title: Identification of galectin-3-binding protein as a factor secreted by tumor cells that stimulates interleukin-6 expression in the bone marrow stroma.
abstract: 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.
authors.affiliation: Division of Hematology-Oncology and Department of Pediatrics, Keck School of Medicine of the University of Southern California and The Saban Research Institute of Childrens Hospital Los Angeles, Los Angeles, California 90027, USA.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Fukaya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shimada
authors.forename: Ling-Chi
authors.initials: LC
authors.lastname: Wang
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Zandi
authors.forename: Yves A
authors.initials: YA
authors.lastname: DeClerck
mesh_terms: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D001854:Bone Marrow Cells / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D045744:Cell Line, Tumor; D017077:Culture Media, Conditioned / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D037502:Galectin 3 / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006023:Glycoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D017154:Stromal Cells / Q000378:metabolism / Q000473:pathology; D016326:Extracellular Matrix Proteins
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D002352:Carrier Proteins; D017077:Culture Media, Conditioned; D037502:Galectin 3; D006023:Glycoproteins; D015850:Interleukin-6; D009363:Neoplasm Proteins; D011994:Recombinant Proteins; C508600:IL6 protein, human; C081856:LGALS3BP protein, human; D016326:Extracellular Matrix Proteins