Differential expression of chromobox 4 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 report here significant differential expression of the gene encoding chromobox 4, CBX4, when comparing primary tumors of the breast to the tissue of origin, the normal breast. CBX4 mRNA was present at significantly higher quantities in tumors of the breast as compared to normal breast tissue. Analysis of human survival data revealed that expression of CBX4 in primary tumors of the breast was correlated with overall survival in patients with luminal A type cancer, demonstrating a relationship between correlation of primary tumor expression with overall survival based on molecular subtype. CBX4 may be of relevance to initiation, maintenance or progression of cancers of the female breast.