RSF-1 siRNA Enhances Tumor Radiosensitivity in Cervical Cancer via Enhanced DNA Damage, Cell Cycle Redistribution, and Promotion of Apoptosis

Jing Tian,1 Enqi Kong,2 Xiangyu Wang,3 Zhaoguang Xie,4 Cherry Yin-Yi Chang,5 Jim Jinn-Chyuan Sheu,6– 9 Quan Hao,1 Li Sun10,11 1Department of Gynecological Oncology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, People’s Republic of China, Key Laboratory of Cancer Prevention and Therapy, Tianjin, Tianjin’s Clinical Research Center for Cancer, Tianjin 300060, People’s Republic of China; 2School of Medicine and Life Sciences, University of Jinan-Shandong Academy of Medical Sciences, Jinan 250200, People’s Republic of China; 3The Third School of Clinical Medicine, Southern Medical University, Guangzhou 510515, People’s Republic of China; 4Department of Maternity, Jinan Maternal and Child Health Hospital Affiliated to Shandong First Medical University, Jinan, 250001, People’s Republic of China; 5Department of Obstetrics and Gynecology, China Medical University Hospital, Taichung 40447, Taiwan; 6Institute of Biomedical Sciences, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; 7Department of Biotechnology, College of Life Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan; 8School of Chinese Medicine, China Medical University, Taichung 40402, Taiwan; 9Department of Health and Nutrition Biotechnology, Asia University, Taichung 41354, Taiwan; 10Department of Gynecological Oncology, Qingdao Central Hospital, The Second Affiliated Hospital of Medical College of Qingdao University, Qingdao, 266042, People’s Republic of China; 11Department of Gynecological Oncology, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan 250117, People’s Republic of ChinaCorrespondence: Li SunDepartment of Gynecological Oncology, Qingdao Central Hospital, The Second Affiliated Hospital of Medical College of Qingdao University, Qingdao 266042, People’s Republic of ChinaTel +86-532-84962590Email sunli766@163.comBackground: Remodeling and spacing factor-1 (RSF-1) is an identified tumor biomarker that is overexpressed in a variety of human cancers, but its effect on radiotherapy remains unclear. In this study, we aimed to explore the effect of RSF-1 siRNA on sensitizing cervical cancer cells to radiation and its underlying mechanism.Methods: The mRNA and protein expression of RSF-1 in tissue and cells were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. Cell counting kit-8 (CCK-8) and colony formation assay were used to examine cell proliferation. Flow cytometry was used to analyzed the cell cycle and cell apoptosis. DNA damage was examined by the comet assay. ATM, ATR, CHK1, CHK2, H2AX, γH2AX and phosphorylated ATM, ATR, CHK1 and CHK2 were detected by Western blotting. γH2AX foci were demonstrated by immunofluorescence staining.Results: RSF-1 was upregulated in cervical cancer tissue and decreased after effective treatment. RSF-1 siRNA in combination with radiation suppressed cell viability, redistributed cell cycles and also induced cell apoptosis in HeLa and SiHa cell lines. Further, knockdown of RSF-1 induced DNA damage by attenuating DNA repair capability, thereby sensitizing cervical cancer cells to radiation.Conclusions: These data demonstrate that RSF-1 siRNA enhanced the sensitivity of radiotherapy, and targeting RSF-1 may be a promising approach for the development of novel radiosensitizing agents for the treatment of cervical cancer.Keywords: RSF-1, cervical cancer, radiotherapy, DNA damage