| Summary: | 碩士 === 國立臺灣大學 === 生理學研究所 === 107 === Hypoxia is a classic feature of tumor microenvironment, which has profound effects on cancer progression and is tightly associated with poor prognosis. Long non-coding RNAs (lncRNAs), a member of non-coding genome, have been increasingly investigated due to their diverse roles in tumorigenesis. Previously, our lab identified a hypoxia-induced lncRNA, NDRG1-OT1, in MCF-7 breast cancer cells using next-generation sequencing. However, the regulatory mechanism and functional roles of NDRG1-OT1 remain elusive. Therefore, the purpose of this study is to investigate the transcriptional mechanism and potential function roles of NDRG1-OT1 in breast cancer cells. Expression profiling of NDRG1-OT1 revealed that it was upregulated under hypoxia in different breast cancer cells. Over-expression and knockdown of HIF-1α up- and down-regulated NDRG1-OT1 respectively. Luciferase reporter assays and chromatin immunoprecipitation assays validated that HIF-1α transcriptionally activated NDRG1-OT1 by binding to its promoter (-1,773 to -1,769 and -647 to -643 bp). Next, to investigate whether NDRG1-OT1 could function as miRNA sponge, in silico analysis, expression profiling of predicted miRNAs, and RNA immunoprecipitation assays were performed, and the results implied that NDRG1-OT1 could not act as miRNA sponge. Lastly, regarding the function of NDRG1-OT1, ectopic expression of NDRG1-OT1 could not affect cell proliferation, migration, and cell cycle distribution under normoxia and hypoxia mimic conditions. In summary, our findings revealed a novel transcriptional mechanism of NDRG1-OT1 regulated by HIF-1α upon hypoxic condition in breast cancer cells.
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