Caveolin-1 in Diagnosis and Prognosis of Canine Mammary Tumours: Comparison of Evaluation Systems

SummaryCaveolin-1 (Cav-1) is a major structural protein of caveolae, plasma membrane invaginations related to several cellular processes including regulation of signal transduction. In recent years there has been some controversy regarding the distribution of Cav-1 in normal and neoplastic mammary cell types, which may be attributed to different scoring systems adopted in different studies. The present study compares Cav-1 immunoexpression in normal (n = 17) and neoplastic (n = 79) canine mammary tissues assessed by two different scoring methods (previously reported by others with conflicting results) and associates Cav-1 expression with metastasis and overall survival (OS). Results obtained with both scoring methods were similar, revealing absence of immunoreactivity in normal luminal epithelium and in benign neoplasms and clearly associating Cav-1 expression with malignant transformation. The data suggest that Cav-1 expression is associated with highly malignant subtypes of mammary tumours (i.e. basal-like carcinoma), invasion and metastasis, thus supporting the hypothesis that it may play a major role in the epithelial–mesenchymal transition process. Furthermore, one of the scoring systems employed associated Cav-1 expression with unfavourable prognosis in canine mammary carcinomas, showing a strong correlation between Cav-1-positive carcinomas and shorter OS.