LncRNA XIST Promotes Growth of Human Chordoma Cells by Regulating miR-124-3p/iASPP Pathway

Bao Hai,1,* Xiaoyu Pan,1,* Chuanchao Du,1 Tianli Mao,1 Fei Jia,1 Yu Liu,1 Yunlong Ma,2 Xiaoguang Liu,1,2 Bin Zhu2 1Department of Orthopedics, Peking University Third Hospital, Beijing, People’s Republic of China; 2The Center for Pain Medicine, Peking University Third Hospital, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Xiaoguang LiuDepartment of Orthopedics, Peking University Third Hospital, North Garden Street No. 49, Haidian District, Beijing 100191, People’s Republic of ChinaTel +86 10 8226 5711Email xgliudoctor@163.comBin ZhuThe Center for Pain Medicine, Peking University Third Hospital, North Garden Street No. 49, Haidian District, Beijing 100191, People’s Republic of ChinaTel +86 10 8226 7368Email zhubin_ortho@126.comIntroduction: Chordoma is a malignant primary bone tumor that is found in the spine and skull. X-inactive specific transcript (XIST) is a long non-coding RNA (lncRNA) is known to be involved in the development of various cancers, but its precise function and mechanism in human chordoma have not been elucidated. Here, we investigated the role of lncRNA XIST in chordoma progression.Methods: Quantitative real time-polymerase chain reaction (qRT-PCR) was performed to determine lncRNA XIST expression in human chordoma tissues and matched-noncancerous tissues. Western blot was used to determine protein expression. Silencing and overexpression of lncRNA XIST were carried out by RNA interference (RNAi) and lentiviral transduction, respectively. Cell Counting Kit-8 (CCK-8) assay and flow cytometry were employed to examine the effects of lncRNA XIST on growth of human chordoma cells. Lastly, the role of lncRNA XIST in vivo was explored using a xenograft model.Results: We found that lncRNA XIST expression was upregulated in chordoma and strongly correlated with poor patient prognosis. Moreover, lncRNA XIST promoted proliferation and inhibited apoptosis of chordoma cells. Mechanistically, upregulation of lncRNA XIST led to a decrease in miR-124-3p expression, thereby promoting the expression of the miR-124-3p target gene, inhibitor of apoptosis-stimulating protein of p53 (iASPP). Addition of miR-124-3p inhibitor or mimic reversed the effects induced by lncRNA XIST silencing or overexpression on chordoma cell proliferation. Lastly, using a xenograft mouse model, we found that silencing of lncRNA XIST decreased tumorigenicity in vivo, as shown by increased tumor cell apoptosis.Conclusion: Our findings demonstrate a key role for lncRNA XIST in chordoma progression by regulating miR124-3p/iAPSS pathway.Keywords: chordoma, lncRNA XIST, miR124-3p, iASPP, proliferation, apoptosis