Dilloo D, Hanenberg H, Lion T, Burdach S
Bone Marrow Transplantation Programme, Heinrich Heine-University Medical Center, Düsseldorf, Germany.
Leukemia. 1995 Mar;9(3):419-24.
Cell lines of myeloid origin have been shown to express interleukin-2 receptors (IL-2R). Here, we demonstrate the expression of IL-2R alpha and IL-R beta on the CML blast cell line K562 by FACS analysis and cross-linking assay. Furthermore, we examined the effect of IL-2 on leukemic progenitor growth, employing K562 as a model. Clonogenic growth was assessed after 3 days of culture by colony formation in a serum-free, semi-solid assay system. IL-2 was found to exhibit a dose-dependent suppressive effect on K562 clonogenicity with 48% inhibition of colony formation at 250 U IL-2 and 60% inhibition at 1000 U IL-2. Philadelphia chromosome (Ph)-positive K562 cells possess multiple copies of the bcr/abl fusion gene whose transcript and protein product (p210) is thought to confer growth advantage to CML cells. We therefore investigated IL-2-dependent modulation of bcr/abl mRNA accumulation and p210 protein levels in K562 cells. After 4 h of culture in the presence of IL-2, a 3-15-fold reduction of bcr/abl mRNA accumulation was demonstrated by competitive reverse PCR. Reduction of bcr/abl fusion protein levels was demonstrated at 24 h of IL-2-supplemented cell culture, employing p210 recognizing monoclonal antibodies (mAbs) in FACS analysis. Levels of proliferation marker Ki67 were only marginally affected. We conclude: (1) K562 cells express both IL-2R alpha and IL-R beta; (2) IL-2 inhibits clonogenic growth of K562 in a dose-dependent manner; and (3) IL-2-mediated inhibition of K562 proliferation is preceded by a reduction of bcr/abl mRNA accumulation and p210 protein levels.
已证明髓系来源的细胞系可表达白细胞介素-2受体（IL-2R）。在此，我们通过流式细胞术分析和交联试验证明了慢性粒细胞白血病原始细胞系K562上IL-2Rα和IL-Rβ的表达。此外，我们以K562为模型，研究了IL-2对白血病祖细胞生长的影响。在无血清半固体检测系统中培养3天后，通过集落形成评估克隆形成生长情况。发现IL-2对K562的克隆形成具有剂量依赖性抑制作用，在250 U IL-2时集落形成抑制率为48%，在1000 U IL-2时抑制率为60%。费城染色体（Ph）阳性的K562细胞拥有多个bcr/abl融合基因拷贝，其转录本和蛋白质产物（p210）被认为赋予慢性粒细胞白血病细胞生长优势。因此，我们研究了K562细胞中IL-2依赖的bcr/abl mRNA积累和p210蛋白水平的调节。在IL-2存在的情况下培养4小时后，通过竞争性逆转录PCR证明bcr/abl mRNA积累减少了3至15倍。在补充IL-2的细胞培养24小时后，通过流式细胞术分析使用识别p210的单克隆抗体（mAb）证明bcr/abl融合蛋白水平降低。增殖标志物Ki67水平仅受到轻微影响。我们得出结论：（1）K562细胞同时表达IL-2Rα和IL-Rβ；（2）IL-2以剂量依赖性方式抑制K562的克隆形成生长；（3）IL-2介导K562增殖的抑制之前是bcr/abl mRNA积累和p210蛋白水平的降低。
