title: Effects of retinoic acid on proliferation and gene expression of cleft and non-cleft palatal keratinocytes.
abstract: BACKGROUND
  Retinoic acid (RA) is a key regulator of embryonic development and linked to several birth defects including cleft lip and palate (CLP). The aim was to investigate the effects of RA on proliferation and gene expression of human palatal keratinocytes (KCs) in vitro.
  
  
  METHODS
  KCs from children with and without CLP were cultured with 2 and 5 μM RA. Proliferation was measured by quantification of DNA after 2, 4, 6, and 8 days. In addition, we analysed the effects of RA on messenger RNA expression of genes for proliferation, differentiation, apoptosis, and RA receptors.
  
  
  RESULTS
  RA similarly inhibited proliferation of palatal KC from cleft and non-cleft subjects. The proliferation of KCs from cleft subjects was reduced to 59.8±13.4% (2 μM) and 41.5±14.0% (5 μM, Day 6), while that of cells from age-matched non-cleft subjects was reduced to 66.9±12.1% (2 μM) and 33.9±10.1% (5 μM). RA treatment reduced the expression of several of the investigated genes; the proliferating cell nuclear antigen (PCNA) was reduced in CLP KCs only. Keratins 10 and 16 were downregulated in keratinocytes from both cleft and non-cleft subjects. P63, a master regulator for epithelial differentiation, was only downregulated in KCs from cleft subjects, as was the RXRa receptor. Two P63 target genes (GJB6 and DLX5) were strongly downregulated by RA in all cell lines. None of the apoptosis genes was affected.
  
  
  CONCLUSIONS
  Overall, RA similarly inhibits proliferation of palatal KCs from cleft and non-cleft subjects and reduces the expression of specific genes.
authors: *Department of Orthodontics and Craniofacial Biology, Radboud University Nijmegen Medical Centre, Nijmegen.
authors: Aysel
authors: A
authors: Mammadova
authors: *Department of Orthodontics and Craniofacial Biology, Radboud University Nijmegen Medical Centre, Nijmegen.
authors: Mignon Mg
authors: MM
authors: Ackermans
authors: *Department of Orthodontics and Craniofacial Biology, Radboud University Nijmegen Medical Centre, Nijmegen.
authors: Marjon
authors: M
authors: Bloemen
authors: **Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, and.
authors: Corien
authors: C
authors: Oostendorp
authors: ***Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors: Huiqing
authors: H
authors: Zhou
authors: *Department of Orthodontics and Craniofacial Biology, Radboud University Nijmegen Medical Centre, Nijmegen.
authors: Carine El
authors: CE
authors: Carels
authors: *Department of Orthodontics and Craniofacial Biology, Radboud University Nijmegen Medical Centre, Nijmegen, h.vondenhoff@dent.umcn.nl.
authors: Johannes W
authors: JW
authors: Von den Hoff
mesh_terms: D016022:Case-Control Studies; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002675:Child, Preschool; D002972:Cleft Palate / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D015536:Down-Regulation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007223:Infant; D015603:Keratinocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D012333:RNA, Messenger; D014212:Tretinoin