Wenger R H, Marti H H, Bauer C, Gassmann M
Institute of Physiology, University of Zürich-Irchel, CH-8057 Zürich, Switzerland.
Int J Mol Med. 1998 Sep;2(3):317-24. doi: 10.3892/ijmm.2.3.317.
Hypoxia is thought to be a common precursor of coronary artery disease and malignant tumors, both diseases representing the leading causes of death in industrial nations. So far, investigations of oxygen-regulated erythropoietin (EPO) gene expression in the human hepatoma cell lines Hep3B and HepG2 allowed many important insights into the mechanisms of oxygen-sensing, signalling and regulation of an increasing number of oxygen-responsive genes. To differentiate the various signalling pathways involved in EPO production by these two cell lines, we examined several factors that positively influenced EPO expression. The results demonstrate a keen differential effect of cell density and oxygen concentration on EPO induction in Hep3B compared to HepG2 cells. Using optimized cell culture conditions, EPO production rates as high as 1 U EPO per 10(6) Hep3B cells in 24 h could be achieved. We also found a moderate but reproducible positive effect of CoCl2 on hypoxia-induced EPO expression in Hep3B but a negative CoCl2 effect on hypoxic induction in HepG2 cells. CoCl2 inhibited cell growth in a concentration-dependent manner. Interleukin-6 was synergistic with hypoxia on EPO induction in Hep3B as well as HepG2 cells, and dexamethasone enhanced this effect in Hep3B but not in HepG2 cells. The moderate CoCl2-dependent increase of EPO production observed in hypoxic Hep3B cells might indicate that CoCl2 and hypoxia do not necessarily act via, identical signalling pathways.
缺氧被认为是冠状动脉疾病和恶性肿瘤的常见先兆，这两种疾病是工业化国家主要的死亡原因。到目前为止，对人类肝癌细胞系Hep3B和HepG2中氧调节促红细胞生成素（EPO）基因表达的研究，使人们对越来越多的氧反应性基因的氧感应、信号传导和调节机制有了许多重要的认识。为了区分这两种细胞系中参与EPO产生的各种信号通路，我们研究了几个对EPO表达有正向影响的因素。结果表明，与HepG2细胞相比，细胞密度和氧浓度对Hep3B细胞中EPO诱导有明显的差异效应。使用优化的细胞培养条件，每24小时每10(6)个Hep3B细胞可实现高达1 U EPO的产生率。我们还发现，CoCl2对Hep3B细胞中缺氧诱导的EPO表达有适度但可重复的正向作用，但对HepG2细胞的缺氧诱导有负向作用。CoCl2以浓度依赖的方式抑制细胞生长。白细胞介素-6在Hep3B细胞和HepG2细胞中与缺氧对EPO诱导具有协同作用，地塞米松增强了Hep3B细胞中的这种作用，但在HepG2细胞中没有。在缺氧的Hep3B细胞中观察到的EPO产生的适度CoCl2依赖性增加可能表明，CoCl2和缺氧不一定通过相同的信号通路起作用。
