Differential expression of topoisomerase IIα in cancers of the breast.
Breast cancer affects women at relatively high frequency (1). We mined published microarray datasets (2, 3) to determine in an unbiased fashion and at the systems level genes most differentially expressed in the primary tumors of patients with breast cancer. We identified significant differential expression of the gene encoding the DNA topoisomerase IIα, TOP2A, when comparing primary tumors of the breast to the tissue of origin, the normal breast. Expression of TOP2A in primary tumors of the breast was significantly higher than in normal breast tissue, and patients with low expression of TOP2A in primary tumors had markedly superior overall and relapse-free survival. TOP2A may be of relevance to initiation, maintenance or progression of cancers of the female breast.