Estrogen and progestin regulate HIF-1alpha expression in ovarian cancer cell lines via the activation of Akt signaling transduction pathway

Our previous study revealed that estrogen regulates nm23-H1 expression thus promoting cell migration-invasion via activating PIK3/Akt pathway. In this study, we explored the effect of hormone on hypoxia-inducible factor-1 (HIF-1alpha), a key factor in cancer invasion and metastasis, via activation of Akt signaling transduction pathway. We treated two ovarian cancer cell lines ES-2 and SKOV3 with 17beta-estradiol, methoxyprogesterone acetate (MPA) only, or hormone combined with and Akt, MAPK pathway inhibitor, or transefected with siRNA targeting Akt sequenced with hormone. Expression of HIF-1alpha was measured by Western blotting. We observed the effect of hormone on nm23-H1 expression after the cells were transfected by siRNA targeting HIF-1alpha or treated with CoCl2 to induce HIF-1alpha overexpression. The 17beta-estradiol increased HIF-1alpha expression in ovarian cancer cells, and this upregulatory effect was abrogated by Akt inhibitor LY294002 (P