The Epigenetic Drug 5-Azacytidine Interferes with Cholesterol and Lipid Metabolism

Steve Poirier,Samaneh Samami,Maya Mamarbachi,Annie Demers,Ta Yuan Chang,Dennis E Vance,Grant M Hatch,Gaétan Mayer

doi:10.1074/jbc.m114.563650

Abstract

DNA methylation and histone acetylation inhibitors are widely used to study the role of epigenetic marks in the regulation of gene expression. In addition, several of these molecules are being tested in clinical trials or already in use in the clinic. Antimetabolites, such as the DNA-hypomethylating agent 5-azacytidine (5-AzaC), have been shown to lower malignant progression to acute myeloid leukemia and to prolong survival in patients with myelodysplastic syndromes. Here we examined the effects of DNA methylation inhibitors on the expression of lipid biosynthetic and uptake genes. Our data demonstrate that, independently of DNA methylation, 5-AzaC selectively and very potently reduces expression of key genes involved in cholesterol and lipid metabolism (e.g. PCSK9, HMGCR, and FASN) in all tested cell lines and in vivo in mouse liver. Treatment with 5-AzaC disturbed subcellular cholesterol homeostasis, thereby impeding activation of sterol regulatory element-binding proteins (key regulators of lipid metabolism). Through inhibition of UMP synthase, 5-AzaC also strongly induced expression of 1-acylglycerol-3-phosphate O-acyltransferase 9 (AGPAT9) and promoted triacylglycerol synthesis and cytosolic lipid droplet formation. Remarkably, complete reversal was obtained by the co-addition of either UMP or cytidine. Therefore, this study provides the first evidence that inhibition of the de novo pyrimidine synthesis by 5-AzaC disturbs cholesterol and lipid homeostasis, probably through the glycerolipid biosynthesis pathway, which may contribute mechanistically to its beneficial cytostatic properties.

Highlights

The anticancer drug 5-azacytidine acts through an incompletely understood mechanism
Independently of DNA methylation, 5-AzaC selectively and very potently reduces expression of key genes involved in cholesterol and lipid metabolism (e.g. proprotein convertase subtilisin/kexin type 9 (PCSK9), HMG-CoA reductase (HMGCR), and FASN) in all tested cell lines and in vivo in mouse liver
We explored the effects of DNA methylation inhibitors 5-AzaC and DAC on cholesterogenic and lipid gene expression and defined a previously unrecognized mechanism regulating the activation of SREBPs

Summary

Background

The anticancer drug 5-azacytidine acts through an incompletely understood mechanism. Results: 5-Azacytidine reprograms the glycerolipid biosynthesis pathway and prevents activation of master transcription factors that regulate lipid homeostasis. Several of these molecules are being tested in clinical trials or already in use in the clinic Antimetabolites, such as the DNA-hypomethylating agent 5-azacytidine (5-AzaC), have been shown to lower malignant progression to acute myeloid leukemia and to prolong survival in patients with myelodysplastic syndromes. Provides the first evidence that inhibition of the de novo pyrimidine synthesis by 5-AzaC disturbs cholesterol and lipid homeostasis, probably through the glycerolipid biosynthesis pathway, which may contribute mechanistically to its beneficial cytostatic properties. Epigenetic marks, such as DNA methylation and histone acetylation, finely alter chromatin structure to precisely control gene expression in a time-, cell-, and tissue-specific manner [1]. DAC is the most effective hypomethylating agent, 5-AzaC is more potent to reduce cell viability and proliferation in acute myeloid leu-

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EXPERIMENTAL PROCEDURES

RESULTS

Findings

DISCUSSION