title: MicroRNA-34a is a tumor suppressor in choriocarcinoma via regulation of Delta-like1.
abstract: BACKGROUND
  Choriocarcinoma is a gestational trophoblastic tumor which causes high mortality if left untreated. MicroRNAs (miRNAs) are small non protein-coding RNAs which inhibit target gene expression. The role of miRNAs in choriocarcinoma, however, is not well understood. In this study, we examined the effect of miR-34a in choriocarcinoma.
  
  
  METHODS
  MiR-34a was either inhibited or ectopically expressed transiently in two choriocarcinoma cell lines (BeWo and JEG-3) respectively. Its actions on cell invasion, proliferation and colony formation at low cell density were examined. The miR-34a putative target Notch ligand Delta-like 1 (DLL1) was identified by adoption of different approaches including: in-silico analysis, functional luciferase assay and western blotting. Real-time quantitative polymerase chain reaction was used to quantify changes in the expression of matrix proteinase in the treated cells. To nullify the effect of miR-34a ectopic expression, we activated Notch signaling through force-expression of the Notch intracellular domain in the miR-34a force-expressed cells. In addition, we studied the importance of DLL1 in BeWo cell invasion through ligand stimulation and antibody inhibition. Furthermore, the induction in tumor formation of miR-34a-inhibited BeWo cells in SCID mice was investigated.
  
  
  RESULTS
  Transient miR-34a force-expression significantly suppressed cell proliferation and invasion in BeWo and JEG-3 cells. In silicon miRNA target prediction, luciferase functional assays and Western blotting analysis demonstrated that miR-34a regulated DLL1 expression in both cell lines. Although force-expression of miR-34a suppressed the expression of DLL1 and NOTCH1, the extent of suppression was higher in DLL1 than NOTCH1 in both cell lines. MiR-34a-mediated DLL1 suppression led to reduced matrix metallopeptidase 9 and urokinase-type plasminogen activator expression. The effect of miR-34a on cell invasion was partially nullified by Notch signaling activation. DLL1 ligand stimulated while anti-DLL1 antibody treatment suppressed cell invasion. Mice inoculated with BeWo cells transfected with miR-34a inhibitor had significantly larger xenografts and stronger DLL1 expression than those with cells transfected with the control inhibitor.
  
  
  CONCLUSIONS
  MiR-34a reduced cell proliferation and invasiveness, at least, partially through its inhibitory effect on DLL1.
authors: Department of Obstetrics and Gynaecology, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors: Ronald Tk
authors: RT
authors: Pang
authors: Carmen On
authors: CO
authors: Leung
authors: Cheuk-Lun
authors: CL
authors: Lee
authors: Kevin Kw
authors: KK
authors: Lam
authors: Tian-Min
authors: TM
authors: Ye
authors: Philip Cn
authors: PC
authors: Chiu
authors: William Sb
authors: WS
authors: Yeung
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002135:Calcium-Binding Proteins; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D002822:Choriocarcinoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D003198:Computer Simulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D016147:Genes, Tumor Suppressor; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D016513:Mice, SCID; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009361:Neoplasm Invasiveness; D011247:Pregnancy; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D047368:Tumor Burden; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism; D014594:Uterine Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology
chemical_list: D002135:Calcium-Binding Proteins; C512941:DLK1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; C522425:MIRN34 microRNA, human; D008565:Membrane Proteins; D035683:MicroRNAs; D014568:Urokinase-Type Plasminogen Activator; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9