Isolation and characterization of allelic losses and gains in colorectal tumors by arbitrarily primed polymerase chain reaction.

The arbitrarily primed polymerase chain reaction (AP-PCR) [Welsh, J. & McClelland, M. (1990) Nucleic Acids Res. 18, 7213-7218] has been used to detect somatic genetic alterations in tumors of the colon and rectum. DNA fingerprints generated by single arbitrary primers were compared between normal and tumor tissue of the same individuals. AP-PCR bands showing decreased and increased intensities in tumor tissue DNA, relative to normal, have been cloned after reamplification with the same arbitrary primer. Standard restriction fragment length polymorphism and Southern blot analyses show that these DNA sequences have undergone allelic losses and gains, respectively, in the tumor cell genome. The deleted sequences have been assigned to the short arm of chromosome 17 by PCR of somatic hamster/human cell hybrids and linkage analysis. These results show the ability of the AP-PCR to detect and isolate, in a single step, DNA sequences representing two of the genetic alterations that underlie the aneuploidy of cancer cells: losses of heterozygosity and chromosomal gains. Altogether, they also show the quantitative nature of the amplification levels obtained in vitro by AP-PCR, which thus provides the basis for an alternative molecular approach to cancer cytogenetics.