title: Regulation of c-myc gene by nitric oxide via inactivating NF-kappa B complex in P19 mouse embryonal carcinoma cells.
abstract: Nitric oxide (NO) may regulate gene expression by directly modifying redox state-sensitive residues of transcription factors. Here we show that the NO donor, sodium nitroprusside (SNP), rapidly represses c-myc gene transcription in a protein synthesis-independent manner in P19 embryonal carcinoma cells by inactivation of NF-kappa B. SNP treatment reduces the DNA binding ability of the constitutively active NF-kappa B heterodimer, p65/p50, and its consequent transactivation of the c-myc promoter. Repression can be blocked by the peroxynitrite scavenger, deferoxamine, but not by dithiothreitol, which triggers reduction of S-nitrosylated residues. In HEK293 cells, where tumor necrosis factor-alpha can activate NF-kappa B, SNP likewise suppresses the binding of the active NF-kappa B complex, restoring the binding of the repressive p50/p50 homodimer complex. This effect of SNP in HEK293 cells is also blocked by deferoxamine. Chromatin immunoprecipitation analysis of SNP-treated P19 cells reveals reduced association of p65, but not of p50, with the promoter region of the endogenous c-myc gene. SNP-induced p65 dissociation was associated with the recruitment of histone deacetylase 1 and 2 to the endogenous c-myc gene promoter and the subsequent deacetylation of its chromatin histone. This study is the first to demonstrate that NO modulates the transcriptional activity of the c-myc gene promoter by dissociating the active form of NF-kappa B and replacing it with a repressive NF-kappa B complex, correlated with the recruitment of gene-silencing histone deacetylases. In light of findings that NF-kappa B stimulates Myc oncoprotein expression in cancers, our findings suggest that NO should be investigated as a prospective therapeutic cancer agent.
authors.affiliation: Department of Pharmacology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
authors.forename: Sung Wook
authors.initials: SW
authors.lastname: Park
authors.forename: Li-Na
authors.initials: LN
authors.lastname: Wei
mesh_terms: D000818:Animals; D019556:COS Cells; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D003676:Deferoxamine / Q000494:pharmacology; D019281:Dimerization; D004229:Dithiothreitol / Q000494:pharmacology; D005786:Gene Expression Regulation; D020868:Gene Silencing; D016259:Genes, myc / Q000235:genetics; D006657:Histones / Q000378:metabolism; D006801:Humans; D007502:Iron Chelating Agents / Q000494:pharmacology; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D030421:Peroxynitrous Acid / Q000494:pharmacology; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
chemical_list: D002843:Chromatin; D006657:Histones; D007502:Iron Chelating Agents; D016328:NF-kappa B; D020030:Nitric Oxide Donors; D011500:Protein Synthesis Inhibitors; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D030421:Peroxynitrous Acid; D009599:Nitroprusside; D009569:Nitric Oxide; D004247:DNA; D003513:Cycloheximide; D003676:Deferoxamine; D004229:Dithiothreitol