The USP7-TRIM27 axis as part of non-canonical PRC1.1 is a druggable target in leukemia

ABSTRACT: In an attempt to unravel the functionality and targettability of the non-canonical PRC1.1 Polycomb complex in human leukemogenesis, we dissected the subunit composition of the PRC1.1 complex and show that USP7 and TRIM27 are integral components. USP7 interactome analyses show that PRC1.1 is the predominant Polycomb complex co-precipitating with USP7. USP7 inhibition results in PRC1.1 disassembly and loss of chromatin binding, coinciding with reduced H2AK119ub and H3K27ac levels and diminished gene transcription of active PRC1.1-controlled loci, whereas H3K4me3 levels remain unaffected. TRIM27 and USP7 are reciprocally required for incorporation into PRC1.1, and TRIM27 knockdown partially rescues USP7 inhibitor sensitivity. USP7 inhibitors effectively impair proliferation in (primary) AML cells in vitro, also independent of the USP7-MDM2-TP53 axis, and MLL-AF9-induced leukemia is significantly delayed in vivo in human leukemia xenografts. We propose a model where USP7 counteracts TRIM27 E3 ligase activity, thereby maintaining PRC1.1 integrity and function. Moreover, USP7 inhibition may be a promising new strategy to treat AML patients.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Blood Cell, Blood

DISEASE(S): Acute Leukemia

SUBMITTER: Vincent van den Boom  

LAB HEAD: Jan Jacob Schuringa

PROVIDER: PXD018365 | Pride | 2021-06-14

REPOSITORIES: Pride