Expression of R-spondin 1 in Apc(Min/+) mice suppresses growth of intestinal adenomas by altering Wnt and transforming growth factor beta signaling Journal Article

Authors: Lähde, M.; Heino, S.; Högström, J.; Kaijalainen, S.; Anisimov, A.; Flanagan, D.; Kallio, P.; Leppänen, V. M.; Ristimäki, A.; Ritvos, O.; Wu, K.; Tammela, T.; Hodder, M.; Sansom, O. J.; Alitalo, K.
Article Title: Expression of R-spondin 1 in Apc(Min/+) mice suppresses growth of intestinal adenomas by altering Wnt and transforming growth factor beta signaling
Abstract: Background & Aims: Mutations in the APC gene and other genes in the Wnt signaling pathway contribute to development of colorectal carcinomas. R-spondins (RSPOs) are secreted proteins that amplify Wnt signaling in intestinal stem cells. Alterations in RSPO genes have been identified in human colorectal tumors. We studied the effects of RSPO1 overexpression in ApcMin/+ mutant mice. Methods: An adeno associated viral vector encoding RSPO1-Fc fusion protein, or control vector, was injected into ApcMin/+mice. Their intestinal crypts were isolated and cultured as organoids. which were incubated with or without RSPO1-Fc and an inhibitor of transforming growth factor beta receptor (TGFBR). Livers were collected from mice and analyzed by immunohistochemistry. Organoids and adenomas were analyzed by quantitative reverse-transcription PCR, single cell RNA sequencing, and immunohistochemistry. Results: Intestines from Apc+/+ mice injected with the vector encoding RSPO1-Fc had significantly deeper crypts, longer villi, with increased EdU labeling, indicating increased proliferation of epithelial cells, in comparison to mice given control vector. AAV-RSPO1-Fc–transduced ApcMin/+ mice also developed fewer and smaller intestinal tumors and had significantly longer survival times. Adenomas of ApcMin/+ mice injected with the RSPO1-Fc vector showed a rapid increase in apoptosis and in the expression of Wnt target genes, followed by reduced expression of messenger RNAs and proteins regulated by the Wnt pathway, reduced cell proliferation, and less crypt branching than adenomas of mice given the control vector. Addition of RSPO1 reduced the number of adenoma organoids derived from ApcMin/+ mice and suppressed expression of Wnt target genes but increased phosphorylation of SMAD2 and transcription of genes regulated by SMAD. Inhibition of TGFBR signaling in organoids stimulated with RSPO1-Fc restored organoid formation and expression of genes regulated by Wnt. The TGFBR inhibitor restored apoptosis in adenomas from ApcMin/+ mice expressing RSPO1-Fc back to the same level as in the adenomas from mice given the control vector. Conclusions: Expression of RSPO1 in ApcMin/+ mice increases apoptosis and reduces proliferation and Wnt signaling in adenoma cells, resulting in development of fewer and smaller intestinal tumors and longer mouse survival. Addition of RSPO1 to organoids derived from adenomas inhibits their growth and promotes proliferation of intestinal stem cells that retain the APC protein; these effects are reversed by TGFB inhibitor. Strategies to increase the expression of RSPO1 might be developed for the treatment of intestinal adenomas. © 2021 AGA Institute
Keywords: colon cancer; familial adenomatous polyposis; prox1; lgr5
Journal Title: Gastroenterology
Volume: 160
Issue: 1
ISSN: 0016-5085
Publisher: Elsevier Inc.  
Date Published: 2021-01-01
Start Page: 245
End Page: 259
Language: English
DOI: 10.1053/j.gastro.2020.09.011
PUBMED: 32941878
PROVIDER: scopus
Notes: Article -- Export Date: 4 January 2021 -- Source: Scopus
Citation Impact
MSK Authors
  1. Tuomas Tammela
    15 Tammela
  2. Katherine Wu
    5 Wu