Sequencing of DICER1 in sarcomas identifies biallelic somatic DICER1 mutations in an adult-onset embryonal rhabdomyosarcoma.

SHORT COMMUNICATION British Journal of Cancer (2017) 116, 1621–1626 | doi: 10.1038/bjc.2017.147 Keywords: sarcoma; DICER1; mutations; biallelic; embryonal rhabdomyosarcoma Sequencing of DICER1 in sarcomas identifies biallelic somatic DICER1 mutations in an adult-onset embryonal rhabdomyosarcoma Leanne de Kock1,2, Barbara Rivera1,2, Timothée Revil3, Paul Thorner4,5, Catherine Goudie6, Dorothée Bouron-Dal Soglio7, Catherine S Choong8,9, John R Priest10, Paul J van Diest11, Jantima Tanboon12,13, Anja Wagner14, Jiannis Ragoussis3, Peter FM Choong15 and William D Foulkes*,1,2,16 1 Department of Human Genetics, McGill University, 1205 Dr. Penfield Avenue, Stewart Biology Building, Room N5/13, Montréal, QC H3A 1B1, Canada; 2Lady Davis Institute, Segal Cancer Centre, Jewish General Hospital, 3755 Cote Sainte Catherine Road, Montréal, QC H3T 1E2, Canada; 3McGill University and Genome Quebec Innovation Centre, 740 Dr Penfield Avenue, Montréal, QC H3A 0G4, Canada; 4Division of Pathology, Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8, Canada; 5 Department of Laboratory Medicine and Pathobiology, University of Toronto, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada; 6Department of Paediatrics, McGill University, 1001 Décarie Boulevard, Montréal, QC H4A 3J1, Canada; 7Department of Pathology, CHU-Sainte Justine and University of Montréal, Montréal, QC H3T 1C4, Canada; 8Princess Margaret Hospital for Children, Roberts Road, Subiaco, WA 6008, Australia; 9The University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia; 10Minneapolis, MN 55454, USA; 11Department of Pathology, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584 CX, The Netherlands; 12Department of Pathology, Siriraj Hospital, Bangkok Noi, Bangkok 10700, Thailand; 13Faculty of Medicine, Mahidol University, Bangkok Noi, Bangkok 10700, Thailand; 14Department of Clinical Genetics, Erasmus MC University Medical Center, Wytemaweg 80, Rotterdam 3015 CN, The Netherlands; 15Department of Surgery, St. Vincent’s Hospital Melbourne, University of Melbourne, 41 Victoria Parade, Melbourne, VIC 3065, Australia and 16Department of Medical Genetics, Research Institute of the McGill University Health Centre, 1001 Décarie Boulevard, Montréal, QC H4A 3J1, Canada Background: Sarcomas are rare and heterogeneous cancers. We assessed the contribution of DICER1 mutations to sarcoma development. Methods: The coding region of DICER1 was sequenced in 67 sarcomas using a custom Fluidigm Access Array. The RNase III domains were Sanger sequenced in six additional sarcomas to identify hotspot DICER1 variants. Results: The median age of sarcoma diagnosis was 45.7 years (range: 3 months to 87.4 years). A recurrent embryonal rhabdomyosarcoma (ERMS) of the broad ligament, first diagnosed at age 23 years, harboured biallelic pathogenic somatic DICER1 variants (1 truncating and 1 RNase IIIb missense). We identified nine other DICER1 variants. One somatic variant (p.L1070V) identified in a pleomorphic sarcoma and one germline variant (c.2257-7A4G) may be pathogenic, but the others are considered to be benign. Conclusions: We show that deleterious DICER1 mutations underlie the genetic basis of only a small fraction of sarcomas, in particular ERMS of the urogenital tract. *Correspondence: Dr WD Foulkes; E-mail: Received 29 November 2016; revised 25 April 2017; accepted 26 April 2017; published online 18 May 2017 r 2017 Cancer Research UK. All rights reserved 0007 – 0920/17 www.bjcancer.com | DOI:10.1038/bjc.2017.147 1621 BRITISH JOURNAL OF CANCER Sarcomas are a rare group of histologically and genetically heterogeneous tumours of mesenchymal origin (Fletcher et al, 2013). Most sarcomas arise sporadically. However, a small number of cases manifest in individuals with germline mutations in genes associated with cancer predisposition syndromes, such as TP53, NF1, RB1, APC, RECQL4, and HRAS (Fletcher et al, 2013; Ballinger et al, 2016; Thomas and Ballinger, 2016). The age of onset of sarcomas is often lower than that observed for most epithelial cancers and, as such, the heritable proportion of sarcomas is likely to be higher than is currently documented (Fletcher et al, 2013; Thomas and Ballinger, 2016). Along with translocations, intraexonic somatic mutations may also contribute to sarcoma development. In a heterogeneous series of 811 next-generationsequenced sarcomas, the Cancer Genome Atlas Research Network identifies TP53, PIK3CA, ATRX, PCLO, and LRP1B to be the five most frequently somatically mutated genes (Supplementary Tables S1a and S1b) (cBioPortal for Cancer Genomics). There are rare reports of sarcomas arising in the context of the DICER1 syndrome (Foulkes et al, 2011; Rio Frio et al, 2011; Kim et al, 2013; Doros et al, 2014; Schultz et al, 2016), a rare paediatric tumour predisposition syndrome caused by germline mutations in DICER1 (OMIM 601200). Priest et al (1996) noted the occurrence of paediatric-onset sarcomas co-occurring with pleuropulmonary blastoma, a tumour now known to be prototypic of the syndrome. Hill et al (2009) further substantiated the association by reporting sarcomas in germline DICER1 mutation carriers. Subsequent reports of sarcomas in DICER1 germline-mutated patients include a para-spinal rhabdomyosarcoma in a 20-year-old (Rio Frio et al, 2011) and a pleomorphic sarcoma of the thigh (consistent with a leiomyosarcoma) in a 26-year-old (Foulkes et al, 2011). A cervical primitive neuroectodermal tumour (Ewing/cPNET) was also reported in a germline DICER1-mutated patient (Foulkes et al, 2011). However, as testing for characteristic second somatic DICER1 RNase IIIb mutations (Foulkes et al, 2014) was not performed, it is not possible to discern whether the lesions are manifestations of the syndrome or co-incidental occurrences. In contrast, an Askin/Ewing family tumour that arose in a 13-year-old germline DICER1 mutation carrier (for more details, see de Kock et al, 2014b) was not found to harbour a characteristic RNase IIIb hotspot mutation (Foulkes, unpublished data). There are also several reports of somatic DICER1 RNase IIIb hotspot mutations in uterine carcinosarcoma (Table 1 and Supplementary Table S1c). More recently, DICER1 mutations have been strongly implicated in the pathogenesis of embryonal rhabdomyosarcoma (ERMS) of the uterine cervix (cERMS) (Tomiak et al, 2014; de Kock et al, 2016) the ovary (de Kock et al, 2015), and anaplastic sarcoma of the kidney (D1ASK) (Doros et al, 2014; Wu et al, 2016). Characteristic hotspot DICER1 RNase IIIb mutations were identified in the three aforementioned lesions. Biallelic somatic DICER1 mutations were similarly detected in a case of adult-onset cERMS (de Kock et al, 2016). Despite the above evidence, the true contribution of DICER1 mutations to sarcomas is not yet known. In this study, we aimed to uncover the contribution of DICER1 mutations to a convenience sample of 61 predominantly adult-onse (...truncated)