Role of β-catenin in canine osteosarcoma

Introduction: The role of Wnt/β-catenin signaling pathway in the pathogenesis of osteosarcoma (OS) is not yet completelyknown, as well as the prognostic signifi cance of β-catenin expression. Recently, the Wnt/β-catenin signaling pathway,known to be essential for proper osteoblast’s maturation, has been suggested to be inactivated during OS induction andprogression.Materials and Methods: Immunohistochemical expression of β-catenin was investigated in canine OS samples, using a semi-quantitative method to analyse results. Its expression was correlated to histological grading, survivin and p53 expression, and follow-up data. β-catenin was also evaluated by immunofl uorescence in canine OS cell cultures. Results: Nuclear β-catenin immunolabelling was detected in osteoblasts surrounding normal bone trabeculae. In all cases cytoplasmic and/or membranous immunostaining were observed, while the highest number of nuclear positive cells wasfound in fi broblastic OS and among spindle cells of mixed OS. Nuclear expression was rarely observed among OS cell lines. Nuclear survivin and p53 positive cells were found in all cases. Conclusion: Nuclear β-catenin immunolabelling, a hallmark of Wnt pathway activation, in normal osteoblasts and the absent/low expression in most of the OS, suggested that this pathway is not activated in canine OS. Furthermore, statistically significant correlation has been found between nuclear β-catenin immunolabelling and a longer survival time.[...]