Department of Neurosurgery, Children's Hospital of Pittsburgh, 4401 Penn Avenue, Pittsburgh, PA 15224, USA.
J Pharmacol Exp Ther. 2012 Jun;341(3):859-72. doi: 10.1124/jpet.112.191536. Epub 2012 Mar 5.
We observed that glioma cells are differentially sensitive to N-{4-[4-(4'-chloro-biphenyl-2-ylmethyl)-piperazin-1-yl]-benzoyl}-4-(3-dimethylamino-1-phenylsulfanylmethyl-propylamino)-3-nitro-benzenesulfonamide (ABT-737) and administration of ABT-737 at clinically achievable doses failed to induce apoptosis. Although elevated Bcl-2 levels directly correlated with sensitivity to ABT-737, overexpression of Bcl-2 did not influence sensitivity to ABT-737. To understand the molecular basis for variable and relatively modest sensitivity to the Bcl-2 homology domain 3 mimetic drug ABT-737, the abundance of Bcl-2 family members was assayed in a panel of glioma cell lines. Bcl-2 family member proteins, Bcl-xL, Bcl-w, Mcl-1, Bax, Bak, Bid, and Noxa, were found to be expressed ubiquitously at similar levels in all cell lines tested. We then examined the contribution of other apoptosis-resistance pathways to ABT-737 resistance. Bortezomib, an inhibitor of nuclear factor-kappaB (NF-κB), was found to enhance sensitivity of ABT-737 in phosphatase and tensin homolog on chromosome 10 (PTEN)-wild type, but not PTEN-mutated glioma cell lines. We therefore investigated the association between phosphatidylinositol 3-kinase (PI3K)/Akt activation and resistance to the combination of ABT-737 and bortezomib in PTEN-deficient glioma cells. Genetic and pharmacological inhibition of PI3K inhibition sensitized PTEN-deficient glioma cells to bortezomib- and ABT-737-induced apoptosis by increasing cleavage of Bid protein, activation and oligomerization of Bax, and loss of mitochondrial membrane potential. Our data further suggested that PI3K/Akt-dependent protection may occur upstream of the mitochondria. This study demonstrates that interference with multiple apoptosis-resistance signaling nodes, including NF-κB, Akt, and Bcl-2, may be required to induce apoptosis in highly resistant glioma cells, and therapeutic strategies that target the PI3K/Akt pathway may have a selective role for cancers lacking PTEN function.
我们观察到神经胶质瘤细胞对 N-{4-[4-(4'-氯联苯-2-基甲基)-哌嗪-1-基]-苯甲酰基}-4-(3-二甲基氨基-1-苯硫基甲基-丙基氨基)-3-硝基-苯磺酰胺（ABT-737）的敏感性存在差异，并且临床可达到的 ABT-737 剂量的给药未能诱导细胞凋亡。虽然 Bcl-2 水平升高与 ABT-737 的敏感性直接相关，但 Bcl-2 的过表达并不影响对 ABT-737 的敏感性。为了了解 Bcl-2 同源结构域 3 模拟药物 ABT-737 敏感性存在差异的分子基础，我们在一系列神经胶质瘤细胞系中检测了 Bcl-2 家族成员的丰度。在所有测试的细胞系中，Bcl-2 家族成员蛋白 Bcl-xL、Bcl-w、Mcl-1、Bax、Bak、Bid 和 Noxa 普遍以相似水平表达。然后，我们检查了其他抗凋亡途径对 ABT-737 耐药性的贡献。发现蛋白酶体抑制剂硼替佐米（Bortezomib）可增强磷酸酶和张力蛋白同系物 on chromosome 10（PTEN）野生型，但不能增强 PTEN 突变型神经胶质瘤细胞系对 ABT-737 的敏感性。因此，我们研究了在 PTEN 缺失的神经胶质瘤细胞中，PI3K/AKT 激活与 ABT-737 和硼替佐米联合耐药性之间的关联。PI3K 抑制的遗传和药理学抑制通过增加 Bid 蛋白的切割、Bax 的激活和寡聚化以及线粒体膜电位的丧失，使 PTEN 缺失的神经胶质瘤细胞对硼替佐米和 ABT-737 诱导的细胞凋亡敏感。我们的数据进一步表明，PI3K/Akt 依赖性保护可能发生在线粒体之前。这项研究表明，干扰包括 NF-κB、Akt 和 Bcl-2 在内的多种抗凋亡信号节点可能是诱导高度耐药的神经胶质瘤细胞凋亡所必需的，并且针对 PI3K/Akt 途径的治疗策略可能对缺乏 PTEN 功能的癌症具有选择性作用。
