Estrogen receptor β-mediated inhibition of actin-based cell migration suppresses metastasis of inflammatory breast cancer.

Inflammatory breast cancer (IBC) is a highly metastatic breast carcinoma with high frequency of estrogen receptor α (ER)α-negativity. Here we explored the role of the second ER subtype, ERβ, and report expression in IBC tumors and its correlation with reduced metastasis. Ablation of ERβ in IBC cells promoted cell migration and activated gene networks that control actin reorganization, including G-protein coupled receptors and downstream effectors that activate Rho GTPases. Analysis of preclinical mouse models of IBC revealed decreased metastasis of IBC tumors when ERβ was expressed or activated by chemical agonists. Our findings support a tumor-suppressive role of ERβ by demonstrating the ability of the receptor to inhibit dissemination of IBC cells and prevent metastasis. Based on these findings, we propose ERβ as a potentially novel biomarker and therapeutic target that can inhibit IBC metastasis and reduce its associated mortality.