Wnt Pathway Implicated in Pituitary Tumorigenesis
Inhibitors may be tumor suppressors
FRIDAY, Dec. 28 (HealthDay News) -- Inhibitors of the Wnt signaling pathway may be tumor suppressors important in the pathogenesis of pituitary tumors, according to study findings published online Dec. 13 in Endocrinology.
Marianne S. Elston, from the Royal North Shore Hospital in Sydney, Australia, and colleagues performed microarray analysis to examine the role of the Wnt signaling pathway in 20 non-functioning and clinically functioning pituitary tumors and three normal pituitary controls.
The researchers found that four secreted frizzled-related protein family members of Wnt pathway inhibitors were differentially expressed in normal pituitaries and pituitary tumors. The expression of Wnt inhibitory factor-1 (WIF1) was low in pituitary tumors, 88 percent of tumors had hypermethylation of the WIF1 promoter, and 76 percent of tumors had weak or absent WIF1 cytoplasmic staining (compared with 92 percent of normal controls). Cyclin D1, which is a target of the Wnt pathway, was upregulated in non-functioning tumors.
"In conclusion, our data suggests that WIF1 may be a tumor suppressor, specifically in non-functioning pituitary tumors, and that the Wnt pathways are important in pituitary tumorigenesis," Elston and colleagues write.