Yang Xiaoxi, Li Zheng, Yang Lei, Lei Han, Yu Haijun, Liao Zhengkai, Zhou Fuxiang, Xie Conghua, Zhou Yunfeng
Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, 430071, China,
J Cancer Res Clin Oncol. 2015 Sep;141(9):1545-52. doi: 10.1007/s00432-015-1911-8. Epub 2015 Jan 22.
To investigate the effects of TRF2 depletion on radiosensitivity in both the telomerase-positive cell lines (A549) and alternative lengthening of telomere (ALT) cell lines (U2OS).
X-ray irradiation was used to establish two radioresistant cancer models (A549R and U2OSR) from A549 and U2OS. Colony formation assay was applied to examine the radiosensitivity of radioresistant A549R and U2OSR cells and TRF2 low-expression cells. Real-time PCR and TeloTAGGG Telomerase PCR ELISA Kit were performed to examine telomere length and telomerase activity separately. γ-H2AX was detected by immunofluorescence to assess the radiation-induced DSBs.
Radioresistant cancer models were established, in which TRF2 was significantly over-expressed. Low expression of TRF2 protein could enhance the radiosensitivity and induce telomere length of A549 and U2OS cell shortening. In A549 cells with TRF2 down-regulated, the telomerase activity was inhibited, too. TRF2 deficiency increases γ-H2AX foci and fails to protect telomere from radiation.
The data suggest that TRF2 is a radioresistant protein in A549 and U2OS cells, and could potentially be a target for radiosensitization of both telomerase-positive and ALT cells in radiotherapy.
研究端粒重复结合因子2（TRF2）缺失对端粒酶阳性细胞系（A549）和端粒替代延长（ALT）细胞系（U2OS）放射敏感性的影响。
采用X射线照射从A549和U2OS细胞建立两种放射抗性癌症模型（A549R和U2OSR）。应用集落形成试验检测放射抗性A549R和U2OSR细胞以及TRF2低表达细胞的放射敏感性。分别进行实时荧光定量PCR和端粒酶PCR ELISA试剂盒检测端粒长度和端粒酶活性。通过免疫荧光检测γ-H2AX以评估辐射诱导的双链断裂（DSBs）。
建立了放射抗性癌症模型，其中TRF2显著过表达。TRF2蛋白低表达可增强A549和U2OS细胞的放射敏感性并诱导端粒长度缩短。在TRF2下调的A549细胞中，端粒酶活性也受到抑制。TRF2缺陷增加γ-H2AX灶点且无法保护端粒免受辐射。
数据表明TRF2是A549和U2OS细胞中的一种放射抗性蛋白，并且可能是放疗中端粒酶阳性和ALT细胞放射增敏的潜在靶点。
