| [Background and Objective]Hepatocellular carcinoma is a common malignant tumor in china, radiotherapy is a effective treatment for unresectable HCC. Radiation-induced liver disease(RILD) is a main complication which restrict enhancement of the radiation dose. The molecular mechanism on RILD remains unclear, many results show that the damage of radiation induced liver non-parenchymal cells, such as Sinusoidal endothelial cells, liver kupffer cells and liver stellate cell may play a key role. hepatic stellate cells are main effector cells to chemical or physical injury of liver, which participate liver injury repair by producing extracellular matrix. Few studies have been carried out on radiation-induced HSC activation and is role in RILD. Transforming growth factorβ1 (TGF-β1) is one of the key cytokines on the pathogenesis study of RILD, TGF-β1 stimulate the activation of HSC and is also an important factor after HSC activation. The objective of this study is to investigate effect of radiotherapy for HSC activation and its correlation with early RILD, and definitude its impact on the RILD by TGF-βreceptor type II transforming growth factor blockingβ1 (TGF-β1) signaling pathway.[Materials and Methods]1. In vitro:HSC-T6 cell line of two Group:Group irradiation and Group control. Draw the specimens at the 24,48,72 hours, respectively. Detect the mRNA of a-SMA, and mensurate the serum TGF-β1 by ELISA.2. Animal experiments and the upbuilding of the RILD model:70 SD male rats were randomized into three groups:Control Group with no treatment but saline, Model Group delivered X-ray irradiation in partial livers, and Intervention. Group.which were treated by intraperitoneal injection of soluble recombinant adenovirus-mediated TGF-βRII. Draw the specimens at 4 and 6 weeks after radiation, respectively. The expression of TGF-β1,α-SMA, TNF-αand collagen-I were observed by immunohistochemistry, TGF-β1,TGF-βRII were examined with real-time fluorescent quantitative PCR, and a-SMA, FN, Col-I were detected by Western Blotting.[Results]1. HSC-T6 cell line in vitro:At 48 and 72 hours, TGF-β1 and a-SMA levels in cell culture medium of irradiated group were all higher than those in the control group. In irradiated group, the level of α-SMA was higher at 72 hours than 48 hours(P<0.05).2. Animal experiments in vivo:4 weeks and 6 weeks after irradiation, vary degrees of liver cells and lobular structural damage appearing acute inflammatory reaction were observed in model group. And the same performance occurred in the intervention group with milder degree. At 4 weeks, the RILD score was both higher in the model group and the intervention group than in control group. The result of immunohistochemistry showed the expression of TGF-β1, a-SMA, FN and collagen-I protein whether at 4 weeks or 6 weeks after irradiation, were significantly higher in the model group than in the control group, while lower than those in the intervention group(P<0.01). Fluorescence real-time quantitative PCR showed the TGF-β1 and TPRII mRNA expression in the treatment group(model and intervention group) were higher compared with the control group both 4 weeks and 6 weeks after irradiation, thereinto, the intervention group had less expression than the model group (P<0.05) Western Blotting also indicated the expression ofα-SMA, collagen-I protein in intervention group was less than those in the model group.[Conclusions]The activation of HSC-T6 cell line was promoted by radiation in vitro. After the activation HSC released extracellular matrix(ECM) such as FN and Col-I which involved in the early stage of RILD. TGF-β1 was considered to be not only the key factor of activation of HSC, but also the effector of the actived HSC. Blocking the TGF-β1 signaling pathway may be expected to be the target of intervention for RILD.
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