The Epstein-Barr Virus-Encoded MicroRNA MiR-BART9 Promotes Tumor Metastasis by Targeting E-Cadherin in Nasopharyngeal Carcinoma
Figure 5
miR-BART9 directly targets E-cadherin.
(A) Predicted duplex formation between miR-BART9 and human E-cadherin 3′UTR (Wt). The seed sequence region is highlighted in bold. The putative target sequence of E-cadherin 3′UTR at nt 1795–1801. Mut indicates the mutated E-cadherin 3′UTR sequence used as a control in the reporter assay. Mutated bases are specified by underlining. (B) Luciferase activity of the wild type (Wt) or mutant (Mut) E-cadherin 3′UTR reporter in BM1, TW04 and HK1 cells expressing miR-BART9 or LacZ. (C) Luciferase activity of the wild type (Wt) or mutant (Mut) E-cadherin 3′UTR reporter in HK1-EBV and C666-1 cells treated with a 12.5 nM concentration of an LNA-modified miR-BART9 antisense oligo (anti-BART9) or a scramble control (anti-Ctrl). (D) Top panel: Immunoblotting analysis of E-cadherin in BM1, TW04 and HK1 cells expressing miR-BART9 or LacZ. (Left) or HK1-EBV cells treated with an LNA-modified miR-BART9 antisense oligo (anti-BART9) or scramble control (anti-Ctrl) (Right). GAPDH was used as a loading control. Bottom panel: E-cadherin protein levels were normalized to GAPDH levels, and then compared with the LacZ or anti-Ctrl cells whose normalized levels were expressed as 1.0. Bar graphs provide the means ± SEM of independent experiments and two-tailed Student's t-test were performed (*, P<0.05; **, P<0.01). (E) Representative immunofluorescence staining of E-cadherin and DAPI staining to detect the nucleus in BM1 and TW04 cells expressing miR-BART9 or LacZ. Arrows indicate cell-cell junctions. Scale bar = 20 µm. (F) Representative IHC staining of GFP, human Mac2BP and E-cadherin in sections of primary tumors formed by BM1 cells expressing miR-BART9 or LacZ. Scale bar = 500 µm.
