title: miR-137 is frequently down-regulated in gastric cancer and is a negative regulator of Cdc42.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are a class of small (19-25 nucleotides) noncoding RNAs that regulate the expressions of a wide variety of genes, including some involved in cancer development. Some recent studies show that DNA methylation contributes to down-regulation of microRNA-137 (miR-137) during tumorigenesis. Whether down-regulation of miR-137 also exists in gastric cancer is unknown.
  
  
  OBJECTIVE
  Our aim was to test the hypothesis that down-regulation of miR-137 also exists in gastric cancer.
  
  
  METHODS
  Expression of levels of miR-137 were examined using real-time PCR on paired gastric cancer and adjacent non-cancerous tissues. The methylation status is detected by MSP.
  
  
  RESULTS
  Results show that miR-137 is downregulated by hypermethylation of the promoter in gastric cancer tissues. Epigenetic silencing of miR-137 induced an up-regulation of its targets, Cdc42. Restoration of the miR-137 expression in gastric cancer cell lines downregulated the Cdc42 expression. Restoration of the miR-137 and inactivation of Cdc42 induce apoptosis and cell cycle G1 arrest in gastric cancer cells. Furthermore, the miR-137 expression was found to be inversely correlated with CDC42 expression in gastric caner.
  
  
  CONCLUSIONS
  miR-137 is frequently down-regulated in gastric cancer and is a negative regulator of Cdc42.
authors.affiliation: Department of Medicine-Oncology, The First Affiliated Hospital, Zhengzhou University, 1 East Jianshe Road, 450000, Zhengzhou, People's Republic of China.
authors.forename: Qingjiang
authors.initials: Q
authors.lastname: Chen
authors.forename: Xiaobing
authors.initials: X
authors.lastname: Chen
authors.forename: Mingzhi
authors.initials: M
authors.lastname: Zhang
authors.forename: Qingxia
authors.initials: Q
authors.lastname: Fan
authors.forename: Suxia
authors.initials: S
authors.lastname: Luo
authors.forename: Xinguang
authors.initials: X
authors.lastname: Cao
mesh_terms: D001483:Base Sequence; D002277:Carcinoma / Q000378:metabolism*; D045744:Cell Line, Tumor; D019175:DNA Methylation; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D035683:MicroRNAs / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D013274:Stomach Neoplasms / Q000378:metabolism*; D020764:cdc42 GTP-Binding Protein / Q000096:biosynthesis* / Q000378:metabolism*
chemical_list: C545567:MIRN137 microRNA, human; D035683:MicroRNAs; D020764:cdc42 GTP-Binding Protein