title: RNF8 plays an important role in the radioresistance of human nasopharyngeal cancer cells in vitro.
abstract: Tumor residue or recurrence is common after radiation therapy for nasopharyngeal cancer (NPC) since the tumor cells can repair irradiation-induced DNA damage. The ubiquitination cascade mediates the assembly of repair and signaling proteins at sites of DNA double-strand breaks (DSBs). Ring finger protein 8 (RNF8) is an E3 ubiquitin ligase that triggers ubiquitination at the site of DSBs. The present study aimed to identify whether and how RNF8 small interfering RNA (siRNA) treatment enhances the radiosensitivity of irradiated human NPC cell lines. The CNE1, CNE2, and SUNE human NPC cell lines were stably transfected with a constructed RNF8-targeting siRNA expression vector. Western blotting was used to detect the effectiveness of RNF8 downregulation by RNF8 siRNA. The siRNA-transfected (RNF8-) and non-transfected (RNF8+) cells were irradiated at different doses by a linear accelerator. The growth inhibition ratio and apoptosis rate were detected by the methyl thiazolyl tetrazolium (MTT) assay and flow cytometry, respectively. The ataxia-telangiectasia mutated (ATM), DNA-PKcs, Chk1, Chk2, Nbs1 and Ku80 protein levels in each group were determined. The growth inhibition ratio and apoptotic percentage of RNF8- cells were higher than those of the RNF8+ cells in each of the three cell lines. Lower protein expression levels of Chk1, Chk2, ATM, and Nbs1 were observed in the irradiated RNF8- cells compared to the irradiated RNF8+ cells in each of the three cell lines (P<0.01). As a result, a conclusion could be drawn that RNF8 recruits and ubiquitinates many factors to repair DNA damage, including DSBs, thereby conferring radioresistance to NPC cells.
authors.affiliation: Fuzong Clinical College of Fujian Medical University, Fuzhou General Hospital of Nanjing Command Zone of PLA, Fuzhou, Fujian, P.R. China.
authors.forename: Maoxin
authors.initials: M
authors.lastname: Wang
authors.affiliation: Fuzong Clinical College of Fujian Medical University, Fuzhou General Hospital of Nanjing Command Zone of PLA, Fuzhou, Fujian, P.R. China.
authors.forename: Xianming
authors.initials: X
authors.lastname: Chen
authors.affiliation: Fuzong Clinical College of Fujian Medical University, Fuzhou General Hospital of Nanjing Command Zone of PLA, Fuzhou, Fujian, P.R. China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.affiliation: Fuzong Clinical College of Fujian Medical University, Fuzhou General Hospital of Nanjing Command Zone of PLA, Fuzhou, Fujian, P.R. China.
authors.forename: Xian
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Fuzong Clinical College of Fujian Medical University, Fuzhou General Hospital of Nanjing Command Zone of PLA, Fuzhou, Fujian, P.R. China.
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Li
authors.affiliation: Fuzong Clinical College of Fujian Medical University, Fuzhou General Hospital of Nanjing Command Zone of PLA, Fuzhou, Fujian, P.R. China.
authors.forename: Hongxun
authors.initials: H
authors.lastname: Gong
authors.affiliation: Fuzong Clinical College of Fujian Medical University, Fuzhou General Hospital of Nanjing Command Zone of PLA, Fuzhou, Fujian, P.R. China.
authors.forename: Chen
authors.initials: C
authors.lastname: Shiyan
authors.affiliation: Fuzong Clinical College of Fujian Medical University, Fuzhou General Hospital of Nanjing Command Zone of PLA, Fuzhou, Fujian, P.R. China.
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000378:metabolism* / Q000532:radiotherapy; D034741:RNA, Small Interfering / Q000494:pharmacology*; D011836:Radiation Tolerance; D044767:Ubiquitin-Protein Ligases; D054875:Ubiquitination
chemical_list: D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; C486521:RNF8 protein, human; D044767:Ubiquitin-Protein Ligases