Decreased expression of claudin-1 correlates with recurrence status in breast cancer

Claudins (CLDNs) constitute the major transmembrane proteins of tight junctions. It may be hypothesized that changes in or loss of expression of tight junctional proteins such as CLDNs can lead to cellular disorientation and detachment, which is commonly seen in neoplasia. Recent studies have suggested that claudin-1 (CLDN1) plays an important role in invasion and metastasis and claudin-4 (CLDN4) has a particular role in mammary glandular cell differentiation and carcinogenesis. In this study, we examined 83 breast cancer cases and demonstrated immunohistochemical expression patterns of CLDN1/CLDN4 in recurrent and non-recurrent groups. We found significant results between the recurrent and non-recurrent group for expression of CLDN1/CLDN4. The recurrent group (26 cases) showed decreased expression patterns of CLDN1 (p<0.001), compared to the non-recurrent group (57 cases). Decreased expression of CLDN1 (p<0.0001) correlated with short disease-free interval. The lymph node metastasis-positive group showed decreased expression patterns of CLDN1 (p=0.001). However, there was no significance between the recurrent group and non-recurrent group in CLDN4 expression. There was no significance between histological factors and CLDN4 expression. The results indicated that CLDN1 expression correlated with the recurrence status and malignant potential of breast cancer.