胰岛素／PI3K信号传导调节survivin在肝癌细胞HepG2中的表达

Insulin/PI3K signalling pathway regulates the expression of survivin in liver cancer HepG2 cells

目的探讨胰岛素因子受体激活后凋亡抑制因子survivin在肝癌细胞株HepG2中的表达变化及其信号传导途径。方法利用实时定量PCR和Western bolt方法，检测HepG2细胞在胰岛素刺激前后survivin的表达变化；在肝癌细胞HepG2中加入Ly294002，特异性阻断磷脂酰肌醇-3羟基激酶（PI3K）信号通路，以观察survivin的表达变化与PI3K信号传导途径的关系。结果在无血清培养条件下，survivin和HepG2中少肇表达；胰岛素能诱导survivin表达，且呈剂量依赖性和时间依赖性：胰岛素浓度在0．26nmol／L时，survivin的表达为胰岛素诱导前的7倍；当胰岛素浓度达到26nmol／L时，survivin的表达明显增加，为胰岛素诱导前的35倍（P〈0．05）。胰岛素诱导HepG2细胞48h后，survivin的表达也明显增加，为胰岛素诱导前的30倍（P〈0．05）。Ly294002预处理的HepG2细胞经胰岛素诱导，可阻断survivin的表达。结论胰岛素通过PI3K信号通路诱导凋亡抑制因子survivin的表达，提示通过干扰PI3K／AKt途径中的关键基因可阻断survivin表达，从而促进肝癌细胞凋亡。

Objective To determine the expression level changes of survivin, a inhibitor of apoptosis protein, followed by activation of insulin receptors in human hepatocellular carcinoma HepG2 cell line, and to investigate the signalling pathway involved in the regulation. Methods Human hepatocellular carcinoma HepG2 cells were treated with insulin alone or pre-treated with LY294002, a specific inhibitor of PI3K signalling pathway, to determine whether blocking PI3K signaling can attenuate the up-regulation of survivin expression. Real time RT-PCR and Western blot analysis were used to measure survivin mRNA and protein changes before and after treatment, respectively. Results Without serum supplement, HepG2 cells expressed a small amount of survivin. Insulin induced survivin expression in a dose- and time-dependent fashion. Survivin expression was blocked if cells were pre-treated with LY294002 prior to insulin stimulation. Conclusion Insulin induces survivin expression via PI3K signalling pathway, suggesting that to interfere the key gene in this signalling pathway may block survivin expression, therefore, promoting apoptosis in hepatocellular carcinoma ceils.