IFN-γ Regulates Expression of BRG1 Associated Factor 155/170 and Sensitivity to Steroid in Astrocytes

Background: The expression of BRG1 associated factors (BAF) 155 and BAF 170 in response to $IFN-{\gamma}$ or $TNF-{\alpha}$ was studied in astrocytoma cell lines and primary astrocytes. BAFs are complexed with BRG1 and are also associated with activated glucocorticoid for glucocorticoid trans-activation. Methods: $IFN-{\gamma}$ was pretreated for 18 hrs and cells were incubated with IL-1 or $TNF-{\alpha}$ for 72 hrs or 96 hrs with different concentrations of steroid. Cell death was measured by LDH assay. BAF expression was assayed by RT-PCR. Results: $IFN-{\gamma}$ increased cell death by dexamethasone in LN215 cells but not in LN319 cells. The $IFN-{\gamma}$ increased the expression of BAF 155 and BAF 170 in adult astrocytes and LN215 cells, but $IFN-{\gamma}$ decreased the expression of BAF 155/170 in LN319 cells. The effect of $IFN-{\gamma}$ on the expression of BAF was not as clear in fetal astrocytes as it was in adult astrocytes. Conclusion: Our results suggest cytokines produced during immune reaction or immunotherapy may modulate steroid susceptibility of astrocytes and astrocytoma cells by influencing the expression of BAFs.