EGF-like growth factors as LH mediators in the human corpus luteum

BACKGROUND: This study aims to investigate the role of epidermal growthfactor-like ligands, amphiregulin (Ar) and epiregulin (Ep),in regulation of apoptosis in luteinized human granulosa cells. METHODS: Luteinized human granulosa cells were obtained from women undergoingIVF treatment. Ar and Ep mRNA levels were measured by real-timeRT–PCR. The rate of apoptosis was measured by TUNEL. Progesteronelevels were measured using radioimmunoassay. Ar- and Ep-inducedactivation of signaling cascades and Ar protein levels weredetected by western blotting. RESULTS: LH stimulation of luteinized human granulosa cells induced biosynthesisof Ar and Ep mRNA in a time-dependent manner. The blockade ofMEK (by U0126) reduced the expression of LH-induced Ar and Epbiosynthesis. Incubation of the cells with Ar and Ep completelyabolished the increase in apoptosis rate induced by serum starvation,and concomitantly caused a pronounced increase in progesteroneproduction. Stimulation of the cells with Ar and Ep also activatedthe ERK and AKT signaling cascades. Finally, we demonstratedthat the pro-survival effect of Ar and Ep is partially dependenton their ability to induce progesterone production. CONCLUSIONS: Ar and Ep serve as pro-survival LH mediators in the human corpusluteum.