Caveolin-1 Expression in Advanced-Stage Ovarian Carcinoma— A Clinicopathologic Study

Objective. The aim of this study was to analyze the correlation among the expression of caveolin-1, the protein constituent of caveolae, and disease outcome in advanced-stage ovarian carcinomas. Methods. Sections from 76 primary ovarian carcinomas and metastatic lesions from 45 patients diagnosed with advanced-stage ovarian carcinoma (FIGO stages III–IV) were evaluated for caveolin-1 expression using immunohistochemistry. Patients were divided into long-term survivors and short-term survivors based on disease outcome. Twenty nonneoplastic fallopian tubes and ovaries were additionally studied. Results. The mean follow-up period was 70 months. The mean values for disease-free survival and overall survival were 109 and 125 months for long-term survivors, compared to 3 and 21 months for short-term survivors, respectively. Caveolin-1 expression was localized to the cell membrane in 24/76 (32%) specimens and was detected in the cytoplasm in 52/76 (68%) cases. Both patterns were more often detected in metastases, when compared with primary tumors. In addition, membrane immunoreactivity was more often seen in tumor of short-term survivors. These differences did not reach statistical significance ( P > 0.05). Combined membrane and cytoplasmic immunoreactivity was seen in 17/20 (85%) nonneoplastic lesions. Despite its role in tyrosine-kinase-mediated signal transduction in vitro studies, caveolin-1 expression in carcinomas showed no association with the protein expression of c-erbB-2 and epidermal growth factor receptor, evaluated in a previous study of this patient cohort. Conclusions. This study provides the first in vivo evidence of caveolin-1 membrane expression in human malignancies. Caveolin-1 is often expressed in advanced-stage ovarian carcinoma, but does not appear to be a powerful predictor of disease outcome in these tumors. The reduced expression level in carcinomas compared to nonneoplastic epithelium may point to a role for caveolin-1 as a tumor suppressor gene.