title: Transcriptional regulation of IER5 in response to radiation in HepG2.
abstract: Radiotherapy is one of the important treatments for patients with hepatocellular carcinoma. The treatment response (or efficacy), however, is limited in many patients due to acquired radiation resistance of cancer cells. Immediate-early response 5 (IER5) is one of the genes upregulated on radiation. The gene could modulate cell cycle checkpoint, leading to a decrease of cancer cell survival in response to radiation. To better understand how IRE5 expression is regulated on radiation, this study aims to identify transcription factors that interact with IER5 promoter region in liver cancer cell line. Using bioinformatic tool, we identified promoter region of IER5 gene. Subsequent luciferase reporter assay revealed two putative GC binding factor (GCF) binding sites. We found mutations of these binding sites increased the luciferase activity, suggesting a negative regulation of GCF on IER5 transcriptional activity. The physical interaction of GCF with the gene promoter was confirmed using chromatin immunoprecipitation and electrophoretic mobility shift assay assays. Different doses of radiation were also applied in these experiments, and we found the formation of protein-DNA complex reduced with the increasing dose of radiation. Together, we propose the GCF regulated transcriptional activity, at least in part, contributed to the upregulation of IER5 on radiation. The present findings provide insights into understanding the regulatory mechanisms of IER5.
authors.affiliation: Department of Gastroenterology, the Second Hospital of Hebei Medical University, Shijiazhuang, China.|Hebei Key Laboratory of Gastroenterology, Hebei Institute of Gastroenterology, Shijiazhuang, Hebei, China.
authors.forename: C
authors.initials: C
authors.lastname: Yang
authors.affiliation: Department of Gastroenterology, the Second Hospital of Hebei Medical University, Shijiazhuang, China.|Hebei Key Laboratory of Gastroenterology, Hebei Institute of Gastroenterology, Shijiazhuang, Hebei, China.|Department of Gastroenterology, People's Hospital of Xintai, Xintai, Shandong, China.
authors.forename: L
authors.initials: L
authors.lastname: Yin
authors.affiliation: Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, Beijing, China.
authors.forename: P
authors.initials: P
authors.lastname: Zhou
authors.affiliation: Hebei Key Laboratory of Gastroenterology, Hebei Institute of Gastroenterology, Shijiazhuang, Hebei, China.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Gastroenterology, the Second Hospital of Hebei Medical University, Shijiazhuang, China.|Hebei Key Laboratory of Gastroenterology, Hebei Institute of Gastroenterology, Shijiazhuang, Hebei, China.
authors.forename: M
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department of Gastroenterology, the Second Hospital of Hebei Medical University, Shijiazhuang, China.|Hebei Key Laboratory of Gastroenterology, Hebei Institute of Gastroenterology, Shijiazhuang, Hebei, China.
authors.forename: F
authors.initials: F
authors.lastname: Yang
authors.affiliation: Department of Gastroenterology, the Second Hospital of Hebei Medical University, Shijiazhuang, China.|Hebei Key Laboratory of Gastroenterology, Hebei Institute of Gastroenterology, Shijiazhuang, Hebei, China.
authors.forename: H
authors.initials: H
authors.lastname: Jiang
authors.affiliation: National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing, China.|Key Laboratory of Radiological Protection and Nuclear Emergency, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: K
authors.initials: K
authors.lastname: Ding
mesh_terms: D017209:Apoptosis; D001665:Binding Sites; D006528:Carcinoma, Hepatocellular / Q000532:radiotherapy*; D002470:Cell Survival / Q000528:radiation effects; D024202:Electrophoretic Mobility Shift Assay; D059565:G2 Phase Cell Cycle Checkpoints; D005786:Gene Expression Regulation / Q000528:radiation effects*; D056945:Hep G2 Cells; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics* / Q000378:metabolism; D008113:Liver Neoplasms / Q000532:radiotherapy*; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011836:Radiation Tolerance; D012097:Repressor Proteins / Q000235:genetics / Q000528:radiation effects*; D014158:Transcription, Genetic / Q000528:radiation effects*; D016896:Treatment Outcome
chemical_list: C072278:GCFC2 protein, human; C118926:IER5 protein, human; D017874:Immediate-Early Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins