Exploratory Analysis of Tannic Acid–Induced Antiproliferative Effects in SH-SY5Y Neuroblastoma Cells: Associations with Toll-like Receptors and microRNAs

Background/Objectives: Neuroblastoma is the most frequent solid tumor outside the brain in children and is associated with unfavorable outcomes in high-risk patients. Tannic acid, a naturally occurring polyphenolic compound, has been reported to exhibit anticancer activity; however, its molecular effects in neuroblastoma remain incompletely characterized. The present study aimed to evaluate the antiproliferative effects of tannic acid in SH-SY5Y neuroblastoma cells and to explore its potential associations with Toll-like receptor (TLR) signaling and selected microRNAs in an exploratory and correlative manner. Methods: Cell viability was assessed using the CCK-8 assay, which showed that tannic acid was associated with reduced cell proliferation in a dose- and time-dependent manner. Changes in the expression of TLR-related genes and selected microRNAs were analyzed by real-time PCR. TLR-4, NF-κB, and Caspase-3 protein concentrations were determined using ELISA assays. Results: Tannic acid treatment was associated with decreased expression of several TLR genes, with statistically significant reductions observed in TLR2, TLR4, and TLR7. Consistently, protein analyses indicated reduced NF-κB levels. MicroRNA analysis revealed a tendency toward increased expression of hsa-miR-146a-5p, whereas no significant changes were detected in other examined microRNAs. Conclusions: Overall, these findings suggest that tannic acid exhibits antiproliferative activity in SH-SY5Y cells and is associated with alterations in TLR-related gene expression and microRNA profiles. However, these observations are descriptive and correlative in nature and do not establish direct mechanistic relationships. Further in vivo and functional studies are required to validate these findings and to clarify their potential biological and therapeutic relevance.