title: Microarray analysis of phosphatase gene expression in human melanoma.
abstract: BACKGROUND
  Tyrosine phosphate is abnormally elevated in malignant melanoma, and this has been interpreted to reflect the activity of oncogenic protein tyrosine kinases. However, elevation may also arise due to decreased protein tyrosine phosphatase (PTP) expression.
  
  
  OBJECTIVE
  To survey phosphatase gene expression in melanoma cell lines, a benign naevus and normal melanocytes: we searched for downregulation of phosphatase gene expression in malignant cells that may indicate a role as melanoma suppressor genes.
  
  
  METHODS
  Microarray analysis was used to compare gene expression for 133 phosphatase genes, comprising 39 PTPs, 16 dual-specificity phosphatases (DSPs), 47 serine/threonine phosphatases and 31 acid/alkaline and lipid-based phosphatases. Northern blotting analysis was used to study gene expression in human melanoma biopsies.
  
  
  RESULTS
  There was decreased expression of four DSP genes (including PTEN); eight receptor PTP genes were downregulated in melanoma, among which were PTP-KAPPA and PTP-PI (consistent with our previous data). In addition, PTP-RF/LAR was downregulated in 13 of 22 metastatic melanomas.
  
  
  CONCLUSIONS
  The expression of multiple PTP receptors is decreased in melanoma; this may be a mechanism which stimulates autonomous growth in advanced melanoma.
authors.affiliation: The Wistar Institute, 3601 Spruce Street, Philadelphia, PA 19104, USA.
authors.forename: L
authors.initials: L
authors.lastname: McArdle
authors.forename: M M
authors.initials: MM
authors.lastname: Rafferty
authors.forename: K
authors.initials: K
authors.lastname: Satyamoorthy
authors.forename: G M
authors.initials: GM
authors.lastname: Maelandsmo
authors.forename: P A
authors.initials: PA
authors.lastname: Dervan
authors.forename: M
authors.initials: M
authors.lastname: Herlyn
authors.forename: D J
authors.initials: DJ
authors.lastname: Easty
mesh_terms: D015152:Blotting, Northern; D018076:DNA, Complementary / Q000235:genetics; D004273:DNA, Neoplasm / Q000235:genetics; D015536:Down-Regulation; D006801:Humans; D008544:Melanocytes / Q000201:enzymology; D008545:Melanoma / Q000201:enzymology / Q000235:genetics* / Q000556:secondary; D046228:Microarray Analysis / Q000379:methods; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis / Q000235:genetics*; D012878:Skin Neoplasms / Q000201:enzymology / Q000235:genetics*; D014407:Tumor Cells, Cultured
chemical_list: D018076:DNA, Complementary; D004273:DNA, Neoplasm; D017027:Protein Tyrosine Phosphatases