title: Redox balance influences differentiation status of neuroblastoma in the presence of all-trans retinoic acid.
abstract: Neuroblastoma is the most common extra-cranial solid tumor in childhood; and patients in stage IV of the disease have a high propensity for tumor recurrence. Retinoid therapy has been utilized as a means to induce differentiation of tumor cells and to inhibit relapse. In this study, the expression of a common neuronal differentiation marker [neurofilament M (NF-M)] in human SK-N-SH neuroblastoma cells treated with 10μM all-trans retinoic acid (ATRA) showed significantly increased expression in accordance with reduced cell number. This was accompanied by an increase in MitoSOX and DCFH2 oxidation that could be indicative of increased steady-state levels of reactive oxygen species (ROS) such as O2(•-) and H2O2, which correlated with increased levels of MnSOD activity and immuno-reactive protein. Furthermore PEG-catalase inhibited the DCFH2 oxidation signal to a greater extent in the ATRA-treated cells (relative to controls) at 96h indicating that as the cells became more differentiated, steady-state levels of H2O2 increased in the absence of increases in peroxide-scavenging antioxidants (i.e., glutathione, glutathione peroxidase, and catalase). In addition, ATRA-induced stimulation of NF-M at 48 and 72h was enhanced by decreasing SOD activity using siRNA directed at MnSOD. Finally, treatment with ATRA for 96h in the presence of MnSOD siRNA or PEG-catalase inhibited ATRA induced increases in NF-M expression. These results provide strong support for the hypothesis that changes in steady-state levels of O2(•-) and H2O2 significantly contribute to the process of ATRA-induced differentiation in neuroblastoma, and suggest that retinoid therapy for neuroblastoma could potentially be enhanced by redox-based manipulations of superoxide metabolism to improve patient outcome.
authors.affiliation: Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25755, USA.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Silvis
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City 52242, USA.
authors.forename: Michael L
authors.initials: ML
authors.lastname: McCormick
authors.affiliation: Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City 52242, USA.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Spitz
authors.affiliation: Department of Pharmaceutical, Social, and Administrative Sciences, Belmont University College of Pharmacy, 1900 Belmont Boulevard, Nashville, TN 37212, USA. Electronic address: kelley.kiningham@belmont.edu.
authors.forename: Kinsley K
authors.initials: KK
authors.lastname: Kiningham
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D005452:Fluoresceins / Q000737:chemistry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009447:Neuroblastoma / Q000188:drug therapy / Q000378:metabolism*; D016900:Neurofilament Proteins / Q000378:metabolism*; D010084:Oxidation-Reduction; D055747:SOX Transcription Factors / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D005452:Fluoresceins; D016900:Neurofilament Proteins; D055747:SOX Transcription Factors; C065013:2',7'-dichlorodihydrofluorescein; C061195:neurofilament protein M; D014212:Tretinoin; D006861:Hydrogen Peroxide
keywords: Differentiation; MnSOD; Neuroblastoma; Reactive oxygen species; Retinoic acid