c-src is consistently conserved in the chromosomal deletion (20q) observed in myeloid disorders

The proto-oncogene c-src has been mapped to two bands in human chromosomes, 1p36 and 20q13, both of which are involved in rearrangements in human tumors. In particular, deletions (loss of part of a chromosome) of the long arm of chromosome 20, del(20q), are commonly observed in hematologic malignant diseases. By using in situ chromosomal hybridization of a c-src probe to metaphase cells prepared from leukemic bone marrow cells of three patients with a del(20q), we observed specific labeling on the deleted chromosome in each patient, indicating that the c-src locus was conserved. The presence on the rearranged chromosomes of c-src, which is normally located on the most distal band of 20q, indicated that the deletions were not terminal as they appeared to be on the basis of chromosome morphology, but rather that they were interstitial. The location of c-src relative to the distal breakpoint in these deletions is unknown. By using the v-src probe in Southern blot analysis of genomic DNA from three patients with a del(20q), we found that no major genomic rearrangements or amplification of the c-src genes had occurred within the regions homologous to v-src. Our observation that c-src is consistently preserved in these rearranged chromosomes suggests that this gene may play a role in the pathogenesis of some myeloid disorders.