胰岛素样生长因子I对结肠平滑肌细胞产生干细胞因子的调控

Regulation of insulin-like growth factor I on the expression of stem cell factor in colonic smooth muscle cells

目的探讨激活胰岛素样生长因子（IGF）-I受体后，大鼠结肠平滑肌细胞（SMC）合成千细胞因子（SCF）的变化及其信号途径。方法酶解法分离培养SD大鼠结肠SMC，免疫组化鉴定。2．5×10^5／mlSMC接种培养，①加入100ttg／LIGF—1分别培养0、8、16、24、48h；②分别加入0、5、10、50、100、150gg／LIGF-I培养16h。同时设空白对照组和IGF-I组。免疫荧光、Western印迹、逆转录（RT）-PCR法检测SMC经不同浓度和不同时间IGF—I刺激后SCF的表达。并用50μmol／LLY-294002、PD-98059分别阻断磷脂酰激醇3激酶（P13K）、丝裂原活化蛋白激酶（MAPK）信号途径，观察SCF的变化是否与P13K、MAPK信号途径有关。结果在无血清培养条件下，SCF在大鼠结肠SMC中少量表达，低剂量IGF—I（5和10μg／L）对SCF表达无影响，中、高剂量IGF—I（50、100、150μg／L）诱导其表达增加，100μg／L可能为体外最大有效浓度，其促SCF合成的最高峰在第16小时。分别用LY-294002、PD-98059预处理SMC、再用IGF—I诱导，LY-294002对SCF的表达无影响、PD-98059能部分阻断SCF的表达。结论IGF—I可能通过MAPK信号通道诱导SCF在结肠SMC中的表达，提示其可能是IGF-I调控结肠SMC产生SCF的机制。

Objective To estimate the effect and the intracellular signal transduction pathway of insulinqike growth factor I （IGF- I ） on the expression of stem cell factor（SCF） in colonic smoothmuscle celts（SMC）. Methods The SMCs isolated from colon of the SD rats by enzymolysis were cultured and identified by a-actin immunocytochemical method. Colonic SMCs were cultured either with 100 μg/L of IGF-I at different time points （0,8, 16,24 and 48 hours） or with different concentrations （0,5,10,50,100 and 150 μg/L） of IGF-I for 16 hours. The expressions of SCF in colonic SMCs pretreated with or without specific phosphatidylinositol 3-kinase （PI 3-kinase） inhibitor LY-294002 or mitogen-activated protein （MAP） kinase （MEK1） inhibitor PD-98059 were examined by Western blotting and quantitative reverse transcription-polymerase chain reaction and immunofluoreseence. Results Low expression of SCF was found in colonic SMCs cultured in the bovine serum free medium. There was no effect of 5 or 10 μg/L of IGF- I on the expression of SCF. However, the expressions of SCF mRNA and protein were increased when stimulated with high concentrations （50,100,150 μg/L） of IGF I. The peak expression of SCF was showed at the 16th hour after stimulating with 100 μg/L of IGF- I that was considered as the most effective concentration in vitro. The expression of SCF was not influenced by LY-294002, but was partly blocked by PD-98059. Coneluslons The expression of SCF in colon SMCs may be induced by IGF- I through MAP kinase signaling pathway.