Pharmacological inhibition of LSD1 triggers myeloid differentiation by targeting GSE1 oncogenic functions in AML

Luciano Nicosia,Isabella Pallavicini,Roberto Ravasio,Tiziana Bonaldi,Enrico Massignani,Elena Ceccacci,Tim C P Somervaille,Fabio Bedin,Saverio Minucci,Fabio Conforti,Francesca Ludovica Boffo

doi:10.1038/s41388-021-02123-7

Abstract

The histone demethylase LSD1 is over-expressed in hematological tumors and has emerged as a promising target for anticancer treatment, so that several LSD1 inhibitors are under development and testing, in preclinical and clinical settings. However, the complete understanding of their complex mechanism of action is still unreached. Here, we unraveled a novel mode of action of the LSD1 inhibitors MC2580 and DDP-38003, showing that they can induce differentiation of AML cells through the downregulation of the chromatin protein GSE1. Analysis of the phenotypic effects of GSE1 depletion in NB4 cells showed a strong decrease of cell viability in vitro and of tumor growth in vivo. Mechanistically, we found that a set of genes associated with immune response and cytokine-signaling pathways are upregulated by LSD1 inhibitors through GSE1-protein reduction and that LSD1 and GSE1 colocalize at promoters of a subset of these genes at the basal state, enforcing their transcriptional silencing. Moreover, we show that LSD1 inhibitors lead to the reduced binding of GSE1 to these promoters, activating transcriptional programs that trigger myeloid differentiation. Our study offers new insights into GSE1 as a novel therapeutic target for AML.

Highlights

By catalyzing the removal of methyl groups from mono- and dimethylated forms of lysine 4 and lysine 9 of histone H3 (H3K4me1/me2 and H3K9me1/me2), the epigenetic enzyme lysine-specific histone demethylase 1 A (LSD1/KDM1A) has emerged as a major player in gene expression modulation in eukaryotes [1, 2]
LSD1 inhibitors reduce the protein expression of GSE1 in acute myeloid leukemia (AML) Using the Differential Enrichment analysis of Proteomics data (DEP) R software package [40], we reinterrogated the recently published dynamic LSD1 interactome upon treatment of NB4 acute promyelocytic leukemia (APL) cells with the LSD1 inhibitor MC2580 (Fig. 1A) [13] and we found that, in addition to the already-described GFI1, interaction with GSE1 protein was significantly downregulated after drug treatment (Fig. 1B and C)
In line with our model, GSE1 was co-immunoprecipitated with LSD1 with the same efficiency in control- and MC2580-treated cells, while GFI1 was evicted by LSD1 after pharmacological inhibition, as previously reported [12, 13] (Fig. 1E)

Summary

Introduction

By catalyzing the removal of methyl groups from mono- and dimethylated forms of lysine 4 and lysine 9 of histone H3 (H3K4me1/me and H3K9me1/me2), the epigenetic enzyme lysine-specific histone demethylase 1 A (LSD1/KDM1A) has emerged as a major player in gene expression modulation in eukaryotes [1, 2]. LSD1 is embedded in transcriptional-repressive complexes such as CoREST and NuRD [4,5,6], where different subunits modulate LSD1 activity: CoREST confers to LSD1 the ability to bind nucleosomes, directs its demethylase activity toward H3K4me1/me, and protects it from proteasomal degradation; HDACs create a hypoacetylated chromatin environment that stimulates LSD1 catalytic activity [6,7,8] Less often, such as in the context of androgen (AR)- and estrogen (ER)receptor-dependent transcription, LSD1 acts as a transcriptional coactivator by demethylating H3K9me1/me and promoting the downstream expression of AR- and ER- target genes [2, 9]. LSD1 exhibits scaffolding activity, which facilitates recruitment of the repressive activity of histone deacetylase to sites on chromatin where SNAG-domain transcription factors such as GFI1 and GFI1B are bound [12, 13]

Methods

Results

Conclusion