Inhibition of the Tcf/beta-catenin complex increases apoptosis and impairs adrenocortical tumor cell proliferation and adrenal steroidogenesis
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Letícia F. Leal1, Ana Carolina Bueno1, Débora C. Gomes1,2, Rafael Abduch1, Margaret de Castro3, Sonir R. Antonini1
1Department of Pediatrics, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, Sao Paulo, Brazil
2Department of Pediatrics, School of Medicine, Federal University of Uberlandia, Uberlândia, Minas Gerais, Brazil
3Department of Internal Medicine, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, Sao Paulo, Brazil
Sonir R. Antonini, e-mail: [email protected]
Keywords: adrenocortical cancer, beta-catenin, steroidogenesis, apoptosis, targeted therapy
Received: April 13, 2015 Accepted: September 05, 2015 Published: October 16, 2015
Background: To date, there is no effective therapy for patients with advanced/metastatic adrenocortical cancer (ACC). The activation of the Wnt/beta-catenin signaling is frequent in ACC and this pathway is a promising therapeutic target.
Aim: To investigate the effects of the inhibition of the Wnt/beta-catenin in ACC cells.
Methods: Adrenal (NCI-H295 and Y1) and non-adrenal (HeLa) cell lines were treated with PNU-74654 (5–200 μM) for 24–96 h to assess cell viability (MTS-based assay), apoptosis (Annexin V), expression/localization of beta-catenin (qPCR, immunofluorescence, immunocytochemistry and western blot), expression of beta-catenin target genes (qPCR and western blot), and adrenal steroidogenesis (radioimmunoassay, qPCR and western blot).
Results: In NCI-H295 cells, PNU-74654 significantly decreased cell proliferation 96 h after treatment, increased early and late apoptosis, decreased nuclear beta-catenin accumulation, impaired CTNNB1/beta-catenin expression and increased beta-catenin target genes 48 h after treatment. No effects were observed on HeLa cells. In NCI-H295 cells, PNU-74654 decreased cortisol, testosterone and androstenedione secretion 24 and 48 h after treatment. Additionally, in NCI-H295 cells, PNU-74654 decreased SF1 and CYP21A2 mRNA expression as well as the protein levels of STAR and aldosterone synthase 48 h after treatment. In Y1 cells, PNU-74654 impaired corticosterone secretion 24 h after treatment but did not decrease cell viability.
Conclusions: Blocking the Tcf/beta-catenin complex inhibits the Wnt/beta-catenin signaling in adrenocortical tumor cells triggering increased apoptosis, decreased cell viability and impairment of adrenal steroidogenesis. These promising findings pave the way for further experiments inhibiting the Wnt/beta-catenin pathway in pre-clinical models of ACC. The inhibition of this pathway may become a promising adjuvant therapy for patients with ACC.
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