title: Genes regulated in human breast cancer cells overexpressing manganese-containing superoxide dismutase.
abstract: The mitochondrial antioxidant enzyme manganese-containing superoxide dismutase (MnSOD) functions as a tumor suppressor gene. Reconstitution of MnSOD expression in several human cancer cell lines leads to reversion of malignancy and induces a resistant phenotype to the cytotoxic effects of TNF and hyperthermia. The signaling pathways that underlie these phenotypic changes in MnSOD-overexpressing cells are unknown, although alterations in the activity of several redox-sensitive transcription factors, including AP-1 and NF-kappaB, have been observed. To determine the downstream signaling molecules involved in MnSOD-induced cell resistant phenotype, in the present study we analyzed the expression profile of several groups of genes related to stress response, DNA repair, and apoptosis, in a human breast cancer MCF-7 cell line overexpressing MnSOD (MCF+SOD). Of 588 genes examined, 5 (0.85%) were up-regulated (2-42-fold), and 11 (1.9%) were down-regulated (2-33-fold) in the MCF+SOD cells compared to the parental MCF-7 cells. The five up-regulated genes were MET, GADD153, CD9, alpha-catenin and plakoglobin. The genes with the most significant down-regulation included: vascular endothelial growth factor receptor 1, TNF-alpha converting enzyme, and interleukin-1beta. GADD153 (involved in the repair of DNA double strand breaks) showed a 33-fold increase in microarray analysis and these results were confirmed by RT-PCR. To further determine the specificity in MnSOD-induced gene regulation, MCF+SOD cells were stably transfected with an antisense MnSOD sequence whose expression was controlled by a tetracycline-inducible regulator. Expression of three up-regulated genes was measured after induction of antisense MnSOD expression. Interestingly, expression level of GADD153 but not MET or CD9 was reduced 24 h after antisense MnSOD induction. Together, these results suggest that reconstitution of MnSOD in tumor cells can specifically modulate the expression of down-stream effector genes. GADD153 and other elements observed in the MCF+SOD cells may play a key role in signaling the MnSOD-induced cell phenotypic change.
authors.affiliation: Department of Radiation Research, Beckman Research Institute, City of Hope National Medical Center, 1500 Duarte Road, Duarte, CA 91010-3000, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.forename: A
authors.initials: A
authors.lastname: Khaletskiy
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: J Y
authors.initials: JY
authors.lastname: Wong
authors.forename: L W
authors.initials: LW
authors.lastname: Oberley
authors.forename: J J
authors.initials: JJ
authors.lastname: Li
mesh_terms: D017209:Apoptosis / Q000235:genetics; D001943:Breast Neoplasms / Q000201:enzymology*; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D004260:DNA Repair / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000235:genetics*; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D022762:CCAAT-Enhancer-Binding Proteins; C497249:DDIT3 protein, human; D014157:Transcription Factors; D051742:Transcription Factor CHOP; D013482:Superoxide Dismutase