Epigenetic silencing of UBXN8 contributes to leukemogenesis of t(8;21) acute myeloid leukemia

The formation of the AML1-ETO fusion protein, resulting from the t(8;21) translocation, is considered to be among the t(8;21) acute myeloid leukemia (AML) initiating events. However, the mechanisms of the oncogenic activity of AML1-ETO remains unclear. In this study, we found that AML1-ETO triggers the heterochromatic silencing of UBXN8 by recognizing the AML1 binding sites and recruiting chromatin remodeling enzymes to the UBXN8 promoter region. Decitabine, a specific inhibitor of DNA methylation, upregulated the expression of UBXN8 in AML1-ETO+ AML cell lines. Overexpression of UBXN8 inhibited the proliferation and colony-forming ability and promoted cell cycle arrest in t(8;21) AML cell lines. Enhancement of UBXN8 level can significantly inhibit the tumor proliferation of AML1-ETO+ cells in vivo. Thus, our results indicated that epigenetic silencing of UBXN8 via its promoter region methylation mediated by the AML1-ETO fusion protein contributes to the leukemogenesis of t(8;21)AML. These results demonstrated the feasibility and effectiveness of the pharmacological disruption of AML1-ETO/HDACs/DNMTs complex and that the UBXN8 targeting maybe an potential therapeutic strategy for t(8;21)AML. Overall design: The SKNO-1, SKNO1-siAE cell lines were maintained in RPMI 1640 medium supplemented with 10% fetal calf serum (Hyclone, Logan, UT, USA), penicillin (107 U/L) and streptomycin (10 mg/L) at 37°C in a 5% CO2 atmosphere. SKNO-1 cells infected with the pRRLcPPT.hPGK, a lentiviral vector encoding the previously described 12siAGF1 oligonucleotides, which were designed against the AML1-ETO mRNA fusion site, allowing the silencing of AML1-ETO in SKNO-1 cells12, 13 to produce the SKNO1-siAE cell lines.