CRISPR Cas9-guided chromatin immunoprecipitation identifies miR483 as an epigenetic modulator ofIGF2imprinting in tumors

// Yiqun Zhang 1, 2 , Ji-Fan Hu 1, 2, * , Hong Wang 1, 2 , Jiuwei Cui 1 , Sujun Gao 1 , Andrew R. Hoffman 2, * and Wei Li 1, * 1 Stem Cell and Cancer Center, First Affiliated Hospital, Jilin University, Changchun, Jilin 130061, P.R. China 2 Department of Medicine, Stanford University Medical School, VA Palo Alto Health Care System, Palo Alto, CA 94304, USA * These authors are co-corresponding and senior authors of this report Correspondence to: Ji-Fan Hu, email: jifan@stanford.edu Wei Li, email: jdyylw@163.com Andrew R. Hoffman, email: arhoffman@stanford.edu. Keywords: IGF2 imprinting, tumor, epigenetics, histone K27 methylation, allelic expression Received: January 08, 2016 Accepted: July 18, 2016 Published: July 29, 2016 ABSTRACT The normally imprinted insulin-like growth factor II ( IGF2 ) gene is aberrantly upregulated in a variety of human malignancies, yet the mechanisms underlying this dysregulation are still poorly defined. In this report, we used a CRISPR Cas9-guided chromatin immunoprecipitation assay to characterize the molecular components that participate in the control of IGF2 gene expression in human tumor cells. We found that miR483, an oncogenic intronic miRNA, binds to the most upstream imprinted IGF2 promoter, P2. Ectopic expression of miR483 induced upregulation of IGF2 expression, in parallel with an increase in tumor cell proliferation, migration, invasion, and tumor colony formation. miR483 induced loss of IGF2 imprinting by altering the epigenotype at P2, with reduction in histone H3K27 methylation and a decrease in chromatin binding of two imprinting regulatory factors, CTCF and SUZ12. This study identifies a new role for miR483 in the regulation of IGF2 gene expression through the alteration of the promoter epigenotype.