Loss of Syk Correlates with Cancer Progression

Abstract

Although the protein tyrosine kinase Syk is best studied in hematopoietic cells, Syk is also found in epithelial cells; however, its role in the epithelium is not understood. Coopman et al . identify a potential role for Syk in suppressing breast cancer progression. Examination of several breast cancer cell lines indicated that Syk expression correlated negatively with invasiveness and colony formation ability. Similarly, normal breast tissue and benign breast lesions expressed Syk. Transfection of Syk into metastatic, highly invasive breast cancer cell lines led to decreased metastatic potential and tumor growth in nude mice. However, expression of catalytically inactive Syk in wild-type Syk-expressing breast cancer cells resulted in increased tumor growth and metastases in nude mice. Other experiments revealed that whereas the Syk SH2 domain also is important for attenuating tumor growth, the activation of Vav and PLC-γ1 may not play a critical role. Coopman, P.J.P., Do, M.T.H., Barth, M., Bowden, E.T., Hayes, A.J., Basyuk, E., Blancato, J.K., Vezza, P.R., McLeskey, S.W., Mangeat, P.H., and Muelle, S.C. (2000) The Syk tyrosine kinase suppresses malignant growth of human breast cancer cells. Nature 406 : 742-747. [Online Journal]