Expression of Wnt5a and its downstream effector beta-catenin in uveal melanoma

Upregulation of the Wnt5a pathway has been reported in some cutaneous melanomas but its role in uveal melanoma has not been assessed. We thus sought to determine whether activation of the Wnt-signalling pathway occurred in uveal melanoma through upregulation of some of the key downstream effectors, and whether expression of these components was associated with tumour characteristics and clinical outcome. Expression of Wnt5a, MMP7, and beta-catenin was determined in 40 primary uveal melanomas by immunohistochemistry and correlated with patient prognosis. The proportion of cells immunoreactive for Wnt5a, MMP7, and beta-catenin was higher in tumours from patients with shorter survival and this difference was statistically significant for Wnt5a (P<0.01) and beta-catenin (P=0.02). These data show for the first time activation of the Wnt/beta-catenin-signalling pathway in uveal melanoma and suggest that components of this pathway might be useful prognostic markers as well as attractive therapeutic targets to treat this disease.