Differential expression of intermediate filament proteins in two rat ascites hepatoma lines of common origin

Two rat ascites hepatoma lines, AH130, originating from a azodye-induced liver carcinoma, and AH130F(N), spontaneously derived from the AH130 line during serial i.p. transplantation were analyzed for their intermediate filament protein expression by one and two-dimensional gel electrophoresis, in vitro translation of their mRNAs and immunolocalization using antisera against distinct subunits and compared with intermediate filament expression of normal hepatocytes. Normal rat hepatocytes synthesize mainly two keratin subunits at 55 and 47 kDa. The AH130 hepatoma line maintains the expression of these proteins, however, in addition also synthesizes a 40-kDa keratin subunit and large amounts of vimentin. In contrast, the AH130F(N) hepatoma line has lost the ability to express keratin subunits; its intermediate-sized filament compound is apparently built up only by vimentin. Even by means of the sensitive immunoblotting technique using antisera against the normal hepatocyte keratin subunits, no keratin synthesis can be demonstrated in this line. The marked differences in the metastatic capacity of the two hepatoma lines make them promising tools to investigate a possible involvement of intermediate-sized filament expression in the process of tumor spreading.