Anaplastic lymphoma kinase aberrations correlate with metastatic features in pediatric rhabdomyosarcoma

// Patrizia Gasparini 1, * , Michela Casanova 2, * , Raffaella Villa 3 , Paola Collini 4 , Rita Alaggio 5 , Angelica Zin 6 , Paolo Bonvini 6 , Cristina R Antonescu 8 , Renata Boldrini 9 , Roberto Caserini 1 , Massimo Moro 1 , Giovanni Centonze 1 , Cristina Meazza 2 , Maura Massimino 2 , Luca Bergamaschi 2 , Roberto Luksch 2 , Stefano Chiaravalli 2 , Gianni Bisogno 10 , Nadia Zaffaroni 7 , MariaGrazia Daidone 3 , Gabriella Sozzi 1, # , Andrea Ferrari 2, # 1 Tumor Genomics Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy 2 Department of Pediatric Oncology, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy 3 Biomarkers Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy 4 Soft Tissue and Bone Pathology, Histopathology and Pediatric Pathology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy 5 Department of Pathology, University Hospital of Padova, Padova, Italy 6 Institute of Pediatric Research Citta della Speranza, Padova, Italy 7 Molecular Pharmacology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy 8 Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA 9 Department of Pathology, Bambino Gesu Children Hospital-Research Institute, Rome, Italy 10 Hematology Oncology Division, Department of Mother and Child’s Health, University Hospital of Padova, Padova, Italy * These authors contributed equally to this work # Co-last authors Correspondence to: Gabriella Sozzi, email: gabriella.sozzi@istitutotumori.mi.it Keywords: anaplastic lymphoma kinase, rhabdomyosarcoma, EML4-ALK, chromosomal rearrangement, metastasis Received: February 11, 2016      Accepted: June 12, 2016      Published: July 01, 2016 ABSTRACT Rhabdomyosarcoma (RMS) is the most frequent soft tissue tumor in childhood and arises from immature mesenchymal cells committed to skeletal muscle differentiation. Anaplastic Lymphoma Kinase (ALK) is a receptor tyrosine kinase aberrantly expressed in several cancers. Moreover, ALK full-length receptor protein has been observed in RMS, although its clinical and functional significance is yet controversial. The role of ALK and its clinical relevance were investigated in a selected cohort of 74 FFPE pediatric RMS and a panel of RMS cell lines, evaluating its gene and protein status, utilizing Fluorescent In Situ Hybridization (FISH), immunohistochemistry (IHC) and Western blot approaches. Moreover, to get insight into its possible therapeutic relevance, effects of ALK silencing on cell proliferation, invasion and apoptosis were studied in RMS cells. ALK IHC positivity was significantly correlated with gene copy number gain, the alveolar subtype, PAX3/7-FOXO1 rearrangements, the presence of metastasis at diagnosis and a worse overall outcome. Furthermore, EML4-ALK fusion gene associated with higher protein expression was identified in an embryonal RMS. ALK silencing in RH30 ALK positive cells strongly inhibited invasion capability. Overall, our data suggest a potential role of ALK in pediatric RMS.