Glucocorticoids inhibit vascular endothelial growth factor expression in growth plate chondrocytes.
Vascular endothelial growth factor (VEGF) plays an essential role in angiogenesis in the growth plate and ultimately in regulating endochondral ossification. Since longitudinal bone growth is often disturbed in children who are treated with glucocorticoids, we investigated the effects of dexamethasone on VEGF expression by epiphyseal chondrocytes. Cells were cultured from tibial growth plates of neonatal piglets. Using Northern blotting and RT-PCR techniques, the chondrocyte-specific markers aggrecan, collagen II and CD-RAP were detected. Also the glucocorticoid receptor (GR) was expressed. VEGF protein secreted from these cells was examined by ELISA and Western immunoblotting. The VEGF(121) and VEGF(165) isoforms were detected in the supernatant. As determined by RT-PCR, all three major mRNA splice variants were produced, including the species encoding VEGF(189). Dexamethasone (100 nM) inhibited both protein and mRNA expression by approximately 45%. Hydrocortisone (cortisol) and prednisolone also inhibited VEGF secretion, but they were less active than dexamethasone. The inhibitory actions of dexamethasone were almost completely blocked by the GR antagonist Org34116, indicating that the GR mediates these actions. Degradation of the VEGF mRNA was not accelerated by dexamethasone. Therefore, a transcriptional mechanism seems likely. Downregulation of this important growth factor could lead to disruption of the normal invasion of blood vessels in the growth plate, which could contribute to disturbed endochondral ossification and growth.
Koedam
Joost A
JA
Department of Pediatric Endocrinology, University Medical Center Utrecht, Room KE3-139.2, P.O. Box 85090, AB-3508 Utrecht, The Netherlands. j.koedam@wkz.azu.nl
Smink
Jeske J
JJ
van Buul-Offers
Sylvia C
SC
D000818:Animals; D000831:Animals, Newborn; D001846:Bone Development / Q000502:physiology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D016228:Endothelial Growth Factors / Q000235:genetics / Q000378:metabolism*; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008222:Lymphokines / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013552:Swine / Q000502:physiology; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D005938:Glucocorticoids; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D020033:Protein Isoforms; D012333:RNA, Messenger; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D003907:Dexamethasone