Influence of endothelial cells on vascular smooth muscle cells phenotype after irradiation: implication in radiation-induced vascular damages

Am J Pathol. 2006 Oct;169(4):1484-95. doi: 10.2353/ajpath.2006.060116.


Damage to vessels is one of the most common effects of therapeutic irradiation on normal tissues. We undertook a study in patients treated with preoperative radiotherapy and demonstrated in vivo the importance of proliferation, migration, and fibrogenic phenotype of vascular smooth muscle cells (VSMCs) in radiation-induced vascular damage. These lesions may result from imbalance in the cross talk between endothelial cells (ECs) and VSMCs. Using co-culture models, we examined whether ECs influence proliferation, migration, and fibrogenic phenotype of VSMCs. In the presence of irradiated ECs, proliferation and migration of VSMCs were increased. Moreover, expressions of alpha-smooth muscle actin, connective tissue growth factor, plasminogen activator inhibitor type 1, heat shock protein 27, and collagen type III, alpha 1 were up-regulated in VSMCs exposed to irradiated ECs. Secretion of transforming growth factor (TGF)-beta1 was increased after irradiation of ECs, and irradiated ECs activated the Smad pathway in VSMCs by inducing Smad3/4 nuclear translocation and Smad-dependent promoter activation. Using small interferring RNA targeting Smad3 and a TGFbeta-RII neutralizing antibody, we demonstrate that a TGF-beta1/TGF-beta-RII/Smad3 pathway is involved in the fibrogenic phenotype of VSMCs induced by irradiated ECs. In conclusion, we show the importance of proliferation, migration, and fibrogenic phenotype of VSMCs in patients. Moreover, we demonstrate in vitro that ECs influence these fundamental mechanisms involved in radiation-induced vascular damages.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / analysis
  • Actins / metabolism
  • Adenocarcinoma / radiotherapy
  • Cell Movement
  • Cell Proliferation
  • Coculture Techniques
  • Collagen Type I / analysis
  • Collagen Type I / metabolism
  • Collagen Type III / analysis
  • Collagen Type III / metabolism
  • Connective Tissue Growth Factor
  • Endothelium, Vascular / pathology*
  • Endothelium, Vascular / radiation effects*
  • Fibrinogen / metabolism
  • Gamma Rays
  • Heat-Shock Proteins / analysis
  • Heat-Shock Proteins / metabolism
  • Humans
  • Immediate-Early Proteins / analysis
  • Immediate-Early Proteins / metabolism
  • Intercellular Signaling Peptides and Proteins / analysis
  • Intercellular Signaling Peptides and Proteins / metabolism
  • Muscle, Smooth, Vascular / pathology*
  • Myocytes, Smooth Muscle / chemistry
  • Myocytes, Smooth Muscle / metabolism
  • Myocytes, Smooth Muscle / pathology*
  • Phenotype
  • Plasminogen Activator Inhibitor 1 / analysis
  • Plasminogen Activator Inhibitor 1 / metabolism
  • Radiation Injuries / pathology*
  • Rectal Neoplasms / radiotherapy
  • Smad2 Protein / analysis
  • Smad2 Protein / metabolism
  • Smad3 Protein / analysis
  • Smad3 Protein / metabolism
  • Transforming Growth Factor beta / analysis
  • Transforming Growth Factor beta / metabolism
  • Up-Regulation
  • Vascular Diseases / pathology*


  • Actins
  • CCN2 protein, human
  • Collagen Type I
  • Collagen Type III
  • Heat-Shock Proteins
  • Immediate-Early Proteins
  • Intercellular Signaling Peptides and Proteins
  • Plasminogen Activator Inhibitor 1
  • Smad2 Protein
  • Smad3 Protein
  • Transforming Growth Factor beta
  • Connective Tissue Growth Factor
  • Fibrinogen