title: N-Myc regulates expression of pluripotency genes in neuroblastoma including lif, klf2, klf4, and lin28b.
abstract: myc genes are best known for causing tumors when overexpressed, but recent studies suggest endogenous myc regulates pluripotency and self-renewal of stem cells. For example, N-myc is associated with a number of tumors including neuroblastoma, but also plays a central role in the function of normal neural stem and precursor cells (NSC). Both c- and N-myc also enhance the production of induced pluripotent stem cells (iPSC) and are linked to neural tumor stem cells. The mechanisms by which myc regulates normal and neoplastic stem-related functions remain largely open questions. Here from a global, unbiased search for N-Myc bound genes using ChIP-chip assays in neuroblastoma, we found lif as a putative N-Myc bound gene with a number of strong N-Myc binding peaks in the promoter region enriched for E-boxes. Amongst putative N-Myc target genes in expression microarray studies in neuroblastoma we also found lif and three additional important embryonic stem cell (ESC)-related factors that are linked to production of iPSC: klf2, klf4, and lin28b. To examine the regulation of these genes by N-Myc, we measured their expression using neuroblastoma cells that contain a Tet-regulatable N-myc transgene (TET21N) as well as NSC with a nestin-cre driven N-myc knockout. N-myc levels closely correlated with the expression of all of these genes in neuroblastoma and all but lif in NSC. Direct ChIP assays also indicate that N-Myc directly binds the lif promoter. N-Myc regulates trimethylation of lysine 4 of histone H3 in the promoter of lif and possibly in the promoters of several other stem-related genes. Together these findings indicate that N-Myc regulates overlapping stem-related gene expression programs in neuroblastoma and NSC, supporting a novel model by which amplification of the N-myc gene may drive formation of neuroblastoma. They also suggest mechanisms by which Myc proteins more generally contribute to maintenance of pluripotency and self-renewal of ESC as well as to iPSC formation.
authors.affiliation: Department of Cell Biology and Human Anatomy, and Stem Cell Program, University of California Davis School of Medicine, Shriners Hospital For Children Northern California, Sacramento, California, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Cotterman
authors.forename: Paul S
authors.initials: PS
authors.lastname: Knoepfler
mesh_terms: D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D053595:Embryonic Stem Cells / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D016259:Genes, myc; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors / Q000096:biosynthesis*; D053605:Leukemia Inhibitory Factor / Q000096:biosynthesis*; D008745:Methylation; D009447:Neuroblastoma / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism / Q000502:physiology*; D016601:RNA-Binding Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019076:Transgenes
chemical_list: D004268:DNA-Binding Proteins; C096161:KLF2 protein, human; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; C507837:LIF protein, human; C516326:LIN28B protein, human; D053605:Leukemia Inhibitory Factor; D016271:Proto-Oncogene Proteins c-myc; D016601:RNA-Binding Proteins