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

Li Chen,1,2 Yi Zuo,2 Ru Pan,2 Zhen Ye,1,2 Kailun Wei,1,2 Shaohuai Xia,1 Wencai Li,1 Jie Tan,2 Xuewei Xia1,2 1Department of Neurosurgery, Affiliated Hospital of Guilin Medical University, Guilin, Guangxi 541001, People’s Republic of China; 2Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin, Guangxi 541004, People’s Republic of ChinaCorrespondence: Xuewei XiaDepartment of Neurosurgery, Affiliated Hospital of Guilin Medical University, 15 Lequn Road, Guilin, Guangxi 541001, People’s Republic of ChinaTel + (86)-(773) 2800672Fax + (86)-(773) 2812650Email xxw7456@163.comPurpose: 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.Keywords: GSK-3β, chordoma, P21, apoptosis