Partial trisomies in two spontaneously arising long-lived human keratinocyte lines.
During experiments concerning the introduction of oncogenes into normal human keratinocytes, we observed long-lived colonies arising spontaneously at the same low frequency in control cultures as in those transfected with Ha-rasEJ or activated c-myc or both. Two of these were karyotyped early in their life span and showed additional chromosomal material on the short arm of chromosome 9 in one case and of chromosome 18 in the other, whereas the parental cells had a normal karyotype. This indicates the presence of a partial trisomy in each line, although the origin of the extra chromosomal material is not known. A similarly long-lived human keratinocyte line containing an isochromosome of the long arm of chromosome 8 has been described elsewhere. Together these results suggest that the spontaneous occurrence of long-lived lines is more common in human keratinocytes than in fibroblasts and that a triple dose of one or more genes may be the initial event in this process.
Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
J D
JD
Weaver
G
G
Stetten
J W
JW
Littlefield
D000328:Adult; D001940:Breast; D002478:Cells, Cultured; D002871:Chromosome Banding; D002887:Chromosomes, Human, Pair 18; D002899:Chromosomes, Human, Pair 9; D005260:Female; D016259:Genes, myc; D011905:Genes, ras; D006801:Humans; D007621:Karyotyping; D015603:Keratinocytes / Q000166:cytology / Q000502:physiology*; D010957:Plasmids; D013997:Time Factors; D014162:Transfection; D014314:Trisomy