Background: Inhibins and activins are important regulators of the female reproductive system. Recently, a novel inhibin subunit, named betaE, has been identified and shown to be expressed in several human tissues. However, only limited data on the expression of this novel inhibin-betaE subunit in normal and pathological human placenta as well as and human chorionic carcinoma cell lines exist.
Materials and methods: Tissue specimens of normal, preeclamptic and HELLP pregnancies (n = 18) were obtained at the course of an cesarean section. Normal and pathological placental tissues as well as chorionic carcinoma cells (BeWo and JEG) were analyzed by using immunohistochemistry and RT-PCR.
Results: Expression of the inhibin betaE subunit could be demonstrated at the protein level by means of immunohistochemical evaluation and at the transcriptional level by betaE-specific RT-PCR analysis. The immunoreactive score for inhibin-betaE did not show any significant differences between normal, preeclamptic and HELLP tissue in extravillous trophoblast and syncytiotrophoblast cells. Expression of inhibin betaE could further be demonstrated for the human chorionic carcinoma cell lines JEG and BeWo.
Discussion: We demonstrated that inhibin-betaE is expressed in normal and pathological human placenta tissues. Although the precise role of this novel inhibin subunit for human placenta development is quite unclear, similarities with the well-characterized betaA- and betaB-subunits suggest an involvement in autocrine/paracrine signaling pathways, angiogenesis, decidualization and tissue remodeling under normal as well as malignant conditions. Additionally, the human chorionic carcinoma cell lines JEG and BeWo synthesize this subunit and therefore can be used as a cell culture model for further functional analysis of this subunit in human placental tissue.