We studied the role of caveolin-1 in tumor progression and prognosis in serous ovarian carcinoma and the association between caveolin-1 and MDR1 expression. The study involved immunohistochemical analysis for caveolin-1 and P-glycoprotein (P-gp) expression in 75 effusions and 90 solid lesions from ovarian and primary peritoneal carcinoma; in situ hybridization for MDR1 messenger RNA (mRNA) expression in 62 effusions and all 90 tumors; and reverse transcription–polymerase chain reaction (RT-PCR) for caveolin-1 mRNA expression in 23 effusions. Immunohistochemical analysis localized caveolin-1 to the cell membrane in 43 effusions and 24 tumors. P-gp membrane expression was detected in 14 effusions and 11 tumors; MDR1 mRNA, in 20 effusions and 30 tumors. Caveolin-1 mRNA was expressed in 19 effusions. Caveolin-1 protein expression showed no association with that of P-gp protein or MDR1 mRNA. The expression of all markers was similar in carcinoma cells in pleural and peritoneal effusions. Caveolin-1 is a novel diagnostic marker for effusions; expression is moderately elevated in tumor cells in effusions, possibly owing to altered signal transduction and metabolism in cancer cells at this site. Expression seems MDR1 independent.

Author notes

Financed in part by grant D-1086 from the Norwegian Cancer Society, Oslo, Norway.