Abstract: Background and purpose: Exploration of the effective early diagnostic and prognostic markers of non-small cell lung cancer (NSCLC) has important scientific significance and clinical value. Recently, the role of long chain non-coding RNA (lncRNA) in the tumor attracts widespread attention. This study intended to investigate the level of lncRNA HOTTIP in NSCLC, the effect of HOTTIP on cell proliferation and its mechanisms. Methods: Expression of lncRNA HOTTIP in tumor and their matched non-tumor tissues were determined by quantitative real-time PCR (qRT-PCR) in NSCLC patients. Then, we analyzed the potential correlation of lncRNA HOTTIP expression levels in tumor tissues with clinicopathological features of NSCLC and clinical outcome. The effects of HOTTIP on NSCLC cell proliferation and apoptosis were tested using in vitro MTT and flow cytometric assays. Western blot method was uesd to detect the expressions of proteins. Results: LncRNA HOTTIP expression level was significantly decreased in NSCLC tissues in comparison to adjacent non-tumor tissues (P<0.05). It was also proved that HOTTIP expression was associated with NSCLC histological grade and lymph node metastasis. Moreover, knockdown of HOTTIP expression in A549 cell line decreased proliferation and enhanced apoptosis compared with transfected negative control. Western blot assay showed that the level of Bax protein was significantly increased, whereas Bcl-2 was significantly decreased in HOTTIP- silencing A549 cell. Conclusion: HOTTIP is a novel prognostic biomarker and a potential therapeutic candidate for NSCLC.

Key words: lncRNA, HOTTIP, Non-small cell lung cancer, Proliferation, Apoptosis