Epigenetic alteration by DNA-demethylating treatment restores apoptotic response to glucocorticoids in dexamethasone-resistant human malignant lymphoid cells

Abstract

BackgroundGlucocorticoids (GCs) are often included in the therapy of lymphoid malignancies because they kill several types of malignant lymphoid cells. GCs activate the glucocorticoid receptor (GR), to regulate a complex genetic network, culminating in apoptosis. Normal lymphoblasts and many lymphoid malignancies are sensitive to GC-driven apoptosis. Resistance to GCs can be a significant clinical problem, however, and correlates with resistance to several other major chemotherapeutic agents.MethodsWe analyzed the effect of treatment with the cytosine analogue 5 aza-2’ deoxycytidine (AZA) on GC resistance in two acute lymphoblastic leukemia (T or pre-T ALL) cell lines- CEM and Molt-4- and a (B-cell) myeloma cell line, RPMI 8226. Methods employed included tissue culture, flow cytometry, and assays for clonogenicity, cytosine extension, immunochemical identification of proteins, and gene transactivation. High throughput DNA sequencing was used to confirm DNA methylation status.ConclusionsTreatment of these cells with AZA resulted in altered DNA methylation and restored GC-evoked apoptosis in all 3 cell lines. In CEM cells the altered epigenetic state resulted in site-specific phosphorylation of the GR, increased GR potency, and GC-driven induction of the GR from promoters that lie in CpG islands. In RPMI 8226 cells, expression of relevant coregulators of GR function was altered. Activation of p38 mitogen-activated protein kinase (MAPK), which is central to a feed-forward mechanism of site-specific GR phosphorylation and ultimately, apoptosis, occurred in all 3 cell lines. These data show that in certain malignant hematologic B- and T-cell types, epigenetically controlled GC resistance can be reversed by cell exposure to a compound that causes DNA demethylation. The results encourage studies of application to in vivo systems, looking towards eventual clinical applications.

Clinical Implications of Inflammation in Acute Myeloid Leukemia

“…Moreover, preclinical studies have shown that the gene signature of cells resistant to hypomethylating agents is also enriched with dexamethasone response genes ( 135 ). In addition, in ALL cell lines, azacitidine has been shown to restore GR expression and sensitivity to dexamethasone ( 136 ). Therefore, a randomized phase 3 clinical trial was designed to assess the impact of dexamethasone added to either intensive chemotherapy or azacitidine, according to the investigator’s choice, in adult patients with R/R AML (NCT03765541).…”

Sequential gene regulatory events leading to glucocorticoid-evoked apoptosis of CEM human leukemic cells:interactions of MAPK, MYC and glucocorticoid pathways

“…Further, manipulation of MAPK levels controls the apoptotic sensitivity of other malignant lymphoid cell lines as well as CEM cells (Garza et al, 2009). Epigenetic manipulation to restore Dex sensitivity of resistant CEM cells alters the levels of ERK/JNK/p38 as would be predicted (Miller, Geng, Golovko et al, 2014). The analysis presented here supports the view that concerted, relatively small effects of many genes and their protein products bring on the circumstances that demands induction and “permits” of the genes ultimately responsible for apoptosis in these GC-treated leukemic cells.…”

BPTF activates the MAPK pathway through coexpression with Raf1 to promote proliferation of T‑cell lymphoma

“…There are many reports about the signaling pathways involved in the occurrence and development of lymphoma ( 20 , 21 ). Miller et al ( 22 ) reported that the MAPK signaling pathway influenced apoptosis in malignant lymphoid cells treated with glucocorticoids. Inhibition of MAPKs restored the drug sensitivity of a glucocorticoid-resistant clone in CEM-C1-15 cells.…”