LncRNA Taurine-Upregulated Gene 1 Promotes Cell Proliferation by Inhibiting MicroRNA-9 in MCF-7 Cells

Abstract

PurposeThis 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).MethodsThe expression of TUG1 in 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 between TUG1 and miR-9. The expression of methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) was measured by western blot.ResultsHigher expression of TUG1 was observed in breast cancer tissues and cell lines than in the corresponding controls. TUG1 knockdown reduced proliferation, suppressed cell cycle progression, and promoted apoptosis of MCF-7 cells. The dual luciferase reporter assay showed that TUG1 could negatively regulate the expression of miR-9. MiR-9 inhibition abrogated the effect of TUG1 knockdown on the proliferation, cell cycle progression, and apoptosis of MCF-7 cells. TUG1 positively regulated the expression of MTHFD2 in breast cancer cells.ConclusionTUG1 knockdown was significantly associated with decreased cell proliferation and it promoted apoptosis of breast cancer cells through the regulation of miR-9.

LncRNA DSCAM‐AS1 acts as a sponge of miR‐137 to enhance Tamoxifen resistance in breast cancer

“…Our study also explores the underlying mechanism of DSCAM-AS1 in the modulation of target miRNA. DSCAM-AS1 regulates (Zhao & Ren, 2016). These previous findings all reveal the important interplay between lncRNAs and miRNAs in the regulation of multiple cancer cells.…”

Long noncoding RNA TUG1 promotes cell proliferation and migration of renal cell carcinoma via regulation of YAP

“…[25][26][27] In the current study, we observed an elevation of TUG1 levels in RCC cell lines compared with the normal kidney cells, and overexpression of TUG1 in RCC tumors compared with the matched adjacent normal tissues. 22,30 The role of miR-9 in cancer progression was controversial. 11 Using siRNA knockdown, our functional study demonstrated that TUG1 could promote both cell proliferation and cell migration in RCC cells, which was consistent with previous findings.…”

“…22 Interestingly, miR-9 levels were remarkably decreased in RCC tumor tissues compared with normal tissues ( Figure 4A). We reviewed several studies on miRNAs regulated by TUG1 and analyzed their expression in RCC tumor tissues.…”

Long non‐coding RNAs as an epigenetic regulator in human cancers

“…Oncogenic function Glioma (53) miRNA sponge (miR-144) Glioma (9) Recruitment of PRC2, miRNA sponge (miR-145) Glioma (54) miRNA sponge (miR-26a) Glioma (55) miRNA sponge (miR-299) Oral squamous cell carcinoma (56) Unknown Esophageal squamous cell carcinoma (57,58) Unknown Cervical cancer (59) Unknown Small cell lung cancer (60) Recruitment of PRC2 Gastric cancer (61) miRNA sponge (miR-144) Gastric cancer (62) Recruitment of PRC2 Hepatocellular carcinoma (63) Recruitment of PRC2 Hepatoblastoma (64) miRNA sponge (miR-34a) Gallbladder carcinoma (65) miRNA sponge (miR-300) Breast cancer (66) miRNA sponge (miR-9) Breast cancer (67) Unknown Colorectal cancer (68)(69)(70) Unknown Ovarian cancer (71) Unknown Renal cell carcinoma (72) Unknown Bladder cancer (49) Unknown Bladder cancer (48) miRNA sponge (miR-145) Bladder cancer (73) Unknown Osteosarcoma (50) Unknown Osteosarcoma (74) miRNA sponge (miR-9) Osteosarcoma (75) miRNA sponge (miR-335) Tumor-suppressive function Cervical cancer (46) Recruitment of PRC1 and PRC2 Non-small-cell lung carcinoma (51,76)…”