Caveolin-1, an essential structural component of caveolae, functions as a negative regulator for signal transduction and has been suggested to be a candidate tumor suppressor gene. Lack of caveolin-1 expression has been implicated in tumorigenesis in many cancers and its importance in mammary tumoral cells has been confirmed. However, the exact functional role of caveolin-1 remains controversial. Based on an immunohistochemical study, the expression levels of caveolin-1 in 73 female dogs with mammary neoplasia were investigated by Real-Time PCR, and correlations with clinicopathologic variables were evaluated statistically. PCR amplifications were performed using a 7500 Fast Real-Time PCR System. The gene expression stability over different samples was analyzed using the geNorm software. There was less expression of caveolin-1 in mammary tumors compared with normal mammary tissue in all group. Multivariate analyses indicated that clinical stage, histologic grade, and outcome were independent prognostic factors. The presence of clinical symptoms and the down-regulation of caveolin-1 were identified as negative prognostic predictors in the univariate analysis (P < .05). Reduced expression of caveolin-1 may indicate a poor prognosis and the current results suggest that caveolin-1 may function as a tumor suppressor gene in mammary cancer.

Financial Support: FAPESP