WNT7B mediates autocrine Wnt/β-catenin signaling and anchorage-independent growth in pancreatic adenocarcinoma

M. D. Arensman, A. N. Kovochich, R. M. Kulikauskas, A. R. Lay, P. T. Yang, X. Li, T. Donahue, M. B. Major, R. T. Moon, A. J. Chien, D. W. Dawson

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58 Scopus citations

Abstract

Developmental and cancer models show Wnt/β-catenin-dependent signaling mediates diverse phenotypic outcomes in the pancreas that are dictated by context, duration and strength of activation. While generally assumed to be pro-tumorigenic, it is unclear to what extent dysregulation of Wnt/β-catenin signaling impacts tumor progression in pancreatic adenocarcinoma (PDAC). In the present study, Wnt/β-catenin activity was characterized across a spectrum of PDAC cell lines and primary tumors. Reporter and gene expression-based assays revealed wide heterogeneity in Wnt/β-catenin transcriptional activity across PDAC cell lines and patient tumors, as well as variable responsiveness to exogenous Wnt ligand stimulation. An experimentally generated, pancreas-specific gene expression signature of Wnt/β-catenin transcriptional activation was used to stratify pathway activation across a cohort of resected, early-stage PDAC tumors (N=41). In this cohort, higher Wnt/β-catenin activation was found to significantly correlate with lymphvascular invasion and worse disease-specific survival (median survival time 20.3 versus 43.9 months, log-rank P=0.03). Supporting the importance of Wnt ligand in mediating autocrine Wnt signaling, Wnt/β-catenin activity was significantly inhibited in PDAC cell lines by WLS gene silencing and the small-molecule inhibitor IWP-2, both of which functionally block Wnt ligand processing and secretion. Transcriptional profiling revealed elevated expression of WNT7B occurred in PDAC cell lines with high levels of cell autonomous Wnt/β-catenin activity. Gene-knockdown studies in AsPC-1 and HPAF-2 cell lines confirmed WNT7B-mediated cell autonomous Wnt/β-catenin activation, as well as an anchorage-independent growth phenotype. Our findings indicate WNT7B can serve as a primary determinant of differential Wnt/β-catenin activation in PDAC. Disrupting the interaction between Wnt ligands and their receptors may be a particularly suitable approach for therapeutic modulation of Wnt/β-catenin signaling in PDAC and other cancer contexts where Wnt activation is mediated by ligand expression rather than mutations in canonical pathway members.

Original languageEnglish
Pages (from-to)899-908
Number of pages10
JournalOncogene
Volume33
Issue number7
DOIs
StatePublished - Feb 13 2014

Keywords

  • WNT7B
  • Wnt/β-catenin signaling
  • pancreatic cancer

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    Arensman, M. D., Kovochich, A. N., Kulikauskas, R. M., Lay, A. R., Yang, P. T., Li, X., Donahue, T., Major, M. B., Moon, R. T., Chien, A. J., & Dawson, D. W. (2014). WNT7B mediates autocrine Wnt/β-catenin signaling and anchorage-independent growth in pancreatic adenocarcinoma. Oncogene, 33(7), 899-908. https://doi.org/10.1038/onc.2013.23