Essential role of the linear ubiquitin chain assembly complex in lymphoma revealed by rare germline polymorphisms.

ABSTRACT: UNLABELLED:Constitutive activation of NF-?B is a hallmark of the activated B cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL), owing to upstream signals from the B-cell receptor (BCR) and MYD88 pathways. The linear polyubiquitin chain assembly complex (LUBAC) attaches linear polyubiquitin chains to I?B kinase-?, a necessary event in some pathways that engage NF-?B. Two germline polymorphisms affecting the LUBAC subunit RNF31 are rare among healthy individuals (?1%) but enriched in ABC DLBCL (7.8%). These polymorphisms alter RNF31 ?-helices that mediate binding to the LUBAC subunit RBCK1, thereby increasing RNF31-RBCK1 association, LUBAC enzymatic activity, and NF-?B engagement. In the BCR pathway, LUBAC associates with the CARD11-MALT1-BCL10 adapter complex and is required for ABC DLBCL viability. A stapled RNF31 ?-helical peptide based on the ABC DLBCL-associated Q622L polymorphism inhibited RNF31-RBCK1 binding, decreased NF-?B activation, and killed ABC DLBCL cells, credentialing this protein-protein interface as a therapeutic target. SIGNIFICANCE:We provide genetic, biochemical, and functional evidence that the LUBAC ubiquitin ligase is a therapeutic target in ABC DLBCL, the DLBCL subtype that is most refractory to current therapy. More generally, our findings highlight the role of rare germline-encoded protein variants in cancer pathogenesis.

SUBMITTER: Yang Y 

PROVIDER: S-EPMC3992927 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature