Glypican-3 (GPC3) expression in human placenta: localization to the differentiated syncytiotrophoblast

The expression of glypican-3 (GPC3), a heparan-sulfate proteoglycan associa ted with the Simpson-Golabi-Behmel fetal overgrowth syndrome, was studied i n normal human placental tissue and cell lines derived from human placentae . Cytotrophoblasts derived from term placentae expressed GPC3 mRNA at low l evels in culture. GPC3 mRNA expression increased markedly during trophoblas t differentiation. By contrast, fibroblast cell lines derived from normal p lacentae did not express GPC3 in culture. Similarly, choriocarcinoma cell l ines derived from human placentae (BeWo, JAR, and JEG) failed to express GP C3 mRNA. In situ hybridization confirmed the localization of GPC3 mRNA to t he syncytiotrophoblast. Furthermore, immunohistochemical staining of paraff in imbedded placental tissue demonstrated intense staining of the syncytiot rophoblast cell layer and less intense staining of cytotrophoblasts. No sta ining of mesenchymal elements was noted. These data confirm the presence of GPC3 in human placenta and suggest it is expressed by the differentiated s yncytiotrophoblast at term.