Identification of a Disease-Defining Gene Fusion in Epithelioid Hemangioendothelioma

Department of Molecular Genetics and Anatomic Pathology, Lerner Research Institute, Taussig Cancer Center, Cleveland Clinic, Cleveland, OH 44195, USA.
Science translational medicine (Impact Factor: 15.84). 08/2011; 3(98):98ra82. DOI: 10.1126/scitranslmed.3002409
Source: PubMed


Integrating transcriptomic sequencing with conventional cytogenetics, we identified WWTR1 (WW domain-containing transcription regulator 1) (3q25) and CAMTA1 (calmodulin-binding transcription activator 1) (1p36) as the two genes involved in the t(1;3)(p36;q25) chromosomal translocation that is characteristic of epithelioid hemangioendothelioma (EHE), a vascular sarcoma. This WWTR1/CAMTA1 gene fusion is under the transcriptional control of the WWTR1 promoter and encodes a putative chimeric transcription factor that joins the amino terminus of WWTR1, a protein that is highly expressed in endothelial cells, in-frame to the carboxyl terminus of CAMTA1, a protein that is normally expressed only in brain. Thus, CAMTA1 expression is activated inappropriately through a promoter-switch mechanism. The gene fusion is present in virtually all EHEs tested but is absent from all other vascular neoplasms, demonstrating it to be a disease-defining genetic alteration. A sensitive and specific break-apart fluorescence in situ hybridization assay was also developed to detect the translocation and will assist in the evaluation of this diagnostically challenging neoplasm. The chimeric WWTR1/CAMTA1 transcription factor may represent a therapeutic target for EHE and offers the opportunity to shed light on the functions of two poorly characterized proteins.

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    • "The TAZ locus is amplified in 27 of 313 breast tumors, and TAZ mRNA expression was specifically increased in the tumors with the amplification [66]. The TAZ locus has also been implicated in a disease-defining chromosomal translocation in a rare vascular sarcoma termed epithelioid hemangioendothelioma. Endothelial cells highly expressing the product of this translocation, which fuses TAZ to the calmodulin-binding transcription activator 1 (CAMTA1), are associated with this cancer, although the oncogenic mechanism of this fusion protein has yet to be elucidated [97,98]. Studies have also shown copy number loss of SAV1 in high-grade ccRCC [76], and loss of heterozygosity at the FAT1 locus has been reported in primary glial tumors [99]. "
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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.
    Clinical and Translational Medicine 07/2014; 3(1):25. DOI:10.1186/2001-1326-3-25
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    • "WWTR1 on 3q23-24, encodes a transcriptional co-activator involved in mesenchymal stem cell differentiation and is highly expressed in endothelial cells [5,12], while CAMTA1, a calmodulin-binding transcription activator, located on 1p36.23, has been proposed as an oncogene under the control of the WWTR1 promotor. The latter is supported by the occurrence of an in-frame fusion of the C terminus of CAMTA1 to WWTR1, arguing against loss of function [5]. "
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    ABSTRACT: Epithelioid hemangioendothelioma is a malignant, often indolent vascular tumor which occurs at various anatomic sites. Based on a reciprocal translocation t (1;3)(p36;q25), a consistent WWTR1-CAMTA1 fusion gene has been found. An alternate YAP1-TFE3 fusion has been detected in a small and distinct subset of cases. Thirty-nine tumors, from 24 females and 15 males with an age range 9–85 years, were located in soft tissue (head and neck [8], trunk [5], upper extremities [3], lower extremities [2], mediastinal [1], and paratesticular [1]), lymph node (1), breast (1), skin (2), bone (6), lung (7), and liver (2). The cases were investigated using a panel of immunohistochemical markers. The aforementioned fusion-genes were examined using RT-PCR and/or FISH in order to validate their diagnostic value. Follow-up available for 17 patients ranged from 3 months to 7 years (median interval 1.5 years). Eleven patients were alive without disease, 2 patients were alive with disease after 1.5 and 2 years, respectively. Four patients died of disease after 4 months (n = 1), 5 months (n = 2), and 1.5 years (n = 1). The size, known for 30 lesions, was >3 cm in 9 of them. Histologically, all lesions had classical features, at least focally. Four tumors counted >3 mitoses/50 HPF. Immunohistochemically, all cases tested stained positive for ERG (21), FLI1 (5) and CD31 (39). CD34 and D2-40 positivity was seen in 81% and 71% of the examined cases, respectively. 11/35 cases expressed pan-keratin and 6/20 cases CK8.18. TFE3 showed a nuclear reaction in 21/24 cases, irrespective of TFE3 rearrangement. Molecular genetically, 35/35 cases revealed one of the fusion genes by FISH and/or RT-PCR with WWTR1-CAMTA1 in 33 cases and YAP1-TFE3 in 2 cases. These results demonstrate the high diagnostic value of FISH and RT-PCR in detecting the fusion genes of EHE. The immunohistochemical utility of TFE3 appears questionable in this study. Virtual Slides The virtual slide(s) for this article can be found here:
    Diagnostic Pathology 07/2014; 9(1):131. DOI:10.1186/1746-1596-9-131 · 2.60 Impact Factor
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    • "RNA-seq experiments for the identification of chimeric transcripts (Tanas et al., 2011; Pierron et al., 2012; Mosquera et al., 2013). Briefly, paired-end reads mapped to different genes are first used to identify potential chimeric candidates. "
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    ABSTRACT: Glomus tumors (GT) have been classified among tumors of perivascular smooth muscle differentiation, together with myopericytoma, myofibroma/tosis, and angioleiomyoma, based on their morphologic overlap. However, no molecular studies have been carried out to date to investigate their genetic phenotype and to confirm their shared pathogenesis. RNA sequencing was performed in three index cases (GT1, malignant GT; GT2, benign GT and M1, multifocal myopericytoma), followed by FusionSeq data analysis, a modular computational tool developed to discover gene fusions from paired-end RNA-seq data. A gene fusion involving MIR143 in band 5q32 was identified in both GTs with either NOTCH2 in 1p13 in GT1 or NOTCH1 in 9q34 in GT2, but none in M1. After being validated by FISH and RT-PCR, these abnormalities were screened on 33 GTs, 6 myopericytomas, 9 myofibroma/toses, 18 angioleiomyomas and in a control group of 5 sino-nasal hemangiopericytomas. Overall NOTCH2 gene rearrangements were identified in 52% of GT, including all malignant cases and one NF1-related GT. No additional cases showed NOTCH1 rearrangement. As NOTCH3 shares similar functions with NOTCH2 in regulating vascular smooth muscle development, the study group was also investigated for abnormalities in this gene by FISH. Indeed, NOTCH3 rearrangements were identified in 9% of GTs, all present in benign soft tissue GT, one case being fused to MIR143. Only 1/18 angioleiomyomas showed NOTCH2 gene rearrangement, while all the myopericytomas and myofibroma/toses were negative. In summary, we describe novel NOTCH1-3 rearrangements in benign and malignant, visceral, and soft tissue GTs. © 2013 Wiley Periodicals, Inc.
    Genes Chromosomes and Cancer 11/2013; 52(11). DOI:10.1002/gcc.22102 · 4.04 Impact Factor
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