Correlation between microRNA-21, microRNA-206 and estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 in breast cancer

Background: Although the function of microRNA-21 and microRNA-206 in breast cancer cells have been investigated in vitro, their association with estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) are not reported. Methods: ER, PR, HER2, and Ki-67 staining pattern were utilized to classify 75 breast cancer patients recruited. The malignancy was predicted with tumor nodes metastases (TNM) classification. RT-qPCR was performed to detect the relative expression of ER, PR, and HER2 in tumor samples and microRNA-21 and microRNA-206 in the serum. Spearman's correlation analysis was used to determine the association between different molecules. According to the staining pattern, the breast cancer patients were classified into five types. Results: microRNA-21 was up-regulated in HER2 positive and Basal-like breast cancer types, while microRNA-206 was up-regulated in Luminal A and B types of breast cancer. microRNA-21 expression negatively correlated with the level of ER and PR but positively correlated with HER2 expression and tumor malignancy, while microRNA-206 showed the opposite trend. Neither microRNA-21 nor microRNA-206 showed any significant correlation with the age of the patients. Conclusion: Both microRNA-21 and microRNA-206 closely correlate with ER, PR, and HER2 expression, which can be considered as clinical biomarkers.