title: MicroRNA-124 regulates STAT3 expression and is down-regulated in colon tissues of pediatric patients with ulcerative colitis.
abstract: OBJECTIVE
  Altered levels and functions of microRNAs (miRs) have been associated with inflammatory bowel diseases (IBDs), although little is known about their roles in pediatric IBD. We investigated whether colonic mucosal miRs are altered in children with ulcerative colitis (UC).
  
  
  METHODS
  We used a library of 316 miRs to identify those that regulate phosphorylation of signal transducer and activator of transcription 3 (STAT3) in NCM460 human colonocytes incubated with interleukin-6. Levels of miR-124 were measured by real-time polymerase chain reaction analysis of colon biopsies from pediatric and adult patients with UC and patients without IBD (controls), and of HCT-116 colonocytes incubated with 5-aza-2'-deoxycytidine (5-AZA). Methylation of the MIR124 promoter was measured by quantitative methylation-specific polymerase chain reaction.
  
  
  RESULTS
  Levels of phosphorylated STAT3 and the genes it regulates (encoding vascular endothelial growth factor (VEGF), BCL2, BCLXL, and matrix metallopeptidase 9 [MMP9]) were increased in pediatric patients with UC compared with control tissues. Overexpression of miR-124, let-7, miR-125, miR-26, or miR-101 reduced STAT3 phosphorylation by ≥ 75% in NCM460 cells; miR-124 had the greatest effect. miR-124 was down-regulated specifically in colon tissues from pediatric patients with UC and directly targeted STAT3 messenger RNA (mRNA). Levels of miR-124 were decreased, whereas levels of STAT3 phosphorylation increased in colon tissues from pediatric patients with active UC compared with those with inactive disease. In addition, levels of miR-124 and STAT3 were inversely correlated in mice with experimental colitis. Down-regulation of miR-124 in tissues from children with UC was attributed to hypermethylation of its promoter region. Incubation of HCT-116 colonocytes with 5-AZA up-regulated miR-124 and reduced levels of STAT3 mRNA.
  
  
  CONCLUSIONS
  miR-124 appears to regulate the expression of STAT3. Reduced levels of miR-124 in colon tissues of children with active UC appear to increase expression and activity of STAT3, which could promote inflammation and the pathogenesis of UC in children.
authors.affiliation: Center for Systems Biomedicine, Division of Digestive Diseases, David Geffen School of Medicine, UCLA, Los Angeles, California; Institute for Molecular Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California; Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, Massachusetts.
authors.forename: Georgios
authors.initials: G
authors.lastname: Koukos
authors.forename: Christos
authors.initials: C
authors.lastname: Polytarchou
authors.forename: Jess L
authors.initials: JL
authors.lastname: Kaplan
authors.forename: Alessio
authors.initials: A
authors.lastname: Morley-Fletcher
authors.forename: Beatriz
authors.initials: B
authors.lastname: Gras-Miralles
authors.forename: Efi
authors.initials: E
authors.lastname: Kokkotou
authors.forename: Mariah
authors.initials: M
authors.lastname: Baril-Dore
authors.forename: Charalabos
authors.initials: C
authors.lastname: Pothoulakis
authors.forename: Harland S
authors.initials: HS
authors.lastname: Winter
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Iliopoulos
mesh_terms: D020413:3' Untranslated Regions; D000293:Adolescent; D000818:Animals; D045744:Cell Line, Tumor; D002648:Child; D002675:Child, Preschool; D003093:Colitis, Ulcerative / Q000378:metabolism*; D003106:Colon / Q000378:metabolism*; D019175:DNA Methylation; D015536:Down-Regulation; D005786:Gene Expression Regulation; D057166:High-Throughput Screening Assays; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000502:physiology*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D050796:STAT3 Transcription Factor / Q000235:genetics*
chemical_list: D020413:3' Untranslated Regions; C509207:MIRN124 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human
keywords: 5-AZA; 5-aza-2′-deoxycytidine; BCLXL; CD; Crohn's disease; DSS; ELISA; Gene Regulation; IBD; IL; IL6; KO; Let-7; MMP9; PCR; STAT3; Tyr705; UC; VEGF; dextran sulfate sodium salt; enzyme-linked immunosorbent assay; inflammatory bowel disease; interleukin; knockout; mRNA; matrix metallopeptidase 9; messenger RNA; miR; microRNA; p-STAT3; phosphorylated STAT3; polymerase chain reaction; signal transducer and activator of transcription 3; tyrosine 705; ulcerative colitis; vascular endothelial growth factor