17β-Estradiol via Orai1 activates calcium mobilization to induce cell proliferation in epithelial ovarian cancer.

Epithelial ovarian cancer (EOC) is the most lethal estrogen-sensitive gynecological cancer. Studies have reported that estrogen induces rapid cellular calcium mobilization in cells and can determine the fate of a cell. We found that estrogen increased the calcium release-activated calcium channel modulator 1 (Orai1) protein expression levels in SK-OV-3 cells. However, to date, there has been no research on the functional relationship and molecular mechanism of estrogen-regulating Orai1 during EOC development. In our study, Orai1 had a high expression level in high-grade serous ovarian tumor tissues and SK-OV-3 cells. Estrogen promoted cell proliferation and migration while inhibiting cell apoptosis in SK-OV-3 cells. Orai1 silencing suppressed estrogen-induced cell migration and proliferation. Overexpression of Orai1, however, enhanced the ability of 17β-estradiol (E2) to exert its function. Estrogen induced rapid calcium influx in SK-OV-3 cells. Knockdown of Orai1 in SK-OV-3 cells blocked E2-induced stored-operated Ca influx. The messenger RNA expression of caspase 3, matrix metallopeptidase 1, and cyclin-dependent kinase 6 were regulated via Orai1 under E2 treatment. Our results suggest that estrogen, by regulating Orai1, induced calcium influx to determine cell fate.