microRNA-206 overexpression inhibits cellular proliferation and invasion of estrogen receptor α-positive ovarian cancer cells.

The expression levels of estrogen receptor (ER α) are closely associated with estrogen-dependent growth, invasion and response to endocrine therapy in ERα-positive ovarian cancer. However, the underlying regulatory mechanisms remain to be fully understood. Previous studies have demonstrated that ERα is a direct target of microRNA (miR)-206. miR-206 has been found to be an important tumor suppressor in several cancer types, including ovarian, gastric and laryngeal cancer. However, the specific role of miR-206 in ovarian cancer remains unclear. The aim of the present study was to investigate the role of miR-206 in ER-a positive ovarian cancer in vitro. The present study demonstrated that miR-206 is significantly downregulated in ERα-positive but not ERα‑negative ovarian cancer tissues, compared with normal ovarian epithelium tissue. It was also found that the expression of miR-206 was decreased in ERα-positive ovarian cancer cell lines, CAOV-3 and BG-1, compared with normal ovarian epithelium tissues. This suggests that miR-206 may play a role in ERα-positive ovarian cancer cells via an estrogen-dependent mechanism. Further analysis revealed that 17β-E2 treatment significantly promoted cellular proliferation and invasion of estrogen-dependent CAOV-3 and BG-1 cells, which could be reversed by the introduction of miR-206 mimics. In conclusion, the present study suggests that miR-206 has an inhibitory role in estrogen-dependent ovarian cancer cells. Thus, miR-206 may be a promising candidate for the endocrine therapy of ERα-positive ovarian cancer.