Abstract
An immunocytochemical study was made to compare the aflatoxin B1-induced rat liver tumor cells with normal rat liver cells in vitro with regard to the development of intermediate filaments, cytokeratin and vimentin. Both intermediate filaments were localized at a perinuclear region of the cytoplasm in the cultured tumor cells, while they were diffusely distributed in the cultured normal liver cells. In the metastatic tumor cells (AFB-1), a part of vimentin filaments extended to form networks among adjacent cells and electron microscopic examination showed a figure that vimentin filaments were connected at an intercellular attachment structure, desmosome. When the tumor cells were transplanted subcutaneously in the syngeneic rats, vimentin was scarecely detected in the tumor nodule of the non-metastatic tumor cells (JB1) but they were still present in that of the metastatic tumor cells (AFB-1). These results suggest that the enhanced and localized development of intermediate filaments could be a measure of the malignant progression of rat liver cells.
