ABSTRACT
@# Objective: To investigate the molecular mechanisms of lncRNA XIST/miR-34a-5p/SIRT6 axis regulating the proliferation and metastasis of oral squamous cell carcinoma (OSCC) cells. Methods: Specimens of tumor tissues and paracancer tissues of 47 patients with OSCC, who visited the Qingdao Stomatological Hospital from March 2013 to March 2018, were enrolled in this study. qPCR was performed to measure the mRNA expressions of lncRNA XIST, miR-34a-5p and SIRT6 in OSCC tissues and cell lines. WB was performed to measure the protein levels of SIRT6, Ki67, pcDNA, cleaved-caspase3, cleaved-caspase8, E-cadherin and vimentin in OSCC tissues and cell lines. CCK-8 assay was performed to observe the effect of lncRNA XIST knockdown on proliferation of Cal-27 and Tca-8113 cells; Tanswell assay was performed to detect migration and invasion of Cal-27 and Tca-8113 cells; flow cytometry was performed to detect the apoptosis of Cal-27 and Tca-8113 cells; and dual luciferase reporter assay was performed to verify the relationship between lncRNAXIST and miR-34a, or miR-34a and SIRT6. Results: Expressions of lncRNAXIST and SIRT6 were up-regulated in OSCC tissues and cell lines (all P<0.05), reversely, miR-34a-5p was down-regulated in OSCC tissues and cell lines (P<0.01). lncRNA XIST knockdown significantly suppressed OSCC cells proliferation, migration and invasion, and induced apoptosis of OSCC cells (all P<0.01); however, simultaneous transfection with miR-34a-5p inhibitor or pcDNA-SIRT6 vector exerted opposite effect. lncRNA XIST knockdown significantly increased cell proliferation and metastasis related protein expression in OSCC cells (all P< 0.01), and simultaneous transfection with miR-34a-5p inhibitor or pcDNA-SIRT6 vector exerted opposite effect. In addition, lncRNA XIST directly targeted miR-34a-5p, and miR-34a-5p targeted SIRT6, lncRNA XIST upregulated SIRT6 expression via inhibiting miR34a-5p (P<0.01). Conclusion: Taken together, lncRNA XIST/miR-34a-5p/SIRT6 axis regulates the proliferation and metastasis of OSCC cells and provides potential therapeutic targets for OSCC.