Loss of β-catenin in adrenocortical cancer cells causes growth inhibition and reversal of epithelial-to-mesenchymal transition

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// Aude Salomon 1, 2, 3 , Michelle Keramidas 1, 2, 3 , Cécile Maisin 1, 2, 3 , Michaël Thomas 1, 2, 3 1 Institut National de la Santé et de la Recherche Médicale, Unité 1036, Grenoble, France 2 Commissariat à l’Energie Atomique, Institute of Life Sciences Research and Technologies, Biology of Cancer and Infection, Grenoble, France 3 Université Grenoble Alpes, Unité Mixte de Recherche-S1036, Grenoble, France Correspondence to: Michaël Thomas, e-mail: michael.thomas@cea.fr Keywords: adrenocortical carcinoma, β-catenin, shRNA, epithelial-mesenchymal transition Received: December 02, 2014      Accepted: January 26, 2015      Published: March 18, 2015 ABSTRACT Adrenal carcinoma (ACC) is a rare neoplasm with a poor outcome. Aberrant expression of β-catenin has been found in approximatively 30% of ACC. We herein studied its effects on the growth of the human ACC cell line H295R. The cells were infected with short hairpin RNA (shRNA)-mediated silencing β-catenin. Two shRNAs used induced down-regulation of β-catenin protein levels. The expression of these shRNAs decreased cell growth and increased H295R cells in S and G 2 /M phases. This cytostatic effect is due to a decrease of phosphorylated MAPK and to an up-regulation expression of the cyclin-dependent kinase inhibitors p57 KIP2 , p21 CIP and p27 KIP1 . In addition, the knockdown of β-catenin decreased phosphorylated Akt and increased apoptosis. Finally, loss of β-catenin was sufficient to induce the reversal of the epithelial-to-mesenchymal transition. We then transplanted these genetically modified H295R cells in Scid mice. Tumor growth suppression was achieved by the two shRNAs showing in vitro efficacy. Proliferation was not reduced in silenced tumors. In contrast, p57, p27 and p21 proteins were found expressed at high levels in silenced tumors along with an increase in apoptotic cells. These findings indicate that β-catenin loss in H295R cells inhibits tumor growth by inducing transcriptional and functional changes.