BRCA1 AND TOP2A GENE AMPLIFICATION AND PROTEIN EXPRESSION IN FOUR MOLECULAR SUBTYPES OF BREAST CANCER

We studied TOP2A amplification (using FISH methods), and TOP2A and BRCA1 protein overexpression (im- munohistochemistry) 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 Lu- minal 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 ex- hibited similar patterns of expression in Luminal B and triple-negative breast cancer, suggesting the same prognosis in those patients.