miRNA Expression Profiling of the Murine TH-MYCN Neuroblastoma Model Reveals Similarities with Human Tumors and Identifies Novel Candidate MiRNAs Marta Terrile1,2, Kenneth Bryan1,2, Lynsey Vaughan 3 , Albert Hallsworth3, Hannah Webber3, Louis Chesler3., Raymond L. Stallings1,2*. 1 Department of Cancer Genetics, Royal College of Surgeons in Ireland, Dublin, Ireland, 2 Ireland and National Children’s Research Centre, Our Lady’s Children’s Hospital, Crumlin, Dublin, Ireland, 3 Division of Cancer Therapeutics, The Institute of Cancer Research, Sutton, Surrey, United Kingdom Abstract Background: MicroRNAs are small molecules which regulate gene expression post-transcriptionally and aberrant expression of several miRNAs is associated with neuroblastoma, a childhood cancer arising from precursor cells of the sympathetic nervous system. Amplification of the MYCN transcription factor characterizes the most clinically aggressive subtype of this disease, and although alteration of p53 signaling is not commonly found in primary tumors, deregulation of proteins involved in this pathway frequently arise in recurrent disease after pharmacological treatment. TH-MYCN is a well- characterized transgenic model of MYCN-driven neuroblastoma which recapitulates many clinicopathologic features of the human disease. Here, we evaluate the dysregulation of miRNAs in tumors from TH-MYCN mice that are either wild-type (TH- MYCN) or deficient (TH-MYCN/p53ERTAM) for the p53 tumor suppressor gene. Principal Findings: We analyzed the expression of 591 miRNAs in control (adrenal) and neuroblastoma tumor tissues derived from either TH-MYCN or TH-MYCN/p53ERTAM mice, respectively wild-type or deficient in p53. Comparing miRNA expression in tumor and control samples, we identified 159 differentially expressed miRNAs. Using data previously obtained from human neuroblastoma samples, we performed a comparison of miRNA expression between murine and human tumors to assess the concordance between murine and human expression data. Notably, the miR-17-5p-92 oncogenic polycistronic cluster, which is over-expressed in human MYCN amplified tumors, was over-expressed in mouse tumors. Moreover, analyzing miRNAs expression in a mouse model (TH-MYCN/p53ERTAM) possessing a transgenic p53 allele that drives the expression of an inactive protein, we identified miR-125b-3p and miR-676 as directly or indirectly regulated by the level of functional p53. Significance: Our study represents the first miRNA profiling of an important mouse model of neuroblastoma. Similarities and differences in miRNAs expression between human and murine neuroblastoma were identified, providing important insight into the efficacy of this mouse model for assessing miRNA involvement in neuroblastoma and their potential effectiveness as therapeutic targets. Citation: Terrile M, Bryan K, Vaughan L, Hallsworth A, Webber H, et al. (2011) miRNA Expression Profiling of the Murine TH-MYCN Neuroblastoma Model Reveals Similarities with Human Tumors and Identifies Novel Candidate MiRNAs. PLoS ONE 6(12): e28356. doi:10.1371/journal.pone.0028356 Editor: Carlo Gaetano, Istituto Dermopatico dell’Immacolata, Italy Received September 16, 2011; Accepted November 7, 2011; Published December 2, 2011 Copyright: 2011 Terrile et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported in part by Science Foundation Ireland (07/IN.1/B1776), Children’s Medical and Research Foundation, and The Neuroblastoma Society, grant NES003X. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. No additional external funding was received for this study. Competing Interests: The authors have declared that no competing interests exist. * E-mail: rstallings@rcsi.ie . These authors contributed equally to this work. Introduction Neuroblastoma is among the most common of childhood tumors and accounts for 15% of pediatric cancer deaths. The disease is clinically heterogeneous, with behavior ranging from spontaneous regression to rapid progression. Multiple genetic abnormalities have been identified that are predictive of clinical outcome and that play important roles in neuroblastoma pathogenesis [1]. Amplification of the gene encoding the MYCN transcription factor is the most potent genetic predictor of poor patient outcome and delineates a distinct genetic subtype of high- risk neuroblastoma [2]. As a transcription factor, MYCN directly regulates the expression of a large set of genes and microRNAs (miRNA), whose major functions include regulation of cell cycle progression, proliferation, differentiation and apoptosis. [3–5]. MiRNAs are small molecules (22–24 nucleotides) of RNA which negatively regulate gene expression at a post-transcriptional level. The binding of miRNAs to complementary sites on the 39 UTRs of protein coding mRNA sequences results in either degradation of the mRNA or translational inhibition [6]. MiRNAs are involved with the regulation of many normal physiological processes and their dysregulation contributes to the pathogenesis of virtually all forms of cancer [7,8], including neuroblastoma [9–11]. A number of miRNA expression profiling studies have shown that miRNA PLoS ONE | www.plosone.org 1 December 2011 | Volume 6 | Issue 12 | e28356