Estradiol promotes epithelial-to-mesenchymal transition in human benign prostatic epithelial cells

Background Epithelial-to-mesenchymal transition (EMT) is involved in pathogenesis of human benign prostatic hyperplasia (BPH). Estrogenic signaling pathways may stimulate the induction of EMT. However, the details of estradiol (E2) and estrogen receptors (ERs) effects on EMT, as well as E2-induced modulation of benign prostatic epithelial cell phenotype in vitro have not been completely clarified. Methods The effects of E2 on EMT markers and cytokeratins (CKs) expression were evaluated in benign epithelial cell lines BPH-1 and RWPE-1, which were cultured both in two-dimensional (2D) culture and three-dimensional (3D) culture model using hanging drop technique or 3D Matrigel model. ER antagonist, ICI182,780, was used to confirm the regulatory effects of E2 on EMT and phenotypic modulation. In 3D culture, immunohistochemical stainings were performed to detect the specific phenotype of cells that underwent EMT in acinar-like spheroids formed by RWPE-1. To illustrate the exact function of ERs in E2-induced EMT and phenotypic modulation, specific short interfering RNAs (siRNAs), and agonists were used to knockdown or activate individual ERs, respectively. Results E2-induced EMT was observed both in 2D and 3D culture, with related regulation of EMT markers expression at both mRNA and protein level. In addition, E2 down-regulated luminal cell type markers CK18 and CK8 and up-regulated basal cell type markers CK5 and CK14. E2 also increased intermediate type markers CK15 and CK17, while it attenuated CK19 in 3D culture. ICI182,780 blocked E2-induced EMT and cell phenotypic switching. In 3D Matrigel culture, Vimentin was co-expressed with ERα and CK17, as well as with SMemb, which is related to cell status switching and proliferation. Knockdown of ERα but not GPR30 inhibited EMT, while ERβ knockdown facilitated EMT process. Knockdown of ERα blocked E2-induced EMT both in RWPE-1 and BPH-1. MRNA expression of EMT markers was stimulated by ERα-specific agonist PPT and inhibited by ERβ-specific agonist DPN. Conclusions Estrogenic effect mediated by ERα can promote EMT. E2 is also an inductive factor of cell phenotypic switching. Cell type modulation is associated with E2-induced EMT in benign prostatic epithelial cells. Taken together the results support a contribution of estrogens to the pathogenesis of BPH in elderly men.