Expression of amphiregulin and transforming growth factor alpha mRNA in gestational tissue at term

Abstract

Among epidermal growth factor (EGF) family growth factors, EGF, transforming growth factor-α (TGF-α) and amphiregulin (AR) are considered to exert their effects through binding to epidermal growth factor receptor (EGFR). Cripto (CR) is homologous to EGF in its structure, but it is postulated that it might not bind with EGFR. We examined localization of TGF-α, AR, CR and EGFR in human chorionic villi of various stages. Chorionic villi were collected from thirty-four cases. Immunohistochemistry was performed on 4% paraformaldehyde fixed and paraffin embedded specimens using an avidin biotin complex-perioxidase technique. TGF-α immunoreactivity was intense in the cytoplasm of the cytotrophoblast (CT), especially in first trimester. AR immunoreactivity was observed predominantly in the nuclei of the CT and some syncytiotrophoblast (ST) only in first trimester. EGFR immunoreactivity was intense in the ST, and weak in the CT and its frequency appeared to decrease as gestational period progressed. CR immunoreactivity was mainly observed in the ST, but marked heterogeneity was observed in its expression and its frequency appeared to increase as pregnancy progressed. Based on these findings, TGF-α is considered to act mainly in a paracrine manner in first trimester chorionic villi. AR is produced to modify the biological function of the trophoblast cells during the first trimester. In contrast, CR may modify ST function, especially during the third trimester.