Abstract

Objective To investigate the effects of radiation on gene expressions of TGF-β1 in human fetal lung fibroblast cells (HFL-1), and to explore the effect of TGF-β1 siRNA on radiation-induced collagen. Methods HFL-1 cells were divided into irradiation and control group. At 24 h of 500 cGy of 6 MV X-rays irradiation, the cellular gene expressions including TGF-β1 were assayed by a gene chip. HFL-1 cells were divided into irradiation, negative control siRNA and TGF-β1 siRNA groups. The effects of TGF-β1 siRNA on TGF-β1 and collagen type-Ⅰ and -Ⅲ after irradiation were detected by RT-PCR, ELISA, immunohistochemistry and Western blot. In addition, HFL-1 cells were divided into irradiation, dexamethasone, TGF-β1 siRNA, and TGF-β1 siRNA combined with dexamethasone groups. After 24 h of irradiation, the expressions of TGF-β1, collagen type-Ⅰ and -Ⅲ were determined by RT-PCR, immunohistochemistry and Western blot, respectively. Results Gene expression profile of HFL-1 cells changed after exposure to radiation and TGF-β1 mRNA was up-regulated. The expression of TGF-β1 mRNA (t=-18.580, P<0.001) and protein (t=-12.445, P<0.001) in the irradiated cells were higher than those in the control group. The expression of HYP (t=-3.987, P=0.016) was consistent with that of TGF-β1. The expression of TGF-β1 (t=13.235, 6.943 and-17.431, P<0.05), α-SMA (t=12.548, 6.966, 13.988, P<0.05), collagen type-I (t=12.433, 8.164, 16.315, P<0.05) and collagen type-Ⅲ (t=5.919, 3.164, 9.420, P<0.05) in the groups of TGF-β1 siRNA, dexamethasone and TGF-β1 siRNA combined with dexamethasone were dramatically suppressed in comparison with those in the irradiation alone group. Moreover, the expression levels of TGF-β1 (t=7.110, P<0.05), α-SMA (t=7.976, P<0.05), collagen type-Ⅰ (t=4.196, P<0.05) and collagen-Ⅲ (t=5.935, P<0.05) were significantly decreased in the TGF-β1 siRNA group compared to the dexamethasone group. Conclusions Gene expression profile of HFL-1 cells is significantly changed with exposure to X-ray irradiation and up-regulation of TGF-β1 in HFL-1 cells. TGF-β1 siRNA effectively inhibits TGF-β1 expression and interfers the production of collagens. Moreover, the anti-fibrosis effect of TGF-β1 siRNA is better than that of dexamethasone. These results provide insights in ameliorating radiation-induced pulmonary fibrosis. Key words: RNA interference; transforming growth factor β1; Gene profile; Radiation induced pulmonary fibrosis

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