In vitro cultured human term cytotrophoblast: a model for normal primary epithelial cells demonstrating a spontaneous differentiation programme that requires EGF for extensive development of syncytium.
Normal human term cytotrophoblast cells prepared by trypsin-DNAse I digestion with and without secondary immunological purification with CD9 antibodies were investigated for the expression of morphological and genetic markers of proliferation and differentiation. After 24 h of culture, the cell preparations demonstrated spontaneous formation of microvilli and formation of small syncytial units as assessed by desmoplakin staining and FITC-dextran microinjection. EGF was required for mature syncytial formation. Compared to log-phase proliferating HeLa cells, uptake of [3H]thymidine incorporation was low and quickly decreased to negligible levels. Expression of the proto-oncogenes c-myc, c-fos, and c-jun and histone 2A decreased rapidly in the first 24 h of culture in both cell preparations, followed by an increase in expression of c-fos and junB over the next 3 days of culture. Proto-oncogene changes were similar in attached and suspension cells. Spontaneous increases in alpha hCG, pregnancy-specific beta(1)-glycoprotein and 3 beta-hydroxysteroid dehydrogenase (3 beta OHSD) occurred within 1 day in both cell preparations. EGF receptor blocking antibodies did not inhibit minor degrees of spontaneous syncytial formation nor inhibit spontaneous expression of alpha hCG or 3 beta OHSD mRNA, but did prevent extensive synctialization induced by EGF. The results demonstrate that term cytotrophoblast cells even in serum-free conditions or suspension culture rapidly commit to a non-proliferative differentiation program in culture which includes limited syncytialization and marked hormone mRNA expression. However, EGF is required for extensive syncytial development.
Morrish
D W
DW
Signal Transduction Laboratories, University of Alberta, Edmonton, Canada.
Dakour
J
J
Li
H
H
Xiao
J
J
Miller
R
R
Sherburne
R
R
Berdan
R C
RC
Guilbert
L J
LJ
D015096:3-Hydroxysteroid Dehydrogenases / Q000235:genetics; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D004847:Epithelial Cells; D005260:Female; D015870:Gene Expression; D015726:Giant Cells / Q000166:cytology*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D011247:Pregnancy; D000090063:Proto-Oncogene Mas; D011519:Proto-Oncogenes / Q000235:genetics; D014327:Trophoblasts / Q000166:cytology*
C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D004815:Epidermal Growth Factor; D015096:3-Hydroxysteroid Dehydrogenases