| Abstrakt: |
Phenotype modulation of the human hepatoblastoma cells HepG2 treated with dimethyl sulfoxide (DMSO) was studied using indirect immunoperoxidase method with monoclonal antibodies against antigens with characteristic localization in the adult liver: cytokeratin 18, membrane antigen AGS5 and embryo-specific alpha-fetoprotein (AFP). Untreated HepG2 cells were found to contain all these antigens. However, their localization was different from that in the adult human liver. Instead of submembrane layer characteristic of liver parenchyma cells in situ, cytokeratin in HepG2 cells formed a cytoplasmic network and bundles. Membrane antigen AGC5 in HepG2 cells was fond only in the cytoplasm. Most HepG2 cells contained AFP which is absent from the adult liver cells. Under the effect of DMSO the "adult" type of cytokeratin 18 and AGS5 localization was re-established only in cells organized in dense cell layers, while in single cells or poorly compacted cell islets it remained unchanged. Treatment of HepG2 cells with DMSO resulted in a drastic decrease in the rate of AFP secretion, as well as in AFP-specific staining of either single cells or cell islets and layers. We suggest that the effect of DMSO on cell differentiation is mediated by different mechanisms. One of them can be associated with cell-to-cell interactions, while another with the direct interaction between DMSO and individual cells. |
