title: microRNA-34a inhibits epithelial mesenchymal transition in human cholangiocarcinoma by targeting Smad4 through transforming growth factor-beta/Smad pathway.
abstract: BACKGROUND
  Extrahepatic Cholangiocarcinoma (EHCC) is one of the uncommon malignancies in the digestive system which is characterized by a poor prognosis. Aberrations of miRNAs have been shown involved in the progression of this disease. In this study, we evaluated the expression and effects of miR-34a on EHCC.
  
  
  METHODS
  miR-34a expression levels were detected in EHCC tissues, adjacent non-tumor tissues, normal bile duct (NBD) specimens of patients and cholangiocarcinoma (CC) cell lines by quantitative real-time polymerase chain reaction (qRT-PCR). Relationships between miR-34a with clinical characteristics of EHCC patients were further analyzed. Computational search, functional luciferase assay and western blot were further used to demonstrate the downstream target of miR-34a in CC cells. Immunohistochemistry was carried on to identify the downstream target gene of miR-34a in EHCC patients. Cell morphology, invasion and migration assays were further applied to confirm the anti-carcinogenic effects of miR-34a through the downstream target.
  
  
  RESULTS
  miR-34a expression was significantly decreased in human EHCC tissues and CC cell lines when compared with the adjacent non-tumor tissues and normal bile duct tissues. miR-34a was found correlated with the migration and invasion in EHCC patients. Smad4 was over-expressed in most of the EHCC patients and was further demonstrated as one of the downstream targets of miR-34a, which was involved in the progression of EHCC. Moreover, activation of miR-34a suppressed invasion and migration through TGF-beta/Smad4 signaling pathway by epithelial-mesenchymal transition (EMT) in vitro.
  
  
  CONCLUSIONS
  Taken together, our results suggest that miR-34a inhibits invasion and migration by targeting Smad4 to suppress EMT through TGF- beta/Smad signaling pathway in human EHCC.
authors.affiliation: Department of General Surgery, the Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, Peoples Republic of China. lunwenqpf@126.com.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Qiao
authors.affiliation: Department of General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, 150001, Peoples Republic of China. liguodong@ems.hrbmu.edu.cn.|Bio-Bank of Department of General Surgery, the Fourth Affiliated Hospital of Harbin Medical University, Harbin, 150001, Peoples Republic of China. liguodong@ems.hrbmu.edu.cn.
authors.forename: Guodong
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of General Surgery, the Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, Peoples Republic of China. byg98@sina.com.
authors.forename: Wen
authors.initials: W
authors.lastname: Bi
authors.affiliation: Department of General Surgery, the Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, Peoples Republic of China. moonlight230@163.com.
authors.forename: Lianmeng
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of General Surgery, the Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, Peoples Republic of China. yaoleihum@163.com.
authors.forename: Lei
authors.initials: L
authors.lastname: Yao
authors.affiliation: Department of General Surgery, the Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, Peoples Republic of China. wudequanhmu@163.com.
authors.forename: Dequan
authors.initials: D
authors.lastname: Wu
mesh_terms: D001650:Bile Duct Neoplasms / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma / Q000235:genetics / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D015398:Signal Transduction; D051901:Smad4 Protein / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: C522425:MIRN34 microRNA, human; D035683:MicroRNAs; C497796:SMAD4 protein, human; D051901:Smad4 Protein; D016212:Transforming Growth Factor beta