Moesin is an independent prognostic marker for ER-positive breast cancer.

Moesin, a cytoskeletal protein belonging to the ezrin-radixin-moesin family serves important roles in cell motility, invasion and metastasis. Moesin has been demonstrated to be of prognostic significance in tumor progression, due to its role in the metastatic process; however, its role in breast cancer is not well characterized. In the present study, the moesin expression was determined using immunohistochemistry in 404 and 46 patients with breast cancer and fibroadenoma, respectively, and the associations between moesin expression and the clinical parameters and prognostic values were analyzed. The positive rate of moesin protein expression was 47.8% (193/404) in breast cancer tissues, which was significantly higher than in fibroadenoma tissues (15.2%, 14/46). Overexpression of moesin was significantly associated with advanced clinical stage (P=0.002), positive lymph node metastasis (P<0.0001), and estrogen receptor (ER; P=0.008) and progesterone receptor (P=0.026) status. Patients with high moesin expression had significantly lower recurrence-free survival time, compared with patient with low moesin expression. Notably, overexpression of moesin was significantly associated with poor prognosis in patients with ER-positive breast cancer, and in patients treated with tamoxifen. Using a Cox proportional hazard regression model, further analysis was conducted, which demonstrated that moesin overexpression was a predictive prognostic factor for reduced overall survival time in patients with ER-positive breast cancer, and in patients treated with tamoxifen. These results indicated that moesin may be a potential marker for poor prognosis in patients with ER-positive breast cancer treated with tamoxifen. In conclusion, moesin serves an important role in the progression of breast cancer, and may be a valuable marker of breast cancer prognosis.