Pyatt D W, Stillman W S, Irons R D
University of Colorado Health Sciences Center, Denver, 80262, USA.
Mol Pharmacol. 1996 Jun;49(6):1097-1103.
Reactive oxygen species (ROS) have been shown to stimulate proliferation and growth responses in a variety of mammalian cell types and to act as important mediators in many cellular processes, including hematolymphopoiesis. We examined the effect on primitive murine hematopoietic progenitor cells (HPC) of ROS generated by xanthine plus xanthine oxidase (xanthine/XO) and various antioxidants. Pretreatment of murine HPC (C57BL/6) with xanthine/XO produced a dose-dependent enhancement of clonogenic response to granulocyte/macrophage colony-stimulating factor (GM-CSF) but not to interleukin-3 or granulocyte colony-stimulating factor. Stem cell factor (SCF), a potent comitogen for many hematopoietic growth factors, also synergized with GM-CSF. However, the synergistic enhancement of GM-CSF with xanthine/XO and SCF was not additive, indicating that xanthine/XO and SCF may target the same subpopulation of HPC. Support for this conclusion came from experiments demonstrating that 1) mutant mice strains constitutively lacking a SCF-responsive population of HPC [White spotted (W/WV) and Steel (SI/SId)] are unresponsive to xanthine/XO- and SCF-induced enhancement of GM-CSF and 2) 3,4-epoxybutene, which selectively abrogates SCF synergy with GM-CSF, inhibits xanthine/XO-induced enhancement. As xanthine/XO can mimic SCF in this population of HPC, the possibility exists that ROS also play a role in normal SCF-mediated proliferation of these cells. To test this hypothesis, we used the antioxidants N-tert-butyl-alpha-phenylnitrone, exogenous superoxide dismutase, and catalase. Both N-tert-butyl-alpha-phenylnitrone and superoxide dismutase effectively inhibited SCF and xanthine/XO synergism with GM-CSF, whereas catalase had no effect, indicating that the superoxide anion may be involved. Also, none of these compounds affected SCF synergism with other hematopoietic growth factors, such as interleukin-3 or granulocyte colony-stimulating factor, suggesting a population-specific phenomenon. These findings indicate that xanthine/XO mimics SCF in stimulating a subpopulation of murine HPC to proliferate and that SCF synergy with GM-CSF in this population is sensitive to antioxidant inhibition.
活性氧（ROS）已被证明可刺激多种哺乳动物细胞类型的增殖和生长反应，并在包括造血淋巴细胞生成在内的许多细胞过程中充当重要介质。我们研究了黄嘌呤加黄嘌呤氧化酶（黄嘌呤/ XO）产生的ROS和各种抗氧化剂对原始小鼠造血祖细胞（HPC）的影响。用黄嘌呤/ XO预处理小鼠HPC（C57BL / 6）可使对粒细胞/巨噬细胞集落刺激因子（GM-CSF）的克隆形成反应呈剂量依赖性增强，但对白介素-3或粒细胞集落刺激因子则无增强作用。干细胞因子（SCF）是许多造血生长因子的有效协同有丝分裂原，它也与GM-CSF协同作用。然而，GM-CSF与黄嘌呤/ XO和SCF的协同增强作用并非相加性的，这表明黄嘌呤/ XO和SCF可能靶向HPC的同一亚群。这一结论得到了实验的支持，实验表明：1）组成性缺乏对SCF有反应的HPC群体的突变小鼠品系[白斑（W / WV）和Steel（SI / SId）]对黄嘌呤/ XO和SCF诱导的GM-CSF增强无反应；2）3,4-环氧丁烯选择性消除了SCF与GM-CSF的协同作用，抑制了黄嘌呤/ XO诱导的增强作用。由于黄嘌呤/ XO在这群HPC中可模拟SCF，因此ROS也可能在这些细胞正常的SCF介导的增殖中起作用。为了验证这一假设，我们使用了抗氧化剂N-叔丁基-α-苯基硝酮、外源性超氧化物歧化酶和过氧化氢酶。N-叔丁基-α-苯基硝酮和超氧化物歧化酶均有效抑制了SCF和黄嘌呤/ XO与GM-CSF的协同作用，而过氧化氢酶则无作用，这表明超氧阴离子可能参与其中。此外，这些化合物均未影响SCF与其他造血生长因子（如白介素-3或粒细胞集落刺激因子）的协同作用，提示这是一种群体特异性现象。这些发现表明，黄嘌呤/ XO在刺激小鼠HPC的一个亚群增殖方面可模拟SCF，并且该群体中SCF与GM-CSF的协同作用对抗氧化剂抑制敏感。
