BH3 mimetic ABT-737 potentiates TRAIL-mediated apoptotic signaling by unsequestering bim and bak in human pancreatic cancer cells
BH3 mimetic ABT-737 potentiates TRAIL-mediated apoptotic signaling by unsequestering bim and bak in human pancreatic cancer cells
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DOI：
10.1158/0008-5472.can-07-2508
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发表时间：
2008-04-15
期刊：
影响因子：
11.2
通讯作者：
Sinicrope, Frank A.
中科院分区：
文献类型：
--
作者：
Huang, Shengbing;Sinicrope, Frank A.
肿瘤坏死因子相关凋亡诱导配体（TRAIL）已被证明可以诱导线粒体凋亡信号，可以负调控的促生存Bcl-2蛋白。ABT-737是一种小分子BH 3模拟物，结合并拮抗Bcl-2/Bcl-x（L），但不拮抗Mcl-1。我们发现ABT-737可以协同增强TRAIL介导的人胰腺癌细胞系的细胞毒性。ABT-737显示出增强TRAIL诱导的细胞凋亡，如通过DNA片段化、半胱天冬酶-8和Bid的活化以及半胱天冬酶-3和poly（ADP-核糖）聚合酶的裂解所示。ABT-737增强了TRAIL诱导的Bax构象变化。ABT-737在两种细胞系中破坏了巴克与Bcl-x（L）的相互作用。此外，ABT-737使促凋亡的仅BH 3蛋白Bim从其被Bcl-x（L）或Bcl-2的隔离中解脱出来。Bim小发夹RNA（shRNA）显示与shRNA对照细胞相比减弱caspase-3切割并降低TRAIL加ABT-737的细胞毒性作用。最后，Mcl-1 shRNA增强了ABT-737对caspase-3的切割，并增强了其细胞毒性作用。综上所述，ABT-737通过解除Bim和巴克的隔离并增强TRAIL诱导的Bax构象变化来增强TRAIL诱导的细胞杀伤。这些发现表明了一种新的策略，以增强外在和内在凋亡途径之间的串扰，以提高对胰腺癌的治疗效果。
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to induce mitochondrial apoptotic signaling that can be negatively regulated by prosurvival Bcl-2 proteins. ABT-737 is a small-molecule BH3 mimetic that binds to and antagonizes Bcl-2/Bcl-x(L) but not Mcl-1. We show that ABT-737 can synergistically enhance TRAIL-mediated cytotoxicity in human pancreatic cancer cell lines. ABT-737 was shown to enhance TRAIL-induced apoptosis as shown by DNA fragmentation, activation of caspase-8 and Bid, and cleavage of caspase-3 and poly(ADP-ribose) polymerase. A Bax conformational change induced by TRAIL was enhanced by ABT-737. ABT-737 disrupted the interaction of Bak with Bcl-x(L) in both cell lines. Furthermore, ABT-737 untethered the proapoptotic BH3-only protein Bim from its sequestration by Bcl-x(L) or Bcl-2. Bim small hairpin RNA (shRNA) was shown to attenuate caspase-3 cleavage and to reduce the cytotoxic effects of TRAIL plus ABT-737 compared with shRNA control cells. Finally, Mcl-1 shRNA potentiated caspase-3 cleavage by ABT-737 and enhanced its cytotoxic effects. Taken together, ABT-737 augments TRAIL-induced cell killing by unsequestering Bim and Bak and enhancing a Bax conformational change induced by TRAIL. These findings suggest a novel strategy to enhance cross-talk between the extrinsic and intrinsic apoptotic pathways to improve therapeutic efficacy against pancreatic cancer.