Survivin expression in canine mammary tumours

Introduction: Survivin, which belongs to the inhibitor of apoptosis protein family (IAP), isubiquitous expressed during tissue development, but absent or expressed at low levels in mostnormal tissues. Survivin has been demonstrated to be re-expressed in most human cancers, aswell as in about 60-70% breast cancers, and its expression has been associated with tumouraggression, poor prognosis and poor response to therapy.Material and methods: This retrospective study included 13 canine mammary tumours (1 solidcarcinoma, 5 tubulo-papillar carcinomas, 2 mixed carcinomas, 4 complex carcinomas) and2 pre-neoplastic lesions (epithelial hyperplasia). Four samples of human colon carcinomas, atumour that frequently expresses survivin, were used as positive controls. Immunohistochemicalexpression of full-length survivin was determined using commercially produced antibody(rabbit polyclonal antibody, 0,8 g/ml, NOVUS Biologicals). Mitotic index was evaluated bycounting positive mitosis in 10 high power fields (HPF).Results: Survivin expression was observed in 73% of cases, with more intense immunolabelingin malignant neoplasms than preneoplastic lesions. The staining was mainly cytoplamic;nuclear immunolabeling and positive mitosis were also observed in 8 samples. Three casesshowed intense cytoplasmic survivin staining and high mitotic index (3-4HPF). Preneoplasticlesions, normal mammary epithelium, as well as myoepithelium, were negative.Discussion: The present results indicate for the first time that in dogs, as in human beings, bothcytoplasmic and nuclear survivin is frequently expressed in malignant mammary tumours,suggesting a direct correlation with histological malignancy and biological behavior of caninebreast carcinoma, consistent with anti-apoptotic and proliferative functions of the molecule.[...]