title: LncRNA Taurine-Upregulated Gene 1 Promotes Cell Proliferation by Inhibiting MicroRNA-9 in MCF-7 Cells.
abstract: OBJECTIVE
  This study was designed to investigate the role of taurine-upregulated gene 1 (TUG1) in MCF-7 breast cancer cells and the molecular mechanism involved in the regulation of microRNA-9 (miR-9).
  
  
  METHODS
  The expression ofTUG1in breast cancer tissues and cells was evaluated using quantitative reverse transcription polymerase chain reaction. Cell viability was examined using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay; cell cycle progression and apoptosis were analyzed using flow cytometry. A dual luciferase reporter assay was used to detect the relationship betweenTUG1and miR-9. The expression of methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) was measured by western blot.
  
  
  RESULTS
  Higher expression ofTUG1was observed in breast cancer tissues and cell lines than in the corresponding controls.TUG1knockdown reduced proliferation, suppressed cell cycle progression, and promoted apoptosis of MCF-7 cells. The dual luciferase reporter assay showed thatTUG1could negatively regulate the expression of miR-9. MiR-9 inhibition abrogated the effect ofTUG1knockdown on the proliferation, cell cycle progression, and apoptosis of MCF-7 cells.TUG1positively regulated the expression of MTHFD2 in breast cancer cells.
  
  
  CONCLUSIONS
  TUG1knockdown was significantly associated with decreased cell proliferation and it promoted apoptosis of breast cancer cells through the regulation of miR-9.
authors.affiliation: Chongqing Key Laboratory of Molecular Oncology and Epigenetics, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.; Department of Breast Surgery, Affiliated Hospital of North Sichuan Medical College, Nanchong, China.
authors.forename: Xiao-Bo
authors.initials: XB
authors.lastname: Zhao
authors.affiliation: Department of Endocrine and Breast Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Guo-Sheng
authors.initials: GS
authors.lastname: Ren
keywords: Apoptosis; Breast neoplasms; Cell proliferation; MicroRNA-9; TUG1 long noncoding RNA