title: MicroRNA-126 suppresses proliferation of undifferentiated (BRAF(V600E) and BRAF(WT)) thyroid carcinoma through targeting PIK3R2 gene and repressing PI3K-AKT proliferation-survival signalling pathway.
abstract: BACKGROUND
  The objectives of this study are to investigate the expression of miR-126 and evaluate its effect on proliferation in undifferentiated thyroid carcinoma.
  
  
  METHODS
  miR-126 expression of undifferentiated thyroid carcinoma cell lines 8505C (BRAF(V600E/V600E)), BHT-101 (BRAF(V600E/WT)) and MB-1 (BRAF(WT/WT)) were quantified with q-PCR. These cell lines were transiently transfected with exogenous miR-126 (mimic). Following transfection, proliferation effects were observed through MTS proliferation assay and colony formation abilities. Immunofluorescence imaging and Western blot assay were also done to check target proteins expression.
  
  
  RESULTS
  Under-expression (p<0.05) of miR-126 was noted in BRAF(V600E) mutated undifferentiated thyroid carcinoma cells (8505C and BHT-101), but no change in expression was noted in non BRAF(V600E) mutated undifferentiated thyroid carcinoma cells (MB-1). In addition, a 30-50% drop in proliferation ability and a 35-45% reduction in colony formation capability were noticed in miR-126 mimic transfected group when compared to control group. Furthermore, immunofluorescence images showed reduced expression of p85β and p-AKT protein in miR-126 mimic transfected cells when compared to un-transfected cells. Also, Western blot analysis revealed a 34-40% suppression of p85β protein and a 21-53% drop in active AKT kinase (p-AKT) protein in miR-126 mimic transfected group when compared to control group.
  
  
  CONCLUSIONS
  Expression of miR-126 was down-regulated in BRAF(V600E) mutated undifferentiated thyroid carcinoma. In addition, miR-126 was found to act as proliferation suppressor targeting PIK3R2 gene and reducing p85β (a regulatory subunit of PI3K kinase) protein translation and lower AKT kinase activity. Therefore, miR-126 could be a potential therapeutic tool in the treatment of undifferentiated thyroid carcinoma.
authors.affiliation: Cancer Molecular Pathology, School of Medicine, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: Md Atiqur
authors.initials: MA
authors.lastname: Rahman
authors.affiliation: Cancer Molecular Pathology, School of Medicine, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia.
authors.forename: Ali
authors.initials: A
authors.lastname: Salajegheh
authors.affiliation: Cancer Molecular Pathology, School of Medicine, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia; Genomics Research Centre, Institute of Health and Biomedical Innovation, Faculty of Health, Queensland University of Technology, Brisbane, Queensland, Australia.
authors.forename: Robert Anthony
authors.initials: RA
authors.lastname: Smith
authors.affiliation: Cancer Molecular Pathology, School of Medicine, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia; Pathology Queensland and Gold Coast University Hospital, Gold Coast, Queensland, Australia. Electronic address: a.lam@griffith.edu.au.
authors.forename: Alfred King-yin
authors.initials: AK
authors.lastname: Lam
mesh_terms: D049109:Cell Proliferation / Q000235:genetics; D002470:Cell Survival / Q000235:genetics; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics*; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D014407:Tumor Cells, Cultured
chemical_list: C527111:MIRN126 microRNA, human; D035683:MicroRNAs; D019869:Phosphatidylinositol 3-Kinases; C560566:phosphoinositol-3 kinase regulatory subunit 2, human; D051057:Proto-Oncogene Proteins c-akt
keywords: BRAF; PIK3R2; Undifferentiated thyroid carcinoma; miR-126