YAP is a candidate oncogene for esophageal squamous cell carcinoma

Department of Molecular Cytogenetics, Medical Research Institute, Tokyo Medical and Dental University,Bunkyo-ku, Tokyo 113-8510, Japan.
Carcinogenesis (Impact Factor: 5.27). 11/2010; 32(3):389-98. DOI: 10.1093/carcin/bgq254
Source: PubMed

ABSTRACT Yes-associated protein (YAP), the nuclear effector of the Hippo pathway, is a key regulator of organ size and a candidate human oncogene located at chromosome 11q22. Since we previously reported amplification of 11q22 region in esophageal squamous cell carcinoma (ESCC), in this study we focused on the clinical significance and biological functions of YAP in this tumor. Frequent overexpression of YAP protein was observed in ESCC cells including those with a robust amplicon at position 11q22. Overexpression of the YAP protein was frequently detected in primary tumors of ESCC as well. Patients with YAP-overexpressing tumors had a worse overall rate of survival than those with non-expressing tumors, and YAP positivity was independently associated with a worse outcome in the multivariate analysis. Further analyses in cells in which YAP was either overexpressed or depleted confirmed that cell proliferation was promoted in a YAP isoform-independent but YAP expression level-dependent manner. YAP depletion inhibited cell proliferation mainly in the G(0)-G(1) phase and induced an increase in CDKN1A/p21 transcription but a decrease in BIRC5/survivin transcription. Our results indicate that YAP is a putative oncogene in ESCC and it represents a potential diagnostic and therapeutic target.

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    ABSTRACT: The Hippo pathway plays a crucial role in regulating tissue homeostasis and organ size, and its deregulation is frequently observed in human cancer. Yap is the major effector of and is inhibited by the Hippo pathway. In mouse model studies, inducible Yap expression in multiple tissues results in organ overgrowth. In the liver, knockout of upstream Hippo pathway components or transgenic expression of Yap leads to liver enlargement and hepatocellular carcinoma. In the small intestine or colon, deletion of upstream Hippo pathway components also results in expansion of intestinal progenitor cells and eventual development of adenomas. Genetic deletion of Yap in the intestine does not change the intestinal structure, but Yap is essential for intestinal repair upon certain types of tissue injury. The function of the Hippo pathway has also been studied in other gastrointestinal tissues, including the pancreas and stomach. Here we provide a brief overview of the Hippo pathway and discuss the physiological and pathological functions of this tumor suppressor pathway in gastrointestinal tissues. Expected final online publication date for the Annual Review of Physiology Volume 77 is February 10, 2015. Please see for revised estimates.
    Annual Review of Physiology 09/2014; 77(1). DOI:10.1146/annurev-physiol-021014-071733 · 14.70 Impact Factor
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    ABSTRACT: Understanding the molecular nature of human cancer is essential to the development of effective and personalized therapies. Several different molecular signal transduction pathways drive tumorigenesis when deregulated and respond to different types of therapeutic interventions. The Hippo signaling pathway has been demonstrated to play a central role in the regulation of tissue and organ size during development. The deregulation of Hippo signaling leads to a concurrent combination of uncontrolled cellular proliferation and inhibition of apoptosis, two key hallmarks in cancer development. The molecular nature of this pathway was first uncovered in Drosophila melanogaster through genetic screens to identify regulators of cell growth and cell division. The pathway is strongly conserved in humans, rendering Drosophila a suitable and efficient model system to better understand the molecular nature of this pathway. In the present study, we review the current understanding of the molecular mechanism and clinical impact of the Hippo pathway. Current studies have demonstrated that a variety of deregulated molecules can alter Hippo signaling, leading to the constitutive activation of the transcriptional activator YAP or its paralog TAZ. Additionally, the Hippo pathway integrates inputs from a number of growth signaling pathways, positioning the Hippo pathway in a central role in the regulation of tissue size. Importantly, deregulated Hippo signaling is frequently observed in human cancers. YAP is commonly activated in a number of in vitro and in vivo models of tumorigenesis, as well as a number of human cancers. The common activation of YAP in many different tumor types provides an attractive target for potential therapeutic intervention.
    01/2014; 3:25. DOI:10.1186/2001-1326-3-25
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    ABSTRACT: Yes-associated protein (YAP) has been reported to be an oncogene in a number of malignancies. It constitutes an important regulatory mechanism for the Hippo pathway, a key regulator of cell growth and apoptosis. The present study aimed to investigate the clinical significance and the role of YAP in the development of clear cell renal cell carcinoma (ccRCC). YAP expression levels were compared between ccRCC and adjacent normal renal tissues by RT-PCR and immunohistochemistry, respectively. YAP expression levels were then detected in ccRCC cell lines 786-0 and ACHN, as well as in human embryonic kidney 293 cells (HEK-293) using western blotting. Three specific YAP-shRNA lentiviral vectors were constructed and transfected into 786-0 cells, and then the mRNA and protein levels of YAP and downstream transcription factor TEAD1 were detected. Finally, the effects of YAP silencing on proliferation and the cell cycle distribution of 786-0 cells were detected by Cell Counting Kit-8 (CCK-8) and flow cytometry (FCM), respectively. The apoptosis rate was also analyzed by FCM. It was observed that the expression levels of YAP mRNA and protein in ccRCC tissues were higher than these levels in the adjacent normal renal tissues. The expression of YAP protein in ccRCC tissues was significantly correlated with clinical stage and differentiation. The YAP protein levels in the two ccRCC cell lines 786-0 and ACHN were significantly higher than that in the HEK-293 cells. Additionally, treatment of 786-0 cells with YAP-shRNA lentiviral vectors significantly reduced the expression levels of YAP and TEAD1 mRNA and protein. Further analyses in 786-0 cells in which YAP was decreased, revealed that cell proliferation was inhibited, cell cycle was arrested at the G1 phase and apoptosis was increased. These results indicate that YAP is an underlying oncogene in ccRCC and it may be a promising biomarker and therapeutic target of ccRCC.
    Oncology Reports 07/2014; 32(4). DOI:10.3892/or.2014.3349 · 2.19 Impact Factor

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