title: MicroRNA-184 inhibits neuroblastoma cell survival through targeting the serine/threonine kinase AKT2.
abstract: BACKGROUND
  Neuroblastoma is a paediatric cancer of the sympathetic nervous system. The single most important genetic indicator of poor clinical outcome is amplification of the MYCN transcription factor. One of many down-stream MYCN targets is miR-184, which is either directly or indirectly repressed by this transcription factor, possibly due to its pro-apoptotic effects when ectopically over-expressed in neuroblastoma cells. The purpose of this study was to elucidate the molecular mechanism by which miR-184 conveys pro-apoptotic effects.
  
  
  RESULTS
  We demonstrate that the knock-down of endogenous miR-184 has the opposite effect of ectopic up-regulation, leading to enhanced neuroblastoma cell numbers. As a mechanism of how miR-184 causes apoptosis when over-expressed, and increased cell numbers when inhibited, we demonstrate direct targeting and degradation of AKT2, a major downstream effector of the phosphatidylinositol 3-kinase (PI3K) pathway, one of the most potent pro-survival pathways in cancer. The pro-apoptotic effects of miR-184 ectopic over-expression in neuroblastoma cell lines is reproduced by siRNA inhibition of AKT2, while a positive effect on cell numbers similar to that obtained by the knock-down of endogenous miR-184 can be achieved by ectopic up-regulation of AKT2. Moreover, co-transfection of miR-184 with an AKT2 expression vector lacking the miR-184 target site in the 3'UTR rescues cells from the pro-apoptotic effects of miR-184.
  
  
  CONCLUSIONS
  MYCN contributes to tumorigenesis, in part, by repressing miR-184, leading to increased levels of AKT2, a direct target of miR-184. Thus, two important genes with positive effects on cell growth and survival, MYCN and AKT2, can be linked into a common genetic pathway through the actions of miR-184. As an inhibitor of AKT2, miR-184 could be of potential benefit in miRNA mediated therapeutics of MYCN amplified neuroblastoma and other forms of cancer.
authors.affiliation: Department of Cancer Genetics, Royal College of Surgeons in Ireland, York House, York Street, Dublin 2, Ireland.
authors.forename: Niamh H
authors.initials: NH
authors.lastname: Foley
authors.forename: Isabella M
authors.initials: IM
authors.lastname: Bray
authors.forename: Amanda
authors.initials: A
authors.lastname: Tivnan
authors.forename: Kenneth
authors.initials: K
authors.lastname: Bryan
authors.forename: Derek M
authors.initials: DM
authors.lastname: Murphy
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Buckley
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Ryan
authors.forename: Anne
authors.initials: A
authors.lastname: O'Meara
authors.forename: Maureen
authors.initials: M
authors.lastname: O'Sullivan
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Stallings
mesh_terms: D017209:Apoptosis / Q000235:genetics; D015153:Blotting, Western; D045744:Cell Line, Tumor; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D015513:Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
chemical_list: C534424:MIRN184 microRNA, human; C459801:MYCN protein, human; D035683:MicroRNAs; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt
references.citation: Drug Resist Updat. 2002 Dec;5(6):234-48
references.pmid: 12531180
references.citation: Int J Cancer. 2008 Feb 1;122(3):699-704
references.pmid: 17943719
references.citation: PLoS One. 2008 May 21;3(5):e2236
references.pmid: 18493594
references.citation: Carcinogenesis. 2004 Sep;25(9):1599-609
references.pmid: 15090470
references.citation: J Natl Cancer Inst. 2009 May 6;101(9):663-77
references.pmid: 19401549
references.citation: PLoS One. 2009 Dec 04;4(12):e8154
references.pmid: 19997598
references.citation: Oncogene. 2007 Jul 26;26(34):5017-22
references.pmid: 17297439
references.citation: Proc Natl Acad Sci U S A. 2001 Sep 25;98(20):10983-5
references.pmid: 11572954
references.citation: Mol Cancer Res. 2008 May;6(5):735-42
references.pmid: 18505919
references.citation: Nature. 2005 Jun 16;435(7044):974-8
references.pmid: 15944714
references.citation: Cancer Res. 2005 Mar 15;65(6):2070-5
references.pmid: 15781614
references.citation: J Cell Biochem. 2002;87(4):470-6
references.pmid: 14735903
references.citation: Cancer Res. 2003 Jan 1;63(1):196-206
references.pmid: 12517798
references.citation: Cancer Res. 2007 Feb 1;67(3):976-83
references.pmid: 17283129
references.citation: Int J Cancer. 1995 Aug 22;64(4):280-5
references.pmid: 7657393
references.citation: Curr Pharm Des. 2009;15(4):456-62
references.pmid: 19199973
references.citation: Science. 1984 Jun 8;224(4653):1121-4
references.pmid: 6719137
references.citation: Cancer Res. 2003 Nov 1;63(21):7081-8
references.pmid: 14612499
references.citation: Genes Dev. 2009 Apr 1;23(7):862-76
references.pmid: 19293287
references.citation: Cell Death Differ. 2001 Dec;8(12):1207-12
references.pmid: 11753568
references.citation: Nat Rev Cancer. 2002 Jul;2(7):489-501
references.pmid: 12094235
references.citation: Oncogene. 2010 Mar 4;29(9):1394-404
references.pmid: 19946337
references.citation: Cancer Res. 2007 Jan 15;67(2):735-45
references.pmid: 17234785
references.citation: Nat Rev Cancer. 2006 Apr;6(4):259-69
references.pmid: 16557279
references.citation: Cancer Res. 2006 Apr 1;66(7):3673-80
references.pmid: 16585193
references.citation: Cancer Res. 2003 Aug 1;63(15):4538-46
references.pmid: 12907629
references.citation: Cancer Res. 2009 Aug 1;69(15):6275-81
references.pmid: 19584290
references.citation: Eur J Cancer. 2007 Nov;43(16):2413-22
references.pmid: 17826980
references.citation: Science. 2004 Jan 2;303(5654):83-6
references.pmid: 14657504
references.citation: FASEB J. 2009 Dec;23(12):4276-87
references.pmid: 19713529
references.citation: Oncogene. 2005 Nov 14;24(50):7455-64
references.pmid: 16288292
references.citation: Oncogene. 2009 Mar 5;28(9):1241-7
references.pmid: 19151757
references.citation: J Neurochem. 2004 Aug;90(3):702-11
references.pmid: 15255949
references.citation: Int J Cancer. 2009 Aug 1;125(3):585-95
references.pmid: 19330838
references.citation: Cancer Lett. 2007 May 18;250(1):17-24
references.pmid: 17141950
references.citation: Cell. 2004 Jan 23;116(2):281-97
references.pmid: 14744438
references.citation: Cancer Res. 2004 Apr 15;64(8):2782-92
references.pmid: 15087394
references.citation: Oncogene. 2008 Sep 4;27(39):5204-13
references.pmid: 18504438
references.citation: PLoS One. 2009 Nov 16;4(11):e7850
references.pmid: 19924232
references.citation: Cancer Lett. 2009 Jan 18;273(2):257-65
references.pmid: 18842333
references.citation: Clin Cancer Res. 2008 May 1;14(9):2588-92
references.pmid: 18451220
references.citation: Oncogene. 2000 May 4;19(19):2324-30
references.pmid: 10822383
references.citation: Cell Cycle. 2006 Jan;5(2):172-5
references.pmid: 16357538