Expression of CTGF in radiation-induced hepatic fibrosis and its relationship with hepatic stellate cell activation in rats

Objective To study the expression of connective tissue growth factor (CTGF) in radiation-induced hepatic fibrosis and explore its correlation with the expression of transforming growth factor β1 (TGF-β1) and α-smooth muscle actin (α-SMA) as well as the activation of hepatic stellate cells (HSC).Methods Forty healthy male Sprague-Dawley rats were randomly divided into model group (30 rats) and control group (10 rats).The right-half liver of rat was irradiated with a single dose of 25 Gy to establish a radiation-induced hepatic fibrosis model.Liver tissues of irradiated rats were collected at 2,4,and 6 months after irradiation.Pathomorphological changes in these liver tissues were stained with hematoxylin-eosin and observed with an optical microscope.The mRNA and protein expressions of CTGF,TGF-β1 and α-SMA were assayed by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry.Results The longer the irradiation time,the degree of liver fibrosis was more serious.The expressions of CTGF,TGF-β1,α-SMA protein in the model group increased along with the time after irradiation (F =55.44,16.22,121.12,P ＜0.05).The mRNA expressions of CTGF,TGF-β1 and α-SMA in the model group had positive correlations (r =0.638,0.715,P ＜ 0.05) and were significantly higher than the control (F =177.11,133.85,217.46,P ＜0.05).Conclusions The expression of CTGF had a positive relationship with the development of hepatic fibrosis.CTGF may be involved in the activation of TGF-β signaling pathway and thereby promotes the activation and proliferation of HSC. Key words: CTGT;  TGF-β1;  α-SMA;  Hepatic fibrosis;  Radiation