-
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
[show abstract]
[hide abstract]
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.
Journal of Biological Chemistry 05/2004; 279(15):15167-76. · 4.77 Impact Factor
-
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
[show abstract]
[hide abstract]
ABSTRACT: Radiation-induced fibrosis is an untoward effect of high dose therapeutic and inadvertent exposure to ionizing radiation.
Transforming growth factor-β (TGF-β) has been proposed to be critical in tissue repair mechanisms resulting from radiation
injury. Previously, we showed that interruption of TGF-β 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-β 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-β type II receptor (TβRII). Attenuation of TβRII levels was noted as early as 1 h and down-regulation
persisted for 24 h. Halofuginone blocked TGF-β-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 μg/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-β signal pathway and show that halofuginone may lessen radiation-induced fibrosis in humans.
Journal of Biological Chemistry 04/2004; 279(15):15167-15176. · 4.77 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Transforming growth factor-beta (TGF-beta) is a multifunctional cytokine signaling to the nucleus through cell surface transmembrane receptor serine/threonine kinases and cytoplasmic effectors, including Smad proteins. We describe a novel modulator of this pathway, TLP (TRAP-1-like protein), which is 25% identical to the previously described Smad4 chaperone, TRAP-1, and shows identical expression patterns in human tissues. Endogenous TLP associates with both active and kinase-deficient TGF-beta and activin type II receptors, but interacts with the common-mediator Smad4 only in the presence of TGF-beta/activin signaling. Overexpression of TLP represses the ability of TGF-beta to induce transcription from SBE-Luc, a Smad3/4-specific reporter, while it potentiates transcription from ARE-Luc, a Smad2/4-specific reporter. Consistent with this, TLP inhibits the formation of Smad3/4 complexes in the absence of effects on phosphorylation of Smad3, while it affects neither Smad2 phosphorylation nor hetero-oligomerization. We propose that TLP might regulate the balance of Smad2 and Smad3 signaling by localizing Smad4 intracellularly, thus contributing to cellular specificity of TGF-beta transcriptional responses in both normal and pathophysiology.
The EMBO Journal 10/2003; 22(17):4465-77. · 9.20 Impact Factor
