Establishment of new ovarian and colon carcinoma cell lines: differentiation is only possible by cytokeratin analysis.

Two human ovarian (OV-MZ-10, OV-MZ-15) and two colon cancer cell lines (CO-MZ-5, CO-MZ-6) were newly established in permanent cell culture. These cell lines have been maintained in vitro for 5-6 years, the passage number varying from 25 to 228. They were established from ascites or solid tumours at the time of primary surgery. By clinical and histopathological judgement alone all four cell lines would have been interpreted as ovarian cancer cell lines. Morphological criteria or the expression of the tumour-associated antigens CA-125 and CEA allowed no differential diagnosis. Only the analysis of the expression of different cytokeratins and vimentin enabled us to verify the different origin of the cell lines. Ovarian cancer cell lines, in contrast to the colon cancer cell lines, are positive for the expression of cytokeratin (CK) 7 and for vimentin. CK 20 proved to be the marker with the best discrimination. CK 20 was found exclusively in the colon carcinoma cell lines, but not in the ovarian carcinoma cell lines. The evaluation of cytokeratin expression is a helpful diagnostic modality in differentiating between adenocarcinoma cell lines derived from ovarian and colon tumours.