The effects of serum depletion and dexamethasone on growth and differentiation of human neuroblastoma cell lines

Background/Purpose: Neuroblastoma is the most solid common extracranial mal ignancy in childhood. Despite multimodality treatment, high-risk disease co ntinues to carry a poor prognosis. Glucocorticoids have been shown previous ly to induce differentiation in murine neuroblastoma cell lines, but no suc h effect has been documented in human neuroblastoma cells. Glucocorticoids are known to be active in the differentiation process of the neural crest. These studies describe the effects of dexamethasone on 6 human neuroblastom a cell lines. Methods: Dexamethasone was added to cultured neuroblastoma cell lines (LA1- 5S, LA1-15N, BE[2]S, BE[2]N, SH-EP-1, SH-SY5Y) maintained in media suppleme nted with either normal serum or charcoal-depleted serum. Proliferation as says were performed, and flow cytometry was used to assess alterations in c ell cycle. Cells were closely monitored for morphological changes with seri al phase-contrast microscopy. Immunohistochemistry (3F8, NF-1, TRK-A) of cu ltured cells was used to evaluate differentiation. Glucocorticoid receptor levels was assessed using immunoblotting. Results: Dexamethasone decreased the rate of cellular proliferation in both standard and charcoal-depleted conditions. Flow cytometry showed a G(1) ac cumulation. Increased expression of the differentiation-associated antigens was found in cells cultured in charcoal-depleted media, and a further augm entation was seen with the addition of dexamethasone. In standard media, de xamethasone had no detectable effect on the expression of these antigens. G lucocorticoid receptor expression was found to be comparable in all cell li nes. Conclusions: Human neuroblastoma cells are sensitive to the differentiating effects of dexamethasone in an environment of charcoal-depleted serum. Thi s phenomenon may be caused by the existence of growth and mitogenic factors in serum that are inhibiting differentiation. Copyright (C) 2000 by W.B. S aunders Company.