title: Altered expression of mir-222 and mir-25 influences diverse gene expression changes in transformed normal and anaplastic thyroid cells, and impacts on MEK and TRAIL protein expression.
abstract: Thyroid cancer is the most common endocrine malignancy and accounts for the majority of endocrine cancer-related deaths each year. Our group and others have previously demonstrated dysfunctional microRNA (miRNA or miR) expression in the context of thyroid cancer. The objective of the present study was to investigate the impact of synthetic manipulation of expression of miR-25 and miR-222 in benign and malignant thyroid cells. miR-25 and miR-222 expression was upregulated in 8505C (an anaplastic thyroid cell line) and Nthy-ori (a SV40-immortalised thyroid cell line) cells, respectively. A transcriptomics-based approach was utilised to identify targets of the two miRNAs and real-time PCR and western blotting were used to validate a subset of the targets. Almost 100 mRNAs of diverse functions were found to be either directly or indirectly targeted by both miR-222 and miR-25 [fold change ≥2, false discovery rate (FDR) ≤0.05]. Gene ontology analysis showed the miR-25 gene target list to be significantly enriched for genes involved in cell adhesion. Fluidigm real-time PCR technologies were used to validate the downregulation of 23 and 22 genes in response to miR-25 and miR-222 overexpression, respectively. The reduction of the expression of two miR-25 protein targets, TNF-related apoptosis‑inducing ligand (TRAIL) and mitogen-activated protein kinase kinase 4 (MEK4), was also validated. Manipulating the expression of both miR-222 and miR-25 influenced diverse gene expression changes in thyroid cells. Increased expression of miR-25 reduced MEK4 and TRAIL protein expression, and cell adhesion and apoptosis are important aspects of miR-25 functioning in thyroid cells.
authors.affiliation: National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin 9, Republic of Ireland.
authors.forename: Sinéad T
authors.initials: ST
authors.lastname: Aherne
authors.affiliation: Department of Histopathology, Trinity College Dublin, Dublin 8, Republic of Ireland.
authors.forename: Paul
authors.initials: P
authors.lastname: Smyth
authors.affiliation: Department of Clinical Medicine and Trinity Translational Medicine Institute, Trinity College Dublin, Dublin 8, Republic of Ireland.
authors.forename: Michael
authors.initials: M
authors.lastname: Freeley
authors.affiliation: Fluidigm Corporation, Suite 100, South San Francisco, CA 94080, USA.
authors.forename: Leila
authors.initials: L
authors.lastname: Smith
authors.affiliation: Department of Histopathology, Trinity College Dublin, Dublin 8, Republic of Ireland.
authors.forename: Cathy
authors.initials: C
authors.lastname: Spillane
authors.affiliation: Department of Histopathology, Trinity College Dublin, Dublin 8, Republic of Ireland.
authors.forename: John
authors.initials: J
authors.lastname: O'Leary
authors.affiliation: Department of Histopathology, Trinity College Dublin, Dublin 8, Republic of Ireland.
authors.forename: Orla
authors.initials: O
authors.lastname: Sheils
mesh_terms: D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000473:pathology; D015536:Down-Regulation / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000235:genetics / Q000378:metabolism*; D065646:Thyroid Carcinoma, Anaplastic / Q000235:genetics* / Q000473:pathology; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000473:pathology
chemical_list: D048670:MAP Kinase Kinase 4; D035683:MicroRNAs; D053221:TNF-Related Apoptosis-Inducing Ligand; C525710:MIR222, human; C543351:MIRN25 microRNA, human; C482559:MAP2K4 protein, human