Irradiation induces up-regulation of E9 protein (CD105) in human vascular endothelial cells

Int J Cancer. 1995 Sep 15;62(6):791-6. doi: 10.1002/ijc.2910620624.


The use of MAb E-9 raised against tissue-cultured endothelial cells (EC) has shown marked heterogeneity in vascular EC lining the blood vessels of normal and tumour tissues. MAb E-9 is human EC-specific and the protein recognized by it is a homodimer with a molecular mass of 97 kDa. The E-9 protein is resistant to treatment by 3 mM sodium periodate, but is sensitive to 10% trichloroacetic acid and 70% ethanol. E-9 protein has been assigned to a new cluster, CD105, and mapped to human chromosome 9q3. It has approximately 70% homology with type-III cell-surface receptor for transforming growth factor beta (TGF-beta). Recently CD105 has been reported to be the gene in patients with hereditary haemorrhagic telangiectasia. We have examined the effects of radiation on its expression in normal human umbilical-vein endothelial cells (HUVEC) and brain-tumour-derived endothelial cells (BTEC). Irradiation induced dose- and time-dependent up-regulation in the expression of the E-9 protein on the plasma membranes of EC, and also resulted in greater increase in the expression of the E-9 protein in semi-confluent (proliferating) as compared with confluent (non-proliferating) EC. It may well be that, following radiotherapy in cancer patients, E-9 protein is also up-regulated. The presence of increased amounts of E-9 protein in EC makes it an attractive target in the control of angiogenesis, especially after radiotherapy in cancer patients. The time scale involved in the up-regulation of E-9 protein following irradiation has led us to suggest that it may be a secondary event, the primary being the production and release of mitogenic factors (such as basic fibroblast growth factor) from irradiated EC.

Publication types

  • Comparative Study

MeSH terms

  • Antibodies, Monoclonal / biosynthesis
  • Antigens, CD
  • Cell Adhesion / radiation effects
  • Cell Count / radiation effects
  • Cell Division / physiology
  • Cell Membrane / physiology
  • Cell Size / radiation effects
  • Cells, Cultured
  • Electrophoresis
  • Endoglin
  • Endothelium, Vascular / metabolism
  • Endothelium, Vascular / radiation effects*
  • Flow Cytometry
  • Humans
  • Immunohistochemistry
  • Neovascularization, Pathologic / metabolism
  • Precipitin Tests
  • Receptors, Cell Surface
  • Up-Regulation / radiation effects
  • Vascular Cell Adhesion Molecule-1 / physiology*


  • Antibodies, Monoclonal
  • Antigens, CD
  • ENG protein, human
  • Endoglin
  • Receptors, Cell Surface
  • Vascular Cell Adhesion Molecule-1