Expression of vimentin and prekeratins in solid and ascites variants of Zajdela's hepatoma

Abstract

Using indirect immunofluorescence with monoclonal antibodies against prekeratins and vimentin, the contents and intracellular distribution of these proteins have been investigated in Seidel hepatoma cells. In ascitic tumour, cells were organized in multicellular unilayer spheric or ellipsoid complexes with an inner cavity. Such complexes have been found to express intracellular vimentin and chaotically distributed prekeratin filaments. One of the constituents of the normal epithelial basal membrane--laminin was not found on the basal surface of cellular complexes but was localized in their inner lumens only. The expression of vimentin and prekeratin filaments was preserved in metastatic tumour cells found in paratracheal lymph nodes and in the majority of solid tumour cells induced by subcutaneous cell injections. In both cases tumour cells did not form regular morphological structures and laminin was visualized as extracellular granules and short fibrils. In several cases subcutaneous injections of Seidel hepatoma cells gave rise to adenocarcinomas. Prekeratin filaments in these tumours were localized predominantly under cellular membranes. Laminin "membranes" outlined the basal surface of adenomatous structures. Vimentin in these cellular structures was completely absent. It is suggested that vimentin expression in Seidel hepatoma cells was suppressed with morphological normalization of tumour structures manifested in the regular distribution of intercellular contacts and in basal membrane reconstitution.