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The Korean Journal of Pathology 2007;41(3): 158-164.
Reduced Expression of Claudin-7 Correlates with Invasiveness and Nuclear Grade of Breast Carcinomas.
Sang Hee Seok, Su Hwan Kang, Soo Jung Lee, Tae Yoon Hwang, Young Kyung Bae
1Department of Pathology, Yeungnam University College of Medicine, Daegu, Korea. ykbae@ynu.ac.kr
2Department of Surgery, Yeungnam University College of Medicine, Daegu, Korea.
3Department of Preventive Medicine, Yeungnam University College of Medicine, Daegu, Korea.
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.
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.
Key Words: Claudin-7; Breast cancer; Immunohistochemistry; Microarray analysis