title: Manganese superoxide dismutase-mediated gene expression in radiation-induced adaptive responses.
abstract: Antioxidant enzymes are critical in oxidative stress responses. Radioresistant variants isolated from MCF-7 human carcinoma cells following fractionated ionizing radiation (MCF+FIR cells) or overexpression of manganese superoxide dismutase (MCF+SOD cells) demonstrated dose-modifying factors at 10% isosurvival of 1.8 and 2.3, respectively. MCF+FIR and MCF-7 cells (exposed to single-dose radiation) demonstrated 5- to 10-fold increases in MnSOD activity, mRNA, and immunoreactive protein. Radioresistance in MCF+FIR and MCF+SOD cells was reduced following expression of antisense MnSOD. DNA microarray analysis and immunoblotting identified p21, Myc, 14-3-3 zeta, cyclin A, cyclin B1, and GADD153 as genes constitutively overexpressed (2- to 10-fold) in both MCF+FIR and MCF+SOD cells. Radiation-induced expression of these six genes was suppressed in fibroblasts from Sod2 knockout mice (-/-) as well as in MCF+FIR and MCF+SOD cells expressing antisense MnSOD. Inhibiting NF-kappa B transcriptional activity in MCF+FIR cells, by using mutant I kappa B alpha, inhibited radioresistance as well as reducing steady-state levels of MnSOD, 14-3-3 zeta, GADD153, cyclin A, and cyclin B1 mRNA. In contrast, mutant I kappa B alpha was unable to inhibit radioresistance or reduce 14-3-3 zeta, GADD153, cyclin A, and cyclin B1 mRNAs in MCF+SOD cells, where MnSOD overexpression was independent of NF-kappa B. These results support the hypothesis that NF-kappa B is capable of regulating the expression of MnSOD, which in turn is capable of increasing the expression of genes that participate in radiation-induced adaptive responses.
authors.affiliation: Radiation Biology, Division of Radiation Oncology, City of Hope National Medical Center, Duarte, California 91010, USA.
authors.forename: Guozheng
authors.initials: G
authors.lastname: Guo
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan-Sanders
authors.forename: Beverly D
authors.initials: BD
authors.lastname: Lyn-Cook
authors.forename: Tieli
authors.initials: T
authors.lastname: Wang
authors.forename: Daniel
authors.initials: D
authors.lastname: Tamae
authors.forename: Julie
authors.initials: J
authors.lastname: Ogi
authors.forename: Alexander
authors.initials: A
authors.lastname: Khaletskiy
authors.forename: Zhongkui
authors.initials: Z
authors.lastname: Li
authors.forename: Christine
authors.initials: C
authors.lastname: Weydert
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Longmate
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Huang
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Spitz
authors.forename: Larry W
authors.initials: LW
authors.lastname: Oberley
authors.forename: Jian Jian
authors.initials: JJ
authors.lastname: Li
mesh_terms: D048948:14-3-3 Proteins; D000222:Adaptation, Physiological / Q000502:physiology / Q000528:radiation effects*; D000230:Adenocarcinoma / Q000378:metabolism* / Q000532:radiotherapy*; D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism* / Q000532:radiotherapy*; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D019925:Cyclin A / Q000235:genetics / Q000378:metabolism; D019926:Cyclin B / Q000235:genetics / Q000378:metabolism; D056744:Cyclin B1; D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects; D005720:Gamma Rays; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology / Q000528:radiation effects; D006801:Humans; D020672:I-kappa B Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D051379:Mice; D018345:Mice, Knockout; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000378:metabolism; D011836:Radiation Tolerance / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D013482:Superoxide Dismutase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics / Q000378:metabolism; D000099156:Superoxide Dismutase 2
chemical_list: D048948:14-3-3 Proteins; D022762:CCAAT-Enhancer-Binding Proteins; D019925:Cyclin A; D019926:Cyclin B; D056744:Cyclin B1; D020672:I-kappa B Proteins; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B; D012333:RNA, Messenger; D013482:Superoxide Dismutase; D051742:Transcription Factor CHOP; D014157:Transcription Factors; D014446:Tyrosine 3-Monooxygenase; D000099156:Superoxide Dismutase 2; C534699:CCNB1 protein, human; C534700:Ccnb1 protein, mouse; C497249:DDIT3 protein, human; C497250:Ddit3 protein, mouse; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse