title: Coordinated epigenetic repression of the miR-200 family and miR-205 in invasive bladder cancer.
abstract: MicroRNAs (miRNA) are small noncoding RNAs commonly deregulated in cancer. The miR-200 family (miR-200a, -200b, -200c, -141 and -429) and miR-205 are frequently silenced in advanced cancer and have been implicated in epithelial to mesenchymal transition (EMT) and tumor invasion by targeting the transcriptional repressors of E-cadherin, ZEB1 and ZEB2. ZEB1 is also known to repress miR-200c-141 transcription in a negative feedback loop, but otherwise little is known about the transcriptional regulation of the miR-200 family and miR-205. Recently, miR-200 silencing was also reported in cancer stem cells, implying that miR-200 deregulation is a key event in multiple levels of tumor biology. However, what prevents miR-200 expression remains largely unanswered. Here we report concerted transcriptional regulation of the miR-200 and miR-205 loci in bladder tumors and bladder cell lines. Using a combination of miRNA expression arrays, qPCR assays and mass spectrometry DNA methylation analyses, we show that the miR-200 and miR-205 loci are specifically silenced and gain promoter hypermethylation and repressive chromatin marks in muscle invasive bladder tumors and undifferentiated bladder cell lines. Moreover, we report that miR-200c expression is significantly correlated with early stage T1 bladder tumor progression, and propose miR-200 and miR-205 silencing and DNA hypermethylation as possible prognostic markers in bladder cancer. In addition, we observe that the mesoderm transcription factor TWIST1 and miR-200 expression are inversely correlated in bladder tumor samples and cell lines. TWIST1 associates directly with the miR-200 and miR-205 promoters, and may act as a repressor of miR-200 and miR-205 expression.
authors.affiliation: Department of Molecular Biology, Aarhus University, Aarhus C, Denmark.
authors.forename: Erik D
authors.initials: ED
authors.lastname: Wiklund
authors.forename: Jesper B
authors.initials: JB
authors.lastname: Bramsen
authors.forename: Toby
authors.initials: T
authors.lastname: Hulf
authors.forename: Lars
authors.initials: L
authors.lastname: Dyrskjøt
authors.forename: Ramshanker
authors.initials: R
authors.lastname: Ramanathan
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Hansen
authors.forename: Sune B
authors.initials: SB
authors.lastname: Villadsen
authors.forename: Shan
authors.initials: S
authors.lastname: Gao
authors.forename: Marie S
authors.initials: MS
authors.lastname: Ostenfeld
authors.forename: Michael
authors.initials: M
authors.lastname: Borre
authors.forename: Marcus E
authors.initials: ME
authors.lastname: Peter
authors.forename: Torben F
authors.initials: TF
authors.lastname: Ørntoft
authors.forename: Jørgen
authors.initials: J
authors.lastname: Kjems
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Clark
mesh_terms: D002478:Cells, Cultured; D019175:DNA Methylation; D057890:Epigenomics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D009361:Neoplasm Invasiveness; D016133:Polymerase Chain Reaction; D001743:Urinary Bladder / Q000378:metabolism / Q000473:pathology; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000473:pathology
chemical_list: D035683:MicroRNAs; C533896:MIRN200 microRNA, human; C534425:MIR205, human