Increased level of the mitochondrial ND5 transcript in chemically induced rat hepatomas

We have constructed a cDNA library from a hepatoma cell line (HTC cells) and isolated the clones corresponding to mRNAs present at a much higher level in hepatomas than in normal hepatocytes. The characterization of one of these clones is described in this paper. This clone is homologous to part of the mitochondrial ND5 gene (a subunit of NADH-ubiquinone oxidoreductase). The level of this mRNA was found increased in HTC cells and in hepatocytes from diethylnitrosamine-treated rats long before the development of tumors and strongly increased in carcinoma nodules as compared to hepatocytes from nontreated rats. Southern blot analysis showed a mitochondrial DNA heterogeneity in hepatomas with an alteration of the structure of part of the molecules.