中文摘要：

背景与目的：放射性肺纤维化以成纤维细胞增殖和细胞外基质过度沉积为特征。转化生长因子β1（transforming growth factor β1，TGFβ1）是放射性肺纤维化发生发展的“开关”性分子并被作为治疗的靶分子，因此阻断TGFβ1的信号转导可能减轻肺纤维化。本研究检测Smad通路抑制剂SB203580和WP631对照射后人肺成纤维细胞（httman lung fibroblast，HLF）中信号转导的影响并探讨其效应。方法：将HLF用25μmol／LSB203580和5nmol／LWP631预处理后，再应用3G^60Coγ射线照射和10μg／LTGFβ1刺激，通过凝胶阻滞电泳（electrophoretic nobility shift assay，EMSA）、免疫印迹、免疫组织化学及细胞周期流式细胞仪检测等方法检测转录因子SP1和AP1活性的变化、Smad3，4，7和p-Smad3及Ⅰ型胶原和Ⅰ型组织纤溶酶原激活物抑制剂（typeⅠ plasminogen activator inhibitor，PAI-1）的表达变化及细胞周期的变化。结果：经3Gy1射线照射及TGFβ1刺激后，与未经预处理的HLF相比，应用SB203580或WP631预处理的HLF出现G2-M期阻滞，s期细胞显著减少。SB203580预处理可减少HLF中P21WAF1/CIPI和p-Smad3的表达．而WP631预处理可减少HLF表达PAI-1，抑制转录因子SP1和AP1的活化。结论：SB203580和WP631通过阻断TGFβ—Smad通路的信号转导，抑制γ射线和TGFβ1作用所导致的HLF过度增殖和P21WAF1/CIPI及PAI-1表达增多。

英文摘要：

BACKGROUND ＆ OBJECTIVE= Radiation pulmonary fibrosis （RPF） is characterized by fibroblast proliferation and excessive accumulation of extracellular matrix （ECM）. Transforming growth factor β （TGFβ） is a switch factor in the initiation and development of RPF and serves as a therapeutic target. Blocking TGFβ1 signal transduction pathway might alleviate RPF. This study was to investigate the effects of two Smad pathway inhibitors, SB203580 and WP631, on Smad signal transduction pathway in human lung fibroblasts （HLFs） after irradiation. METHODS= HLFs were pretreated with 25 iJmol/L SB203580 or 5 nmol/L WP631, then irradiated with 3 Gy ^60Coγ rays and stimulated by 10μg/L TGFβ1. The transcriptional activity of SP1 and AP1 were measured using electrophoretic mobility shift assay （EMSA）. Expressions of Smad3, Smad4, Smad7, p-Smad3 and P21WAF1/CP1 were detected by Western blot. The expression of type I plasminogen activator inhibitor （PAI- I ） was detected by immunohistochemical staining The cell cycle was measured by FACS, RESULTS： After irradiation, with 3 Gy γ rays and stimulation by TGFβ1, HLFs pre-incubated with SB203580 or WP631 were increased in G2-M phase and decreased in S phase as compared with cells without pretreatment. p21WAF1/CP1 and p-Smad3 were decreased in HLFs pretreated with SB203580, while PAl-1 was decreased in HLFs pretreated with WP631. Furthermore, the transcriptional activity of SP1 and AP1 was inhibited by WP631. CONCLUSIONS. SB203580 and WP631 can abrogate excessive proliferation, expressions of p21WAF1/CP1 and PAI-1 induced by γ rays and TGFβ1 in HLFs through blocking Smad signal transduction pathway.