Abstract
Angiogenesis is well known to be deeply involved in many pathological conditions such as rheumatoid arthritis, ocular disease in diabetes mellitus and tumor growth in vivo. As a specific growth factor and permeability factor for endothelial cells, recently a new protein molecule VEGF and its receptor (Fit tyrosine kinase family) have been identified. VEGF mRNA is upregulated or overexpressed in a variey of normal or tumor cells under many conditions like hypoxia, hypoglycemia, hormones and growth factor stimulation.
On the other hand, Flt family (Flt-1 and KDR as VEGF receptors) are basically expsessed only on endothelial cells. Thus, except for a rare case, VEGF-Flt system is used through a paracrine mechanism in vivo. Regulation of this system with some chemicals, nucleic acids or polypeptides may be quite useful and important for the control of abnormal angiogenesis/hyperpermeability processes.
