title: MicroRNA-494 suppresses cell proliferation and induces senescence in A549 lung cancer cells.
abstract: OBJECTIVE
  MicroRNAs (miRNAs) are small functional RNAs that regulate mRNAs for degradation or translational suppression. In the present study, we aimed to reveal functional importance of miRNA-494 (miR-494) in A549 human lung cancer cells.
  
  
  METHODS
  We established A549 cells that constitutively expressed miR-494. Next, we sought to investigate insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1) mRNA as an miR-494 target. For this, we constructed a reporter plasmid bearing potential miR-494 binding sequences derived from the 3'-untranslated region (3'-UTR) of IGF2BP1 mRNA in the 3'-UTR of the luciferase gene.
  
  
  RESULTS
  Through comparison between miR-494 expressing cells and control cells, we revealed that miR-494 suppressed cell proliferation and colony forming activity, and induced senescence. Reporter activity was inhibited by miR-494. In addition, IGF2BP1 mRNA levels were down-regulated in A549 cells that constitutively expressed miR-494. IGF2BP1 has been shown to bind and suppress IGF2 mRNA, and this could be a reason why IGF2BP1 can regulate cell function. Therefore, we analysed IGF2 mRNA levels and revealed that IGF2 was up-regulated in A549 cells that constitutively expressed miR-494. Finally, elevated IGF2 mRNA levels in A549 cells that constitutively expressed miR-494 were suppressed to basal level by an miR-494 inhibitor.
  
  
  CONCLUSIONS
  Taken together, IGF2BP1 and its downstream target IGF2 could be a crucial axis for miR-494 in regulation of the destiny of A549 cells.
authors.affiliation: Department of Life Sciences, Meiji University, Kawasaki, Kanagawa, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ohdaira
authors.forename: M
authors.initials: M
authors.lastname: Sekiguchi
authors.forename: K
authors.initials: K
authors.lastname: Miyata
authors.forename: K
authors.initials: K
authors.lastname: Yoshida
mesh_terms: D017209:Apoptosis; D001483:Base Sequence; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D017931:DNA Primers / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics; D008175:Lung Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics; D014170:Transformation, Genetic; D014410:Tumor Stem Cell Assay
chemical_list: D017931:DNA Primers; C035170:IGF2 protein, human; C406144:IGF2BP1 protein, human; C547168:MIRN494 microRNA, human; D035683:MicroRNAs; D012334:RNA, Neoplasm; D016601:RNA-Binding Proteins; D007335:Insulin-Like Growth Factor II