Insabato, Luigi and Quarto, Maria and Riccio, Patrizia and Condorelli, Gerolama (2009) Elevated expression of the tyrosine phosphatase SHP-1 defines a subset of high-grade breast tumors. [Rivista]

Abstract

OBJECTIVES: 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.

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