Trophoblast subtype-specific EGFR/ERBB4 expression correlates with cell cycle progression and hyperplasia in complete hydatidiform moles.
OBJECTIVE
Do trophoblast subtypes differ in their expression of erythroblastic leukaemia viral oncogene homologue (ERBB) receptor family members and responsiveness towards specific growth factor ligands?


CONCLUSIONS
Our data reveal a reciprocal expression pattern of epidermal growth factor receptor (EGFR)/ERBB4 in proliferative and ERBB2/ERBB3 in invasive trophoblast subtypes, as well as a restricted responsiveness to epidermal growth factor (EGF) and heparin-binding (HB)-EGF.


BACKGROUND
EGFR is expressed by villous cytotrophoblasts (vCTBs), but absent from extravillous trophoblasts (EVTs), which specifically up-regulate ERBB2.


METHODS
Tissue samples of human first trimester placentae (n = 50) and deciduae (n = 5) obtained from elective pregnancy terminations were used to study trophoblast subtype-specific ERBB receptor expression and responsiveness to recombinant human EGF and HB-EGF. Age-matched complete hydatidiform mole (CHM) placentae (n = 12) were assessed for EGFR and ERBB4 expression in proliferation-competent regions.


METHODS
ERBB receptor expression was analysed in primary trophoblast cell isolates by means of microarray, quantitative real-time PCR and western blotting, as well as immunofluorescence stainings of placental and decidual tissue sections. EGF and HB-EGF were tested for their potential to activate ERBB receptors in purified EGFR(+) and HLA-G(+) trophoblasts. 5-Ethynyl-2'-deoxyuridine incorporation assays were performed to study the effect of both ligands on the proliferative capacity of primary trophoblasts as well as of vCTBs and proximal cell column trophoblasts (pCCTs) in placental floating explants. Finally, the average number of EGFR(+) vCTB and pCCT layers was determined in CHM placentae and compared with healthy age-matched controls.


RESULTS
Proliferative vCTBs and pCCTs co-express EGFR and ERBB4, but are devoid of ERBB2 and ERBB3. In contrast, HLA-G(+) trophoblast subtypes exhibit an EGFR/ERBB4(-) and ERBB2/ERBB3(+) phenotype. EGF and HB-EGF activate EGFR, ERBB4, AKT and extracellular signal-regulated kinase 1/2 in EGFR(+) primary trophoblasts; however, they do not show an effect on HLA-G(+) EVTs. Both ligands strongly induce cell cycle progression in primary trophoblasts (P < 0.05) and placental explant-associated vCTBs (P < 0.05) and pCCTs (P < 0.05). Notably, EGFR(+) vCTB (P < 0.0001) and pCCT (P < 0.0001) layers are significantly expanded in CHM placentae when compared with healthy controls.


CONCLUSIONS
Cells were removed from their physiological context and may therefore respond differently to various stimuli.


CONCLUSIONS
In this study we define EGFR as a marker for proliferative trophoblast subtypes within the human placenta. Manipulation of EGFR signalling might thus offer a promising therapeutic avenue for the treatment of molar pregnancies associated with trophoblast hyperplasia.


BACKGROUND
This study was supported by the Austrian Science Fund (grant P-25187-B13 to J.P.). There are no competing interests to declare.
Department of Obstetrics and Fetal-Maternal Medicine, Reproductive Biology Unit, Medical University of Vienna, Währinger Gürtel 18-20, 5Q, 1090, Vienna, Austria.
Valerie
V
Fock
Department of Obstetrics and Fetal-Maternal Medicine, Reproductive Biology Unit, Medical University of Vienna, Währinger Gürtel 18-20, 5Q, 1090, Vienna, Austria.
Kerstin
K
Plessl
Department of Ecology and Evolution, Neurosignaling and Neuroecology Unit, University of Salzburg, Salzburg, Austria.
Roman
R
Fuchs
Clinical Institute of Pathology, Medical University of Vienna, Vienna, Austria.
Sabine
S
Dekan
Department of Obstetrics and Fetal-Maternal Medicine, Reproductive Biology Unit, Medical University of Vienna, Währinger Gürtel 18-20, 5Q, 1090, Vienna, Austria.
Stephanie K
SK
Milla
Department of Obstetrics and Fetal-Maternal Medicine, Reproductive Biology Unit, Medical University of Vienna, Währinger Gürtel 18-20, 5Q, 1090, Vienna, Austria.
Sandra
S
Haider
Gynmed Clinic, Vienna, Austria.
Christian
C
Fiala
Department of Obstetrics and Fetal-Maternal Medicine, Reproductive Biology Unit, Medical University of Vienna, Währinger Gürtel 18-20, 5Q, 1090, Vienna, Austria.
Martin
M
Knöfler
Department of Obstetrics and Fetal-Maternal Medicine, Reproductive Biology Unit, Medical University of Vienna, Währinger Gürtel 18-20, 5Q, 1090, Vienna, Austria juergen.pollheimer@meduniwien.ac.at.
Jürgen
J
Pollheimer
D002453:Cell Cycle; D049109:Cell Proliferation; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D066257:Heparin-binding EGF-like Growth Factor / Q000378:metabolism; D006801:Humans; D006828:Hydatidiform Mole / Q000378:metabolism*; D008024:Ligands; D008856:Microscopy, Fluorescence; D020411:Oligonucleotide Array Sequence Analysis; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D060888:Real-Time Polymerase Chain Reaction; D066247:Receptor, ErbB-4 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D014327:Trophoblasts / Q000166:cytology* / Q000378:metabolism; D015854:Up-Regulation
D066257:Heparin-binding EGF-like Growth Factor; D008024:Ligands; D011994:Recombinant Proteins; D004815:Epidermal Growth Factor; C512478:EGFR protein, human; C587689:ERBB4 protein, human; D066246:ErbB Receptors; D066247:Receptor, ErbB-4
ERBB receptor; complete hydatidiform mole; epidermal growth factor; extravillous trophoblast; proliferation