to monitor tumor growth, and pathological staining was applied to evaluate tumor cell proliferation and apoptosis. Epithelial-mesenchymal transition (EMT) markers, ferroptosis-related proteins, stem cell markers, and Wnt/β-catenin axis-related proteins were determined through Western blot. FBXO17 expression was markedly decreased in PCa cell lines. FBXO17 overexpression suppressed malignant behaviors and the EMT process, promoted cell apoptosis, down-regulated stem cell marker expression, reduced CD44+CD133+ cell subsets, and inhibited tumor sphere formation in DU-145 and PC3 cells. Overexpression of FBXO17 also significantly increased the levels of Fe2+ and lipid peroxides and led to abnormal mitochondrial morphology. Combined with the ferroptosis inducer Erastin, further enhanced the tumor suppressor effect of FBXO17 overexpression. Moreover, FBXO17 overexpression hindered the Wnt/β-catenin axis; the pathway activator LiCl reversed the ferroptosis and tumor suppressor effects mediated by FBXO17 overexpression, and combined with Erastin could restore the above effects. In vivo, FBXO17 overexpression effectively suppressed tumor growth, while inhibiting stem cell-like properties and promoting ferroptosis; LiCl weakened the anti-tumor effect of FBXO17, and combined with Erastin reversed this effect. In conclusion, by hindering the Wnt/β-catenin pathway, overexpression of FBXO17 promotes ferroptosis and subsequently inhibits the malignant phenotype and stemness properties of PCa cells.