title: Superoxide signaling mediates N-acetyl-L-cysteine-induced G1 arrest: regulatory role of cyclin D1 and manganese superoxide dismutase.
abstract: Thiol antioxidants, including N-acetyl-L-cysteine (NAC), are widely used as modulators of the intracellular redox state. We investigated the hypothesis that NAC-induced reactive oxygen species (ROS) signaling perturbs cellular proliferation by regulating the cell cycle regulatory protein cyclin D1 and the ROS scavenging enzyme Mn-superoxide dismutase (MnSOD). When cultured in media containing NAC, mouse fibroblasts showed G(1) arrest with decreased cyclin D1 protein levels. The absence of a NAC-induced G(1) arrest in fibroblasts overexpressing cyclin D1 (or a nondegradable mutant of cyclin D1-T286A) indicates that cyclin D1 regulates this G(1) arrest. A delayed response to NAC exposure was an increase in both MnSOD protein and activity. NAC-induced G(1) arrest is exacerbated in MnSOD heterozygous fibroblasts. Results from electron spin resonance spectroscopy and flow cytometry measurements of dihydroethidine fluorescence showed an approximately 2-fold to 3-fold increase in the steady-state levels of superoxide (O(2)(*-)) in NAC-treated cells compared with control. Scavenging of O(2)(*-) with Tiron reversed the NAC-induced G(1) arrest. These results show that an O(2)(*-) signaling pathway regulates NAC-induced G(1) arrest by decreasing cyclin D1 protein levels and increasing MnSOD activity.
authors.affiliation: Department of Microbiology and Immunology, State University of New York at Buffalo School of Medicine, Buffalo, New York, USA.
authors.forename: Sarita G
authors.initials: SG
authors.lastname: Menon
authors.forename: Ehab H
authors.initials: EH
authors.lastname: Sarsour
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Kalen
authors.forename: Sujatha
authors.initials: S
authors.lastname: Venkataraman
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Hitchler
authors.forename: Frederick E
authors.initials: FE
authors.lastname: Domann
authors.forename: Larry W
authors.initials: LW
authors.lastname: Oberley
authors.forename: Prabhat C
authors.initials: PC
authors.lastname: Goswami
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology*; D000818:Animals; D019938:Cyclin D1 / Q000378:metabolism*; D003997:Dicarbethoxydihydrocollidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D005347:Fibroblasts / Q000378:metabolism; D016193:G1 Phase; D006801:Humans; D051379:Mice; D041681:NIH 3T3 Cells; D010084:Oxidation-Reduction; D017382:Reactive Oxygen Species; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism*
chemical_list: D017382:Reactive Oxygen Species; C514241:dihydroethidine; D013481:Superoxides; D019938:Cyclin D1; D003997:Dicarbethoxydihydrocollidine; D013482:Superoxide Dismutase; D000111:Acetylcysteine