Estrogen and progestin regulate metastasis through the PI3K/AKT pathway in human ovarian cancer

Estrogen and progestin are involved in ovarian carcinogenesis. Change in nm23-H1 expression and the PIK3/AKT pathway are involved in carcinogenesis, development, invasion and metastasis of ovarian cancers. Therefore, it is critical to understand the signaling pathways that regulate hormone-induced cell migration and invasion in ovarian cancer. We investigated nm23-H1, AKT and pAKT expression by using immunohistochemical staining in ovarian clear cell adenocarcinoma, ovarian benign, borderline and malignant serous tumors and analyzed their relationship with prognostic factors. Using ES-2 and SKOV-3 ovarian cancer cell lines, we studied the modulation of estrogen and progestin on cell migration and invasion as well as their effect on AKT, pAKT and nm23-H1 expression. Furthermore, the signaling pathways were examined using pharmacological inhibitors (LY294002 and PD98059) or AKT siRNA combined with estrogen or progestin in the two cell lines. Weak nm23-H1 and high AKT and pAKT expression was observed in ovarian serous adeno-carcinoma and ovarian clear cell adenocarcinoma. Our data demonstrated that the expression of nm23-H1 was negatively correlated with tumor stage and grade and lymph node metastasis, whereas the expression of AKT/pAKT was positively correlated with these clinic factors. Estrogen up-regulated pAKT expression and reduced nm23-H1 expression, which ultimately resulted in increased cell migration and invasion. In contrast, progestin reduced pAKT expression and increased nm23-H1 expression, which inhibited cell migration. PIK3 kinase inhibitor LY294002 antagonized the effect of estrogen. On the other hand, it reinforced the effect of progestin. Our data suggest that AKT and pAKT are unfavorable prognostic factors for ovarian serous adenocarcinoma and clear cell carcinomas whereas nm23-H1 expression predicates favorable patient prognosis. Estrogen down-regulates nm23-H1 expression and promotes cell migration and invasion by activating the PIK3/AKT pathway. Progestin has an opposing effect.