Dexamethasone regulation of the expression of cytokine mRNAs induced by interleukin 1 in astrocytoma cell line U373MG.

BSF-2, GM-CSF and IL-1β mRNAs were induced by recombinant IL-1β in human astrocytoma cell line U373MG. The induction of BSF-2 and IL-1β mRNAs by recombinant IL-1β did not require de novo protein synthesis while that of GM-CSF mRNA by recombinant IL-1β required a newly synthesized protein. Therefore it is possible that mRNAs for various cytokines may be regulated entirely by different mechanisms by IL-1 in the same cell line, dexamethasone inhibited the induction of these cytokine mRNAs by recombinant IL-1β in a dose-dependent fashion. However accumulation of BSF-2 and IL-1β mRNAs by recombinant IL-1β was not inhibited by dexamethasone in the presence of cycloheximide. Therefore as yet undiscovered gene product (s) that may be induced by dexamethasone might be involved in the decrease of the level of BSF-2, GM-CSF and IL-1β mRNAs.These results suggest that the production of these cytokines are positively and negatively controlled by IL-1 and glucocorticoids respectively in astrocytes.