EGFR RNA干扰抑制博莱霉素诱导的小鼠肺纤维化

EGFR RNAi inhibits bleomycin induced pulmonary fibrosis in mice

目的探讨降低表皮生长因子受体（EGFR）在肺内的表达对博莱霉素致小鼠肺纤维化的影响。方法将40只4-6周龄C57BLB／c雄性小鼠按简单随机法分为正常对照组（气管滴入PBS）、纤维化组（气管滴入博莱霉素3mg／kg）、RNAi组（气管滴入博莱霉素3mg／kg＋气管滴入siR-NA20μl）和RNAi阴性对照组（气管滴入博莱霉素3mg／kg＋气管滴人siRNA阴性对照20μl）。实验第10天处死小鼠，收获肺组织，检测羟脯氨酸含量。肺组织切片行HE染色观察肺组织病理改变，采用逆转录一聚合酶链反应（RT-PCR）法检测EGFR的表达。Westernblot检测EGFR、磷酸化EGFR表达。结果RNAi组与纤维化组比较，肺组织EGFRmRNA表达（0．31±0．05 vs 0．75±0．08，P〈0．01）和EGFR蛋白表达（1．53±O．47vs2．56±0．37，P〈0．01）均显著下降；肺病理损伤较纤维化组减轻，肺羟脯氨酸含量显著减少（543．00±25．89vs900．73±31．77，P〈0．01）；磷酸化EGFR蛋白表达亦较纤维化组明显减少（1．78±0．35 vs 2．84±0．51，P〈0．01）。结论EGFRRNAi抑制了EGFR活化，减轻了博莱霉素诱导的肺纤维化改变。

Objective To investigate the effect of down-regulating epidermal growth factor receptor （EGFR） expression on Bleomycin induced pulmonary fibrosis in mice. Methods Forty 4 ± 6 week aged C57BL/c male mice were randomly divided into control, bleomycin, bleomycin plus EGFR RNAi groups and RNAi negative control group. Bleomycin group were treated with bleomyein （3 rag/kg） by endotrachealinjection on day 0, control group were treated with PBS. And bleomycin plus EGFR RNAi group were re- ceived EGRF siRNA plus bleomycin intratracheal administration. RNAi negative control group received neg- ative EGRF siRNA plus bleomycin intratracheal administration. Mice were sacrificed 10 days after the treat- ments. Hydroxyproline （HYP） assay was performed in the lung tissue. The lung tissue slides were exam- ined pathologically with l-I. E. staining, and EGFR mRNA expression was detected by reverse transcriptase- polymerase chain reaction （RT-PCR） technique. Western blot were performed to identify the protein levelof total EGFR and phosphorylated EGFR. Results Histological examination of lung specimens demonstra- ted that EGFR siRNA administration lessened lung fibrosis induced by bleomycin and significantly reduced HYP content （543.00±25.89 vs 900.73 ±31.77, P 〈0. 01）. EGFR mRNA （0.31 ±0.05 vs 0.75 ± 0.08, P 〈 0.01 ） and protein expression （ 1.53 ± 0. 47 vs 2. 56 ± 0. 37, P 〈 0. 01 ） in EGFR siRNA-treated mice was significantly decreased. The expression of phosphorylation of EGFR protein （ 1.78±0. 35 vs 2. 84 ±0.51, P 〈0.01 ） and EGFR protein in RNAi group was less than in bleomycin group. Conclusions EGFR RNAi reduced the BLM-indueed lung fibrosis by inhabiting EGFR activation.