Dual inhibition of EZH2 and G9a suppresses multiple myeloma cell proliferation by regulating interferon signal and IRF4-MYC axis
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ABSTRACT: Epigenetic mechanisms including histone modifications play key roles in the pathogenesis of multiple myeloma (MM). We have previously shown that a histone H3 lysine 27 (H3K27) methyltransferase EZH2 and a H3K9 methyltransferase G9a are potential therapeutic targets in MM. Recent studies suggested that EZH2 and G9a cooperate to regulate gene expression. We thus aimed to evaluate the anti-tumor effect by dual targeting of EZH2 and G9a in MM. A combination of an EZH2 inhibitor and a G9a inhibitor strongly suppressed myeloma cell proliferation through inducing cell cycle arrest and apoptosis in vitro. Dual inhibition of EZH2 and G9a also repressed xenograft formation by myeloma cells in vivo. Higher expression levels of EZH2 and EHMT2, which encodes G9a, are significantly associated with poorer prognosis in MM patients, respectively. Microarray analysis revealed that EZH2/G9a inhibition significantly upregulated interferon (IFN)-stimulated genes and suppressed IRF4-MYC axis genes in myeloma cells. Notably, we found increased expression and reduced H3K27/H3K9 methylation levels of endogenous retrovirus (ERV) genes in myeloma cells with the dual inhibition, suggesting that activation of the ERV genes may cause the IFN response. These results suggest that dual targeting of EZH2 and G9a may be a novel therapeutic strategy in MM.
ORGANISM(S): Homo sapiens
PROVIDER: GSE155135 | GEO | 2021/01/27
REPOSITORIES: GEO
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