胰岛素样生长因子-1对大鼠结肠平滑肌细胞增殖、凋亡及MAPK通路的影响

Effects of insulin-like growth factor-1 on the proliferation, apoptosis and MAPK signaling pathway of rat colonic smooth muscle cells

目的 探讨胰岛素样生长因子-1（IGF-1）对大鼠结肠平滑肌细胞（SMCs）增殖、凋亡及丝裂原活化蛋白激酶（MAPK）信号转导通路的影响.方法 利用酶解法分离培养Sprague-Dawley大鼠结肠SMCs,进行免疫组化染色鉴定后,将其分为对照组、IGF-1组和IGF-1＋ PD98059[细胞外信号调节激酶（ERK）抑制剂]组,分别采用噻唑蓝（MTT）法检测SMCs增殖,流式细胞术AnnexinV-FITC/PI检测SMCs凋亡,Western印迹检测磷酸化ERK、ERK、磷酸化p38MAPK、p38MAPK和磷酸化c-Jun氨基末端激酶（JNK）、JNK的表达.结果 分离培养的细胞经免疫组化鉴定为结肠SMCs,IGF-1组较对照组细胞增殖增强[（1.786 ±0.271）比（0.998±0.057）,P＜0.01],凋亡率降低[（2.59±0.28）％比（20.68±2.48）％,P＜0.01],磷酸化ERK表达增强,磷酸化ERK/ERK比值升高[（42.71±3.74）％比（23.88±2.52％）,P均＜0.01]；磷酸化p38MAPK、p38MAPK、磷酸化JNK、JNK表达无差异（P均＞0.05）.IGF-1＋ PD98059组较对照组细胞增殖下降[（0.154±0.021）比（0.998±0.057）,P＜0.01],凋亡率升高[（84.31±7.54）％比（20.68±2.48）％,P＜0.01],磷酸化ERK表达减弱,磷酸化ERK/ERK比值降低[（10.47±1.22）％比（23.88±2.52）％,P均＜0.01].结论 IGF-1可能通过激活结肠SMCs MAPK通路中的ERK途径,促进细胞增殖,抑制凋亡,可能与p38MAPK途径和JNK途径无关.

Objective To study the effects of insulin-like growth factor-1 （IGF-1） on the proliferation,apoptosis and mitogen-activated protein kinase （MAPK） signaling pathway of rat colonic smooth muscle cells （SMCs）.Methods Colonic SMCs in Sprague Dawley were isolated and cultured by enzymatic method.After immunohistochemical staining for identification of SMCs,SMCs were divided into control group,IGF-1 group,and IGF-1 ＋ PD98059[extracellular signal-regulated kinase（ERK） inhibitor] group.3-（4,5-Dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide （MTT） method was used for the detection of SMCs proliferation,flow cytometric Annexin V-FITC/PI for the detection of SMCs apoptosis,and Western blots for the detection of phosphorylated ERK,ERK,phosphorylated p38MAPK,p38MAPK and phosphorylated c-Jun N-terminal kinase（JNK）,JNK expressions.Results The cultured cells were identified as colonic SMCs by immunohistochemical method.Compared with control group,cells proliferation of IGF-1 group was enhanced [（1.786 ± 0.271） vs.（0.998 ± 0.057）,P ＜ 0.01],and apoptosis rate was reduced [（2.59 ± 0.28） ％ vs.（20.68 ±2.48） ％,P ＜ 0.01].Phosphorylated ERK expression in IGF-1 group was enhanced,and the ratio of phosphorylated ERK/ERK was increased [（42.71 ± 3.74） ％ vs.（23.88 ± 2.52） ％,all P ＜ 0.01].There were no differences for the expressions of phosphorylated p38MAPK,p38MAPK,phosphorylated JNK and JNK between IGF-1 group and control group （all P ＞ 0.05）.Compared with control group,cells proliferation in IGF-1 ± PD98059 group was decreased significantly [（0.154 ± 0.021） vs.（0.998 ± 0.057）,P ＜ 0.01],while apoptosis rate was increased [（84.31 ± 7.54） ％ vs.（20.68 ± 2.48） ％,P ＜ 0.01],phosphorylated ERK expression was reduced,and the ratio of phosphorylated ERK/ERK was decreased [（10.47 ± 1.22） ％ vs.（23.88 ± 2.52） ％,all P ＜ 0.01].Conclusion IGF-1 can promote the proliferation and inhibit apoptosis of colonic SMCs through activation of the ERK route of MAPK pathway,and p38MAPK and JNK routes may not be involved in this process.