Zixin Zhang1, Haifeng Huo2, Kui Liao3, Zhihai Wang2, Zhitao Gong2, Yanshi Li2, Chuan Liu2, Guohua Hu4. 1. Department of Otorhinolaryngology, the First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China; Department of Radiotherapy, the General Hospital of Ningxia Medical University, Yinchuan 750004, China. 2. Department of Otorhinolaryngology, the First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China. 3. Department of Oncology, the First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China. 4. Department of Otorhinolaryngology, the First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China. Electronic address: hghcq@sina.com.
Abstract
BACKGROUND/AIM: Nasopharyngeal cancer (NPC) has a high local recurrence rate due to its resistance to ionizing radiation (IR). Replication protein A1 (RPA1) is one of the main elements in the homologous repair (HR) pathway, which is closely associated with the repair of DNA double strand breaks (DDBs). Studies on the relationship between RPA1 and the radiosensitivity of NPC are substantially limited. It was hypothesized that RPA1 plays a crucial role in predicting the radiosensitivity of NPC. METHODS: The protein expression of RPA1 in 182 patients with NPC in the complete response (CR) and non-complete response (nCR) groups was evaluated using immunohistochemistry. Then, univariate and multivariate analysis were performed using SPSS software vision 22 to determine the relationship between the expression of RPA1 and the clinicopathological features. In addition, the mRNA expression of RPA1 was tested in 24 fresh samples using qRT-PCR. RPA1 was silenced in CNE-2R cell lines combined with IR to measure the radiosensitivity, proliferation, DNA damage repair and cell cycle of CNE-2R cells. Xenograft models in nude mice were used to determine the effect of RPA1 on tumor growth after IR. Immunoblotting and immunofluorescence staining were performed to identify proteins that interacted with RPA1. All statistical tests were two-sided. RESULTS: RPA1 protein was overexpressed in NPC patients with nCR (65.31%), and was an independent predictor of radiosensitivity (HR: 3.755, 95% CI: 1.990-7.085), in addition to Epstein-Barr virus (EBV; HR: 3.984; 95% CI: 1.524-10.410). The silencing of RPA1 increased the radiosensitivity of CNE-2R cells, blocked the repair of DNA, impaired cell proliferation, and contributed to G2/M cell cycle arrest. Furthermore, the xenograft models in nude mice revealed that silencing RPA1 combined with irradiation significantly retarded the growth of tumors. Moreover, the knockdown of RPA1 decreased Rad51 collection to the damage site and prolonged the time of DNA repair. CONCLUSION: RPA1 protein is frequently overexpressed in NPC patients with nCR. The silencing of RPA1 enhanced the radiosensitivity of CNE-2R cells. These present findings reveal that RPA1 is a potential biomarker for predicting the radiosensitivity in NPC.
BACKGROUND/AIM: Nasopharyngeal cancer (NPC) has a high local recurrence rate due to its resistance to ionizing radiation (IR). Replication protein A1 (RPA1) is one of the main elements in the homologous repair (HR) pathway, which is closely associated with the repair of DNA double strand breaks (DDBs). Studies on the relationship between RPA1 and the radiosensitivity of NPC are substantially limited. It was hypothesized that RPA1 plays a crucial role in predicting the radiosensitivity of NPC. METHODS: The protein expression of RPA1 in 182 patients with NPC in the complete response (CR) and non-complete response (nCR) groups was evaluated using immunohistochemistry. Then, univariate and multivariate analysis were performed using SPSS software vision 22 to determine the relationship between the expression of RPA1 and the clinicopathological features. In addition, the mRNA expression of RPA1 was tested in 24 fresh samples using qRT-PCR. RPA1 was silenced in CNE-2R cell lines combined with IR to measure the radiosensitivity, proliferation, DNA damage repair and cell cycle of CNE-2R cells. Xenograft models in nude mice were used to determine the effect of RPA1 on tumor growth after IR. Immunoblotting and immunofluorescence staining were performed to identify proteins that interacted with RPA1. All statistical tests were two-sided. RESULTS:RPA1 protein was overexpressed in NPCpatients with nCR (65.31%), and was an independent predictor of radiosensitivity (HR: 3.755, 95% CI: 1.990-7.085), in addition to Epstein-Barr virus (EBV; HR: 3.984; 95% CI: 1.524-10.410). The silencing of RPA1 increased the radiosensitivity of CNE-2R cells, blocked the repair of DNA, impaired cell proliferation, and contributed to G2/M cell cycle arrest. Furthermore, the xenograft models in nude mice revealed that silencing RPA1 combined with irradiation significantly retarded the growth of tumors. Moreover, the knockdown of RPA1 decreased Rad51 collection to the damage site and prolonged the time of DNA repair. CONCLUSION:RPA1 protein is frequently overexpressed in NPCpatients with nCR. The silencing of RPA1 enhanced the radiosensitivity of CNE-2R cells. These present findings reveal that RPA1 is a potential biomarker for predicting the radiosensitivity in NPC.
Authors: Yun-Miao Guo; Jie-Rong Chen; Yan-Chun Feng; Melvin L K Chua; Yanni Zeng; Edwin Pun Hui; Allen K C Chan; Lin-Quan Tang; Lin Wang; Qian Cui; Hui-Qiong Han; Chun-Ling Luo; Guo-Wang Lin; Yan Liang; Yang Liu; Zhong-Lian He; Yu-Xiang Liu; Pan-Pan Wei; Chu-Jun Liu; Wan Peng; Bo-Wei Han; Xiao-Yu Zuo; Enya H W Ong; Eugenia L L Yeo; Kar Perng Low; Gek San Tan; Tony K H Lim; Jacqueline S G Hwang; Bo Li; Qi-Sheng Feng; Xiaojun Xia; Yun-Fei Xia; Josephine Ko; Wei Dai; Maria L Lung; Anthony T C Chan; Dennis Y M Lo; Mu-Sheng Zeng; Hai-Qiang Mai; Jianjun Liu; Yi-Xin Zeng; Jin-Xin Bei Journal: Adv Sci (Weinh) Date: 2020-03-20 Impact factor: 16.806