Hexokinase RFLP's in tumor versus normal cells and evidence for multiple hexokinase genes in hepatoma cells
Wigley, William Christian
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Genomic DNA isolated from a series of rat hepatomas and from normal rat liver tissue has been compared by restriction fragment analysis. The objective has been to identify a tumor-specific restriction fragment that would be present in rapidly growing tumors and missing in normal tissues. Using a hexokinase probe, several changes in DNA restriction fragment lengths in rat hepatoma versus normal rat liver have been identified. One Hinf I fragment of 13.4 kilobase pairs was found to be present in rapidly growing rat hepatomas, but missing in hormal rat tissue and in hepatomas of slow or intermediate growth rate. Also, Southern blots of rat hepatoma DNA probed with types I, II and III hexokinase sequences showed several fragments recognized by both the type I and II clones, while no resemblance was observed between the type III probe and the other two isozymes. It therefore appears that the type I-like and type Il-like hepatoma isozymes are coded for by similar yet separate genes, while a dissimilar third gene codes for the type Ill-like isozyme. In addition, a loss of heterozygosity was detected at the type III locus in the AS-3 0D hepatoma when compared to normal tissue.