Project description:BRD4, a member of the BET family of histone readers, binds to acetylated lysine of histone H3 and promotes assembly of super-enhancer complexes that drive expression of key oncogenes in acute myeloid leukemia (AML) and other cancers. ARV-825 is a proteolysis-targeting chimera (PROTAC) that targets BRD4 for CRBN-mediated ubiquitination and degradation. We treated the AML cell line OCI-AML3, as well as primary tumor cells from a case of AML, with ARV-825 in vitro. At low concentrations, ARV-825 caused profound and sustained reduction in BRD4 protein levels. This caused reduction in transcription of key genes including MYC, anti-apoptotic BCL2 and BCLXL, PIM1, and CD44. Downstream effects included loss of CXCR4 surface expression and mitochondrial respiration; increased reactive oxygen species; toxicity to AML cells in vitro; and efficacy vs. OCI-AML3 cells in a mouse model of AML.
Project description:BRD4, a member of the BET family of histone readers, binds to acetylated lysine of histone H3 and promotes assembly of super-enhancer complexes that drive expression of key oncogenes in acute myeloid leukemia (AML) and other cancers. ARV-825 is a proteolysis-targeting chimera (PROTAC) that targets BRD4 for CRBN-mediated ubiquitination and degradation. BM-MSCs are an important element of the bone marrow microenvironment of AML. To understand how targeting BRD4 in BM-MSCs may contribute to the overall effect on AML of targeting BRD4, we treated BM-MSCs from two normal donors with ARV-825 in vitro. Treatment of BM-MSC monocultures with ARV-825 for 24 hr caused extensive changes in gene expression, highly uniform between triplicates. Although the cultures from the two normal donors showed different profiles, their changes with ARV-825 were highly similar. These changes implicated effects on oxidative stress, osteogenic differentiation, retinoid metabolism, F-actin polymerization, CXCL12, and proliferation.
