Amelioration of radiation-induced fibrosis: inhibition of transforming growth factor-beta signaling by halofuginone.

Abstract

Radiation-induced fibrosis is an untoward effect of high dose therapeutic and inadvertent exposure to ionizing radiation. Transforming growth factor-beta (TGF-beta) has been proposed to be critical in tissue repair mechanisms resulting from radiation injury. Previously, we showed that interruption of TGF-beta signaling by deletion of Smad3 results in resistance to radiation-induced injury. In the current study, a small molecular weight molecule, halofuginone (100 nm), is demonstrated by reporter assays to inhibit the TGF-beta signaling pathway, by Northern blotting to elevate inhibitory Smad7 expression within 15 min, and by Western blotting to inhibit formation of phospho-Smad2 and phospho-Smad3 and to decrease cytosolic and membrane TGF-beta type II receptor (TbetaRII). Attenuation of TbetaRII levels was noted as early as 1 h and down-regulation persisted for 24 h. Halofuginone blocked TGF-beta-induced delocalization of tight junction ZO-1, a marker of epidermal mesenchymal transition, in NMuMg mammary epithelial cells and suggest halofuginone may have in vivo anti-fibrogenesis characteristics. After documenting the in vitro cellular effects, halofuginone (intraperitoneum injection of 1, 2.5, or 5 microg/mouse/day) efficacy was assessed using ionizing radiation-induced (single dose, 35 or 45 Gy) hind leg contraction in C3H/Hen mice. Halofuginone treatment alone exerted no toxicity but significantly lessened radiation-induced fibrosis. The effectiveness of radiation treatment (2 gray/day for 5 days) of squamous cell carcinoma (SCC) tumors grown in C3H/Hen was not affected by halofuginone. The results detail the molecular effects of halofuginone on the TGF-beta signal pathway and show that halofuginone may lessen radiation-induced fibrosis in humans.

• Authors: Sandhya Xavier, Ester Piek, Makiko Fujii, Delphine Javelaud, Alain Mauviel, Kathy C Flanders, Ayelet M Samuni, Angelina Felici, Michael Reiss, Shai Yarkoni, Anastasia Sowers, James B Mitchell, Anita B Roberts, Angelo Russo
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 279 Issue 15 Pg. 15167-76 (Apr 09 2004) ISSN: 0021-9258 [Print] United States
• PMID: 14732719 (Publication Type: Journal Article)

Chemical References

• DNA-Binding Proteins
• Piperidines
• Protein Synthesis Inhibitors
• Quinazolines
• Quinazolinones
• SMAD3 protein, human
• Smad3 Protein
• Smad3 protein, mouse
• TGFB1 protein, human
• Tgfb1 protein, mouse
• Trans-Activators
• Transforming Growth Factor beta
• Transforming Growth Factor beta1
• halofuginone

Topics

• Animals
• Blotting, Northern
• Blotting, Western
• COS Cells
• Carcinoma, Squamous Cell (drug therapy)
• Cell Line
• Cell Line, Tumor
• Cells, Cultured
• DNA-Binding Proteins (metabolism)
• Dose-Response Relationship, Drug
• Down-Regulation
• Fibrosis (metabolism)
• Gene Deletion
• Genes, Reporter
• Humans
• Immunoblotting
• MAP Kinase Signaling System
• Mice
• Mice, Inbred C3H
• Microscopy, Confocal
• Microscopy, Fluorescence
• Piperidines
• Plasmids (metabolism)
• Protein Synthesis Inhibitors (therapeutic use)
• Quinazolines (therapeutic use)
• Quinazolinones
• Radiation Pneumonitis (drug therapy)
• Reverse Transcriptase Polymerase Chain Reaction
• Signal Transduction
• Smad3 Protein
• Time Factors
• Trans-Activators (metabolism)
• Transforming Growth Factor beta (metabolism)
• Transforming Growth Factor beta1