Endostatin inhibits fibrosis by modulating the PDGFR/ERK signal pathway: an in vitro study

Abstract

Accumulating evidence indicates that endostatin inhibits fibrosis. However, the mechanism is yet to be clarified. The aim of this study is to evaluate the effect of endostatin on platelet-derived growth factor-BB (PDGF-BB)-or transforming growth factor β1 (TGF-β1)-induced fibrosis in cultured human skin fibroblasts, and to further examine the molecular mechanisms involved. Human dermal fibroblasts were cultured in Dulbecco's modified Eagle's medium (DMEM) and serum-starved for 48 h before treatment. Cells were grouped as follows: "PDGF-BB", "PDGF-BB+ endostatin", "TGF-β1", "TGF-β1+endostatin", "endostatin", and "blank control". The fibroblasts were stimulated with either TGF-β1 or PDGF-BB for 72 h in order to set up the fibrosis model in vitro. The cells were co-cultured with either TGF-β1 or PDGF-BB and endostatin and were used to check the inhibiting effect of endostatin. A blank control group and an endostatin group were used as negative control groups. The biomarkers of fibrosis, including the expression of collagen I, hydroxyproline, and α-smooth muscle actin (α-SMA), were evaluated using an enzyme-linked immunosorbent assay (ELISA) and Western blot. The expression of phosphorylated PDGF receptor β (p-PDGFRβ), PDGFRβ, phosphorylated extracellular signal-regulated kinase (p-ERK), and ERK was detected using Western blot and immunofluorescent staining was used to explore the mechanisms. Both PDGF-BB and TGF-β1 significantly up-regulated the expression of collagen I, hydroxyproline, and α-SMA. Endostatin significantly attenuated both the PDGF-BB-and TGF-β1-induced over-expression of collagen I, hydroxyproline, and α-SMA. PDGF-BB and TGF-β1 both promoted the expression of PDGFR, ERK, and p-ERK. Endostatin inhibited the expression of PDGFR and p-ERK but did not affect the expression of total ERK. Endostatin inhibited hypertrophic scar by modulating the PDGFRβ/ERK pathway. Endostatin could be a promising multi-target drug in future fibrosis therapy.

Molecular and tissue alterations of collagens in fibrosis

“…This suggests that the anti-fibrotic effect of endostatin could be mediated by the VEGF pathway, in agreement with the fact that endostatin bind to these receptors [319]. The inhibition of fibrosis by endostatin may also be mediated by the modulation of the PDGFR/ERK signal pathway [326].…”

“…Indeed endostatin decreases both PDGF-BB-and TGF-β1-induced over-expression of collagen I in human dermal fibroblasts, and inhibits the expression of PDGFR and p-ERK [326]. The expression of VEGF/VEGFR-2 and the activation of ERK1/2 are inhibited by endostatin, which…”

Endostatin attenuates PDGF-BB- or TGF-β1-induced HSCs activation via suppressing RhoA/ROCK1 signal pathways

“…Endostatin is the C-terminal of collagen type XVIII present in the liver sinusoidal and basement membrane, and discovered to ameliorate liver fibrosis 13. Our previous studies found that endostatin ameliorates scar formation in the rabbit ear model14 and inhibits fibrosis in human fibroblasts 8,15. In the present study, endostatin significantly inhibited the upregulated expressions of collagen I, α-SMA, and F-actin induced by PDGF-BB and TGF-β1 in HSCs.…”

“…HSCs were treated with 4% (0.04 g/mL) paraformaldehyde solution followed by 0.2% (v/v) Triton X-100. Immunofluorescent staining with the antibody against F-actin was performed according to the manufacturer’s instruction as described previously 8. DAPI reagent (4′,6-diamidino-2-phenylindole, MP Biomedicals, 1:7,500) was used to stain the nucleus.…”

Review article: the signalling and functional role of the extracellular matrix in the development of liver fibrosis

“…Suppression of cancer growth by endostatin acts through control of cell phenotype which is seen to ameliorate liver, lung and other fibrotic organs 30,31 . In addition, endostatin elicits anti‐fibrotic properties by reducing TGF‐β‐induced fibrosis through the PDGFR/Erk pathway 32 . In other words, it is a very potent signalling peptide.…”