Zhang Dejun, Xiang Jie, Gu Yuming, Xu Wei, Xu Hao, Zu Maoheng, Pei Dongsheng, Zheng Junnian
Department of Interventional Radiology, Affiliated Hospital of Xuzhou Medical College, Xuzhou, Jiangsu 221002, P.R. China.
Department of Rehabilitation Medicine, Affiliated Hospital of Xuzhou Medical College, Xuzhou, Jiangsu 221002, P.R. China.
Oncol Lett. 2014 Aug;8(2):575-581. doi: 10.3892/ol.2014.2186. Epub 2014 May 27.
The aim of the present study was to investigate whether radiation induces the mammalian target of rapamycin (Rap) (mTOR) signaling pathway in esophageal carcinoma Eca109 cells, and whether mTOR inhibition by rapamycin increases Eca109 cell radiosensitivity. Changes in the levels of mTOR signaling pathway and DNA damage-repair proteins in Eca109 cells prior to and following radiation were determined. The Eca109 cells were treated with Rap (0, 100, 200 and 400 nmol/l) in combination with radiation (0, 2, 4 and 6 Gy). The cell proliferation inhibition rate was determined by MTT assay. The optimum Rap concentration and radiation dose, which appropriately inhibited cell proliferation, were then selected for further study. An appropriate combination of Rap and radiation for the Eca109 cells was also selected and changes in the mTOR signaling pathway, apoptosis and DNA damage-repair proteins, as well as in cell clone formation, survival curves, the apoptosis rate and radiation-induced DNA damage were determined. The expression of the mTOR signaling pathway and DNA damage-repair proteins were found to increase following the irradiation of the Eca109 cells. In addition, Rap was found to inhibit the mTOR signaling pathway and the expression of the DNA damage-repair proteins. At the same radiation dose, with increasing Rap concentration, the proliferation inhibition rates of the Eca109 cells were found to improve. The clone formation and survival curves of the experimental group were less than those of the control groups. Furthermore, the cell apoptosis rate and expression of cleaved caspase-3 and bax in the experimental group were higher than those of the control groups, whereas the expression of bcl-2 was less than that of the control groups. The radiation-induced DNA damage of the experimental group was greater than that of the control group. The inhibition of mTOR by Rap was found to effectively inhibit the proliferation, survival and radiation-induced DNA damage repair of the Eca109 cells following irradiation, as well as promoting radiation-induced apoptosis, thereby increasing the radiosensitivity of the esophageal carcinoma Eca109 cells.
本研究的目的是探讨辐射是否能诱导食管癌Eca109细胞中的哺乳动物雷帕霉素靶蛋白（Rap）（mTOR）信号通路，以及雷帕霉素抑制mTOR是否会增加Eca109细胞的放射敏感性。测定了Eca109细胞在辐射前后mTOR信号通路和DNA损伤修复蛋白水平的变化。将Eca109细胞用Rap（0、100、200和400 nmol/l）与辐射（0、2、4和6 Gy）联合处理。通过MTT法测定细胞增殖抑制率。然后选择适当抑制细胞增殖的最佳Rap浓度和辐射剂量进行进一步研究。还为Eca109细胞选择了Rap与辐射的适当组合，并测定了mTOR信号通路、凋亡和DNA损伤修复蛋白的变化，以及细胞克隆形成、存活曲线、凋亡率和辐射诱导的DNA损伤。发现照射Eca109细胞后mTOR信号通路和DNA损伤修复蛋白的表达增加。此外，发现Rap可抑制mTOR信号通路和DNA损伤修复蛋白的表达。在相同辐射剂量下，随着Rap浓度的增加，Eca109细胞的增殖抑制率提高。实验组的克隆形成和存活曲线低于对照组。此外，实验组的细胞凋亡率以及裂解的caspase-3和bax的表达高于对照组，而bcl-2的表达低于对照组。实验组的辐射诱导DNA损伤大于对照组。发现Rap抑制mTOR可有效抑制照射后Eca109细胞的增殖、存活和辐射诱导的DNA损伤修复，同时促进辐射诱导的凋亡，从而增加食管癌Eca109细胞的放射敏感性。
