Baron Frédéric, Turhan Ali G, Giron-Michel Julien, Azzarone Bruno, Bentires-Alj Mohamed, Bours Vincent, Bourhis Jean Henri, Chouaib Salem, Caignard Anne
INSERM 487, Laboratoire de thérapie cellulaire, Institut Gustave Roussy, 39 rue Camille Desmoulins, F-94805 Villejuif, France.
Blood. 2002 Mar 15;99(6):2107-13. doi: 10.1182/blood.v99.6.2107.
Chronic myeloid leukemia is a clonal myeloproliferative expansion of transformed primitive hematopoietic progenitor cells characterized by high-level expression of BCR-ABL chimeric gene, which induces growth factor independence. However, the influence of BCR-ABL expression on cell-mediated cytotoxicity is poorly understood. In the present study, we asked whether BCR-ABL expression interferes with leukemic target sensitivity to natural killer (NK) cell cytolysis. Our approach was based on the use of 2 BCR-ABL transfectants of the pluripotent hematopoietic cell line UT-7 expressing low (UT-7/E8, UT-7/G6) and high (UT-7/9) levels of BCR-ABL. As effector cells, we used CD56(bright), CD16-, CD2- NK cells differentiated in vitro from CD34 cord blood progenitors. We demonstrated that BCR-ABL transfectants UT-7/9 were lysed by NK cells with a higher efficiency than parental and low UT-7/E8.1 and UT-7/G6 transfectants. This enhanced susceptibility to lysis correlated with an increase in expression of intercellular adhesion molecule 1 (ICAM-1) by target cells. Treatment of UT-7/9 cells by STI571 (a specific inhibitor of the abl kinase) resulted in a decrease in NK susceptibility to lysis and ICAM-1 down-regulation in target cells. Furthermore, the constitutive activation of nuclear factor-kappaB (NF-kappaB) detected in BCR-ABL transfectant UT-7/9, was significantly attenuated when cells were treated by STI571. Interestingly, inhibition of NF-kappaB activation by BAY11-67082 (a specific NF-kappaB inhibitor) resulted in down-regulation of ICAM-1 expression and a subsequent decrease in NK-induced killing of UT-7/9 transfectants. Our results show that oncogenic transformation by BCR-ABL may increase susceptibility of leukemic progenitors to NK cell cytotoxicity by a mechanism involving overexpression of ICAM-1 as a consequence of NF-kappaB activation.
慢性粒细胞白血病是一种由转化的原始造血祖细胞发生克隆性骨髓增殖性扩张所导致的疾病，其特征为BCR-ABL嵌合基因的高水平表达，该基因可诱导细胞不依赖生长因子。然而，BCR-ABL表达对细胞介导的细胞毒性的影响尚不清楚。在本研究中，我们探讨了BCR-ABL表达是否会干扰白血病靶细胞对自然杀伤（NK）细胞溶解的敏感性。我们的方法基于使用多能造血细胞系UT-7的两种BCR-ABL转染子，它们分别表达低水平（UT-7/E8、UT-7/G6）和高水平（UT-7/9）的BCR-ABL。作为效应细胞，我们使用了从CD34脐带血祖细胞体外分化而来的CD56(bright)、CD16-、CD2-NK细胞。我们证明，与亲本细胞以及低表达的UT-7/E8.1和UT-7/G6转染子相比，NK细胞对BCR-ABL转染子UT-7/9的裂解效率更高。这种对裂解的易感性增强与靶细胞细胞间黏附分子1（ICAM-1）表达的增加相关。用STI571（abl激酶的特异性抑制剂）处理UT-7/9细胞会导致NK细胞对裂解的敏感性降低以及靶细胞中ICAM-1表达下调。此外，在BCR-ABL转染子UT-7/9中检测到的核因子-κB（NF-κB）的组成性激活，在细胞用STI571处理后显著减弱。有趣的是，用BAY11-6708（一种特异性NF-κB抑制剂）抑制NF-κB激活会导致ICAM-1表达下调，随后NK细胞对UT-7/9转染子的杀伤作用降低。我们的结果表明，BCR-ABL介导的致癌转化可能通过一种机制增加白血病祖细胞对NK细胞细胞毒性的敏感性，该机制涉及由于NF-κB激活导致ICAM-1的过表达。
