Variant protein patterns in hepatomas and transformed liver cell lines as determined by high resolution two-dimensional gel electrophoresis (2DE).

Deviations in the pattern of soluble proteins from chemically induced primary rat hepatomas and from transformed, tumorigenic liver cell lines were determined by high resolution two-dimensional gel electrophoresis (2DE). As compared with the protein pattern of normal rat liver with approximately 1300 protein spots visible in silver-stained gels, quantitative and qualitative alterations were found in hepatomas including neoexpression of glutathione-S-transferase P, as described earlier. After correction for proliferation-related changes by comparison with gels of cells from regenerating rat liver, 30 protein variants remained, which were identically up- (n = 6) or down-regulated (n = 18) or were detected as new spots (n = 6) in primary hepatomas and transformed tumorigenic liver cell lines which are devoid of contaminating nonparenchymal cells. Seven of these variants showed a reduced expression in short-term cultured liver cells indicating dedifferentiation processes in the transformed state. Several hepatoma- and transformation-associated variants were found in clusters of similar mol. wt and/or pI, among them a complex of eight protein variants at approximately 33-35.5 kDa and a pI of approximately 6.6-7.4. Spots of this cluster show considerable changes between the investigated experimental groups and might be suited for being studied at the level of posttranslational modification during carcinogenesis.