Activation of phosphatidylinositol 3-kinase-protein kinase B(PI3K-PKB) induced by 17β-estradiol in endometrial carcinoma cell (Ishikawa)

目的探讨17β-雌二醇(E2)对子宫内膜癌细胞系Ishikawa细胞磷脂酰肌醇3激酶/蛋白激酶B(PI-3K/PKB)信号传导通路的激活作用以及PI-3K抑制剂对其的影响.方法应用免疫印迹杂交技术,检测一定浓度(1×10-6 mol/L)17β-E2 作用于Ishikawa细胞不同时间(分别为0、5、15、30、60、120 min)后和不同浓度(分别为0、1×10-10、1×10-8、1×10-6、1×10-4 mol/L)17β-E2作用Ishikawa细胞一定时间(30 min)后PKB的活化情况[以磷酸化PKB和总PKB比值(p-PKB/PKB)表示],以及用同法检测PI-3K抑制剂LY294002对17β-E2活化PKB的影响.结果 1×10-6 mol/L 17β-E2作用于Ishikawa细胞15 min时,PKB的活化水平(0.533±0.029)已明显高于对照(0.361±0.029,P<0.05),30 min时最明显(0.666±0.021,P<0.001),而且持续至少达120 min时;随着17β-E2浓度(分别为1×10-10、1×10-8、1×10-6、1×10-4 mol/L)的增加,PKB的活化水平逐渐增高,与对照比较, 差异有显著性(除1×10-10 mol/L外, P值分别为>0.05、<0.05、<0.05、<0.001).随着LY294002作用浓度 (分别为0.1、10、50、100 μmol/L) 的增加,17β-E2作用Ishikawa细胞后PKB的活化水平逐渐下降(分别为0.415±0.032、0.111±0.035、0、0),同对照(0.443±0.032)比较,差异有显著性(除0.1 μmol/L外, P值分别为>0.05、<0.05、<0.001、<0.001),50 μmol/L 的LY294002已完全阻断了17β-E2对Ishikawa细胞PKB的活化作用.结论 17β-E2可通过非转录效应,迅速激活Ishikawa细胞的PI-3K/PKB信号传导通路,LY294002可抑制17β-E2对此通路的激活.Cellular response to estradiol is mediated both by estrogen receptor (ER) binding to estrogen response element (ERE) and by non-nuclear actions like activation of signal transduction pathways such as mitogen activated protein kinase (MAPK) pathway. However, the signal transduction of estrogen involving phosphatidylinositol 3-kinase-protein kinase B (PI3K-PKB) is not clear in endometrial carcinoma. Our purpose was to study if PI3K-PKB signaling pathway could be activated rapidly by 17beta-E(2) through non-nuclear action and also, whether PI3K inhibitor, LY294002, could inhibit such non-nuclear action of 17beta-E(2) in endometrial carcinoma cell line Ishikawa.Levels of phosphorylated PKB (Ser473 site, p-PKB) and total PKB were examined by western blotting in Ishikawa cells after stimulation with 17beta-E(2) at 1 x 10(-6) mol/L for different time periods and at varied doses for 30 min. Optimal time and appropriate dose for 17beta-E(2) to activate PKB in Ishikawa cells were observed. Inhibitory effect of LY294002 on activation of PKB induced by 17beta-E(2) was also studied. p-PKB/PKB ratio was used to indicate levels of activation of PKB.p-PKB/PKB at 15 min (0.533 +/- 0.029) was significantly higher than the control (0.361 +/- 0.029, P < 0.05). Maximal activation of PKB (maximal levels of p-PKB/PKB) took place at 30 min (0.666 +/- 0.021, P < 0.001) and the activation persisted at least 2 h after stimulation with 1 x 10(-6) mol/L 17beta-E(2) in Ishikawa cells. With increased doses of 17beta-E(2) (vehicle, 1 x 10(-10), 1 x 10(-8), 1 x 10(-6), 1 x 10(-4) mol/L), the activation of PKB (p-PKB/PKB was 0.300 +/- 0.098, 0.312 +/- 0.081, 0.625 +/- 0.100, 0.771 +/- 0.041, 0.902 +/- 0.043 accordingly) increased gradually (in comparison with vehicle, P > 0.05, < 0.05, < 0.05, < 0.001 accordingly). PI3K inhibitor, LY294002 could inhibit the activation of PKB induced by 17beta-E(2) in Ishikawa cells. Levels of PKB (p-PKB/PKB) decreased (0.443 +/- 0.032, 0.415 +/- 0.032, 0.111 +/- 0.035, 0, 0) gradually with increased concentrations (vehicle, 0.1, 10, 50, 100 micro mol/L) of LY294002 (compared with vehicle, P > 0.05, < 0.05, < 0.001, < 0.001) and 50 micro mol/L LY294002 completely blocked the activation of PKB induced by 17beta-E(2).17beta-estradiol, by non-nuclear action, can activate promptly PI3K-PKB signaling pathway in endometrial carcinoma cell line, Ishikawa. This action of 17beta-E(2) is PI3K dependent and can be inhibited or blocked by LY294002.PubMed中文核心期刊要目总览(PKU)中国科学引文数据库(CSCD)07469-4733