Yu Da-Yong, Zhao Qing-Li, Wei Zheng-Li, Nomura Takaharu, Kashiwakura Ikuo, Kagiya Tsutomu V, Kondo Takashi
Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama, 930-0194, Japan.
Apoptosis. 2009 May;14(5):655-64. doi: 10.1007/s10495-009-0329-7.
Sanazole has been tested clinically as a hypoxic cell radiosensitizer. In this study, we determined whether sanazole enhances the radiation-induced apoptosis of human lymphoma U937 cells. Our results revealed that, compared with 10 mM sanazole or radiation alone, the combination of both resulted in a significant enhancement of apoptosis after 6 h, which was evaluated on the basis of DNA fragmentation, morphological changes, and phosphatidylserine externalization. Sanazole alone enhanced intracellular superoxide and hydrogen peroxide formation, which further increased when the cells were irradiated. Significant enhancement of Fas externalization, loss of mitochondrial membrane potential (MMP), and activation of caspase-3 and caspase-8 were observed after the combined treatment. Moreover, this combination could also enhance Bid activation, reduction of Hsp70 expression level and release of cytochrome c from the mitochondria to the cytosol. An immediate increase in the intracellular Ca(2+) concentration (Ca(2+)) was observed after the combined treatment. These results suggest that the intracellular superoxide and peroxide generated by sanazole might be involved in the enhancement of radiation-induced apoptosis, and that these effects are associated with modulation of the Fas-mitochondria-caspase-dependent pathway, an increase in Ca(2+), and a decrease in the Hsp70 expression levels.
三氮唑已作为一种乏氧细胞放射增敏剂进行了临床测试。在本研究中，我们确定了三氮唑是否能增强辐射诱导的人淋巴瘤U937细胞凋亡。我们的结果显示，与单独使用10 mM三氮唑或辐射相比，二者联合使用在6小时后导致凋亡显著增强，这是基于DNA片段化、形态变化和磷脂酰丝氨酸外翻进行评估的。单独使用三氮唑可增强细胞内超氧化物和过氧化氢的生成，在细胞接受照射时其生成进一步增加。联合处理后观察到Fas外翻显著增强、线粒体膜电位（MMP）丧失以及caspase-3和caspase-8激活。此外，这种联合还可增强Bid激活、降低Hsp70表达水平以及细胞色素c从线粒体释放到细胞质中。联合处理后立即观察到细胞内Ca(2+)浓度（[Ca(2+)]i）升高。这些结果表明，三氮唑产生的细胞内超氧化物和过氧化物可能参与增强辐射诱导的凋亡，并且这些效应与Fas-线粒体-caspase依赖性途径的调节、[Ca(2+)]i升高以及Hsp70表达水平降低有关。
