Frequent multiplication of the long arm of chromosome 8 in hepatocellular carcinoma.

Frequent allelic losses at loci on several chromosomes have been detected in human hepatocellular carcinomas, but other types of chromosomal abnormalities have not been characterized well. Using eight polymorphic DNA markers on chromosome 8, we examined 120 primary hepatocellular carcinomas for abnormalities in the copy number of these loci in tumor cells. A 2- to 6-fold increase in intensities of bands representing single alleles was observed in 32 of the 78 tumors that were informative for one or more of the markers, indicating an increase in copy number ("multiplication") of alleles on 8q. The regions that multiplied varied from almost the entire long arm to a distal segment of chromosome 8, but a terminal region distal to 8q24.11 was multiplied in all 32 cases. Similar multiplications on 8q were detected in nine of 56 colorectal carcinomas that were informative for one or more of the markers. Our study demonstrated that polymorphic DNA markers can be used to detect numerical abnormalities of chromosomal material in solid tumors in which cytogenetic analysis is technically difficult.