Detection of chromosomal imbalances in leiomyosarcoma by comparative genomic hybridization and interphase cytogenetics

Leiomyosarcomas comprise a group of malignant soft-tissue tumors with smoot h-muscle differentiation. In this study, 14 cases of leiomyosarcoma were sc reened for changes in relative chromosome copy number by comparative genomi c hybridization. A high number of imbalances (mean, 16.3; range, 6-26) was detected, with chromosomal gains occurring about twice as much as losses. T he most frequent gains were found in 5p15, 8q24, 15q25-->q26, 17p, and Xp ( 43% to 50%), whereas the most frequent losses were found in 10q and 13q (50 % and 78%, respectively). Twenty high-level amplifications affecting 15 dif ferent chromosomal subregions were detected in nine different tumors. In th ree leiomyosarcomas, sequences on chromosome arm 17p were found to be highl y amplified, with a minimal overlapping region on subbands 17p12-->p11. We further discovered that the Smith-Magenis syndrome critical region on 17p11 .2 is included in the 17p amplicons of two leiomyosarcoma cases. Using prob es flanking this genetically unstable region, a mean of 14 and 22 signals p er nucleus, respectively, was detected in both leiomyosarcomas by fluoresce nce in situ hybridization. In conclusion, this analysis identifies a number of characteristic chromosomal imbalances in leiomyosarcomas and provides e vidence for the localization of potential oncogenes and tumor suppressor ge nes active in leiomyosarcoma genomes. Copyright (C) 2000 S. Karger AG, Base l.