Ye Yun-Bin, Lin Jian-Yin, Chen Qiang, Liu Fang, Chen Hui-Jing, Li Jie-Yu, Liu Wang-Qing, Garbay Christiane, Vidal Michel
Université Paris Descartes, Laboratoire de Pharmacochime Moléculaire et Cellulaire, INSERM U648, 45 Rue des Saints Peres, Paris 75006, France.
Biochem Pharmacol. 2008 Jun 1;75(11):2080-91. doi: 10.1016/j.bcp.2007.12.021. Epub 2008 Mar 22.
Chronic myelogenous leukemia (CML) is characterized by the presence of Bcr-Abl oncoprotein. Gleevec has been designed to treat many CML patients by specifically targeting Bcr-Abl, but resistance to it is already apparent in many cases. In CML cells, Bcr-Abl activates several signaling pathways, including the Ras-dependent pathway, in which growth factor receptor binding 2 (Grb2) acts as an adaptor protein. A specific Grb2-SH3 inhibitor (denoted as peptidimer-c) that disrupts Grb2-Sos complex was designed and synthesized in our laboratory. In this study, we investigated the effect and the molecular mechanism of this inhibitor. Peptidimer-c was shown to bind to Grb2 in K562 cells, a cell line over-expressing Bcr-Abl oncoprotein. It caused cytotoxicity in the cells, and inhibited their ability of colony formation in the semi-solid medium. It was shown to induce apoptosis of K562 cells in a dose-dependent mode, the apoptotic effect of peptidimer-c being associated with caspase-3 activation. The effect of peptidimer-c on growth inhibition was also shown to be accompanied by S-phase arrest of cell cycle mediated by down-regulation of cyclin A and Cdk2, as well as phospho-Cdk2. The above results indicated that peptidimer-c may be another potential therapeutic agent for CML, which can induce S-phase arrest in the Bcr-Abl positive K562.
慢性粒细胞白血病（CML）的特征是存在Bcr-Abl癌蛋白。格列卫被设计用于通过特异性靶向Bcr-Abl来治疗许多CML患者，但在许多病例中对其的耐药性已经很明显。在CML细胞中，Bcr-Abl激活多种信号通路，包括Ras依赖性通路，其中生长因子受体结合蛋白2（Grb2）作为衔接蛋白发挥作用。我们实验室设计并合成了一种破坏Grb2-Sos复合物的特异性Grb2-SH3抑制剂（称为肽二聚体-c）。在本研究中，我们研究了该抑制剂的作用效果及其分子机制。肽二聚体-c被证明能与K562细胞中的Grb2结合，K562细胞是一种过表达Bcr-Abl癌蛋白的细胞系。它在细胞中引起细胞毒性，并抑制其在半固体培养基中的集落形成能力。结果表明，肽二聚体-c能以剂量依赖的方式诱导K562细胞凋亡，肽二聚体-c的凋亡作用与半胱天冬酶-3的激活有关。肽二聚体-c对生长抑制的作用还表现为通过下调细胞周期蛋白A、细胞周期蛋白依赖性激酶2（Cdk2）以及磷酸化Cdk2介导细胞周期的S期阻滞。上述结果表明，肽二聚体-c可能是另一种潜在的CML治疗药物，它能诱导Bcr-Abl阳性的K562细胞发生S期阻滞。
