Prognostic significance of Claudin 12 in estrogen receptor-negative breast cancer.
Altered expression of the Claudin (CLDN) superfamily of tight junction proteins has been reported in breast cancer. The aim of this study was to examine the immunohistochemical expression of CLDN 12 and its prognostic significance in breast cancer tissues. Immunohistochemical expression of CLDN 12 was performed on tissue microarrays consisting of 232 cases of breast carcinoma and correlated with clinicopathological features as well as survival of the patients with breast cancer. For the estrogen receptor (ER)-negative subgroup of patients with breast cancer, CLDN 12 expression was shown to be an independent predictor of poor overall survival (HR=2.345; p=0.020) and disease-free survival (HR=2.177; p=0.026) but not for the ER-positive tumours. The findings suggest that CLDN 12 expression could be clinically useful for predicting the survival of the ER-negative subgroup of patients with breast cancer.