Role of YAP1 oncogene in tumorigenesis and metastasis processes, and its inhibition in pediatric adrenocortical tumors by verteporfin

Abstract

Pediatric Adrenocortical Tumors (ACTs) are rare and occur more frequently in children up to 5 years. Currently, tumor surgical resection is the most effective treatment for these patients; however, it is effective only in the earlier stages of ACT. In this way, new therapeutic targets are necessary to treat this tumor at any stage. YAP1 oncogene, a key downstream effector of the Hippo pathway, has been studied in several types of cancer, wherein it is overexpressed and it has been associated with epithelial-mesenchymal transition - which plays an important role in metastases formation. In a recent research, our laboratory found overexpression of YAP1 oncogene both at gene and protein levels and this was associated with poor outcome in pediatrics patients with ACT. Aims: To study the implications of YAP1 oncogene in cell growth and cell proliferation processes related to tumor formation, also cell invasion and epithelial-mesenchymal transition related to metastases. Moreover, we will evaluate the potential in vivo inhibition of tumorigenesis and metastases trough pharmacological treatment with verteporfin. Methods: NCI-H295 and cell lines secondary from pediatric ACTs will be subjected to genic silencing of YAP1 and treatment with verteporfin in order to evaluate the implications of YAP1 oncogene in cell proliferation, apoptosis, cell cycle progression, cell invasion and cell growth. In addition, the cell lines will be subcutaneously implanted and tail vein injected in immunodeficient mice and these animals will be treated with verteporfin to evaluate the inhibition of tumor growth and metastases. After treatment, the animals will be killed and tumors will be collected. Due to the YAP1 ability to activate its target genes when is unphosphorylated and translocated to the cell nucleus, its phosphorylation state and subcellular location will be evaluated in the cell lines and tumors. In silico analysis will be performed using ACT genomics data available on TCGA and GEO databases on YAP1, target genes and hippo pathway genes. Finally, gene and protein expression profile of the Hippo pathway, beta-catenin and epithelial-mesenchymal transition markers will be assessed in cell lines and tumors in order to evaluate the deregulation of these genes after treatments. (AU)