Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, India.
J Environ Pathol Toxicol Oncol. 2011;30(4):333-40. doi: 10.1615/jenvironpatholtoxicoloncol.v30.i4.60.
The present study investigated the effect of irradiated conditioned medium (ICM), obtained from human promyelocytic leukemic cells (HL-60) γ-irradiated either with low-dose (5 cGy; ICM-L) or high-dose radiation (1 Gy; ICM-H) on unirradiated HL-60 and normal human blood lymphocytes. A dose-dependent increase in apoptosis was observed in HL-60 cells cultured in ICM obtained after different doses of irradiation (0.5-10 cGy), which showed saturation in ICM from 5 cGy. Furthermore, ICM-L and ICM-H induced differential apoptotic responses in unirradiated HL-60 cells and lymphocytes. Apoptosis in lymphocytes cultured in ICM-H was significantly higher than when cells were cultured in unirradiated conditioned medium or ICM-L. Furthermore, induction of apoptosis in bystander HL-60 cells and lymphocytes cultured in ICM-L/ICM-H seems to be associated with an increase in intracellular reactive oxygen species (ROSs) and alterations in mitochondrial membrane potential. These results suggest that differential bystander responses from irradiated cancer cells toward cancer and normal cells depending on the applied dose and/or dose rate of radiation.
本研究探讨了辐照条件培养基（ICM）对未辐照的人早幼粒细胞白血病细胞（HL-60）和正常人血淋巴细胞的影响。用低剂量（5 cGy；ICM-L）或高剂量（1 Gy；ICM-H）γ射线辐照人早幼粒细胞白血病细胞（HL-60）后获得的 ICM，培养未辐照的 HL-60 细胞，观察到细胞凋亡呈剂量依赖性增加，其中 5 cGy 的 ICM 达到饱和。此外，ICM-L 和 ICM-H 对未辐照的 HL-60 细胞和淋巴细胞诱导出不同的凋亡反应。在高剂量辐照条件培养基（ICM-H）中培养的淋巴细胞的凋亡明显高于未辐照条件培养基或低剂量辐照条件培养基（ICM-L）中培养的细胞。此外，在 ICM-L/ICM-H 中培养的旁观者 HL-60 细胞和淋巴细胞中诱导的凋亡似乎与细胞内活性氧（ROS）的增加和线粒体膜电位的改变有关。这些结果表明，辐照癌细胞对癌细胞和正常细胞的旁观者反应取决于应用的剂量和/或辐射剂量率。
