title: Retinoic acid-induced CHD5 upregulation and neuronal differentiation of neuroblastoma.
abstract: BACKGROUND
  Chromodomain-helicase DNA binding protein 5 (CHD5) is an important tumor suppressor gene deleted from 1p36.31 in neuroblastomas (NBs). High CHD5 expression is associated with a favorable prognosis, but deletion or low expression is frequent in high-risk tumors. We explored the role of CHD5 expression in the neuronal differentiation of NB cell lines.
  
  
  METHODS
  NB cell lines SH-SY5Y (SY5Y), NGP, SK-N-DZ, IMR5, LAN5, SK-N-FI, NB69 and SH-EP were treated with 1-10 μM 13-cis-retinoic acid (13cRA) for 3-12 days. qRT-PCR and Western blot analyses were performed to measure mRNA and protein expression levels, respectively. Morphological differences were examined by both phase contrast and immunofluorescence studies.
  
  
  RESULTS
  Treatment of SY5Y cells with 13cRA caused upregulation of CHD5 expression in a time- and dose-dependent manner (1, 5, or 10 μM for 7 or 12 days) and also induced neuronal differentiation. Furthermore, both NGP and SK-N-DZ cells showed CHD5 upregulation and neuronal differentiation after 13cRA treatment. In contrast, 13cRA treatment of IMR5, LAN5, or SK-N-FI induced neither CHD5 expression nor neuronal differentiation. NB69 cells showed two different morphologies (neuronal and substrate adherent) after 12 days treatment with 10 μM of 13cRA. CHD5 expression was high in the neuronal cells, but low/absent in the flat, substrate adherent cells. Finally, NGF treatment caused upregulation of CHD5 expression and neuronal differentiation in SY5Y cells transfected to express TrkA (SY5Y-TrkA) but not in TrkA-null parental SY5Y cells, and both changes were blocked by a pan-TRK inhibitor.
  
  
  CONCLUSIONS
  Treatment with 13cRA induces neuronal differentiation only in NB cells that upregulate CHD5. In addition, NGF induced CHD5 upregulation and neuronal differentiation only in TrkA expressing cells. Together, these results suggest that CHD5 is downstream of TrkA, and CHD5 expression may be crucial for neuronal differentiation induced by either 13cRA or TrkA/NGF signaling.
authors.affiliation: Division of Oncology, Children's Hospital of Philadelphia, and the Department of Pediatrics, University of Pennsylvania School of Medicine, CTRB Rm. 3018, 3501 Civic Center Blvd, Philadelphia, PA, 19104 - 4302, USA. Mayhigashi@gmail.com.|Department of Pediatric Surgery, Kyoto Prefectural University of Medicine, Kyoto, 602 - 8566, Japan. Mayhigashi@gmail.com.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Higashi
authors.affiliation: Division of Oncology, Children's Hospital of Philadelphia, and the Department of Pediatrics, University of Pennsylvania School of Medicine, CTRB Rm. 3018, 3501 Civic Center Blvd, Philadelphia, PA, 19104 - 4302, USA. Kolla@email.chop.edu.
authors.forename: Venkatadri
authors.initials: V
authors.lastname: Kolla
authors.affiliation: Division of Oncology, Children's Hospital of Philadelphia, and the Department of Pediatrics, University of Pennsylvania School of Medicine, CTRB Rm. 3018, 3501 Civic Center Blvd, Philadelphia, PA, 19104 - 4302, USA. Iyerr@email.chop.edu.
authors.forename: Radhika
authors.initials: R
authors.lastname: Iyer
authors.affiliation: Division of Oncology, Children's Hospital of Philadelphia, and the Department of Pediatrics, University of Pennsylvania School of Medicine, CTRB Rm. 3018, 3501 Civic Center Blvd, Philadelphia, PA, 19104 - 4302, USA. Naraparajuk@email.chop.edu.
authors.forename: Koumudi
authors.initials: K
authors.lastname: Naraparaju
authors.affiliation: Division of Oncology, Children's Hospital of Philadelphia, and the Department of Pediatrics, University of Pennsylvania School of Medicine, CTRB Rm. 3018, 3501 Civic Center Blvd, Philadelphia, PA, 19104 - 4302, USA. tiangang08@hotmail.com.
authors.forename: Tiangang
authors.initials: T
authors.lastname: Zhuang
authors.affiliation: Division of Oncology, Children's Hospital of Philadelphia, and the Department of Pediatrics, University of Pennsylvania School of Medicine, CTRB Rm. 3018, 3501 Civic Center Blvd, Philadelphia, PA, 19104 - 4302, USA. Kollas@email.chop.edu.
authors.forename: Sriharsha
authors.initials: S
authors.lastname: Kolla
authors.affiliation: Division of Oncology, Children's Hospital of Philadelphia, and the Department of Pediatrics, University of Pennsylvania School of Medicine, CTRB Rm. 3018, 3501 Civic Center Blvd, Philadelphia, PA, 19104 - 4302, USA. Brodeur@email.chop.edu.
authors.forename: Garrett M
authors.initials: GM
authors.lastname: Brodeur
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D020932:Nerve Growth Factor / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009447:Neuroblastoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D020917:Receptor, trkA / Q000235:genetics / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D009419:Nerve Tissue Proteins; D014212:Tretinoin; D020932:Nerve Growth Factor; D020917:Receptor, trkA; D004265:DNA Helicases; C471926:CHD5 protein, human