Correlation between ER, PR, HER-2, Bcl-2, p53, proliferative and apoptotic indexes with HER-2 gene amplification and TOP2A gene amplification and deletion in four molecular subtypes of breast cancer.

The aim of our study was to investigate HER-2 and TOP2A gene status and their correlation with Bcl-2, p53, Ki67, ssDNA, and clinicopathological parameters in four molecular subtypes of breast cancer. Seventy-four paraffin-embedded samples are immunohistochemically studied for the expression of estrogen receptor (ER), progesterone receptor (PR), HER-2, p53, Bcl-2, ssDNA, and Ki67, while HER-2 and TOP2A gene status by fluorescence in situ hybridization was investigated in 60 samples. Luminal A and B subtypes were characterized with small tumor size, intermediate histological grade, negative lymph node, and metastatic status, while triple negative and HER-2 positive subtypes were associated with larger tumor size, poorly differentiated tumors, and positive lymph node status. p53, Ki67, and ssDNA expression was higher in triple negative and HER-2 positive than in luminal subtypes, while ER, PR, and Bcl-2 dominated in luminal subtypes. HER-2 gene status was higher in luminal B and HER-2 positive than in luminal A and triple negative subtypes, while TOP2A gene status was similar. HER-2 gene status positively correlated with TOP2A gene status, HER-2 receptor, and histological grade, while negative correlation characterized relationship between HER-2 gene status and ER, PR, and Bcl-2. The shortened overall survival period characterized patients from triple negative breast cancer subtype (18.7 months). HER-2 and TOP2A gene amplification showed a tendency to be associated with larger tumor size, positive lymph node status, high level of apoptotic and proliferative indexes, and low level of p53 and Bcl-2 expression, which all together indicate group of patients with similar outcome during the progression of the disease.