Knockdown of telomeric repeat binding factor 2 enhances tumor radiosensitivity regardless of telomerase status
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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.
KeywordsTRF2 Radioresistant Telomere DNA damage response
This research was supported by the National Natural Science Foundation of China (No. 81071825, 81201755), the Doctoral Fund of Ministry of Education of China (No. 20120141130010) and the Fundamental Research Funds for the Central Universities. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Conflict of interest
The authors declare that they have no conflict of interest.
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