title: Effect of retinoic acid on apoptosis and DNA repair in human keratinocytes after UVB irradiation.
abstract: BACKGROUND
  Skin cancer is extremely common. Epidemiological studies indicated that ultraviolet radiation (UV) is the primary cause for skin cancers, and that retinoic acid (RA) is able to inhibit this UV-induced skin carcinogenesis; however, the molecular mechanism of the anti-UV action of RA is unclear.
  
  
  OBJECTIVE
  The purpose of this study is to investigate if RA enhances the removal of UV-induced DNA damage.
  
  
  METHODS
  The effect of RA on UV-induced apoptosis and DNA repair was investigated by ELISA apoptosis assay and CAT assay.
  
  
  RESULTS
  Both all-trans-RA and 9-cis-RA did not promote UV-induced apoptosis nor the repair of UV-damaged DNA in human keratinocytes. Furthermore, RA did not induce the expression of p53.
  
  
  CONCLUSIONS
  The inhibition of RA on skin carcinogenesis is not due to enhanced removal of UV-damaged DNA. Therefore, RA does not inhibit skin cancer development at the initiation stage, but possibly at the promotion and progression stages.
authors.affiliation: Division of Dermatology, Department of Medicine, Vancouver Hospital and Health Science Centre, The University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Li
authors.forename: J A
authors.initials: JA
authors.lastname: Bush
authors.forename: V C
authors.initials: VC
authors.lastname: Ho
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D004260:DNA Repair / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D015603:Keratinocytes / Q000187:drug effects / Q000528:radiation effects*; D014212:Tretinoin / Q000494:pharmacology*; D014466:Ultraviolet Rays
chemical_list: D000970:Antineoplastic Agents; D014212:Tretinoin