Vascular endothelial growth factor stimulates proliferation but not migration or invasiveness in human extravillous trophoblast.
Vascular endothelial growth factor (VEGF) is a homodimeric glycoprotein that promotes angiogenesis and vascular hyperpermeability and interacts with two receptors, fms-like tyrosine kinase (Flt-1) and kinase domain-containing region (KDR). In situ localization in the pregnant human uterus revealed that VEGF mRNA is expressed primarily by the maternal decidua, whereas the receptor Flt-1 is expressed primarily by chorionic vascular endothelium and trophoblast cells-in particular, the extravillous trophoblast (EVT). We examined whether the mRNA and protein of VEGF and its receptors are expressed by invasive human first-trimester EVT cells propagated in culture and whether VEGF influences EVT cell proliferation, migration, and invasiveness. Proliferation was assessed by the uptake of [3H]thymidine. Invasion and migration across transwells were assessed by the degree of cellular transgression of a Millipore membrane coated, respectively, with and without Matrigel. Results of immunocytochemical and reverse transcription-polymerase chain reaction analysis revealed that both protein and mRNA of VEGF, Flt-1, and KDR were expressed by cultured normal EVT cells as well as their premalignant derivative produced by SV-40 Tag-immortalization, and BeWo choriocarcinoma cells. Under serum-free conditions, exogenous VEGF121 (the non-heparin-binding isoform) stimulated proliferation of all three cell lines in a concentration-dependent manner. The effects were abolished with a VEGF-neutralizing antibody. The same stimulatory effects on EVT cells were also seen with exogenous VEGF165 (a heparin-binding isoform), only after a cleaving of the heparin-binding domain with plasmin or a blocking of heparin binding sites with excess soluble heparan sulphate proteoglycans (HSPGs), suggesting a regulatory role of HSPGs. However, VEGF121 and VEGF165 (with and without the HSPG pretreatment) had no effect on normal EVT cell migration or invasiveness. Thus, VEGF may provide a dual role in angiogenesis and EVT cell proliferation during normal placental development.
Athanassiades
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Department of Anatomy and Cell Biology, The University of Western Ontario, London, Ontario, Canada N6A 5C1.
Hamilton
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Lala
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D002455:Cell Division; D003656:Decidua / Q000737:chemistry; D016228:Endothelial Growth Factors / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008222:Lymphokines / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011518:Proto-Oncogene Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D012194:RNA-Directed DNA Polymerase; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D017978:Receptors, Growth Factor / Q000235:genetics; D040262:Receptors, Vascular Endothelial Growth Factor; D014327:Trophoblasts / Q000502:physiology*; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D017978:Receptors, Growth Factor; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor; D040281:Vascular Endothelial Growth Factor Receptor-1; D012194:RNA-Directed DNA Polymerase