BRCA1 and TOP2A gene amplification and protein expression in four molecular subtypes of breast cancer

Abstract

We studied TOP2A amplification (using FISH methods), and TOP2A and BRCA1 protein overexpression (immunohistochemistry) in four molecular subtypes of breast cancer. Of 53 patients, 32 showed TOP2A and 38 showed BRCA1 overexpression. The highest percentage of TOP2A amplification (47.8%) and deletion (13%) was detected in Luminal B subtypes. Of 11 Luminal B tumors with TOP2A amplification, 9 (81.8%) overexpressed TOP2A. BRCA1 protein overexpression showed significant positive correlation with TOP2A protein expression. BRCA1 and TOP2A proteins exhibited similar patterns of expression in Luminal B and triple-negative breast cancer, suggesting the same prognosis in those patients.