Leukemia inhibitory factor (LIF) stimulates the human HLA-G promoter in JEG3 choriocarcinoma cells

HLA-G is a non-classic class I MHC molecule specifically expressed by human invasive cytotrophoblast cells, which has been suggested to play a role in facilitating the immune tolerance of the conceptus. So far, very little is known about the regulation of the human HLA-G gene. The present study was, thus, designed to investigate the regulation of the human HLA-G promoter. JEG3 choriocarcinoma cells, which express HLA-G endogenously, were used as a model. A 890 bp fragment of the human HLA-G promoter was amplified by nes ted PCR from genomic DNA, cloned into pCR-Script and, after sequencing, sub cloned into pGL3-Luc in front of the luciferase reporter gene. This vector was then used in transient transfection experiments in JEG3 cells. Parallel transfection experiments were performed using an alpha subunit (alpha SU)- Luc reporter plasmid as a control. Using this system, several potential mod ulating substances were tested in different concentrations and for differen t periods of time: phorbol ester FA), cAMP, IFN gamma, IL-1, and leukemia i nhibitory factor (LIF), with only LIF administration resulting in induction of the HLA-G promoter. LIF treatment also resulted in induction of HLA-G m RNA. JEG3 cells are shown to possess LIF receptors. LIF is a pleiotropic cy tokine produced at the maternal-fetal interface which has been shown to pla y an essential role in implantation in mice. LIF is produced in high amount s by the human endometrium and the trophoblast itself, and UF receptors are present on cytotrophoblast cells. LIF could, thus, play a role in modulati ng HLA-G production and immune tolerance at the maternal-fetal interface.