Back to Search
Start Over
Syndecan-1 promotes Wnt/β-catenin signaling in multiple myeloma by presenting Wnts and R-spondins.
- Source :
-
Blood [Blood] 2018 Mar 01; Vol. 131 (9), pp. 982-994. Date of Electronic Publication: 2017 Dec 06. - Publication Year :
- 2018
-
Abstract
- Multiple myeloma (MM) is characterized by the expansion of malignant plasma cells in the bone marrow (BM). Most MMs display aberrant Wnt/β-catenin signaling, which drives proliferation; however, they lack oncogenic Wnt pathway mutations, suggesting activation by autocrine Wnt ligands and/or paracrine Wnts from the BM microenvironment. Expression of the heparan sulfate (HS) proteoglycan syndecan-1 is a hallmark of MM. Syndecan-1 is a critical player in the complex reciprocal interaction between MM cells and their BM niche, mediating growth factor/cytokine binding and signaling by its HS chains. Here, by means of CRISPR/Cas9-mediated knockout and doxycycline-inducible short hairpin RNA-mediated knockdown of EXT1, a critical enzyme for HS polymerization, we demonstrate that the HS chains decorating syndecan-1 mediate aberrant Wnt pathway activation in MM. HS-deficient MM cells exhibited strongly decreased autocrine Wnt/β-catenin pathway activity and reduced Wnt pathway-dependent proliferation. In addition, we demonstrate that Wnts bind to the HS side chains of syndecan-1 and that this binding contributes to paracrine Wnt pathway activation through the Wnt receptor Frizzled (Fzd). Furthermore, in an HS-dependent fashion, syndecan-1 also binds osteoblast-produced R-spondin, which represses Fzd degradation by activation of LGR4, an R-spondin receptor aberrantly expressed on MM cells. Costimulation with R-spondin and its binding to HS chains decorating syndecan-1 are indispensable for optimal stimulation of Wnt signaling in MM. Taken together, our results identify syndecan-1 as a crucial component of the Wnt signalosome in MM cells, binding Wnts and R-spondins to promote aberrant Wnt/β-catenin signaling and cell growth, and suggest HS and its biosynthetic enzymes as potential targets in the treatment of MM.<br /> (© 2018 by The American Society of Hematology.)
- Subjects :
- Cell Line, Tumor
Frizzled Receptors genetics
Frizzled Receptors metabolism
Heparitin Sulfate genetics
Heparitin Sulfate metabolism
Humans
Multiple Myeloma genetics
Multiple Myeloma pathology
Neoplasm Proteins genetics
Receptors, G-Protein-Coupled genetics
Receptors, G-Protein-Coupled metabolism
Syndecan-1 genetics
Thrombospondins genetics
Wnt Proteins genetics
beta Catenin genetics
beta Catenin metabolism
Multiple Myeloma metabolism
Neoplasm Proteins metabolism
Syndecan-1 metabolism
Thrombospondins metabolism
Wnt Proteins metabolism
Wnt Signaling Pathway
Subjects
Details
- Language :
- English
- ISSN :
- 1528-0020
- Volume :
- 131
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- Blood
- Publication Type :
- Academic Journal
- Accession number :
- 29212806
- Full Text :
- https://doi.org/10.1182/blood-2017-07-797050