Our results might contribute to understanding the mechanisms of CLDN4 regulation and suggest PAK4-CEBPB-CLDN4 axis as a potential therapeutic target for breast cancer.
In conclusion, significant changes in the expression of claudin-1 and -3 but not in the expression of claudin-4, E- and N-cadherin were observed in samples taken from patients with BC following chemotherapy.
BRCAmut tumors bear stem cell characteristics displaying a distinct cell adhesion molecule profile characterized by high expression of CDH1 and CLDN4 according to public gene expression data set analysis, and higher claudin-3 expression as detected by IHC; thus, BRCAmut breast carcinomas are not identical with the previously identified claudin-low subtype of breast cancer.
Western blot analysis revealed a possible correlation between claudin-4 and -6 expression in breast cancer cell lines and tumor aggressiveness, with protein levels correlating with the ability to form vascular channels.
High claudin-4 expression was also associated with worse breast cancer-specific survival (p = 0.003), recurrence-free survival (p = 0.025) and overall survival (p = 0.034).
High claudin-4 expression was also associated with worse breast cancer-specific survival (p = 0.003), recurrence-free survival (p = 0.025) and overall survival (p = 0.034).
However, CLDN4 was highly positive in normal epithelial cells and was decreased or absent in 17 out of 21 ductal carcinoma grade 1, in special types of breast carcinoma (mucinous, papillary, tubular) and in areas of apocrine metaplasia.