title: A minicircuitry comprised of microRNA-9 and SIRT1 contributes to leukemogenesis in t(8;21) acute myeloid leukemia.
abstract: The AML1-ETO fusion protein (AE) resulting from the t(8;21) translocation is highly related to the pathogenesis and development of leukemia. microRNA-9 (miR-9) acts as a tumor suppressor gene in AE-positive acute myeloid leukemia (AML). Silent mating type information regulation 2 homolog-1 (SIRT1) is overexpressed in most cancer cells by increasing proliferation as a tumorigenic gene. The present study was performed to investigate the underlying interaction between miR-9 and SIRT1 in AE-positive AML.
  
  
  
  Expression of miR-9 and SIRT1 in AE-positive AML patients, healthy donors and AML cell lines were detected by qPCR. Relevance between miR-9 and SIRT1 was assessed by plasmid transfection, Western blot and correlation analysis. Luciferase assay was used to confirm the target gene of miR-9. Knockdown of SIRT1 in different cell lines was achieved by shRNA transfection and CCK-8 assay was used to investigate the effects on cell proliferation.
  
  
  
  The miR-9 expression was lower in AE-positive cell lines compared to that in other AE-negative AML cell lines, while expression of SIRT1 was higher in AE-positive cell lines. Expression of miR-9 was also downregulated in adult primary t(8;21) AML patients compared to healthy donors. The over-expression of miR-9 decreased luciferase activity of wild-type SIRT1, which was recovered after transfection with mutant SIRT1. The miR-9 directly targets SIRT1 by binding to its 3'-untranslated region and reducing its protein levels. Importantly, miR-9 and SIRT1 mRNA levels were inversely correlated in AE-positive AML cell lines and t(8;21) AML primary leukemia cells. Knockdown of SIRT1 levels using shSIRT1 inhibited cell proliferation in AE-positive AML cell lines.
  
  
  
  SIRT1 is the target gene of miR-9 and the signaling pathway connecting miR-9 and SIRT1 is a therapeutic target for t(8;21) AML.
authors.affiliation: Department of Hematology, Chinese PLA General Hospital, Beijing, China. chunhuiliyu@yahoo.com.
authors.forename: L
authors.initials: L
authors.lastname: Zhou
authors.forename: L
authors.initials: L
authors.lastname: Fu
authors.forename: N
authors.initials: N
authors.lastname: Lv
authors.forename: X-S
authors.initials: XS
authors.lastname: Chen
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: Q-Y
authors.initials: QY
authors.lastname: Xu
authors.forename: S
authors.initials: S
authors.lastname: Huang
authors.forename: X-D
authors.initials: XD
authors.lastname: Zhang
authors.forename: L-P
authors.initials: LP
authors.lastname: Dou
authors.forename: L L
authors.initials: LL
authors.lastname: Wang
authors.forename: Y-H
authors.initials: YH
authors.lastname: Li
authors.forename: L
authors.initials: L
authors.lastname: Yu
mesh_terms: D020413:3' Untranslated Regions; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics*; D035683:MicroRNAs / Q000235:genetics*; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D000075142:RUNX1 Translocation Partner 1 Protein; D015398:Signal Transduction; D056564:Sirtuin 1 / Q000235:genetics*; D014178:Translocation, Genetic
chemical_list: D020413:3' Untranslated Regions; C107844:AML1-ETO fusion protein, human; D050676:Core Binding Factor Alpha 2 Subunit; C541874:MIRN92 microRNA, human; D035683:MicroRNAs; D015514:Oncogene Proteins, Fusion; D000075142:RUNX1 Translocation Partner 1 Protein; C447939:SIRT1 protein, human; D056564:Sirtuin 1