Dysregulated claudin expression significantly effect breast cancer disease progression.

Abstract

In this study, the role of claudins in cancer progression was explored among breast cancer-affected women. Two cohorts (discovery and validated) of breast cancer-affected women were used. In discovery cohort, 90 freshly excised breast tumor tissues along with adjacent cancer free specimens were collected at the time of surgery. These specimens were processed for RNA isolation and complementary DNA synthesis. After designing primers for claudin 3, claudin 4, and claudin 7, these sequences were synthesized from Macrogen, Korea. Claudin expression in respective tumors and controls was assessed using quantitative reverse transcription polymerase chain reaction. Any probable correlation of these molecules with various clinicopathological parameters was explored. For validation, a publicly available dataset of 2088 breast cancer patients was accessed. Claudin expression of these patients was analyzed for given clinical parameters and compared with earlier findings of discovery cohort. Discovery cohort comprised 17% luminal A, 63% luminal B, 8% human epidermal growth factor receptor 2 enrich, and 12% triple-negative breast cancer tumor. High claudin 3 expression was significantly correlated with tumor size >2 cm and menopausal status. Claudin 7 expression was upregulated among poorly differentiated tumor patients. Both claudins 3/4 showed significant correlation with tumor grade, stage, size, and metastasis. Claudin-low subtype was also found in 18% of the cohort. Claudins impart a significant role in cell differentiation and disease progression. Hence, claudin cluster can be ascertained as the disease biomarkers for breast cancer.