Abstract: Objective To investigate the influence of long non-coding RNA HOTAIR in proliferation and apoptosis of human tongue squamous cell carcinoma in vitro and in vivo. Methods siHOTAIR was used to inhibit the HOTAIR expression in Tb3.1 human tongue squamous cell carcinoma cell line. The experiments were divided into siHOTAIR group, nonsense sequence group and blank control group. Real-time PCR was used to detect the HOTAIR expression. MTT assay was employed to determine the cell survival. The expression levels of Bcl2, BAX, caspase- 3, cleaved caspase- 3 were examined by Western blot assay. Tb3.1 xenograft tumor model was established in BALB/c nude mice, and the tumor model was divided into control group, negative group, and siHOTAIR treated group. The tumor tissues were measured by immunohistochemistry stain (IHC) and TUNEL assay. Results The detection of real- time PCR showed that HOTAIR expression was reduced after treated with siHOTAIR. Western blots assay showed that Bcl-2 protein was suppressed while cleaved caspase- 3 and BAX protein were up-regulated after treated with siHOTAIR. MTT assay indicated that the cell survival rate was significantly reduced in siHOTAIR treated group. Flow cytometry detected that apoptosis levels were increased in siHOTAIR group. The level of cell senescence was higher in the siHOTAIR group than that of control group. Results of IHC indicated that Ki-67 and Bcl-2 protein of tumor tissue were inhibited, while BAX and cleaved caspase- 3 protein expressions were elevated simultaneously in the siHOTAIR group. TUNEL assay suggested that more apoptosis was observed in siHOTAIR group. Conclusion HOTAIR can affect proliferation and apoptosis of tongue squamous cancer cells. HOTAIR may be one of the new candidate targets for human tongue cancer therapy.

Key words: tongue neoplasms, carcinoma, squamous cell, RNA, small interfering, cell proliferation, apoptosis, HOTAIR