Costes S, Streuli C H, Barcellos-Hoff M H
Nuclear Engineering Department, Lawrence Berkeley National Laboratory, University of California, Berkeley, 94720, USA.
Radiat Res. 2000 Oct;154(4):389-97. doi: 10.1667/0033-7587(2000)154[0389:qiaoli]2.0.co;2.
We previously reported that laminin immunoreactivity in mouse mammary epithelium is altered shortly after whole-body irradiation with 0.8 Gy from 600 MeV/nucleon iron ions but is unaffected after exposure to sparsely ionizing radiation. This observation led us to propose that the effect could be due to protein damage from the high ionization density of the ion tracks. If so, we predicted that it would be evident soon after radiation exposure in basement membranes of other tissues and would depend on ion fluence. To test this hypothesis, we used immunofluorescence, confocal laser scanning microscopy, and image segmentation techniques to quantify changes in the basement membrane of mouse skin epidermis. At 1 h after exposure to 1 GeV/nucleon iron ions with doses from 0.03 to 1.6 Gy, neither the visual appearance nor the mean pixel intensity of laminin in the basement membrane of mouse dorsal skin epidermis was altered compared to sham-irradiated tissue. This result does not support the hypothesis that particle traversal directly affects laminin protein integrity. However, the mean pixel intensity of laminin immunoreactivity was significantly decreased in epidermal basement membrane at 48 and 96 h after exposure to 0.8 Gy 1 GeV/nucleon iron ions. We confirmed this effect with two additional antibodies raised against affinity-purified laminin 1 and the E3 fragment of the long-arm of laminin 1. In contrast, collagen type IV, another component of the basement membrane, was unaffected. Our studies demonstrate quantitatively that densely ionizing radiation elicits changes in skin microenvironments distinct from those induced by sparsely ionizing radiation. Such effects may might contribute to the carcinogenic potential of densely ionizing radiation by altering cellular signaling cascades mediated by cell-extracellular matrix interactions.
我们之前报道过，用600兆电子伏特/核子的铁离子对小鼠进行0.8戈瑞的全身照射后不久，小鼠乳腺上皮中的层粘连蛋白免疫反应性会发生改变，但暴露于低线性能量传递辐射后则不受影响。这一观察结果使我们推测，这种效应可能是由于离子径迹的高电离密度导致的蛋白质损伤。如果是这样，我们预测在辐射暴露后不久，其他组织的基底膜中也会出现这种效应，并且这将取决于离子注量。为了验证这一假设，我们使用免疫荧光、共聚焦激光扫描显微镜和图像分割技术来量化小鼠皮肤表皮基底膜的变化。在暴露于剂量为0.03至1.6戈瑞的1吉电子伏特/核子铁离子1小时后，与假照射组织相比，小鼠背部皮肤表皮基底膜中层粘连蛋白的视觉外观和平均像素强度均未改变。这一结果不支持粒子穿越直接影响层粘连蛋白蛋白质完整性的假设。然而，在暴露于0.8戈瑞的1吉电子伏特/核子铁离子后48小时和96小时，表皮基底膜中层粘连蛋白免疫反应性的平均像素强度显著降低。我们用另外两种针对亲和纯化的层粘连蛋白1和层粘连蛋白1长臂的E3片段产生的抗体证实了这一效应。相比之下，基底膜的另一个成分IV型胶原蛋白则未受影响。我们的研究定量地证明，高电离辐射引发的皮肤微环境变化与低线性能量传递辐射诱导的变化不同。这种效应可能通过改变由细胞 - 细胞外基质相互作用介导的细胞信号级联反应，从而对高电离辐射的致癌潜力产生影响。
