Regulation of vascular endothelial growth factor receptor KDR in vitro by a soluble factor in confluent endothelial cells.
Hypoxia regulates the expression of both vascular endothelial growth factor (VEGF) and its receptor (KDR). We have shown that cell density regulates VEGF expression in colon cancer and hypothesized that a similar mechanism regulates KDR in endothelial cells. Human umbilical vein endothelial cells were grown as sparse and confluent monolayers. Northern blot analysis revealed that KDR and VEGF mRNA expression in confluent cells was more than two-fold greater than in sparse cells. In contrast, flt-1 expression increased only slightly in cells grown to confluence. Cells were then plated at various concentrations and subjected to semi-quantitative PCR; KDR mRNA expression increased as cell density increased. Serum-free conditioned medium from cells grown to confluency for 48 h was added to sparsely plated cells, and KDR expression in the sparse cells increased twofold. We conclude that cell density regulates KDR endothelial cell expression via an unidentified soluble factor.
Liu
W
W
Department of Surgical Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Tex., USA.
Ellis
L M
LM
D015152:Blotting, Northern; D015153:Blotting, Western; D002452:Cell Count; D016228:Endothelial Growth Factors / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008222:Lymphokines / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D014471:Umbilical Veins; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D012333:RNA, Messenger; D017978:Receptors, Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor