B-cell lymphoma-2 receptor in human primary breast and its lymph node metastases: more than a surrogate marker

Abstract

Background: Due to its anti-apoptotic and anti-proliferative contradictory functions, BCL2 role in breast carcinoma progression is not clearly understood. The purpose of this study was to highlight BCL2 expression during metastatic progression of invasive breast carcinoma of no special type (NST). Materials and methods: The specimens, primary tumors and corresponding lymph node metastases (LNM) from 84 patients were immunostained for estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor (HER)-2, basal cytokeratin CK5, nuclear protein Ki67 and B-cell lymphoma (Bcl)-2 receptor. Results: BCL2 expression was higher at primary site than in axillary metastases. Its score correlates positively with hormone receptors’ level and negatively with HER2, CK5 and Ki67 at both sites. Switch of molecular profile was determined in 22.62% of cases. BCL2 expression was not influenced by subtypes switch. Changes of BCL2 expression were found in 25% of cases with stable molecular subtype. The Luminal A and Luminal B/Ki67 were encountered in the majority of BCL2 transitions, mainly from positive to negative state. Conclusions: Molecular subtypes and BCL2 expression are not stable during tumor progression and metastatic development. In the present study we established immunohistochemically that BCL2 is not influenced by subtypes’ transitions. BCL2 switches were encountered only in cases with a stable HER2, Luminal A or B phenotypes. We expect a further confirmation of our results by other research groups.