氧化苦参碱对转化生长因子-β_1促肝星状细胞活化及跨膜信号转导影响

Effects of oxymatrine on hepatic stellate cells activation and its transmembrane signaling stimulated by TGF-β_1

目的 观察低浓度氧化苦参碱对大鼠肝星状细胞 (HSC)培养活化和转化生长因子 - β1 ,(TGF - β1 )促活化作用影响 ,并探讨该作用与TGF - β1 受体后信号通路的关系。方法 原代分离培养 2dHSC ,MTT法检测低浓度氧化苦参碱 (0 .2 5～ 8mg/L)对HSC细胞毒作用 (作用 12h)和增殖影响 (作用 48h) ,或给予TGF- β1 (5ng/ml)和 /(或 )氧化苦参碱 (2mg/L)干预 ,相差显微镜观察HSC形态变化 ,分别以RT PCR或Westernblot法检测TGF - β1 及其Ⅰ、Ⅱ型受体、Smad 2 /3、Smad 7以及α 平滑肌肌动蛋白 (α SMA)mRNA和 /(或 )蛋白表达。结果 氧化苦参碱 (0 .2 5～ 8mg/L)对HSC无明显细胞毒作用 ,大于 8mg/L能抑制HSC增殖。氧化苦参碱 (2mg/L)抑制TGF β1 诱导HSC激活时的α SMA表达和形态转化 ,伴随TGF β1 受体mRNA表达升高 ,Smad 7mRNA表达上调及TGF - β1 mRNA表达下降 (与单纯TGF - β1 处理组相比 ,分别上升 1.2 5、0 .87倍或下降 1.92倍 ,P均 <0 .0 5 ) ,但不影响TGF β1 Ⅱ型受体和Smad 3mR NA表达。Westernblot检测Smad 2 /3、Smad 7蛋白表达 ,与RT PCR结果相似。氧化苦参碱对单纯培养激活的HSC有类似作用。结论 低浓度氧化苦参碱 (2mg/L)上调Smad 7表达并抑制TGF β1 表达、上调TGF β1 Ⅰ型受体。

Objective To investigate the effects of lower concentrations of oxymatrine on culture-activation and transforming growth factor-β_1(TGF-β_1) stimulated activation of quiescent rat hepatic stcllatc cclls(HSCs), and the possible relations between the mechanism of the effects and TGF-β signaling via its receptors. Methods Freshly isolated HSCs from rat livers were subjected to treatment with lower concentrations of oxymatrine (0.25, 0.5, 1, 2, 4, 8 mg/L, respectively) at given period, and effects of oxymatrine on cell viability and proliferation were tested by MTT assay. Otherwise, HSCs were stimulated with TGF-β_1 (5 ng/mL), with or without oxymatrine (2 mg/L). Morphological features of HSCs were detected by microscopic observation, and TGF-β_1 mRNA, type Ⅰ and type ⅡTGF-β_1 receptor mRNA, Smad 3 mRNA and Smad 7 mRNA were analyzed by RT-PCR, while protein levels of α-SMA, Smad 2/3 and Smad 7 were evaluated by Western blot.Results Oxymatrine at the concentrations of 0.25-8 mg/L did not decrease the viability of primary cultured HSCs, while inhibited the proliferation of HSCs when reached a concentration of 8 mg/L. Oxymatrine (2 mg/L) prevented morphological transformation of HSCs stimulated by TGF-β_1 from the quiescent state to the activated one,and it also inhibited α-SMA expression stimulated by TGF-β_1.In parallel, RT-PCR showed an up-regulation of type Ⅰ TGF-β_1 receptor mRNA and Smad 7 mRNA in comparison with a decreased TGF-β_1 mRNA ( increased 1.25, 0.87 times or reduced 1.92 times than that of TGF-β_1 group, respectively, P<0.05 ), while the expression of type Ⅱ TGF-β_1 receptor and Smad 3 mRNA was insignificantly altered by oxymatrine.The same changes of Smad 7 and Smad 2/3 protein were also conformed by Western blot. And similar effects were observed in HSCs activated by culture. Conclusion Lower concentration of oxymatrine (2 mg/L) has a significant inhibiting effect on culture-activation and TGF-β_1-stimulated activation of rat HSCs. It may execute its effects through the up-regulation of Smad 7, blockage of TGF-β_1 expression, increase of type Ⅰ TGF-β_1 receptor and restoration of the normal transmembrane signaling of TGF-β_1.