Epidermal growth factor (EGF) regulates trophoblast proliferation and endocrine function in synergy with thyroid hormone: A review

Abstract

In order to elucidate the role of EGF in human placental development, effects of EGF on the proliferation and endocrine function of trophoblast cells were investigated. Explants of trophoblastic tissues obtained from 4–5 week or 6–12 week placentae were, respectively, cultured with or without EGF, in the presence or absence of triiodo-L-thyronine (T3) in a serum-free condition. The proliferative activity was examined by immunocytochemical staining with an antibody to the proliferating cell nuclear antigen (PCNA), while the endocrine function was assessed by the ability to secrete hCG and hPL. In 4–5 week placentae, EGF and EGF receptor were localized in cytotrophoblast (C-cell) and EGF augmented the proliferation of C-cell without affecting the ability to secrete hCG and hPL. By contrast, in 6–12 week placentae, EGF and EGF receptor were localized in syncytiotrophoblast (S-cell) and EGF stimulated the secretion of hCG and hPL without affecting the proliferation of C-cell. In situ hybridization with c-erb B probe revealed that c-erb B mRNA is expressed in the S-cell after 6 weeks gestation. Column chromatography of the serum-free media obtained by 5-day culture of early placental tissues resulted in the elution of immunoreactive EGF. The addition of T3 (10 −8 mol/l) resulted in increased secretion of immunoreactive EGF by placental explants. These findings suggest that EGF acts as an autocrine factor in regulating early placental growth and function in synergy with thyroid hormone.