Inhibition of ALK5 signaling induces physeal dysplasia in rats.
TGF-beta, and its type 1 (ALK5) receptor, are critical to the pathogenesis of fibrosis. In toxicologic studies of 4 or more days in 10-week-old Sprague-Dawley rats, using an ALK5 inhibitor (GW788388), expansion of hypertrophic and proliferation zones of femoral physes were noted. Subphyseal hyperostosis, chondrocyte hypertrophy/hyperplasia, and increased matrix were present. Physeal zones were laser microdissected from ALK5 inhibitor-treated and control rats sacrificed after 3 days of treatment. Transcripts for TGF-beta1, TGF-beta2, ALK5, IHH, VEGF, BMP-7, IGF-1, bFGF, and PTHrP were amplified by real-time PCR. IGF and IHH increased in all physis zones with treatment, but were most prominent in prehypertrophic zones. TGF-beta2, bFGF and BMP7 expression increased in proliferative, pre-and hypertrophic zones. PTHrP expression was elevated in proliferative zones but decreased in hypertrophic zones. VEGF expression was increased after treatment in pre- and hypertrophic zones. ALK5 expression was elevated in prehypertrophic zones. Zymography demonstrated gelatinolytic activity was reduced after treatment. Apoptotic markers (TUNEL and caspase-3) were decreased in hypertrophic zones. Proliferation assessed by Topoisomerase II and Ki67 was increased in multiple zones. Movat stains demonstrated that proteoglycan deposition was altered. Physeal changes occurred at doses well above those resulting in fibrosis. Interactions of factors is important in producing the physeal dysplasia phenotype.
Frazier
Kendall
K
GlaxoSmithKline-Safety Assessment, King of Prussia, PA 19406, USA. kendall.s.frazier@gsk.com
Thomas
Roberta
R
Scicchitano
Marshall
M
Mirabile
Rosanna
R
Boyce
Rogely
R
Zimmerman
Dawn
D
Grygielko
Eugene
E
Nold
James
J
DeGouville
Anne-Charlotte
AC
Huet
Stephane
S
Laping
Nicholas
N
Gellibert
Francoise
F
D030201:Activin Receptors, Type I / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001549:Benzamides / Q000009:adverse effects; D001848:Bone Diseases, Developmental / Q000139:chemically induced* / Q000473:pathology; D049109:Cell Proliferation; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D006132:Growth Plate / Q000187:drug effects / Q000473:pathology*; D017346:Protein Serine-Threonine Kinases; D011720:Pyrazoles / Q000009:adverse effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000502:physiology
C509927:4-(4-(3-(pyridin-2-yl)-1H-pyrazol-4-yl)pyridin-2-yl)-N-(tetrahydro-2H-pyran-4-yl)benzamide; D001549:Benzamides; D011720:Pyrazoles; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D042461:Vascular Endothelial Growth Factor A; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625843:Tgfbr1 protein, rat