Targeting PBR by hexaminolevulinate-mediated photodynamic therapy induces apoptosis through translocation of apoptosis-inducing factor in human leukemia cells
Targeting PBR by hexaminolevulinate-mediated photodynamic therapy induces apoptosis through translocation of apoptosis-inducing factor in human leukemia cells
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DOI：
10.1158/0008-5472.can-05-0510
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发表时间：
2005-12-01
期刊：
影响因子：
11.2
通讯作者：
Peng, Q
中科院分区：
文献类型：
--
作者：
Furre, IE;Shahzidi, S;Peng, Q
光动力疗法（PDT）与内源性原卟啉IX衍生自5-氨基乙酰丙酸或其衍生物已被建立用于治疗几个癌前病变和恶性肿瘤，然而，该模式的机制尚未完全阐明。线粒体通透性转换孔主要由线粒体外膜电压依赖性阴离子通道、外周苯二氮卓受体（PBR）和线粒体内膜腺嘌呤核苷酸转运体（ANT）组成。这些线粒体蛋白负责导致细胞凋亡的渗透性转变。在本研究中，人白血病细胞系，Reh，与PDT使用hexaminolevulinate（HAL）。HAL介导的PDT（HAL-PDT）后，发现80%以上的凋亡Reh细胞与高分子量（50 kbp）的DNA片段。在HAL-PDT过程中加入PBR的两种配体PK 11195或Ro 5 -4864可显著抑制细胞凋亡效应。ANT的配体邦奎酸也降低PDT效应。虽然线粒体跨膜电位下降，但线粒体细胞色素c的胞浆转位和caspase-9、caspase-8、caspase-3及聚ADP核糖聚合酶的激活均未被发现，而线粒体凋亡诱导因子（AIF）的核转位则被免疫印迹和免疫细胞化学所证实。由于AIF是参与caspase依赖性和caspase非依赖性途径的所有促凋亡因子中唯一一个诱导高分子量DNA片段化的因子，因此我们得出结论，HAL-PDT特异性靶向PBR，通过线粒体AlF的核转位导致Reh细胞的凋亡。本研究提示PBR可能成为基于HAL的肿瘤光动力治疗的新靶点。
Photodynamic therapy (PDT) with endogenous protoporphyrin IX derived from 5-aminolevulinic acid or its derivatives has been established for treatments of several premalignancies and malignancies; however, the mechanism of the modality is not fully elucidated. The mitochondrial permeability transition pore consists mainly of the mitochondrial outer membrane voltage-dependent anion channel and the peripheral benzodiazepine receptor (PBR) and the mitochondrial inner membrane adenine nucleotide translocator (ANT). These mitochondrial proteins are responsible for the permeability transition that leads to apoptosis. In the present study, the human leukemia cell line, Reh, was treated with PDT using hexaminolevulinate (HAL). More than 80% of apoptotic Reh cells were found after HAL-mediated PDT (HAL-PDT) with high-molecular-weight (50 kbp) DNA fragmentation. Addition of PK11195 or Ro5-4864, two ligands of PBR, during HAL-PDT significantly inhibited the apoptotic effect. Bongkrekic acid, a ligand for ANT, also reduced the PDT effect. Although the mitochondrial transmembrane potential collapsed, neither cytosolic translocation of mitochondrial cytochrome c nor activation of caspase-9, caspase-8, caspase-3, and poly(ADP-ribose) polymerase were found. However, nuclear translocation of mitochondrial apoptosis-inducing factor (AIF) was shown by both immunoblotting and immunocytochemistry. Because AIF is the sole one among all proapoptotic factors involved in caspase-dependent and caspase-independent pathways that induces the high-molecular-weight DNA fragmentation, we conclude that HAL-PDT specifically targets PBR, leading to apoptosis of the Reh cells through nuclear translocation of mitochondrial AlF. This study suggests PBR as a possible novel therapeutic target for HAL-based PDT of cancer.