Regulatory Effects of Gonadotropin-Releasing Hormone (GnRH) I and GnRH II on the Levels of Matrix Metalloproteinase (MMP)-2, MMP-9, and Tissue Inhibitor of Metalloproteinases-1 in Primary Cultures of Human Extravillous Cytotrophoblasts

An intricate balance between the production of matrix metalloproteinases (MMPs) and their endogenous inhibitors, tissue inhibitors of metalloproteinases (TIMPs), modulates the overall proteolytic activity of trophoblasts during human implantation. In these studies we have examined the ability of classical GnRH I and the second form of this hormone (GnRH II) to regulate MMP-2, MMP-9, and TIMP-1 mRNA and protein levels in extravillous cytotrophoblasts propagated from explants of first trimester chorionic villi. GnRH I and GnRH II were found to increase MMP-2 and MMP-9 mRNA and protein levels in these primary cell cultures in a dose- and time-dependent manner using quantitative competitive-PCR and ELISA. In contrast, these two hormones decreased trophoblastic TIMP-1 mRNA and protein levels. Cetrorelix, a GnRH receptor antagonist, inhibited the regulatory effects of GnRH I, but not GnRH II, on MMP-2, MMP-9, and TIMP-1 expression in these cells. Collectively, these observations suggest that GnRH I and GnRH II differentially regulate MMP-2, MMP-9, and TIMP-1 expression in human trophoblasts, possibly via distinct receptor-mediated intracellular signaling pathways.