Progesterone enhances HLA-G gene expression in JEG-3 choriocarcinoma cells and human cytotrophoblasts in vitro

BACKGROUND: Evidence suggests that HLA-G plays a critical role in maternal immune tolerance to the fetus. However, regulation of HLA-G gene expression is not well understood. Many studies have suggested that progesterone may also be important in suppressing maternal immune response to the fetus. Therefore, we hypothesized that this steroid hormone may play a role in regulating HLA-G gene expression. The objective of the study was to explore potential effects of progesterone on HLA-G gene expression in vitro. METHODS: Cultured first trimester trophoblasts and JEG-3 choriocarcinoma cells were treated with progesterone and its antagonist RU486. HLA-G gene transcription was determined by real-time PCR while HLA-G translation was investigated by a specific enzyme-linked immunosorbent assay for HLA-G and western blot analysis. RESULTS: HLA-G mRNA and protein expression in trophoblasts and JEG-3 cells were elevated by progesterone in dose- and time-dependent manners. The effect of progesterone can be completely inhibited by co-incubation with RU486 at the same concentrations. CONCLUSION: Progesterone has an up-regulatory effect on HLA-G gene expression in first trimester trophoblasts and JEG-3 cells in vitro.