title: Unlocking pathology archives for microRNA-profiling.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are approximately 22 nucleotide long, non-coding RNAs that regulate gene expression by binding to the 3'-untranslated region of target mRNAs and also a variety of cellular processes. It has recently been established that dysregulation of miRNA expression can be detected in the majority of human cancers. A variety of high-throughput screening methods has been developed to identify dysregulated miRNA species in tumours. For retrospective clinical studies formalin-fixed, paraffin-embedded (FFPE) tissue is the most widely used material.
  
  
  METHODS
  The miRNA expression profiles of freshly frozen (CRYO) and FFPE tissues of seven tonsil and four liver samples were compared, using a qPCR-based assay, profiling 157 miRNA species.
  
  
  RESULTS
  The significance of miRNA-profiles was barely influenced by FFPE treatment in both tissues and the variance induced by FFPE treatment was much smaller than the variance caused by biologically based differential expression.
  
  
  CONCLUSIONS
  FFPE material is well suited for miRNA profiling.
authors.affiliation: Institute for Pathology, UKSH Campus Luebeck, Luebeck, Germany.
authors.forename: Kai P
authors.initials: KP
authors.lastname: Hoefig
authors.forename: Christoph
authors.initials: C
authors.lastname: Thorns
authors.forename: Anja
authors.initials: A
authors.lastname: Roehle
authors.forename: Christian
authors.initials: C
authors.lastname: Kaehler
authors.forename: Kai O
authors.initials: KO
authors.lastname: Wesche
authors.forename: Dirk
authors.initials: D
authors.lastname: Repsilber
authors.forename: Biggi
authors.initials: B
authors.lastname: Branke
authors.forename: Marlen
authors.initials: M
authors.lastname: Thiere
authors.forename: Alfred C
authors.initials: AC
authors.lastname: Feller
authors.forename: Hartmut
authors.initials: H
authors.lastname: Merz
mesh_terms: D001483:Base Sequence; D005557:Formaldehyde; D005629:Frozen Sections; D020869:Gene Expression Profiling; D006801:Humans; D008113:Liver Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D035683:MicroRNAs / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012189:Retrospective Studies; D016707:Tissue Fixation; D014067:Tonsillar Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000473:pathology
chemical_list: D035683:MicroRNAs; D005557:Formaldehyde