The binding sites between SNHG3 and miR-139-5p, and the target genes of miR-139-5p were predicted using starBase 3.0 (http://starbase.sysu.edu.cn/index.php) (15 (link)) and TargetScan 7.2 database (www.targetscan.org) (16 (link)). The pmirGLO vector (v) was used to construct vectors [wild-type (SNHG3-wt and Notch1-wt) and mutant type (SNHG3-mut and Notch1-mut)] for luciferase reporter assays. Cells were seeded into a 24-well plate. After the cell density in the well reached ~80%, miR-139-5p mimic or miR-NC (GenePharma Co., Ltd, Shanghai, China) was transfected into OC cells with luciferase reporter vectors using Lipofectamine 2000 (Invitrogen; Thermo Fisher Scientific, Inc.). After 48-h transfection, fluorescence activity was assessed according to the instructions of the dual luciferase detection system (Promega Corp.). The luciferase activity was normalized to that of Renilla luciferase activity. The experiment was repeated three times independently.