Expression of Syk in invasive breast cancer: correlation to proliferation and invasiveness.

BACKGROUND: Spleen tyrosine kinase (Syk) kinase has recently been considered as a tumor suppressor gene in breast cancer. MATERIALS AND METHODS: Syk expression in patients with invasive breast cancer was immunohistochemically assessed. RESULTS: Decreased expression was found in 26% of the specimens examined. In cases with vascular invasion, expression of Syk was lost in the intravascular emboli. A significant relationship between increased proliferation levels (as estimated by the proliferative index, Ki67) and decreased Syk expression (p <0.05) was found. CONCLUSION: Our data suggest that Syk protein expression inversely correlates with the proliferation and invasive capacity of breast cancer.