Browsing by Subject "PROX1"

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  • Haegerling, Rene; Pollmann, Cathrin; Andreas, Martin; Schmidt, Christian; Nurmi, Harri; Adams, Ralf H.; Alitalo, Kari; Andresen, Volker; Schulte-Merker, Stefan; Kiefer, Friedemann (2013)
  • Lähde, Marianne; Heino, Sarika; Högström, Jenny; Kaijalainen, Seppo; Anisimov, Andrey; Flanagan, Dustin; Kallio, Pauliina; Leppänen, Veli-Matti; Ristimäki, Ari; Ritvos, Olli; Wu, Katherine; Tammela, Tuomas; Hodder, Michael; Sansom, Owen J.; Alitalo, Kari (2021)
    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/thorn mutant mice. METHODS: An adeno associated viral vector encoding RSPO1-Fc fusion protein, or control vector, was injected into ApcMin/thornmice. 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 Apcthorn/thorn 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-Fctransduced ApcMin/thorn mice also developed fewer and smaller intestinal tumors and had significantly longer survival times. Adenomas of ApcMin/thorn 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/thorn 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/thorn mice expressing RSPO1Fc back to the same level as in the adenomas from mice given the control vector. CONCLUSIONS: Expression of RSPO1 in ApcMin/thorn 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.
  • Saukkonen, Kapo; Hagstrom, Jaana; Mustonen, Harri; Juuti, Anne; Nordling, Stig; Kallio, Pauliina; Alitalo, Kari; Seppanen, Hanna; Haglund, Caj (2016)
    Background: The Wnt/beta-catenin pathway has a key role in regulating cellular processes and its aberrant signaling can lead to cancer development. The role of beta-catenin expression in pancreatic ductal adenocarcinoma is somewhat controversial. Transcription factor PROX1 is a target of Wnt/beta-catenin signaling and it is involved in carcinogenesis through alterations in its expression. The actions can be either oncogenic or tumor suppressive depending on the tissue. The aim of this study was to investigate PROX1 and beta-catenin expression in pancreatic ductal adenocarcinoma (PDAC). Methods: Expression of PROX1 and beta-catenin were evaluated in 156 patients by immunohistochemistry of tissue microarrays. Associations between tumor marker expression and clinicopathological parameters were assessed by the Fischer's exact-test or the linear-by-linear association test. The Kaplan-Meier method and log-rank test were used for survival analysis. Uni- and multivariate survival analyses were carried out by the Cox regression proportional hazard model. Results: High PROX1 expression was seen in 74 (48 %) tumors, and high beta-catenin expression in 100 (65 %). High beta-catenin expression was associated with lower tumor grade (p = 0.025). High PROX1 and beta-catenin expression associated significantly with lower risk of death from PDAC in multivariate analysis (HR = 0.63; 95 % CI 0.42-0.95, p = 0.026; and HR = 0.54; 95 % CI 0.35-0.82, p = 0.004; respectively). The combined high expression of PROX1 and beta-catenin also predicted lower risk of death from PDAC (HR = 0.46; 95 % CI 0.28-0.76, p = 0.002). Conclusion: In conclusion, high PROX1 and beta-catenin expression were independent factors for better prognosis in pancreatic ductal adenocarcinoma.