title: Epigenetic control of trefoil factor family (TFF) peptide expression in human retinoblastoma cell lines.
abstract: BACKGROUND
  Recent studies demonstrated that epigenetic mechanisms are involved in the regulation of trefoil factor family (TFF) peptide expression in cancer. In human tissues with endogenous TFF1, TFF2 or TFF3 gene expression, the corresponding promoter is unmethylated and in organs without TFF expression, the promoter of the three genes is highly methylated.
  
  
  METHODS
  Retinoblastoma (Rb) cell lines were treated with the DNA methyltransferase inhibitor 5-Aza-2`deoxycytidine (5-Aza-dC), the histone deacetylase inhibitor 4-Phenylbutyric acid (PBA) or both and analyzed for changes (i) in TFF mRNA expression by Real-time PCR and (ii) in the methylation status of the TFF promoters by genomic bisulfite sequencing.
  
  
  RESULTS
  The degree of promoter methylation correlates with endogenous TFF expression in the retinoblastoma cell lines analyzed. Nearly all Rb cell lines exhibiting high endogenous TFF1 expression displayed low methylation of the CpGs in the corresponding promoter region. Low expression of TFF3 in Rb cell lines is linked with high density methylation of the TFF3 promoter. 5-Aza-dC treatment induced TFF1 and TFF3 expression in nearly all cell lines investigated and combined treatment with PBA further increased this effect. The number of methylated CpG dinucleotides of the TFF promoter is clearly reduced upon treatment with 5-Aza-dC and combined treatment with PBA further extended the degree of demethylation.
  
  
  CONCLUSIONS
  Our data clearly show that the expression of TFF3 in retinoblastoma cell lines is epigenetically regulated, whereas the level of TFF1 and TFF2 seems to be regulated by other or additional mechanisms.
authors.affiliation: University of Duisburg-Essen, Medical Faculty, Institute of Anatomy, Department of Neuroanatomy, Essen, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Philippeit
authors.forename: Maike
authors.initials: M
authors.lastname: Busch
authors.forename: Nicole
authors.initials: N
authors.lastname: Dünker
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001483:Base Sequence; D045744:Cell Line, Tumor; D019175:DNA Methylation; D017931:DNA Primers; D000077209:Decitabine; D044127:Epigenesis, Genetic; D005260:Female; D006801:Humans; D008297:Male; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010654:Phenylbutyrates / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012175:Retinoblastoma / Q000235:genetics / Q000378:metabolism*; D000071163:Trefoil Factor-1; D000071164:Trefoil Factor-2; D000071165:Trefoil Factor-3; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D010446:Peptide Fragments; D010455:Peptides; D010654:Phenylbutyrates; C051838:TFF1 protein, human; C000604007:TFF2 protein, human; C082495:TFF3 protein, human; D000071163:Trefoil Factor-1; D000071164:Trefoil Factor-2; D000071165:Trefoil Factor-3; D025521:Tumor Suppressor Proteins; D000077209:Decitabine; C075773:4-phenylbutyric acid; D001374:Azacitidine