title: Elevated expression of the tyrosine phosphatase SHP-1 defines a subset of high-grade breast tumors.
abstract: OBJECTIVE
  Protein tyrosine phosphatases are key regulators of intracellular signaling that contribute to determining cancer cell growth, which thus makes them attractive targets for therapeutic and diagnostic agents. SHP-1 phosphotyrosine phosphatase is rarely expressed in epithelial tumor cells, but expression has been found in several breast cancer cell lines and tumors. To determine the potential significance of SHP-1 as a prognostic marker in the clinical setting, we examined SHP-1 protein expression in breast tumors.
  
  
  METHODS
  We analyzed SHP-1 expression by immunohistochemistry in a breast tissue microarray composed of 2,081 cores, either alone or in combination with known prognostic markers.
  
  
  RESULTS
  Our data showed that SHP-1 expression was confined to a well-defined subset of high-grade tumors characterized by unique biological parameters. SHP-1 expression correlated directly with expression of the tyrosine kinase receptor HER-2 and inversely with expression of the estrogen receptor, while it was weakly associated with Bcl-2 expression.
  
  
  CONCLUSIONS
  Levels of SHP-1 were correlated with conventional pathologic parameters of tumor aggressiveness and were associated with reduced patient survival, suggesting that elevated expression of SHP-1 is a common molecular abnormality in a defined subset of breast tumors and might be used in routine diagnosis to identify patients with high-risk tumors.
authors.affiliation: Biomorphological and Functional Science, Anatomic Pathology Section, Faculty of Medicine, Università degli Studi di Napoli Federico II, Napoli, Italia.
authors.forename: Luigi
authors.initials: L
authors.lastname: Insabato
authors.forename: Ivano
authors.initials: I
authors.lastname: Amelio
authors.forename: Maria
authors.initials: M
authors.lastname: Quarto
authors.forename: Antonella
authors.initials: A
authors.lastname: Zannetti
authors.forename: Fabio
authors.initials: F
authors.lastname: Tolino
authors.forename: Gaia
authors.initials: G
authors.lastname: de Mauro
authors.forename: Laura
authors.initials: L
authors.lastname: Cerchia
authors.forename: Patrizia
authors.initials: P
authors.lastname: Riccio
authors.forename: Daniel
authors.initials: D
authors.lastname: Baumhoer
authors.forename: Gerolama
authors.initials: G
authors.lastname: Condorelli
authors.forename: Luigi
authors.initials: L
authors.lastname: Terracciano
authors.forename: Vittorio
authors.initials: V
authors.lastname: de Franciscis
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology* / Q000401:mortality / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000032:analysis; D005260:Female; D019254:Genes, bcl-2; D006801:Humans; D007150:Immunohistochemistry; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6 / Q000032:analysis*
chemical_list: D019941:Cyclin-Dependent Kinase Inhibitor p16; C509249:PTPN6 protein, human; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6