Expression of connexin 43 in breast cancer in comparison with mammary dysplasia and the normal mammary gland.

Gap junctional intercellular communication (GJIC) plays a critical role in tissue development and differentiation and probably in carcinogenesis. The purpose of the study was to evaluate the expression and localisation of Cx43 in 40 cases of mammary dysplasia and 29 cases of breast cancer (without primary chemotherapy). The tissue sections were investigated for Cx43 expression by immunohistochemistry. In the normal mammary gland there was an intercellular, punctate staining pattern, mainly between myoepithelial cells, characteristic of functional gap junctions. In dysplasias there was mainly mixed (cytoplasmic and intercellular) staining and in most cases of breast cancer we observed diffuse or granular, but cytoplasmic, staining of Cx43. Our results demonstrated that expression of Cx43 in dysplasias and breast cancer is changed and GJIC is probably impaired because of disruption of functional gap junction formation especially between breast cancer cells.