SARI, a novel target gene of glucocorticoid receptor, plays an important role in dexamethasone-mediated killing of B lymphoma cells

Dexamethasone (Dex) has been commonly used in lymphoma and leukemia treatment, but the detailed mechanisms are not fully understood. Suppressor of AP-1 regulated by interferon (SARI) has tumor-selective growth inhibitory effect. However, it's unclear whether SARI is involved in the Dex-mediated lymphoma growth suppression. In this study, we found that Dex-treated B lymphoma tissues had a higher level of SARI. Dex repressed the growth of B lymphoma cells and upregulated SARI expression by activating glucocorticoid receptor (GR) in vitro and in vivo. Silencing of SARI attenuated the Dex-mediated growth suppression of B lymphoma cells and inhibition of AP-1 activity. Reporter assays revealed that activation of GR enhanced the transcriptional activity of SARI promoter. EMSA and ChIP assays showed that GR directly bound to the ER9 element in SARI promoter region. These results for the first time demonstrated that SARI is a novel target gene of GR, and the upregulation of SARI plays an important role in Dex's killing effect on B lymphoma cells, suggesting that SARI may serve as a novel target and a potential indicator of Dex sensitivity in B lymphoma treatment.