Olsson A, Diaz T, Aguilar-Santelises M, Osterborg A, Celsing F, Jondal M, Osorio L M
Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden.
Leukemia. 2001 Dec;15(12):1868-77. doi: 10.1038/sj.leu.2402287.
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent activator of the cell death pathway and exerts tumoricidal activity in vivo with minimal toxicity. In order to investigate the therapeutic potential of TRAIL in B chronic lymphocytic leukemia (B-CLL) we have analyzed the expression of TRAIL receptors (TRAIL-Rs) in leukemic cells from B-CLL patients and their in vitro sensitivity to apoptosis induced by recombinant human TRAIL. We have found TRAIL-R1 and -R2 death receptor, and TRAIL-R3 and -R4 decoy receptor mRNA expression in most of the 57 B-CLL patients studied (R1 82%, R2 100%, R3 96% and R4 82%). TRAIL-R1 and R2 proteins were expressed on the surface and within the cells, whereas R3 and R4 decoy receptors were almost exclusively expressed in the cytoplasm. Despite TRAIL death receptor expression, B-CLL cells were relatively resistant to induction of apoptosis by recombinant human TRAIL (300 ng/ml). However, the susceptibility to TRAIL-induced apoptosis was increased by treatment of B-CLL cells with actinomycin D (Act D). Western blot analysis showed higher constitutive expression of the long form of FLICE-inhibitory protein (FLIP(L)) in B-CLL as compared to normal tonsillar B cells. Act D treatment down-regulated both long and short FLIP expression, which was correlated with the increase in B-CLL sensitivity to TRAIL. Although the surface TRAIL death receptor expression was up-regulated both by cell culture and by Act D treatment, the changes were not correlated with a gain in susceptibility to TRAIL. In addition, neither decoy receptors nor Bcl-2 expression were affected by Act D. Our findings suggest the possible involvement of FLIP in regulating TRAIL-mediated apoptosis in B-CLL.
肿瘤坏死因子相关凋亡诱导配体(TRAIL)是细胞死亡途径的有效激活剂,在体内具有强大的杀瘤活性且毒性极小。为了研究TRAIL在B细胞慢性淋巴细胞白血病(B-CLL)中的治疗潜力,我们分析了B-CLL患者白血病细胞中TRAIL受体(TRAIL-Rs)的表达及其对重组人TRAIL诱导凋亡的体外敏感性。我们发现,在所研究的57例B-CLL患者中,大多数患者的TRAIL-R1和-R2死亡受体以及TRAIL-R3和-R4诱饵受体mRNA均有表达(R1 82%,R2 100%,R3 96%,R4 82%)。TRAIL-R1和R2蛋白在细胞表面和细胞内均有表达,而R3和R4诱饵受体几乎仅在细胞质中表达。尽管有TRAIL死亡受体表达,但B-CLL细胞对重组人TRAIL(300 ng/ml)诱导的凋亡相对耐药。然而,用放线菌素D(Act D)处理B-CLL细胞可增加其对TRAIL诱导凋亡的敏感性。蛋白质印迹分析显示,与正常扁桃体B细胞相比,B-CLL中长形式的FLICE抑制蛋白(FLIP(L))的组成性表达更高。Act D处理可下调长、短形式FLIP的表达,这与B-CLL对TRAIL敏感性的增加相关。尽管细胞培养和Act D处理均可上调表面TRAIL死亡受体的表达,但这些变化与对TRAIL敏感性的增加无关。此外,Act D对诱饵受体和Bcl-2的表达均无影响。我们的研究结果提示FLIP可能参与调节B-CLL中TRAIL介导的凋亡。