Endocrine Abstracts

Introduction: Decidualisation of the endometrial stromal cell (ESC) is pivotal for successful implantation and is initiated in response to increasing progesterone levels. Transforming Growth Factor-β1 (TGFβ-1), a potent cytokine involved in many diverse cellular responses, is activated from the latent form in the mid-late secretory phase. Previous reports suggest that TGFβ-1 might oppose the action of progesterone, although no mechanism has been proposed. We have investigated whether TGFβ-1 may have an effect on progesterone receptor (PR) expression or function and inhibit decidualisation.

Methods: Quantitative real time PCR (TaqMan) and Promoter-Reporter studies were used to investigate the role of TGFβ-1 in mediating nuclear PR expression and the decidualisation markers, IGFBP-1 and Prolactin expression, within ESCs decidualised in vitro. ESCs were isolated from patients undergoing gynaecological procedures for benign indications. Institutional ethical approval and written informal consent were obtained.

Results: TGFβ-1 (10 ng/ml, 2 h) upregulated nuclear PR expression in decidualised ESCs 2-fold (P<0.001) (n=5) however, at 12 h, 24 h and 36 h this upregulation was not seen. At 72 hours the nuclear PR mRNA expression levels were significantly downregulated 2-fold (P<0.05) (n=5). Western blotting and immunocytochemistry validated protein expression. The Promoter-Reporter study demonstrated that TGFβ-1 does not interfere with the transactivation potential of PR, indicating that the TGFβ-1 effect on PR expression is due to a decrease in genomic PR. IGFBP-1 and Prolactin mRNA and protein levels are downregulated with addition of TGFβ-1 indicating that TGFβ-1 inhibits decidualisation.

Summary: We have shown that TGFβ-1 interacts with progesterone, via its receptor, and could inhibit the decidualisation process. These findings highlight the complexity of interactions controlling the hormonal responses of the endometrial stromal cell.