title: RSPO3 expands intestinal stem cell and niche compartments and drives tumorigenesis.
abstract: The gross majority of colorectal cancer cases results from aberrant Wnt/β-catenin signalling through adenomatous polyposis coli (APC)orCTNNB1mutations. However, a subset of human colon tumours harbour, mutually exclusive withAPCandCTNNB1mutations, gene fusions inRSPO2orRSPO3,leading to enhanced expression of these R-spondin genes. This suggested thatRSPOactivation can substitute for the most common mutations as an alternative driver for intestinal cancer. Involvement of RSPO3 in tumour growth was recently shown inRSPO3-fusion-positive xenograft models. The current study determines the extent into which solely a gain in RSPO3 actually functions as a driver of intestinal cancer in a direct, causal fashion, and addresses the in vivo activities of RSPO3 in parallel.
  
  
  
  We generated a conditionalRspo3transgenic mouse model in which theRspo3transgene is expressed upon Cre activity. Cre is provided by cross-breeding withLgr5-GFP-CreERT2mice.
  
  
  
  Upon in vivoRspo3expression, mice rapidly developed extensive hyperplastic, adenomatous and adenocarcinomatous lesions throughout the intestine. RSPO3 induced the expansion of Lgr5+stem cells, Paneth cells, non-Paneth cell label-retaining cells and Lgr4+cells, thus promoting both intestinal stem cell and niche compartments. Wnt/β-catenin signalling was modestly increased uponRspo3expression and mutantKrassynergised withRspo3in hyperplastic growth.
  
  
  
  We provide in vivo evidence that RSPO3 stimulates the crypt stem cell and niche compartments and drives rapid intestinal tumorigenesis. This establishes RSPO3 as a potent driver of intestinal cancer and proposes RSPO3 as a candidate target for therapy in patients with colorectal cancer harbouringRSPO3fusions.
authors: Department of Molecular Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: John
authors: J
authors: Hilkens
authors: Department of Molecular Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Nikki C
authors: NC
authors: Timmer
authors: Department of Molecular Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Mandy
authors: M
authors: Boer
authors: Department of Molecular Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Gerjon J
authors: GJ
authors: Ikink
authors: Department of Pathology, Josephine Nefkens Institute, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors: Matthias
authors: M
authors: Schewe
authors: Department of Pathology, Josephine Nefkens Institute, Erasmus Medical Centre, Rotterdam, The Netherlands.
authors: Andrea
authors: A
authors: Sacchetti
authors: Department of Molecular Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Martijn A J
authors: MAJ
authors: Koppens
authors: Department of Experimental Animal Pathology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Ji-Ying
authors: JY
authors: Song
authors: Department of Molecular Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors: Elvira R M
authors: ERM
authors: Bakker
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology; D000236:Adenoma / Q000235:genetics* / Q000473:pathology; D000818:Animals; D063646:Carcinogenesis / Q000235:genetics*; D049108:Cell Enlargement; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation / Q000235:genetics; D015870:Gene Expression; D006965:Hyperplasia / Q000235:genetics / Q000473:pathology; D007413:Intestinal Mucosa / Q000378:metabolism; D007414:Intestinal Neoplasms / Q000235:genetics* / Q000473:pathology; D007422:Intestines / Q000473:pathology*; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D009940:Organoids / Q000473:pathology; D019879:Paneth Cells / Q000378:metabolism / Q000473:pathology*; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000032:analysis; D013234:Stem Cells / Q000737:chemistry / Q000378:metabolism / Q000473:pathology*; D019699:Thrombospondins / Q000235:genetics* / Q000378:metabolism*; D051153:Wnt Proteins / Q000378:metabolism; D060449:Wnt Signaling Pathway; D051176:beta Catenin / Q000378:metabolism
chemical_list: C496200:LGR4 protein, mouse; C493597:Lgr5 protein, mouse; C517523:R-spondin3 protein, mouse; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D019699:Thrombospondins; D051153:Wnt Proteins; D051176:beta Catenin; C495971:Hras protein, mouse; D016283:Proto-Oncogene Proteins p21(ras)
keywords: CANCER; INTESTINAL STEM CELL; SIGNALING