title: Inverse correlation of miRNA and cell cycle-associated genes suggests influence of miRNA on benign thyroid nodule tumorigenesis.
abstract: BACKGROUND
  The molecular etiology of cold and benign thyroid nodules (CBTNs) is largely unknown. Increased thyroid epithelial cell proliferation is a hallmark of CBTNs. MicroRNAs (miRNAs) are prominent regulators of cell proliferation.
  
  
  OBJECTIVE
  Our objective was to assess the influence of miRNAs on the increased proliferation and thus the molecular etiology of CBTNs.
  
  
  METHODS
  By using microarrays, we defined the molecular pattern of increased proliferation of CBTNs as a differential expression of cell-cycle-associated genes and miRNAs. In silico integration of differentially expressed miRNAs and mRNAs showed an inverse correlation between the expression of 59 miRNAs and 133 mRNAs. Inverse correlations between cell-cycle-associated genes such as CDKN1C and miR-221, CCND1 and miR-31, GADD45A and miR-130b, or CDKN1A and let-7f suggest a modulation of proliferation in CBTNs by miRNAs. Their expression was validated using quantitative RT-PCR and functionally characterized in cell line models.
  
  
  RESULTS
  Comparative quantitative RT-PCR of 20 samples of CBTNs and their surrounding tissue revealed an 11-fold down-regulation of miR-31 with a 2.6-fold up-regulation of CCND1, and a 2.6-fold up-regulation of miR-130b with a 2.3-fold down-regulation of its target GADD45A. Using HTori and FTC-133 cell lines, we analyzed proliferation, cell cycle, and apoptosis after transfection of miRNA-31 and miRNA-130b mimic and inhibitors. Overexpression of miR-31 and the resultant down-regulation of CCND1 led to an arrest in the cell cycle phase G1. Overexpression of miR-130b led to an increase of apoptosis and necrosis within 72 h.
  
  
  CONCLUSIONS
  miR-31 and miR-130b may have an effect on tumorigenesis of CBTNs by regulating proliferation and apoptosis and the cell cycle through cyclin D1.
authors.affiliation: Department for Endocrinology and Nephrology, University of Leipzig, Liebigstrasse. 20, D-04103 Leipzig, Germany.
authors.forename: Carolina
authors.initials: C
authors.lastname: Ferraz
authors.forename: Stephan
authors.initials: S
authors.lastname: Lorenz
authors.forename: Bartosz
authors.initials: B
authors.lastname: Wojtas
authors.forename: Stefan R
authors.initials: SR
authors.lastname: Bornstein
authors.forename: Ralf
authors.initials: R
authors.lastname: Paschke
authors.forename: Markus
authors.initials: M
authors.lastname: Eszlinger
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D004843:Epistasis, Genetic; D015972:Gene Expression Regulation, Neoplastic; D019940:Genes, bcl-1 / Q000502:physiology; D018816:Genes, cdc / Q000235:genetics / Q000502:physiology; D006801:Humans; D035683:MicroRNAs / Q000235:genetics* / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D013964:Thyroid Neoplasms / Q000235:genetics / Q000473:pathology; D016606:Thyroid Nodule / Q000235:genetics* / Q000473:pathology*; D059467:Transcriptome; D054928:Validation Studies as Topic
chemical_list: C554019:MIRN130 microRNA, human; C534612:MIRN31 microRNA, human; D035683:MicroRNAs; D012333:RNA, Messenger