In Vitro Effects of Retinoic Acid and Sodium Selenite on Neuroblastoma Cell Line (SH-SY5Y)

Background/Objectives: Neuroblastoma is a pediatric embryonal tumor of the autonomic nervous system, characterized by high heterogeneity. Recent research has explored the therapeutic potential of retinoic acid and selenium derivatives as antiproliferative agents. This study aims to assess the antiproliferative effects of sodium selenite and retinoic acid, as well as the conventional chemotherapeutic agents, cyclophosphamide and cisplatin, using the SH-SY5Y neuroblastoma cell line. Methods: Cells were treated with the compounds at concentrations ranging from 0 to 1000 µM for 72 h. The following assays were performed: cell viability, clonogenic assay, cell migration, cell cycle analysis, and gene expression (BCL2 and BAX). Data were analyzed using the Kruskal–Wallis test followed by Dunn’s or the Mann–Whitney test (p < 0.05). IC50 values were obtained from dose–response curves. Results: Sodium selenite (100–1000 µM) significantly reduced cell viability by more than 50% (IC50: 166 µM at 72 h). Retinoic acid (300 µM) reduced viability by 65% (IC50: 198 µM at 72 h), and cisplatin (10 µM) reduced viability by 79% (IC50: 3.4 µM at 72 h). All compounds significantly decreased colony formation. Sodium selenite and retinoic acid induced arrest in the G0/G1 phase of the cell cycle. Gene expression analysis revealed downregulation of the BCL2 gene by all compounds and upregulation of BAX only by sodium selenite at IC50 concentration. Conclusions: Sodium selenite and retinoic acid showed antiproliferative effects on neuroblastoma cells, suggesting their potential as adjuvant therapeutic agents. To reach this goal, we suggest further investigation of their mechanisms of action and evaluation of the combined strategies.