Clinical value of R-spondins in triple-negative and metaplastic breast cancers

Br J Cancer. 2017 Jun 6;116(12):1595-1603. doi: 10.1038/bjc.2017.131. Epub 2017 May 4.


Background: RSPO ligands, activators of the Wnt/β-catenin pathway, are overexpressed in different cancers. The objective of this study was to investigate the role of RSPOs in breast cancer (BC).

Methods: Expression of RSPO and markers of various cancer pathways were measured in breast tumours and cell lines by qRT-PCR. The effect of RSPO on the Wnt/β-catenin pathway activity was determined by luciferase assay, western blotting, and qRT-PCR. The effect of RSPO2 inhibition on proliferation was determined by using RSPO2 siRNAs. The effect of IWR-1, an inhibitor of the Wnt/β-catenin pathway, was examined on the growth of an RSPO2-positive patient-derived xenograft (PDX) model of metaplastic triple-negative BC.

Results: We detected RSPO2 and RSPO4 overexpression levels in BC, particularly in triple-negative BC (TNBC), metaplastic BC, and triple-negative cell lines. Various mechanisms could account for this overexpression: presence of fusion transcripts involving RSPO, and amplification or hypomethylation of RSPO genes. Patients with RSPO2-overexpressing tumours have a poorer metastasis-free survival (P=3.6 × 10-4). RSPO2 and RSPO4 stimulate Wnt/β-catenin pathway activity. Inhibition of RSPO expression in a TN cell line inhibits cell growth, and IWR-1 significantly inhibits the growth of an RSPO2-overexpressing PDX.

Conclusions: RSPO overexpression could therefore be a new prognostic biomarker and therapeutic target for TNBC.

MeSH terms

  • Animals
  • Antineoplastic Agents / therapeutic use
  • Carcinoma, Ductal, Breast / chemistry
  • Carcinoma, Ductal, Breast / drug therapy
  • Carcinoma, Ductal, Breast / genetics*
  • Carcinoma, Ductal, Breast / secondary*
  • Cell Proliferation
  • Culture Media, Conditioned / pharmacology
  • Female
  • Gene Expression* / drug effects
  • HEK293 Cells
  • Humans
  • Imides / therapeutic use
  • Intercellular Signaling Peptides and Proteins / analysis
  • Intercellular Signaling Peptides and Proteins / genetics
  • Intercellular Signaling Peptides and Proteins / metabolism
  • Metaplasia / genetics
  • Metaplasia / pathology
  • Mice, Nude
  • Neoplasm Transplantation
  • Quinolines / therapeutic use
  • RNA, Messenger / analysis*
  • RNA, Small Interfering / genetics
  • Receptors, G-Protein-Coupled / genetics
  • TATA-Box Binding Protein / genetics
  • Thrombospondins / genetics
  • Thrombospondins / metabolism
  • Triple Negative Breast Neoplasms / chemistry
  • Triple Negative Breast Neoplasms / drug therapy
  • Triple Negative Breast Neoplasms / genetics*
  • Triple Negative Breast Neoplasms / pathology*
  • Wnt Signaling Pathway
  • Wnt3A Protein / metabolism


  • Antineoplastic Agents
  • Culture Media, Conditioned
  • IWR-1 compound
  • Imides
  • Intercellular Signaling Peptides and Proteins
  • LGR4 protein, human
  • LGR5 protein, human
  • LGR6 protein, human
  • Quinolines
  • RNA, Messenger
  • RNA, Small Interfering
  • RSPO1 protein, human
  • RSPO3 protein, human
  • RSPO4 protein, human
  • Receptors, G-Protein-Coupled
  • Rspo2 protein, human
  • TATA-Box Binding Protein
  • TBP protein, human
  • Thrombospondins
  • WNT3A protein, human
  • Wnt3A Protein