Identification of galectin-3-binding protein as a factor secreted by tumor cells that stimulates interleukin-6 expression in the bone marrow stroma

J Biol Chem. 2008 Jul 4;283(27):18573-81. doi: 10.1074/jbc.M803115200. Epub 2008 May 1.


We have previously demonstrated that neuroblastoma cells increase the expression of interleukin-6 by bone marrow stromal cells and that stimulation does not require cell-cell contact. In this study we report the purification and identification of a protein secreted by neuroblastoma cells that stimulates interleukin-6 production by stromal cells. Using a series of chromatographic purification steps including heparin-affinity, ion exchange, and molecular sieve chromatography followed by trypsin digestion and liquid chromatography tandem mass spectrometry, we identified in serum-free conditioned medium of neuroblastoma cells several secreted peptides including galectin-3-binding protein, also known as 90-kDa Mac-2-binding protein. We demonstrated the presence of the galectin-3-binding protein in the conditioned medium of several neuroblastoma cell lines and in chromatographic fractions with interleukin-6 stimulatory activity. Consistently, bone marrow stromal cells express galectin-3, the receptor for galectin-3-binding protein. Supporting a role for galectin-3-binding protein in stimulating interleukin-6 expression in bone marrow stromal cells, we observed that recombinant galectin-3-binding protein stimulated interleukin-6 expression in these cells and that interleukin-6 stimulation by neuroblastoma-conditioned medium was inhibited in the presence of lactose or a neutralizing anti-galectin-3 antibody. Down-regulation of galectin-3-binding protein expression in neuroblastoma cells also decreased the interleukin-6 stimulatory activity of the conditioned medium on bone marrow stromal cells. We also provide evidence that stimulation of interleukin-6 by galectin-3-binding protein involves activation of the Erk1/2 pathway. The data, thus, identifies galectin-3-binding protein as a factor secreted by neuroblastoma cells that stimulates the expression of interleukin-6 in bone marrow stromal cells and provides a novel function for this protein in cancer progression.

MeSH terms

  • Antigens, Neoplasm
  • Biomarkers, Tumor
  • Bone Marrow Cells / metabolism*
  • Bone Marrow Cells / pathology
  • Carrier Proteins / biosynthesis*
  • Carrier Proteins / genetics
  • Carrier Proteins / pharmacology
  • Cell Line, Tumor
  • Culture Media, Conditioned / pharmacology
  • Down-Regulation / drug effects
  • Galectin 3 / genetics
  • Galectin 3 / metabolism
  • Galectin 3 / pharmacology
  • Gene Expression Regulation, Neoplastic / drug effects
  • Glycoproteins / biosynthesis*
  • Glycoproteins / genetics
  • Glycoproteins / pharmacology
  • Humans
  • Interleukin-6 / biosynthesis*
  • Interleukin-6 / genetics
  • Interleukin-6 / pharmacology
  • MAP Kinase Signaling System* / drug effects
  • MAP Kinase Signaling System* / genetics
  • Neoplasm Proteins / biosynthesis*
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / pharmacology
  • Neuroblastoma / genetics
  • Neuroblastoma / metabolism*
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / genetics
  • Recombinant Proteins / pharmacology
  • Stromal Cells / metabolism
  • Stromal Cells / pathology


  • Antigens, Neoplasm
  • Biomarkers, Tumor
  • Carrier Proteins
  • Culture Media, Conditioned
  • Galectin 3
  • Glycoproteins
  • IL6 protein, human
  • Interleukin-6
  • LGALS3BP protein, human
  • Neoplasm Proteins
  • Recombinant Proteins