title: MiR-29c is downregulated in gastric carcinomas and regulates cell proliferation by targeting RCC2.
abstract: BACKGROUND
  Previously, using miRNA microarray, we have found that miR-29c is significantly downregulated in advanced gastric carcinoma. In the present study, we investigated whether miR-29c functions as a tumor-suppressor miRNA in gastric carcinoma cells. For this purpose, we verified the downregulation of miR-29c in gastric carcinoma tissues, and assessed the biological effect of miR-29c on gastric carcinoma cells.
  
  
  RESULTS
  In miR-29c-transfected cells, both proliferation and colony formation ability on soft agar were significantly decreased. Although apoptosis was not induced, BrdU incorporation and the proportion of cells positive for phospho-histone H3 (S10) were significantly decreased in miR-29c-transfected cells, indicating that miR-29c may be involved in the regulation of cell proliferation. To explain the mechanism of growth suppression by miR-29c, we explored differentially expressed genes (>2-fold) in miR-29c-transfected cells in comparison with negative control transfected cells using microarray. RCC2, PPIC and CDK6 were commonly downregulated in miR-29c-transfected MKN45, MKN7 and MKN74 cells, and all of the genes harbored miR-29c target sequences in the 3'-UTR of their mRNA. RCC2 and PPIC were actually upregulated in gastric carcinoma tissues, and therefore both were identified as possible targets of miR-29c in gastric carcinoma. To ascertain whether downregulation of RCC2 and/or PPIC is involved in the growth suppression by miR-29c, we transfected siRNAs against RCC2 and PPIC into MKN45 and determined cell viability, the rate of BrdU incorporation, and caspase activity. We found that RCC2-knockdown decreased both cell viability and BrdU incorporation without any increase of caspase activity, while PPIC-knockdown did not, indicating that downregulation of RCC2 may be at least partly responsible for the growth suppression by miR-29c.
  
  
  CONCLUSIONS
  Our findings indicate that miR-29c may have tumor-suppressive functions in gastric carcinoma cells, and that its decreased expression may confer a growth advantage on tumor cells via aberrant expression of RCC2.
authors: Department of Molecular Pathology, Faculty of Medicine, Oita University, Oita, Japan.
authors: Mitsuhiro
authors: M
authors: Matsuo
authors: Chisato
authors: C
authors: Nakada
authors: Yoshiyuki
authors: Y
authors: Tsukamoto
authors: Tsuyoshi
authors: T
authors: Noguchi
authors: Tomohisa
authors: T
authors: Uchida
authors: Naoki
authors: N
authors: Hijiya
authors: Keiko
authors: K
authors: Matsuura
authors: Masatsugu
authors: M
authors: Moriyama
mesh_terms: D017209:Apoptosis / Q000235:genetics; D002277:Carcinoma / Q000235:genetics* / Q000378:metabolism; D049109:Cell Proliferation; D002470:Cell Survival; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000378:metabolism; D051361:Cyclin-Dependent Kinase 6 / Q000235:genetics / Q000378:metabolism; D044127:Epigenesis, Genetic; D005341:Fibrinolysin / Q000235:genetics / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism; D000979:alpha-2-Antiplasmin / Q000235:genetics / Q000378:metabolism
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D020662:Guanine Nucleotide Exchange Factors; C532045:MIRN29a microRNA, human; D035683:MicroRNAs; C477650:RCC2 protein, human; D000979:alpha-2-Antiplasmin; C037742:plasmin-plasmin inhibitor complex; D051361:Cyclin-Dependent Kinase 6; D005341:Fibrinolysin