Study Finds Broken Genomes Behind Breast Cancers
23 December 2009 - An international team of scientists has completed the first detailed study of rearrangements in the genome of breast cancers. Rearrangements involve reshuffling and reorganisation of the genome and include deletions, duplications and novel juxtaposition of DNA sequences.
Scientists from the Wellcome Trust Sanger Institute, The Institute of Cancer Research and centres in The Netherlands, the US and Norway used next-generation DNA sequencing to produce maps of genome rearrangements in 24 breast cancer samples. The samples were chosen to include the major subtypes of breast cancer and also included examples of breast cancers arising in families with BRCA1 and BRCA2 mutations.
The study shows that breast cancer samples can differ greatly in the extent to which they are subject to genomic rearrangements: some are relatively undisturbed whereas others are fractured extensively and then reassembled with more than 200 rearrangements present. These multiple distinctive patterns of rearrangement observed supported the view that breast cancer is not one, but several diseases. The research will add a new dimension to tumour classification, helping to refine diagnosis and treatment.
This investigation also provided detailed insights into the ways that the genome in some cancers have broken and also the processes that the cancer cells used to glue the broken bits of genome back together again. Dissecting out the complexity and the diversity of the breast cancer genomes is crucial for understanding how the cancers arise. Importantly, some breast cancers appeared to have a defect in the machinery that maintains and repairs DNA, which resulted in a large number of abnormalities, and raises the possibility of new therapeutic opportunities.
