GSK-3β Regulates the Expression of P21 to Promote the Progression of Chordoma

PURPOSE: Chordoma is a rare malignant bone tumor transformed from the remnants of notochord. It is characterized as highly aggressive and locally invasive, difficult to be completely removed by surgery, and has a poor clinical prognosis. Glycogen synthase kinase 3 beta (GSK-3β) is involved in many cellular processes. GSK-3β overexpression has been shown to promote the development of many cancers, according to previous studies. However, the role of GSK-3β in chordoma remains unclear. METHODS: Immunohistochemistry (IHC) and Western blotting (WB) were performed on clinical specimens to measure GSK-3β expression in chordoma, and immunofluorescence and quantitative real-time polymerase chain reaction (QRT-PCR) were performed to examine the expression of GSK-3β and P21 in cell lines. Cell proliferation was detected by the CCK-8 assay and colony formation analysis, cell migration and invasion checked by Transwell experiments, and cell apoptosis was determined by Annexin V/propidium iodide staining. P21 was predicted as a downstream target gene of GSK-3β using STRING and UNIHI databases. Moreover, we used immunoprecipitation to confirm that GSK-3β and P21 interacted with each other. The double luciferase reporter gene assay showed that GSK-3β could regulate the promoter activity of P21. Finally, the role of the GSK-3β -P21 pathway in chordoma tumorigenesis was analyzed in vivo in nude mice. RESULTS: Our study showed that GSK-3β was significantly higher in chordoma tissues than in paracancer tissues, and siRNA knockdown of GSK-3β inhibited chordoma cell proliferation and promoted cell apoptosis. Additionally, our research found that GSK-3β bound and downregulated the expression of the P21 gene, and the expression of silencing P21 partially reversed the inhibitory effect of knockdown GSK-3β on chordoma. Furthermore, xenografts showed that knockdown GSK-3β inhibited the formation of chordomas in vivo. CONCLUSION: Our results indicated that the GSK-3β-P21 axis may be an important signaling pathway for the occurrence and development of chordoma, providing a new therapeutic target for the clinical treatment of this disorder.