title: The superoxide dismutase 1 3'UTR maintains high expression of the SOD1 gene in cancer cells: The involvement of the RNA-binding protein AUF-1.
abstract: Superoxide dismutase 1 (SOD1) is ubiquitously expressed and the predominant dismutase in the cytoplasm. Whereas transcriptional regulation of the SOD1 gene has been well characterized, posttranscriptional regulation of the gene remains largely unknown in eukaryotes. In this study, a full-length 3'UTR of the SOD1 transcript was cloned and characterized for its ability to regulate SOD1 gene expression in human cancer cells. Inclusion of the SOD1 3'UTR in the pGL3 reporter construct dramatically enhanced the reporter activity by 10- to 220-fold in various cell lines. RT-PCR analysis, however, indicated that the reporter gene mRNA levels were only modestly altered by the SOD1 3'UTR, suggesting that the SOD1 3'UTR enhances the reporter gene activity not simply by stabilizing the mRNA but primarily by promoting translation of the protein. Bioinformatics analysis showed multiple stem and loop structures of the SOD1 3'UTR, and alterations in this secondary structure led to remarkably reduced reporter gene activity. Importantly, introducing the SOD1 3'UTR into cancer cells attenuated endogenous SOD1 expression in a concentration-dependent manner, indicating the involvement of RNA trans-acting factors in this process. Using siRNA and RNA immunoprecipitation techniques, we identified AUF-1, an RNA-binding protein, as a positive regulator of SOD1 expression through its 3'UTR. Consequently, AUF-1 was found to regulate redox balance in our cell model systems. Furthermore, in human ovarian, esophageal, and pancreatic cancer tissues, the expression of SOD1 was significantly correlated with that of AUF-1, further supporting the importance of AUF-1 in regulating SOD1 gene expression.
authors.affiliation: School of Radiation Medicine and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Medical College of Soochow University, Suzhou 215123, China; Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Shuyu
authors.initials: S
authors.lastname: Zhang
authors.affiliation: School of Radiation Medicine and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Medical College of Soochow University, Suzhou 215123, China; Department of Radio-Oncology, Nanjing Medical University Affiliated Suzhou Hospital, Suzhou 215001, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xue
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Shuai
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Radio-Oncology, Nanjing Medical University Affiliated Suzhou Hospital, Suzhou 215001, China.
authors.forename: Jundong
authors.initials: J
authors.lastname: Zhou
authors.affiliation: School of Radiation Medicine and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Medical College of Soochow University, Suzhou 215123, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Jiao
authors.affiliation: School of Radiation Medicine and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Medical College of Soochow University, Suzhou 215123, China.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Geng
authors.affiliation: Department of Radio-Oncology, Nanjing Medical University Affiliated Suzhou Hospital, Suzhou 215001, China.
authors.forename: Jinchang
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
authors.forename: Bethany N
authors.initials: BN
authors.lastname: Hannafon
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA. Electronic address: weiqun-ding@ouhsc.edu.
authors.forename: Wei-Qun
authors.initials: WQ
authors.lastname: Ding
mesh_terms: D020413:3' Untranslated Regions; D045744:Cell Line, Tumor; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D / Q000502:physiology*; D006801:Humans; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000235:genetics*; D000072105:Superoxide Dismutase-1
chemical_list: D020413:3' Untranslated Regions; C000630986:HNRNPD protein, human; D000081035:Heterogeneous Nuclear Ribonucleoprotein D0; D034502:Heterogeneous-Nuclear Ribonucleoprotein D; D017382:Reactive Oxygen Species; C000606290:SOD1 protein, human; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1
keywords: 3′UTR; AU-rich element; AUF-1; Cancer; Free radicals; SOD1