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

S. Khan1, M. Blackburn2, D-L. Mao3, R. Huber4, D. Schlessinger4 and M. Fant1

Departments of 1Pediatrics and 2Biochemistry and Molecular Biology, University of Texas-Houston Medical School, Houston, Texas, 3Department of Pediatrics, Washington University School of Medicine, St. Louis, Mo, and the
4Laboratory of Molecular Genetics, National Institute on Aging, National Institute of Health, Baltimore, Maryland, USA

Offprint requests to: Michael Fant, M.D., Ph.D., University of Texas-Houston Medical School, Department of Pediatrics, MSB 3.236 6431 Fannin, Houston, Texas, USA. e-mail: michael.e.fant@uth.tmc.edu

Summary. The expression of glypican-3 (GPC3), a heparan-sulfate proteoglycan associated with the Simpson-Golabi-Behmel fetal overgrowth syndrome, was studied in normal human placental tissue and cell lines derived from human placentae. Cytotrophoblasts derived from term placentae expressed GPC3 mRNA at low levels in culture. GPC3 mRNA expression increased markedly during trophoblast differentiation. By contrast, fibroblast cell lines derived from normal placentae did not express GPC3 in culture. Similarly, choriocarcinoma cell lines derived from human placentae (BeWo, JAR, and JEG) failed to express GPC3 mRNA. In situ hybridization confirmed the localization of GPC3 mRNA to the syncytiotrophoblast. Furthermore, immunohistochemical staining of paraffin imbedded placental tissue demonstrated intense staining of the syncytiotrophoblast cell layer and less intense staining of cytotrophoblasts. No staining of mesenchymal elements was noted. These data confirm the presence of GPC3 in human placenta and suggest it is expressed by the differentiated syncytiotrophoblast at term. Histol. Histopathol. 16, 71-78 (2001)

Key words: Placenta, Glypican-3, Trophoblast, Choriocarcinoma

DOI: 10.14670/HH-16.71