Department of Surgery, Ludwig-Maximilians-University of Munich Hospital Grosshadern, Munich, Germany.
Biochem Biophys Res Commun. 2010 Apr 16;394(4):915-20. doi: 10.1016/j.bbrc.2010.03.074. Epub 2010 Mar 15.
BACKGROUND/AIM: Augmenter of liver regeneration (ALR) is a potent growth factor which supports liver regeneration in experimental animals. The aim of this study was to compare proliferation as well as the kinetics of ERK1/2 and Akt/PKB phosphorylation by recombinant human ALR (rhALR) and EGF in human hepatocytes and extrahepatic cells.
Kinetics of ERK1/2 and Akt/PKB phosphorylation were determined in primary human hepatocytes (phh) after stimulation with rhALR and EGF. Induction of proliferation was analyzed in phh and several cell lines of hepatic and extrahepatic origin by the MTT and [(3)H]-thymidine assay.
The kinetics of ERK phosphorylation showed clear differences, whereby rhALR caused a transient and EGF a permanent increase during the observation period of 60 min. For both, Akt and ERK phosphorylation, EGF caused a faster effect with maximal levels observed already after 2 min, whereas rhALR caused maximal phosphorylation between 10 and 15 min. Using the EGF receptor inhibitor AG1478 we provide evidence of an EGF receptor independent induction of proliferation by rhALR. Furthermore, rhALR induced proliferation only in phh and the human liver derived cell lines HepG2 and Chang. In contrast, EGF enhanced proliferation in all analyzed cell types including cell lines of colon, bronchial, pancreatic and gastric origin (SW480, BC1, L36PL and GC1).
rhALR and EGF induce different kinetics of ERK and Akt phosphorylation in human hepatocytes. The mitogenic effect of rhALR is liver specific and seems to be at least partially independent from EGF receptor mediated signaling.
背景/目的：肝再生增强因子（ALR）是一种有效的生长因子，可支持实验动物的肝再生。本研究的目的是比较重组人 ALR（rhALR）和 EGF 在人肝细胞和肝外细胞中对 ERK1/2 和 Akt/PKB 磷酸化的增殖作用和动力学。
用 rhALR 和 EGF 刺激原代人肝细胞（phh）后，测定 ERK1/2 和 Akt/PKB 磷酸化的动力学。通过 MTT 和[3H]-胸腺嘧啶测定法分析 phh 和几种肝外来源的细胞系的增殖诱导。
ERK 磷酸化的动力学显示出明显的差异，rhALR 引起短暂的增加，而 EGF 在观察期 60 分钟内引起持续的增加。对于 Akt 和 ERK 磷酸化，EGF 引起更快的作用，最大水平在 2 分钟后即可观察到，而 rhALR 引起最大磷酸化在 10 至 15 分钟之间。使用表皮生长因子受体抑制剂 AG1478，我们提供了证据表明 rhALR 诱导增殖的表皮生长因子受体非依赖性。此外，rhALR 仅在 phh 和人源肝来源细胞系 HepG2 和 Chang 中诱导增殖。相比之下，EGF 增强了所有分析的细胞类型的增殖，包括结肠、支气管、胰腺和胃来源的细胞系（SW480、BC1、L36PL 和 GC1）。
rhALR 和 EGF 在人肝细胞中诱导不同的 ERK 和 Akt 磷酸化动力学。rhALR 的有丝分裂作用是肝脏特异性的，并且似乎至少部分独立于表皮生长因子受体介导的信号传导。
