Abstract

Background
: Claudins are important components of the tight junctions in the intercellular barriers and cell polarity. Among them, claudin-7 is down-regulated in breast cancers compared with the normal breast epithelium. The aim of this study was to determine the expression pattern and prognostic value of claudin-7 in breast carcinomas.
Methods
: Claudin-7 expression was evaluated immunohistochemically in 42 cases of ductal carcinoma in situ (DCIS) and in 142 cases of invasive breast carcinoma (IBC) using a tissue microarray (TMA).
Results
: Claudin- 7 was strongly expressed in the normal luminal epithelial cells in the breast lobule. The level of claudin-7 expression was significantly lower or absent in 45.2% (19/42) of DCIS and 72.5% (103/142) of IBC. A loss or reduced expression of claudin-7 correlated with the invasiveness (p=0.001) of breast carcinomas and a high nuclear grade (p=0.013) in IBC.
Conclusion
Claudin-7 is an important tight junction protein in the breast and a loss of expression may assist in the dissociation and invasion of tumor cells.

• Keywords: Claudin-7;Breast cancer;Immunohistochemistry;Microarray analysis;