title: MicroRNA-30b/c inhibits non-small cell lung cancer cell proliferation by targeting Rab18.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are small noncoding RNAs that post-transcriptional regulate gene expression in a variety of cancers. Increasing evidences indicate that miR-30 expression is down-regulated in numerous human cancers including non-small cell lung cancer (NSCLC) which hypothesizes that miR-30 may play an important role in tumorigenesis. The aim of this study was to investigate the target gene of miR-30 and its roles in tumor growth of NSCLC.
  
  
  METHODS
  Luciferase reporter assays were employed to validate regulation of a putative target of miR-30. The effect of miR-30 on endogenous levels of this target were subsequently confirmed via Western blot (WB). Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to determine the expression level of miR-30 in NSCLC specimens and adjacent non-tumor tissues. MTT assays were conducted to explore the impact of miR-30 overexpression on the proliferation of human NSCLC cells.
  
  
  RESULTS
  Both miR-30b and miR-30c (miR-30b/c) were found having target site in same region of Rab18 mRNA. Luciferase assays using a reporter carrying a putative miR-30b/c target site in the coding DNA sequence (CDS) region of Rab18 revealed that miR-30b/c directly targeted Rab18. Overexpression of miR-30b/c led to down-regulation of Rab18 in A549 and H23 cells at protein levels but not mRNA levels. Down-regulation of miR-30b/c and up-regulation of Rab18 protein levels were detected in NSCLC specimens compared with adjacent non-tumor tissues. Overexpression of miR-30b/c suppressed NSCLC cells growth. Knockdown of Rab18 by siRNA significantly inhibited the proliferation of NSCLC cells.
  
  
  CONCLUSIONS
  We demonstrated that miR-30b/c was down-regulated in NSCLC specimens compared with adjacent non-tumor tissues. miR-30b/c directly targeted and down-regulated Rab18 expression and inhibited NSCLC cells proliferation. These data indicated that miR-30b/c could serve as a tumor suppressor gene involved in NSCLC pathogenesis.
authors.forename: Keng
authors.initials: K
authors.lastname: Zhong
authors.forename: Kun
authors.initials: K
authors.lastname: Chen
authors.affiliation: Department of Cardiothoracic Surgery, Changhai Hospital affiliated to Second Military Medical University, Shanghai 200433, China. sh_hanlin@163.com.
authors.forename: Lin
authors.initials: L
authors.lastname: Han
authors.forename: Bailing
authors.initials: B
authors.lastname: Li
mesh_terms: D001483:Base Sequence; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics* / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015870:Gene Expression; D017930:Genes, Reporter; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology*; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics*; D034622:RNA Interference; D020691:rab GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics*
chemical_list: C546086:MIRN30b microRNA, human; D035683:MicroRNAs; C484168:RAB18 protein, human; D020691:rab GTP-Binding Proteins