Abstract: PURPOSE: To investigate the effect of lncRNA-HOTTIP on hypoxia induced epithelial-to-mesenchymal transition in human tongue squamous cell carcinoma (TSCC). METHODS: TSCC cell lines SCC9 and CAL27 were cultured under hypoxia (1% O₂) or normoxia (20% O₂) for 48 h. qRT-PCR was used to detect expressions of lncRNA-HOTTIP and HIF-1α at mRNA level. After transfection of HIF-1α with siRNA, HIF-1α and lncRNA-HOTTIP level were furthered detected. TSCC cell lines were further transfected lncRNA-HOTTIP with siRNA under hypoxia, the expression of HIF-1α, Vimentin, Fibronectin and E-cadherin, as well as invasion, were detected. The date was statistically analyzed with SPSS13.0 software package. RESULTS: Both SCC9 and CAL27 cells under hypoxia for 48 h showed increased lncRNA-HOTTIP and HIF-1α expression.After knocking down of HIF-1α with siRNA, lncRNA-HOTTIP level was significantly reduced. After knocking down of lncRNA-HOTTIP with siRNA, lncRNA-HOTTIP, Vimentin and Fibronectin were significantly downregulated but E-cadherin was upregulated under hypoxia; the invasion ability was decreased in SCC9 and CAL27 cells. CONCLUSIONS: Hypoxia increases HIF-1α and lncRNA-HOTTIP expression, and hypoxia induces epithelial-to-mesenchymal transition and metastasis of TSCC via upregulating lncRNA-HOTTIP.

Key words: Hypoxia, Tongue squamous cell carcinoma, Epithelial-to-mesenchymal transition, HOTTIP, HIF-1α