A multiprotein supercomplex controlling oncogenic signalling in lymphoma

Nature. 2018 Aug;560(7718):387-391. doi: 10.1038/s41586-018-0290-0. Epub 2018 Jun 20.

Abstract

B cell receptor (BCR) signalling has emerged as a therapeutic target in B cell lymphomas, but inhibiting this pathway in diffuse large B cell lymphoma (DLBCL) has benefited only a subset of patients1. Gene expression profiling identified two major subtypes of DLBCL, known as germinal centre B cell-like and activated B cell-like (ABC)2,3, that show poor outcomes after immunochemotherapy in ABC. Autoantigens drive BCR-dependent activation of NF-κB in ABC DLBCL through a kinase signalling cascade of SYK, BTK and PKCβ to promote the assembly of the CARD11-BCL10-MALT1 adaptor complex, which recruits and activates IκB kinase4-6. Genome sequencing revealed gain-of-function mutations that target the CD79A and CD79B BCR subunits and the Toll-like receptor signalling adaptor MYD885,7, with MYD88(L265P) being the most prevalent isoform. In a clinical trial, the BTK inhibitor ibrutinib produced responses in 37% of cases of ABC1. The most striking response rate (80%) was observed in tumours with both CD79B and MYD88(L265P) mutations, but how these mutations cooperate to promote dependence on BCR signalling remains unclear. Here we used genome-wide CRISPR-Cas9 screening and functional proteomics to determine the molecular basis of exceptional clinical responses to ibrutinib. We discovered a new mode of oncogenic BCR signalling in ibrutinib-responsive cell lines and biopsies, coordinated by a multiprotein supercomplex formed by MYD88, TLR9 and the BCR (hereafter termed the My-T-BCR supercomplex). The My-T-BCR supercomplex co-localizes with mTOR on endolysosomes, where it drives pro-survival NF-κB and mTOR signalling. Inhibitors of BCR and mTOR signalling cooperatively decreased the formation and function of the My-T-BCR supercomplex, providing mechanistic insight into their synergistic toxicity for My-T-BCR+ DLBCL cells. My-T-BCR supercomplexes characterized ibrutinib-responsive malignancies and distinguished ibrutinib responders from non-responders. Our data provide a framework for the rational design of oncogenic signalling inhibitors in molecularly defined subsets of DLBCL.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biopsy
  • CRISPR-Cas Systems / genetics
  • Carcinogenesis* / genetics
  • Drug Design
  • Female
  • Humans
  • Lymphoma, Large B-Cell, Diffuse / genetics
  • Lymphoma, Large B-Cell, Diffuse / metabolism*
  • Lymphoma, Large B-Cell, Diffuse / pathology*
  • Mice
  • Multiprotein Complexes / chemistry
  • Multiprotein Complexes / metabolism*
  • Mutation
  • Myeloid Differentiation Factor 88 / genetics
  • Myeloid Differentiation Factor 88 / metabolism
  • NF-kappa B / metabolism
  • Proteomics
  • Pyrazoles / pharmacology
  • Pyrazoles / therapeutic use
  • Pyrimidines / pharmacology
  • Pyrimidines / therapeutic use
  • Receptors, Antigen, B-Cell / antagonists & inhibitors
  • Receptors, Antigen, B-Cell / genetics
  • Receptors, Antigen, B-Cell / metabolism
  • Signal Transduction* / drug effects
  • Signal Transduction* / genetics
  • TOR Serine-Threonine Kinases / antagonists & inhibitors
  • TOR Serine-Threonine Kinases / metabolism
  • Toll-Like Receptor 9 / genetics
  • Toll-Like Receptor 9 / metabolism
  • Tumor Cells, Cultured
  • Xenograft Model Antitumor Assays

Substances

  • MYD88 protein, human
  • Multiprotein Complexes
  • Myeloid Differentiation Factor 88
  • NF-kappa B
  • Pyrazoles
  • Pyrimidines
  • Receptors, Antigen, B-Cell
  • TLR9 protein, human
  • Toll-Like Receptor 9
  • ibrutinib
  • MTOR protein, human
  • TOR Serine-Threonine Kinases