3-WAY AND 2-WAY REARRANGEMENTS INVOLVING CHROMOSOMES 10, 2, 5 AND 5, 2 IN 2 MARKER CHROMOSOMES OF A HUMAN-MELANOMA CELL-LINE

Two marker chromosomes (marl and mar2), provided with two closely spac ed heterochromatic bands, were observed in the 14932 cell line establi shed from a human metastatic melanoma. Fluorescence in situ hybridizat ion (FISH) with the alphoid sequence p82H common to all human centrome res showed strong signals over the double C-bands of mar1 and mar2. Th ese were recognized by a chromosome 2-specific alphoid probe, although chromosome in situ suppression (CISS) hybridization with a chromosome 2 library failed to reveal any painting along marl and mar2. The cent romere of mar1 was identified by a chromosome 10-specific alphoid sequ ence and the marker chromosome was decorated from pter to a region pro ximal to the interpolated C-band by a chromosome 10 library. The centr omere of mar2 could not be recognized by any chromosome-specific alpho id probe, but the whole mar2 was decorated by a chromosome 5 library. This library also painted the distal q arm of mar1, which was not pain ted by the chromosome 10 library, as well as a small band proximal to the double C-band. Identification of the two marker chromosomes reveal s their common origin and indicates a role for chromosomes 2, 5 and 10 in the genesis and/or progression of the 14932 melanoma. Alteration t o the chromosome-specific alphoid sequence in the centromere of mar2 p rovides evidence for rearrangement of constitutive heterochromatin alp hoid sequences in human tumours.