REPRODUCTIVE ENDOCRINOLOGYAND INFERTILITY FELLOWS' RESEARCH

OBJECTIVE: Evidence suggests that disruption of LH-induced transactivation of the epidermal growth factor (EGF) signaling network in a murine model impairs fertility. We have previously shown the EGF-like growth factor amphiregulin (AREG) in human follicular fluid (FF) is a mediator of cumulus cell expansion. We sought to further characterize EGF-like ligands in FF, evaluate EGF receptor subtype expression in mural and cumulus granulosa cells (GC) and assess whether production of these ligands is associated with clinical outcomes. DESIGN: Prospective cohort with in vitro studies. MATERIALS AND METHODS: Human FF, mural and cumulus GCs were obtained from patients undergoing IVF. EGF receptor isoform expression was evaluated by quantitative RT-PCR. AREG biologic activity was assessed by cumulus oocyte complex (COC) expansion and mitogenic assays. Pooled FF from individuals was used to characterize EGF-like ligands and the mouse COC expansion assay. FF from single dominant follicles was used to evaluate AREG with oocyte outcomes of fertilization, nuclear maturation, and early embryo development. RESULTS: Cumulus GCs express higher levels of EGF receptor isoforms than mural GCs. Selective immunoprecipitation of AREG completely blocks the ability of human FF to induce mouse COC expansion, while the overall mitogenic signaling remains unchanged. FF AREG is positively correlated with FF hCG (p¼0.016). AREG is significantly lower in abnormally fertilized oocytes and germinal vesicle oocytes compared to normally fertilized oocytes (means 25.0, 19.1, 33.1 ng/ml respectively; ANOVA p¼0.008). CONCLUSIONS: AREG is expressed at high levels in human FF, and follicular AREG is correlated with follicular hCG. AREG is lower in follicles producing abnormally fertilized or germinal vesicle oocytes, consistent with the idea that this growth factor is important for oocyte maturation. Future work will elucidate whether levels of AREG are correlated with oocyte maturation and embryo quality. Supported by: NIH grants HD 1R01HD058939, 5R01HD020788, and 5R01GM080527.