Trace Element Analysis in Human Neuroblastoma Cell Spheroids Supplemented With <scp> ZnCl ₂ </scp> by Micro‐ <scp>XRF</scp>

ABSTRACT Neuroblastoma, the most common extracranial solid tumor of childhood, is responsible for ~10% of pediatric cancer deaths and has high potential for metastasis. Metals are extremely important in biological processes, and changes in their levels have been correlated with the development of cancerous growth. Zinc plays important roles in the proliferation and differentiation of neural cells and in the function of several regulatory proteins and has been linked to carcinogenic processes. The elemental distribution and concentration in 3D cell culture of neuroblastoma cells (SHSY‐5Y) were investigated after supplementation with zinc chloride with the aim of analyzing zinc and other metals concentrations using X‐ray microfluorescence (micro‐XRF). The obtained results showed a significant increase in the intracellular concentration of the metals analyzed in relation to the control and that their distributions occur heterogeneously along the spheroids. The methyl thiazole tetrazolium (MTT) reduction assay results showed that treatment with zinc chloride does not significantly alter cell viability. It could be concluded that zinc chloride supplementation in human neuroblastoma cells influenced the intracellular concentrations of zinc and the other metals analyzed. Furthermore, the micro‐XRF technique was efficient in the analysis of cellular spheroids and in association with other techniques, provides valuable information for characterization of biological samples.