miR‐491‐5p functions as a tumor suppressor by targeting JMJD2B in ERα‐positive breast cancer

The involvement of miR‐491‐5p in breast cancer development is unclear. This study showed that miR‐491‐5p is significantly downregulated in ERα‐positive breast cancer tissues and cell lines and is generally hypermethylated in ERα‐positive breast cancer. MiR‐491‐5p overexpression significantly suppressed estrogen signaling and estrogen‐stimulated proliferation of breast cancer cells. Furthermore, the histone demethylase JMJD2B was identified as a direct target of miR‐491‐5p. The ectopic expression of JMJD2B abrogated the phenotypic changes induced by miR‐491‐5p in breast cancer cells. Collectively, our data indicate that miR‐491‐5p plays a tumor suppressor role in the development and progression of breast caner and may be a novel therapeutic target against ERα‐positive breast cancer.