Abstract
The effect of glucocorticoid on cell proliferation, the expression of glucocorticoid receptor, and the relationship between inhibition of cell growth and apoptosis were investigated in four established neuroepithelial tumor cell lines (KNS42, T98G, A172, and U251MG). Glucocorticoid receptor expression was located in the cytoplasm of untreated cells, but translocated into nuclei after treatment with dexamethasone in KNS42, T98G, and A172 cells. U251MG did not express glucocorticoid receptors. Dexamethasone significantly inhibited the growth of KNS42 and T98G cell lines, at high concentrations in contrast to growth stimulation at low concentration. Dexamethasone inhibited proliferation of A172 cell line at all concentrations from 10-4M to 10-7M. These were prevented by RU38486, a specific glucocorticoid antagonist. Apoptosis did not occur in any cell lines after dexamethasone treatment. There was no response to glucocorticoid by U251MG cells. Dexamethasone treatment of neuroepithelial tumor cells expressing glucocorticoid receptors causes translocation into the nucleus to modulate cell proliferation upon binding of different concentrations of dexamethasone in vitro. Dexamethasone inhibits proliferation of some neuroepithelial cell lines, not by glucocorticoid-induced apoptosis. The bimodal potential of glucocorticoid to stimulate or suppress proliferation of neuroepithelial tumor cells expressing glucocorticoid receptor must be considered in clinical trials.
