Regulation of connective tissue growth factor gene expression in retinal vascular endothelial cells by angiogenic growth factors

Abstract 

Background: Connective tissue growth factor (CTGF) is a novel, cysteine-rich secreted protein, which is implicated in fibrotic disorders and atherosclerosis. To elucidate the role of CTGF in fibrovascular proliferative retinopathy, we investigated the regulation of CTGF gene expression in a cell line of retinal vascular endothelial cells (RVEC) stimulated with fetal calf serum (FCS) and angiogenic growth factors, including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet-derived growth factor-BB (PDGF-BB), endothelial growth factor (EGF), transforming growth factor-β1 and -β3 (TGF-β1, TGF-β3), and insulin-like growth factor-I (IGF-I). Methods: RVEC derived from Macaca mulatta (CRL-1780; ATCC) were stimulated with 10% FCS as well as with VEGF, bFGF, PDGF-BB, TGF-β1, TGF-β3, EGF, or IGF-I. Time-dependent CTGF gene expression was assessed by northern blot analysis. Results: FCS, TGF-β1, TGF-β3, bFGF, and EGF induced an upregulation of CTGF gene expression in RVEC in a time-dependent manner. Highest expression was induced with TGF-β1. No response on CTGF gene ex- pression could be detected to VEGF, PDGF-BB, or IGF-I. Conclusion: The present study demonstrates for the first time that CTGF mRNA is expressed at high levels in RVEC, and that the level of the temporal pattern of its expression is differentially regulated by angiogenic growth factors, indicating a significant role of CTGF in the pathological course of uncontrolled retinal angiogenesis.