Fig. 3: NURR1 can activate the Wnt/β-catenin signaling in prostate cancer cells via its direct transactivation of CTNNB1 and also activation of β-catenin. | Cell Death & Disease

Fig. 3: NURR1 can activate the Wnt/β-catenin signaling in prostate cancer cells via its direct transactivation of CTNNB1 and also activation of β-catenin.

From: Nuclear receptor NURR1 functions to promote stemness and epithelial-mesenchymal transition in prostate cancer via its targeting of Wnt/β-catenin signaling pathway

Fig. 3

A Schematic diagram of reporter construct driven by a 1.3 kb-fragment of CTNNB1 promoter containing the NGFI-B response element (NBRE; AAATATCT) and also three reporter constructs containing the point-mutated NBRE. B Luciferase reporter assay. Results showed that only intact NURR1 but not its DBD-deleted mutant NURR1-ΔDBD could transactivate the CTNNB1 promoter-driven reporter in a dose-dependent manner. However, NURR1 could not transactivate the reporters containing the point-mutated NBRE. C Chromatin immunoprecipitation (ChIP) assay. Results showed that the putative NURR1-binding site on the CTNNB1 promoter was enriched of NURR1 in HEK293 cells. IgG was set as a negative control. D, E Immunoblot analysis of β-catenin in AR-positive (LNCaP, 22Rv1) and -negative (DU 145) prostate cancer cells with either NURR1 overexpression or its knockdown. Results showed that NURR1 overexpression in LNCaP and DU 145 cells could increase, whereas its knockdown in 22Rv1 and DU 145 cells could reduce the protein levels of total β-catenin and its active form (dephosphorylated or nuclear) in target cells respectively. However, no significant changes in protein levels of non-active or phosphorylated β-catenin were seen in these prostate cancer cells with either NURR1 overexpression or its shRNA-knockdown. F, G Immunoblot analyses of downstream regulators of β-catenin signaling in DU 145 and 22Rv1 cells upon treatments with a NURR1 agonist C-DIM-12 (5 μM) or Wnt inhibitor IWP-2 (10 μM). Results showed that DU 145-NURR1 infectants or treatment of parental DU 145 cells with C-DIM-12 could increase the expressions of TCF-4, TCF-7 and c-Myc in target cells. Conversely, knockdown (shNURR1) or knockout (sgNURR1) of NURR1 in target DU 145 or 22Rv1 cells and also treatment of parental DU 145 cells with IWP-2 could reduce the expressions of TCF-7, c-Myc and cyclin D1 in these target cells.

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