Received: 11 October 2017 | Accepted: 10 September 2018 DOI: 10.1002/jcb.27793 RESEARCH ARTICLE Status of topoisomerase‐2β protein in all‐trans retinoic acid–treated human neuroblastoma (SK‐N‐SH) cells Venkanna Bhanothu MSc, MTech, PhD | Anand Kumar Kondapi MSc, PhD Department of Biotechnology and Bioinformatics, SLS, University of Hyderabad, Hyderabad, India Correspondence Venkanna Bhanothu, Room No. F70, Department of Biotechnology and Bioinformatics, SLS, University of Hyderabad, Hyderabad 500046, Telangana, India. Email: banothu.venkanna@gmail.com Funding information National Post Doctoral Fellowship Scheme, SERB‐DST, Govt of India Abstract Of the mammalian topoisomerase (Topo)‐2 isozymes (α and β), Topo‐2β protein has been reported to regulate neuronal development and differentiation. However, the status of Topo‐2β in all‐trans retinoic acid (ATRA)‐treated human neuroblastoma (SK‐N‐SH) cells is not understood. More information about the effects of ATRA on SK‐N‐SH cells is needed to reveal the role of ATRA in the regulation of Topo‐2β levels and spontaneous regression of SK‐N‐SH cells to predict the clinical activity. This study was proposed to investigate the status and role of Topo‐2β protein in ATRA‐induced survival and neuronal differentiation of SK‐N‐SH cells. Microscopic, sodium dodecyl sulfate poly- acrylamide gel electrophoresis after immunoprecipitations and Western blot analysis were used to study and compare Topo‐2β protein among 10 μM ATRA‐ treated SK‐N‐SH cells and controls at different time points. The level of Topo‐2β protein increased in the initial days of treatment but markedly decreased upon induction of differentiation by ATRA in later stages. Upon ATRA treatment, SK‐N‐SH cells stretched, exhibited neurite extensions, and acquired a neuronal phenotype. Both treated and untreated SK‐N‐SH cells were able to migrate, occupy the scratched area, and completely recolonized 24 hours later. These results suggest an indirect role of Topo‐2β protein in regulation of genes involved in cell migration and differentiation of ATRA‐treated SK‐N‐SH cells. This study suggests that Topo‐2β may be part of activation/repression of protein complexes activated by epigenetic modifying agents, differentiating signals, and inducible locus. However, detailed studies are needed to explore the ATRA‐ downstream genes leading to Topo‐2β regulation and regulatory proteins of neuronal differentiation. KEYWORDS all‐trans retinoic acid, human neuroblastoma (SK‐N‐SH) cells, neuronal differentiation, topoisomerase‐2β 1 | INTRODUCTION Human neuroblastoma (SK‐N‐SH) cells derived from human bone marrow metastasis can be used exten- sively as a cell culture model system for studying cell signaling processes, mechanism of neurodifferentia- tion, and neurotoxicity. 1 Their growth, biochemical, and cytogenetic properties established that these cell lines comprise malignant cells of neurogenic basis that retain many of their original characteristics over J Cell Biochem. 2018;1-14. wileyonlinelibrary.com/journal/jcb © 2018 Wiley Periodicals, Inc. | 1