Molecular cytogenetic analysis of breast cancer cell lines

The extensive chromosome rearrangements of breast carcinomas must contribut e to tumour development, but have been largely intractable to classical cyt ogenetic banding. We report here the analysis by 24-colour karyotyping and comparative genomic hybridization (CGH) of 19 breast carcinoma cell lines a nd one normal breast epithelial cell line, which provide model examples of karyotype patterns and translocations present in breast carcinomas. The CGH was compared with CGH of 106 primary breast cancers. The lines varied from perfectly diploid to highly aneuploid. Translocations were very varied and over 98% were unbalanced. The most frequent in the carcinomas were 8;11 in five lines; and 8;17, 1;4 and 1;10 in four lines. The most frequently invo lved chromosome was 8. Several lines showed complex multiply-translocated c hromosomes. The very aneuploid karyotypes appeared to fall into two groups that evolved by different routes: one that steadily lost chromosomes and at one point doubled their entire karyotype; and another that steadily gained chromosomes, together with abnormalities. All karyotypes fell within the r ange seen in fresh material and CGH confirmed that the lines were broadly r epresentative of fresh tumours. The karyotypes provide a resource for the c ataloguing and analysis of translocations in these tumours, accessible at h ttp://www.path.cam.ac.uk/-pawefish. (C) 2000 Cancer Research Campaign.