PLoS ONE (Jan 2013)

Components of the canonical and non-canonical Wnt pathways are not mis-expressed in pituitary tumors.

  • Leandro Machado Colli,
  • Fabiano Saggioro,
  • Luciano Neder Serafini,
  • Renata Costa Camargo,
  • Helio Rubens Machado,
  • Ayrton Custodio Moreira,
  • Sonir R Antonini,
  • Margaret de Castro

DOI
https://doi.org/10.1371/journal.pone.0062424
Journal volume & issue
Vol. 8, no. 4
p. e62424

Abstract

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IntroductionCanonical and non-canonical Wnt pathways are involved in the genesis of multiple tumors; however, their role in pituitary tumorigenesis is mostly unknown.ObjectiveThis study evaluated gene and protein expression of Wnt pathways in pituitary tumors and whether these expression correlate to clinical outcome.Materials and methodsGenes of the WNT canonical pathway: activating ligands (WNT11, WNT4, WNT5A), binding inhibitors (DKK3, sFRP1), β-catenin (CTNNB1), β-catenin degradation complex (APC, AXIN1, GSK3β), inhibitor of β-catenin degradation complex (AKT1), sequester of β-catenin (CDH1), pathway effectors (TCF7, MAPK8, NFAT5), pathway mediators (DVL-1, DVL-2, DVL-3, PRICKLE, VANGL1), target genes (MYB, MYC, WISP2, SPRY1, TP53, CCND1); calcium dependent pathway (PLCB1, CAMK2A, PRKCA, CHP); and planar cell polarity pathway (PTK7, DAAM1, RHOA) were evaluated by QPCR, in 19 GH-, 18 ACTH-secreting, 21 non-secreting (NS) pituitary tumors, and 5 normal pituitaries. Also, the main effectors of canonical (β-catenin), planar cell polarity (JNK), and calcium dependent (NFAT5) Wnt pathways were evaluated by immunohistochemistry.ResultsThere are no differences in gene expression of canonical and non-canonical Wnt pathways between all studied subtypes of pituitary tumors and normal pituitaries, except for WISP2, which was over-expressed in ACTH-secreting tumors compared to normal pituitaries (4.8x; p = 0.02), NS pituitary tumors (7.7x; p = 0.004) and GH-secreting tumors (5.0x; p = 0.05). β-catenin, NFAT5 and JNK proteins showed no expression in normal pituitaries and in any of the pituitary tumor subtypes. Furthermore, no association of the studied gene or protein expression was observed with tumor size, recurrence, and progressive disease. The hierarchical clustering showed a regular pattern of genes of the canonical and non-canonical Wnt pathways randomly distributed throughout the dendrogram.ConclusionsOur data reinforce previous reports suggesting no activation of canonical Wnt pathway in pituitary tumorigenesis. Moreover, we describe, for the first time, evidence that non-canonical Wnt pathways are also not mis-expressed in the pituitary tumors.