Immunocytochemistry for hepatocyte nuclear factor-1beta (HNF-1beta): a marker for ovarian clear cell carcinoma.

Recent microarray studies have shown that the expression of hepatocyte nuclear factor-1beta (HNF-1beta) was significantly up-regulated in clear cell carcinoma (CCC) of the ovary. HNF-1beta may be a useful marker for CCC in peritoneal fluid cytology. We designed an experimental study using three CCC cell lines to evaluate the influence of alcohol fixation or air drying on immunocytochemistry for HNF-1beta. Each cell line was cultured on chamber slides or transplanted into the abdominal cavity of nude mice, then the slides or ascites smears of nude mice were immunostained with or without microwave-mediated epitope retrieval. Immunoreactivity with HNF-1beta, which was either alcohol-fixed or air-dried, was noticeably improved after microwave heating. In contrast, two serous adenocarcinoma cell lines never showed immunoreactivity. Based on these results, 21 archival Papanicolaou-stained slides of peritoneal fluid (5 CCCs, 12 serous, 2 mucinous, and 2 endometrioid adenocarcinomas) were decolorized and immunostained under heating pretreatment. Five of 5 CCCs were distinctively positive for HNF-1beta, whereas all non-CCC ovarian cancers were negative for this protein. The present study clearly demonstrated that heating epitope retrieval improved the immunoreactivity for a nuclear protein in alcohol-fixed or air-dried cytology specimens. HNF-1beta is likely to be helpful for the diagnosis of CCC in the peritoneal fluid.