Nucleolin inhibits Fas ligand binding and suppresses Fas-mediated apoptosis in vivo via a surface nucleolin-Fas complex

Blood. 2013 Jun 6;121(23):4729-39. doi: 10.1182/blood-2012-12-471094. Epub 2013 Apr 18.

Abstract

Resistance to Fas-mediated apoptosis is associated with poor cancer outcomes and chemoresistance. To elucidate potential mechanisms of defective Fas signaling, we screened primary lymphoma cell extracts for Fas-associated proteins that would have the potential to regulate Fas signaling. An activation-resistant Fas complex selectively included nucleolin. We confirmed the presence of nucleolin-Fas complexes in B-cell lymphoma cells and primary tissues, and the absence of such complexes in B-lymphocytes from healthy donors. RNA-binding domain 4 and the glycine/arginine-rich domain of nucleolin were essential for its association with Fas. Nucleolin colocalized with Fas on the surface of B-cell lymphoma cells. Nucleolin knockdown sensitized BJAB cells to Fas ligand (FasL)-induced and Fas agonistic antibody-induced apoptosis through enhanced binding, suggesting that nucleolin blocks the FasL-Fas interaction. Mice transfected with nucleolin were protected from the lethal effects of agonistic anti-mouse Fas antibody (Jo2) and had lower rates of hepatocyte apoptosis, compared with vector and a non-Fas-binding mutant of nucleolin. Our results show that cell surface nucleolin binds Fas, inhibits ligand binding, and thus prevents induction of Fas-mediated apoptosis in B-cell lymphomas and may serve as a new therapeutic target.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Apoptosis*
  • B-Lymphocytes / metabolism
  • B-Lymphocytes / pathology*
  • Blotting, Western
  • Cell Membrane / metabolism*
  • Cell Proliferation
  • Fas Ligand Protein / metabolism*
  • Flow Cytometry
  • Humans
  • Immunoprecipitation
  • Lymphoma, B-Cell / genetics
  • Lymphoma, B-Cell / metabolism
  • Lymphoma, B-Cell / pathology*
  • Mice
  • Mice, Inbred C57BL
  • Molecular Sequence Data
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Protein Binding
  • RNA, Messenger / genetics
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction
  • Tumor Cells, Cultured

Substances

  • Fas Ligand Protein
  • Phosphoproteins
  • RNA, Messenger
  • RNA-Binding Proteins
  • nucleolin