Division of Radiation Life Science, Department of Radiation Life Science and Radiation Medical Science, Kyoto University Research Reactor Institute, Sennan-gun, Osaka, Japan.
Photochem Photobiol. 2012 Mar-Apr;88(2):389-97. doi: 10.1111/j.1751-1097.2011.01046.x. Epub 2011 Dec 16.
We successfully identified the bystander effect in B16 murine melanoma cells exposed to UVA irradiation. The effect was identified based on melanogenesis following the medium transfer of the B16 cells, which had been cultured for 24 h after being exposed to UVA irradiation, to nonirradiated cells (bystander cells). Our confirmation study of the functional mechanism of bystander cells confirmed the reduced levels of mitochondrial membrane potential 1-4 h after the medium transfer. In addition, we observed increased levels of intracellular oxidation after 9-12 h, and the generation of melanin radicals, including long-lived radicals, 24 h after medium transfer. Further analysis of bystander factors revealed that the administration of EGTA treatment at the time of medium transfer led to an inhibition of melanogenesis and to neutralization of the mitochondrial membrane potential level, as well as to the restoration of intracellular oxidation levels to those of controls. The results demonstrated that the UVA irradiation bystander effect in B16 cells, as indicated by melanogenesis, was induced by the increase in intracellular oxidation due to the mitochondrial activity of calcium ions, which were among the bystander factors involved in the increase.
我们成功地鉴定了 UVA 照射的 B16 鼠黑色素瘤细胞中的旁观者效应。这种效应是基于在将 24 小时前接受 UVA 照射的 B16 细胞转移到未照射的细胞（旁观者细胞）的培养基中后黑色素生成来鉴定的。我们对旁观者细胞的功能机制的确认研究证实，在培养基转移后 1-4 小时，线粒体膜电位降低。此外，我们观察到 9-12 小时后细胞内氧化水平增加，24 小时后生成黑色素自由基，包括长寿命自由基。进一步分析旁观者因子表明，在培养基转移时给予 EGTA 处理会抑制黑色素生成，并使线粒体膜电位水平中和，以及使细胞内氧化水平恢复到对照水平。结果表明，B16 细胞中的 UVA 照射旁观者效应，如黑色素生成所示，是由钙离子的线粒体活性引起的细胞内氧化增加所诱导的，钙离子是参与增加的旁观者因子之一。
