title: Uveal and cutaneous melanoma: shared expression characteristics of melanoma-associated antigens.
abstract: OBJECTIVE
  Downregulation of melanoma-associated antigens (MAAs), against which natural cytolytic T lymphocytes (CTLs) exist in humans, is one of the mechanisms that aids in evasion of immune surveillance. In view of putative re-expression strategies for MAAs during immunotherapy, this study was conducted to investigate MAA silencing in malignant melanoma.
  
  
  METHODS
  The expression of the MAA Melan-A/MART-1 was analyzed in 10 uveal and 10 cutaneous patient-derived melanoma cell lines by Western blot analysis and RT-PCR. Expression characteristics of four other MAAs-Tyr, Tyrp1, Dct, and gp100/Pmel17-were analyzed by RT-PCR. DNA methylation patterns at the Melan-A/MART-1 promoter region were investigated by methylation-sensitive restriction enzyme digestion and subsequent Southern blot analysis. Exogenous promoter activity was assessed in all 20 melanoma cell lines to correlate the DNA methylation patterns with Melan-A/MART-1 expression.
  
  
  RESULTS
  MAA expression was observed in 15 of the 20 melanoma cell lines. Furthermore, there is a direct correlation between DNA methylation patterns at the Melan-A/MART-1 promoter region, exogenous Melan-A/MART-1 promoter activity, and Melan-A/MART-1 protein expression. These data reveal the division of patient-derived melanoma cell lines into two distinct subsets, which are identical for both uveal and cutaneous tumor types.
  
  
  CONCLUSIONS
  The authors propose a categorization of melanoma cell lines into two different panels based on shared MAA-expression characteristics: panel I, MAA-expressing cell lines, and panel II, MAA-deficient cell lines. This categorization can be used to obtain knowledge about the regulation of MAA-expression and for further research concerning MAA-based immunotherapy.
authors.affiliation: Department of Immunohematology and Blood Transfusion, Division of Molecular Biology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Leonie C
authors.initials: LC
authors.lastname: van Dinten
authors.forename: Nicolien
authors.initials: N
authors.lastname: Pul
authors.forename: A Frans
authors.initials: AF
authors.lastname: van Nieuwpoort
authors.forename: Coby J
authors.initials: CJ
authors.lastname: Out
authors.forename: Martine J
authors.initials: MJ
authors.lastname: Jager
authors.forename: Peter J
authors.initials: PJ
authors.lastname: van den Elsen
mesh_terms: D000951:Antigens, Neoplasm / Q000235:genetics* / Q000378:metabolism; D015139:Blotting, Southern; D015153:Blotting, Western; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000378:metabolism; D015870:Gene Expression; D017930:Genes, Reporter; D006801:Humans; D058965:MART-1 Antigen; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012878:Skin Neoplasms / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014604:Uveal Neoplasms / Q000235:genetics* / Q000378:metabolism
chemical_list: D000951:Antigens, Neoplasm; D004273:DNA, Neoplasm; D058965:MART-1 Antigen; C548667:MLANA protein, human; D009363:Neoplasm Proteins; D012333:RNA, Messenger