Explanations for telomerase maintenance get complicated by the observation that a considerable fraction of STS do neither apply telomerase activation nor

the ALT mechanism that is so far known, or even may be equipped with both mechanisms [7, 36]. Further studies concerning molecular alterations in STS will in particular draw more attention to the non-coding genomic regions and hopefully elucidate the remaining unanswered questions, which mechanisms these tumors exploit to prevent telomere attrition. Conclusion We determined PU-H71 clinical trial the prevalence of TERT promoter hotspot ARN-509 nmr mutations in STS. Despite the overall low prevalence in this tumor group, TERT promoter mutations revealed to be a highly recurrent event in MLS and currently represent the most prevalent mutation identified in this

sarcoma entity (74%). Forthcoming studies will be needed to determine whether the TERT promoter mutational status could be of clinical relevance, especially in advanced MLS. Additionally, TERT promoter mutations were also found in a subset of SFTs (13%), and in a number of MPNSTs (6%) and SSs (4%). Given the relative frequency of telomerase activation reported in MPNSTs and in SSs, the low TERT promoter mutation rate in these sarcoma types implies that a so far unknown mechanism, different from the presently known TERT promoter hotspot mutations, provides telomerase reactivation in these sarcoma entities. Acknowledgements The work was supported by the interdisciplinary research group KoSar (Kompetenznetz Sarkome, DKH 107153, DKH 109742) with a grant from the Deutsche Krebshilfe (German Cancer Aid). We thank the Tissue

Bank of the National Center for Tumor Diseases Heidelberg Rigosertib for providing tissues. The authors thank Katja Böhmer, Jochen Meyer, Marion however Moock, Andrea Müller and Kerstin Mühlburger for their excellent technical assistance. We acknowledge the financial support of the Deutsche Forschungsgemeinschaft and Ruprecht-Karls-Universität Heidelberg within the funding programme Open Access Publishing. Electronic supplementary material Additional file 1: Table S1: Clinicopathological patients’ characteristics. Internal identifier, diagnosis, patients’ age at surgery, gender, tumor localization, presence/absence of a fusion transcript, and TERT promoter mutational status with nucleotide exchange, are indicated for all cases. Abbreviations: UPS = undifferentiated pleomorphic sarcoma; DDLS = dedifferentiated liposarcoma; PLS = pleomorphic liposarcoma; MLS = myxoid liposarcoma; LMS = leiomyosarcoma; SS = synovial sarcoma; MFS = myxofibrosarcoma; MPNST = malignant nerve sheath tumor; EMCS = extraskeletal myxoid chondrosarcoma; SFT = solitary fibrous tumors; ASPS = alveolar soft part sarcoma; CCS = clear cell sarcoma; EPS = epithelioid sarcoma; DFSP = dermatofibrosarcoma protuberans; LGFMS = low-grade fibromyxoid sarcoma; AS = angiosarcoma. Additional file 1: Table S2. Molecular and histological features of the myxoid liposarcomas.