VEGF-A regulates sFlt-1 production in trophoblasts through both Flt-1 and KDR receptors

Studies have shown that sFlt-1 overproduction stimulated by excess VEGF of deciduous origin in trophoblasts can cause preeclampsia. However, the mechanism underlying how VEGF regulates sFtl-1 expression in trophoblasts remains unknown. To address this issue, JEG3 and HTR-8/SV neo (HTR8) trophoblast cell lines were used to investigate the signaling pathways involved in the regulation of sFlt-1 production via VEGF overexpression in vitro. JEG3 (VEGF-GFP-JEG3, V-J) and HTR8 (VEGF-GFP-HTR8, V-H) cells overexpressing VEGF165 were established by infecting the JEG3 and HTR8 cell lines with lentivirus expressing VEGF165. Both the mRNA and protein levels of VEGF and sFlt-1 were dramatically up-regulated in the V-J and V-H cells compared to the JEG3 and HTR8 cells, and they were significantly decreased after treatment with an Flt-1 receptor inhibitor (MK-2461), a KDR receptor inhibitor (XL-184), or an Flt-1 and KDR receptor inhibitor (ABT-869). The mRNA levels of sFlt-1, Flt-1, and KDR were increased in V-H cells after treatment, and the VEGF-A mRNA levels were also elevated. The migration and invasion abilities of JEG3 and HTR8 cells were decreased after VEGF overexpression, and this reduction could be reversed with VEGF receptor inhibitor treatment. In addition, after the different treatments, the cell migration rates of V-J cells were significantly increased compared with the control treatment. Taken together, these results indicate that sFlt-1 up-regulation by VEGF may be mediated by the VEGF/Flt-1 and/or VEGF/KDR signaling pathways. However, elucidating which pathway plays this key role requires further investigation.