MYCN-targeting miRNAs are predominantly downregulated during MYCN‑driven neuroblastoma tumor formation

// Anneleen Beckers 1,* , Gert Van Peer 1,* , Daniel R. Carter 2 , Evelien Mets 1 , Kristina Althoff 3,4 , Belamy B. Cheung 2 , Johannes H. Schulte 3,4,5, 6 , Pieter Mestdagh 1 , Jo Vandesompele 1 , Glenn M. Marshall 2,7 , Katleen De Preter 1 and Frank Speleman 1 1  Center for Medical Genetics (CMGG), Ghent University, Ghent, Belgium 2  Children’s Cancer Institute, University of New South Wales, Sydney, Australia 3  Department of Pediatric Oncology and Hematology, University Children’s Hospital Essen, Essen, Germany 4  German Cancer Consortium (DKTK), Germany 5  German Cancer Research Center (DKFZ), Heidelberg, Germany 6  Translational Neuro-Oncology, West German Cancer Center, University Hospital Essen, University Duisburg-Essen, Essen, Germany 7  Kids Cancer Centre, Sydney Children’s Hospital, Sydney, Australia * These authors contributed equally to this work Correspondence: Frank Speleman, email: // Keywords : MYCN, microRNA, neuroblastoma, feedback regulation, cross-species Received : July 01, 2014 Accepted : September 15, 2014 Published : September 16, 2014 Abstract MYCN is a transcription factor that plays key roles in both normal development and cancer. In neuroblastoma, MYCN acts as a major oncogenic driver through pleiotropic effects regulated by multiple protein encoding genes as well as microRNAs (miRNAs). MYCN activity is tightly controlled at the level of transcription and protein stability through various mechanisms. Like most genes, MYCN is further controlled by miRNAs, but the full complement of all miRNAs implicated in this process has not been determined through an unbiased approach. To elucidate the role of miRNAs in regulation of MYCN, we thus explored the MYCN-miRNA interactome to establish miRNAs controlling MYCN expression levels. We combined results from an unbiased and genome-wide high-throughput miRNA target reporter screen with miRNA and mRNA expression data from patients and a murine neuroblastoma progression model. We identified 29 miRNAs targeting MYCN, of which 12 miRNAs are inversely correlated with MYCN expression or activity in neuroblastoma tumor tissue. The majority of MYCN-targeting miRNAs in neuroblastoma showed a decrease in expression during murine MYCN-driven neuroblastoma tumor development. Therefore, we provide evidence that MYCN-targeting miRNAs are preferentially downregulated in MYCN-driven neuroblastoma, suggesting that MYCN negatively controls the expression of these miRNAs, to safeguard its expression.