H. Huang1,2, W. Hu2, G. Zhou2, and L. N. Zhao3; 1Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, Xian, Shanxi, China, 2State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Soochow University, Suzhou, Jiangsu, China, 3Department of Radiation Oncology, First Affiliated Hospital of Air Force Medical University, Xian, China
Purpose/Objective(s): Radiotherapy plays an irreplaceable role in numerous tumor clinical treatments and over 65% of cancer patients need radiotherapy all over the world. However, it has been demonstrated that radiation-stimulated secretion of radioresistant factors promoted tumor angiogenesis, which facilitates tumor metastasis. Heavy-ion radiotherapy has demonstrated an exceptional tumor cure rate and controllable tumor angiogenesis. Nevertheless, the precise molecular mechanisms responsible for the differential angiogenic responses to photon and heavy-ion irradiation remain elusive. Materials/
Methods: Transcriptomic sequencing was performed to find differentially expressed genes that are responsive to X-ray or carbon ion treatment. Loss-of-function and gain-of-function experiments were performed to explore the biological roles of screened differentially expressed genes in angiogenesis and metastasis. Comprehensive biochemical and biological techniques were utilized to explore the functions of screened differentially expressed genes in tumor angiogenesis and metastasis induced by different radiation types. Results: Here, we identified the 61.94±4.03 (p<0.001) times up-regulation of LINC00167 and 12.4±0.43 times enhancement of pro-angiogenesis level (p<0.001) in X-ray irradiated NSCLC cells compared with unirradiated cells. However, the 3.58±0.43 (p<0.01) times up-regulation of LINC00167 and no significant enhanced pro-angiogenesis level were found in C-ion irradiated cells compared with control ones. The overexpression of LINC00167 triggers tumor angiogenesis, migration, and invasion by upregulating TGF-ß1 (11.45±1.13 vs control, p<0.001) and VEGF (8.52±0.9 vs control, p<0.001). Moreover, the transcription factor SP1 played a role in facilitating the transcriptional expression of LINC00167 by binding to the promoter region of the LINC00167 DNA sequence. Notably, the DNA binding activity of SP1 (1.5±0.1 vs control, p<0.01) was augmented by reactive oxygen species (ROS). The knockdown of either LINC00167 or SP1 effectively inhibits lung adenocarcinoma angiogenesis both in vivo and in vitro. Conclusion: These results illustrate the pro-angiogenic function of the LINC00167 via the TGF-ß1/VEGF axis and reveal the regulatory role of ROS and SP1 in the upstream response to radiation-mediated differential angiogenesis level after X-ray and C-ion irradiation. Our findings suggest the potential of targeting the LINC00167 as a therapeutic strategy to counteract angiogenesis in NSCLC radiotherapy.
