title: Genomic instability induced by mutant succinate dehydrogenase subunit D (SDHD) is mediated by O2(-•) and H2O2.
abstract: SDHD mutations are associated with human cancers but the mechanisms that may contribute to transformation are unknown. The hypothesis that mutations in SDHD increase levels of superoxide leading to genomic instability was tested using site-directed mutagenesis to generate a truncated SDHD cDNA that was expressed in Chinese hamster fibroblasts. Stable expression of mutant SDHD resulted in 2-fold increases in steady-state levels of superoxide that were accompanied by a significantly increased mutation rate as well as a 70-fold increase in mutation frequency at the hprt locus. Overexpression of MnSOD or treatment with polyethylene glycol conjugated (PEG)-catalase suppressed mutation frequency in SDHD mutant cells by 50% (P<0.05). Simultaneous treatment with PEG-catalase and PEG-SOD suppressed mutation frequency in SDHD mutant cells by 90% (P<0.0005). Finally, 95% depletion of glutathione using l-buthionine-[S,R]-sulfoximine (BSO) in SDHD mutant cells caused a 4-fold increase in mutation frequency (P<0.05). These results demonstrate that mutations in SDHD cause increased steady-state levels of superoxide which significantly contributed to increases in mutation rates and frequency mediated by superoxide and hydrogen peroxide. These results support the hypothesis that mutations in SDHD may contribute to carcinogenesis by increasing genomic instability mediated by increased steady-state levels of reactive oxygen species.
authors: Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa, Iowa City, IA 52242, USA.
authors: Kjerstin M
authors: KM
authors: Owens
authors: Nūkhet
authors: N
authors: Aykin-Burns
authors: Disha
authors: D
authors: Dayal
authors: Mitchell C
authors: MC
authors: Coleman
authors: Frederick E
authors: FE
authors: Domann
authors: Douglas R
authors: DR
authors: Spitz
mesh_terms: D000818:Animals; D019328:Buthionine Sulfoximine / Q000009:adverse effects; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism*; D006224:Cricetinae; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D015870:Gene Expression; D042822:Genomic Instability; D005978:Glutathione / Q000172:deficiency; D006801:Humans; D006861:Hydrogen Peroxide / Q000009:adverse effects*; D016297:Mutagenesis, Site-Directed; D059645:Mutation Rate; D009369:Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D010957:Plasmids; D017354:Point Mutation; D011092:Polyethylene Glycols / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000009:adverse effects* / Q000378:metabolism; D014162:Transfection
chemical_list: D021122:Protein Subunits; C070295:catalase-polyethylene glycol; D013481:Superoxides; D011092:Polyethylene Glycols; D019328:Buthionine Sulfoximine; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; C063471:polyethylene glycol-superoxide dismutase; D013385:Succinate Dehydrogenase; D005978:Glutathione