Placenta Growth Factor and Vascular Endothelial Growth Factor B and C Expression in Microvascular Endothelial Cells and Pericytes

Abstract

We have shown previously that vascular endothelial growth factor (VEGF) synthesized by the cellular constituents of small vessels per se, viz. endothelial cells and pericytes, participates in the hypoxia-driven proliferation of both cell types (Nomura, M., Yamagishi, S., Harada, S., Hayashi, Y., Yamashima, T., Yamashita, J., Yamamoto, H. (1995) J. Biol. Chem. 270, 28316-28324; Yamagishi, S., Yonekura, H., Yamamoto, Y., Fujimori, H., Sakurai, S., Tanaka, N., and Yamamoto, H. (1999) Lab. Invest. 79, 501-509). In this study, we examined the expression of the recently isolated VEGF gene family members (placenta growth factor (PlGF), VEGF-B, and VEGF-C) in human dermal microvascular endothelial cells and bovine retinal pericytes cultured under various oxygen tensions. Quantitative reverse transcription-polymerase chain reaction analyses demonstrated that the two cell types possess not only VEGF (VEGF-A) mRNA, but also VEGF-B, VEGF-C, and PlGF mRNAs. Among them, only VEGF-A mRNA was induced under hypoxia. Competitive reverse transcription-polymerase chain reaction showed that, under normoxic conditions, the rank order of mRNA content in endothelial cells was PlGF > VEGF-B > VEGF-C > VEGF-A and that mRNA coding for PlGF was expressed at >100-fold higher levels than VEGF-A mRNA. In pericytes, the rank order was VEGF-C > VEGF-A > VEGF-B > PlGF, and approximately 7-fold higher levels of VEGF-C mRNA compared with VEGF-A mRNA were noted in this cell type. Furthermore, antisense inhibition of PlGF protein production lowered the endothelial cell synthesis of DNA under hypoxic conditions. The results suggest that these VEGF family members may also take active parts in angiogenesis.