Genome-wide multi-omics profiling reveals extensive genetic complexity in 8p11-p12 amplified breast carcinomas [aCGH]

DNA copy number alterations play an important role in cancer development and progression by changing the transcriptional levels of key cancer-related genes. However, gene expression patterns may also be affected by other mechanisms. To test these basic principles, we have applied genome-wide screening techniques to 53 invasive breast tumors with array comparative genomic hybridization and gene expression microarrays to assess the direct effect of gene dosage on gene expression levels and independently to test the effect of other mechanisms on transcriptional levels. Low-level gain, high-level gain/amplification, heterozygous loss and homozygous deletion (henceforth referred to as gain, amplification, loss and deletion) were defined as log2 ratio thresholds set at +0.2, ≥+0.5, -0.2 and ≤-1.0, respectively. Genomic DNA was isolated from fresh-frozen tissue samples