Unraveling the expression of the oncogene YAP1, a Wnt/beta-catenin target, in adrenocortical tumors and its association with poor outcome in pediatric patients

// Rafael H. Abduch 1, * , Ana Carolina Bueno 1, * , Leticia F. Leal 1, # , Marcelo M. Cavalcanti 1 , Débora C. Gomes 6 , Silvia R. Brandalise 5 , Maria J. Masterallo 5 , José A. Yunes 5 , Carlos E. Martinelli Jr 1 , Luiz G. Tone 1 , Silvio Tucci 3 , Carlos A.F. Molina 3 , Fernando S. Ramalho 4 , Ayrton C. Moreira 2 , Izilda A. Cardinalli 5 , Carlos A. Scrideli 1 , Leandra N.Z. Ramalho 4 , Margaret de Castro 2 , Sonir R. Antonini 1 1 Department of Pediatrics, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, Brazil 2 Department of Internal Medicine, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, Brazil 3 Department of Surgery, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, Brazil 4 Department of Pathology, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, Brazil 5 Boldrini Children’s Center, Campinas, Brazil 6 Federal University of Uberlandia, Brazil # Molecular Oncology Research Center, Barretos Cancer Hospital, Barretos, SP, Brazil * These authors have contributed equally to this work Correspondence to: Sonir R. Antonini, email: antonini@fmrp.usp.br Keywords: adrenocortical tumor, outcome, YAP1, Hippo pathway, Wnt/beta-catenin pathway Received: February 12, 2016 Accepted: September 12, 2016 Published: October 1, 2016 ABSTRACT Background: Overexpression of the oncogene yes-associated-protein-1 (YAP1) is associated with increased cell proliferation in human cancers. YAP1 is a potential target of the Wnt/beta-catenin pathway, which plays an important role in adrenocortical tumors (ACT). The role of YAP1 in adrenocortical tumorigenesis has not been assessed. Aims: To evaluate YAP1 expression in normal adrenals and pediatric ACT and its association with disease outcome. To investigate the interaction between YAP1 and the Wnt/beta-catenin pathway in adrenocortical cells. Results: Strong YAP1 staining was present in fetal adrenals and pediatric ACT but weak in postnatal adrenals. In pediatric ACT, YAP1 mRNA overexpression was associated with death, recurrent/metastatic disease and lower overall survival. The inhibition of the Wnt/beta-catenin pathway increased YAP1 mRNA expression. siYAP1 increased CTNNB1 /beta-catenin expression and nuclear staining regardless of DLV2 , moreover, it decreased cell growth and impaired cell migration. Materials and methods: We assessed in 42 pediatric ACT samples the YAP1 protein expression by immunohistochemistry and mRNA expression by RT-qPCR and analyzed their association with outcome. As controls, we resort 32 fetal and postnatal normal adrenals for IHC and 10 normal adrenal cortices for RT-qPCR. The interaction between YAP1 and the Wnt/beta-catenin pathway was assessed in NCI-H295 adrenocortical cells by inhibiting the TCF/beta-catenin complex and by knocking down YAP1 . Conclusion: YAP1 overexpression is a marker of poor prognosis for pediatric patients with ACT. In adrenocortical cells, there is a close crosstalk between YAP1 and Wnt/beta-catenin. These data open the possibility of future molecular therapies targeting Hippo/YAP1 signaling to treat advanced ACT.