Identification of amplified DNA sequences on double minute chromosomes in a leukemic cell line KY821 by means of spectral karyotyping and comparative genomic hybridization.

Double minute chromosomes (dmin) are cytogenetic hallmarks of amplified genes. Using spectral karyotyping (SKY) and comparative genomic hybridization (CGH), we identified the origin of amplified DNA in a leukemic cell line, KY821, that harbors numerous dmin. The SKY revealed that the DNA sequences of dmin are derived from materials of chromosome 8, and CGH showed a high degree of overrepresentation only at 8q22-24, indicating that in KY821 only chromosomal material of 8q22-24, containing MYC, is amplified in dmin. An approach combining SKY with CGH should facilitate efforts to identify novel chromosomal regions of gene amplification and contribute information about genetic lesions that underly neoplastic tumors.