Attenuation of EGFL7 Expression Inhibits Growth Hormone-Producing Pituitary Adenomas Growth and Invasion

Invasiveness of growth hormone-producing pituitary adenomas (GHPAs) causes difficulties in safe and complete adenoma removal during surgery and often leads to high recurrence. Epidermal growth factor-like domain 7 (EGFL7) has been shown to be able to promote tumor angiogenesis, growth, invasiveness, and metastasis through the Notch signaling pathway. It was previously demonstrated that EGFL7 was overexpressed in GHPAs. This study reports that EGFL7 and Notch2 (positive correlation with EGFL7) are overexpressed in invasive GHPA. A long-rank test (Kaplan-Meier method) shows that invasive GHPAs with EGFL7 strong expression results in reduced recurrence-free survival. Multivariate Cox regression analysis reveals that weak EGFL7 expression is an independent prognostic factor for recurrence-free survival. In addition, knockdown of EGFL7 expression suppresses proliferation and invasion of GH3 and GT1-1 cells in vitro. Moreover, attenuation of EGFL7 inhibits human GHPA growth in vivo. The data suggest that as a Notch agonist, EGFL7 may potentially be an appropriate novel molecular target for future development of GHPA medical therapy.