A novel oncogene from a human hepatocellular carcinoma.

Primary human hepatocellular carcinomas (HCC) were surveyed for oncogenes by transformation assays using NIH 3T3 cells and calcium phosphate coprecipitation method. One new transforming DNA, called lca (for liver cancer) was obtained, and its properties were studied in detail. The lca DNA, localized in a 10.5 kb DNA fragment, was assigned to human chromosome 2. It showed identical restriction enzyme cleavage profiles as its counterpart DNA obtained from normal tissue, indicating that there is no extensive DNA rearrangement associated with activation process of the lca DNA. The normal counterpart DNA shows no transforming activity. Recombinant genes of the laca and its normal counterpart made in vitro have allowed localization of the site of "activation" to a limited region of the 10.5 kb fragment. An independently obtained transforming DNA from another HCC exhibited identical restriction enzyme cleavage profiles. Thus, lca DNA is likely to represent a commonly encountered transforming DNA in HCC.