Shamimi-Noori S, Yeow W-S, Ziauddin M F, Xin H, Tran T L N, Xie J, Loehfelm A, Patel P, Yang J, Schrump D S, Fang B L, Nguyen D M
Section of Thoracic Oncology, Surgery Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA.
Cancer Gene Ther. 2008 Jun;15(6):356-70. doi: 10.1038/sj.cgt.7701120. Epub 2008 Feb 29.
Despite adequately expressing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors DR4/DR5, malignant cells are frequently refractory to the cytotoxic effect of this apoptosis-inducing ligand. The susceptibility of cancer cells to TRAIL can be potentiated by cisplatin (CDDP). This study was designed to evaluate the ability of cisplatin to enhance the cytotoxic effect of TRAIL gene therapy using the recombinant adenovirus-mediated tumor-selective expression of membrane-bound green fluorescence protein (GFP)-TRAIL fusion protein (AdVgTRAIL) on thoracic cancer cells and to elucidate the putative mechanisms responsible for this synergistic combination effect. While causing little death of cultured thoracic cancer cells by itself, AdVgTRAIL in combination with CDDP, on the other hand, mediated profound supra-additive cytotoxicity and apoptosis via a strong bystander effect. CDDP/AdVgTRAIL-induced cytotoxicity was completely abrogated either by the pancaspase inhibitor zVAD-fmk or by the selective caspase 9 inhibitor or by transient knockdown of caspase 9 by siRNA, indicating that this process was caspase-mediated and mitochondria-dependent. This was confirmed by the observation that Bcl2 overexpression protected the cells from combination-induced cytotoxicity. Robust activation of caspase 8 activity in combination-treated cells was blocked by overexpression of Bcl2, indicating that caspase 8 activation was secondary to the mitochondria-mediated amplification feedback loop. Combining CDDP with AdVgTRAIL greatly enhances its tumoricidal efficacy in cultured thoracic cancer cells in vitro. The two agents interact to mediate profound activation of caspase cascade via recruitment of the mitochondria and positive feedback loop. The CDDP/AdVgTRAIL combination also exhibits a strong antitumor effect in in vivo animal model of human cancer xenografts.
尽管恶性细胞能够充分表达肿瘤坏死因子相关凋亡诱导配体（TRAIL）受体DR4/DR5，但它们通常对这种凋亡诱导配体的细胞毒性作用具有抗性。顺铂（CDDP）可增强癌细胞对TRAIL的敏感性。本研究旨在评估顺铂增强TRAIL基因治疗细胞毒性作用的能力，该治疗采用重组腺病毒介导的膜结合绿色荧光蛋白（GFP）-TRAIL融合蛋白（AdVgTRAIL）在胸癌细胞中的肿瘤选择性表达，并阐明这种协同联合效应的潜在机制。AdVgTRAIL单独作用时对培养的胸癌细胞几乎没有致死作用，但与CDDP联合使用时，通过强大的旁观者效应介导了显著的超相加细胞毒性和凋亡。CDDP/AdVgTRAIL诱导的细胞毒性可被泛半胱天冬酶抑制剂zVAD-fmk、选择性半胱天冬酶9抑制剂或通过siRNA瞬时敲低半胱天冬酶9完全消除，表明此过程是由半胱天冬酶介导且依赖线粒体的。Bcl2过表达可保护细胞免受联合诱导的细胞毒性，这一观察结果证实了上述结论。联合处理细胞中半胱天冬酶8活性的强烈激活被Bcl2过表达所阻断，表明半胱天冬酶8的激活是线粒体介导的放大反馈环的继发效应。在体外培养的胸癌细胞中，将CDDP与AdVgTRAIL联合使用可大大增强其杀瘤效果。这两种药物相互作用，通过募集线粒体和正反馈环介导半胱天冬酶级联的深度激活。CDDP/AdVgTRAIL联合用药在人癌异种移植体内动物模型中也表现出强大的抗肿瘤作用。
