G banding, chromosome painting, FISH, and SKY prove that
DCPC21 is a translocation-negative PCT. (a) G banded
karyotype of DCPC21 lacking any PCT-associated chromosomal
translocations involving chromosomes 12 (IgH), 6
(IgK), 16 (IgL), and 15
(c-myc). The duplicated band on one chromosome 15
(arrow) was mapped to band 15D2, where c-myc is located.
Additional chromosomal aberrations (see ▴), such as the
elongated chromosome 9 and the marker chromosome M1 as well as the
centromerically fused Rb16;19 and the Rb19 isochromosome, probably are
acquired during neoplastic progression (see text). (b
and c) Chromosome painting of DCPC21 metaphases with
chromosome 12 (red) (b) and with chromosome 15 paint
(green) (c). No translocation between chromosomes 12 and
15 is visible. In addition, no chromosome 12- or 15-derived material is
found as part of any other chromosome. (d) Painting of a
DCPC21 metaphase with chromosome 12 (red) and FISH with
c-myc (green). The arrow points a large EE that
hybridizes with red and green, indicating the presence of chromosome
12-derived sequences and c-myc on the EE.
(e) SKY analysis of a DCPC21 metaphase. The data are
presented as follows. The image in the upper left corner of the
composite shows a representative metaphase obtained with the Spectra
Cube before the classification of the spectral colors. The upper center
image shows the inverted 4′,6-diamidino-2-phenylindole (DAPI) banding
of the same metaphase plate, and the image in the upper right corner
displays the spectral colors as classified by skyview
1.2 (Applied Spectral Imaging). The lower image shows
identical chromosome pairs of nonclassified and classified DCPC21
chromosomes. SKY corroborates the results of the G banding and
chromosome painting: DCPC21 PCT cells do not exhibit any chromosomal
translocation. SKY revealed the translocation of chromosome 16-derived
material onto the telomeric part of chromosome 9 (see arrows) and the
insertion of a chromosome 3-derived band into chromosome 2 (arrow). A
centromeric fusion occurred between chromosomes 16 and 19 (Rb 16;19).
The M1 marker contains both chromosome X- and 5-derived
chromosomal segments (arrow).