CHARACTERIZATION OF CULTURED HUMAN OVARIAN SURFACE EPITHELIAL-CELLS -PHENOTYPIC PLASTICITY AND PREMALIGNANT CHANGES

BACKGROUND: The ovarian surface epithelium (OSE) is a modified mesothe lium that gives rise to most human ovarian carcinomas. In culture, OSE cells tend to assume atypical morphologies that make it difficult to accurately identify normal OSE cells and to recognize pathologic chang es. The present study was undertaken to improve the accuracy of OSE id entification and to distinguish phenotypic variations of normal OSE ce lls from early (pre)neoplastic changes. EXPERIMENTAL DESIGN: The expre ssion of epithelial and stromal markers was compared between OSE cultu res in low passage, three simian virus 40-immortalized OSE lines (IOSE lines) and two ovarian carcinoma lines, using immunofluorescence micr oscopy, immunocytochemistry, and Western blots, with fibroblasts and v ascular endothelial cells as controls. RESULTS: Whereas keratin remain ed a convenient and specific epithelial marker for normal OSE, it was not expressed by all cells, and it diminished with passages in culture . E-cadherin and desmoplakins were absent in cultured OSE, mucin was d etected in few cells, and microvilli diminished within one to two pass ages. Laminin and collagen IV were uniformly expressed and stable with time but were also found in endothelial cells. In contrast to endothe lial cells, OSE lacked Factor VIII and did not bind Ulex Europaeus Lec tin. The three IOSE lines were more stable than OSE morphologically, a nd keratin was expressed consistently in 100%, 90%, and 0% of the cell s, respectively. All IOSE cells produced laminin and collagen IV but l acked E-cadherin. Microvilli persisted in 50% of the cells in one IOSE line and were lacking in the others. The antibody to breast/ovarian c arcinoma, 2G3, reacted with few OSE cells but with significantly more IOSE cells. All fibroblast markers tested (vimentin, collagen types I and III, and prolyl-4-hydroxylase) were expressed in OSE and IOSE cult ures, concurrently with the epithelial markers. There was no consisten t relationship between any of the markers and cell morphology. CONCLUS IONS: Cultured OSE is more accurately identified if the demonstration of keratin is supplemented by 2G3, laminin, or the lack of endothelial markers. The modulation to a fibroblastlike morphology by OSE cells m ay reflect the expression of their dual epithelio-mesenchymal phenotyp e rather than epithelio-mesenchymal conversion. Possible indicators of early neoplastic change in immortalized OSE cells include reduced mor phologic plasticity and increased 2G3 binding.