# Dexamethasone Inhibits the Growth of B‐Lymphoma Cells by Downregulating DOT1L

## TL;DR

Dexamethasone fights B-lymphoma by reducing DOT1L levels, a protein linked to cancer, offering a new treatment target.

## Contribution

The study identifies DOT1L as a novel target gene of dexamethasone in B-lymphoma cells.

## Key findings

- DOT1L is a target gene of the glucocorticoid receptor and is downregulated by dexamethasone.
- Dexamethasone reduces DOT1L mRNA levels posttranscriptionally, not by affecting its promoter activity.
- Knockdown of DOT1L significantly inhibits B-lymphoma cell growth.

## Abstract

Dexamethasone (Dex), a synthetic glucocorticoid that acts by binding to the glucocorticoid receptor (GR), has been widely applied to treat leukemia and lymphoma; however, the precise mechanism underlying Dex action is still not well elucidated. DOT1L, a histone H3‐lysine79 (H3K79) methyltransferase, has been linked to multiple cancer types, particularly mixed lineage leukemia (MLL) gene rearranged leukemia, but its contribution to lymphoma is yet to be delineated. Analysis from the TCGA database displayed that DOT1L was highly expressed in lymphoma and leukemia.

We initially demonstrated that DOT1L served as a new target gene controlled by GR, and the downregulation of DOT1L was critical for the killing of B‐lymphoma cells by Dex. Further study revealed that Dex had no impact on the transcriptional activity of the DOT1L promoter, rather it reduced the mRNA level of DOT1L at the posttranscriptional level. In addition, knockdown of DOT1L remarkably inhibited the B‐lymphoma cell growth.

Overall, our findings indicated that DOT1L may serve as a potential drug target and a promising biomarker of Dex sensitivity when it comes to treating B lymphoma.