aCGH local copy number aberrations associated with overall copy number genomic instability in colorectal cancer: coordinate involvement of the regions including BCR and ABL

In order to identify small regions of the genome whose specific copy number alteration is associated with high genomic instability in the form of overall genome-wide copy number aberrations, we have analyzed array-based comparative genomic hybridization (aCGH) data from 33 sporadic colorectal carcinomas. Copy number changes of a small number of specific regions were significantly correlated with elevated overall amplifications and deletions scattered throughout the entire genome. One significant region at 9q34 includes the c-ABL gene. Another region spanning 22q11-q13 includes the breakpoint cluster region (BCR) of the Philadelphia chromosome. Coordinate 22q11-q13 alterations were observed in 9 of 11 tumors with the 9q34 alteration. Additional regions on 1q and 14q were associated with overall genome-wide copy number changes, while copy number aberrations on chromosome 7p, 7q, and 13q21.1-q31.3 were found associated with this instability only in tumors from patients with a smoking history. Our analysis demonstrates there are a small number of regions of the genome where gain or loss is commonly associated with a tumor's overall level of copy number aberrations. Our finding BCR and ABL located within two of the instability-associated regions, and the involvement of these two regions occurring coordinately, suggests a system akin to the BCR-ABL translocation of CML may be involved in genomic instability in about one-third of human colorectal carcinomas.