Sprouting Angiogenesis in Human Pituitary Adenomas.

Area of Science:

• Endocrinology
• Oncology
• Molecular Biology

Background:

• Angiogenesis, the formation of new blood vessels, plays a critical role in tumor growth and progression.
• The specific mechanisms of angiogenesis in pituitary tumors are not fully elucidated, hindering the development of targeted therapies.

Purpose of the Study:

• To investigate the role of angiogenesis in human pituitary tumors.
• To identify key angiogenic factors involved in pituitary tumor development.
• To evaluate the efficacy of angiogenesis inhibitors as potential therapeutic agents for aggressive pituitary tumors.

Main Methods:

• Quantitative analysis of 71 angiogenic genes in 219 human pituitary tumors and 12 normal pituitary glands using qPCR arrays and TaqMan probes.
• In vitro endothelial tube formation assays to assess angiogenesis inhibition.
• In vivo studies in RbΔ19 mice to evaluate the therapeutic potential of angiogenesis inhibitors.

Main Results:

• Pituitary tumors displayed significantly elevated expression of endothelial markers (CD31, CD34, ENG) and angiogenesis growth factors (VEGFC, PGF, ANGPT2, PDGFB, TGFB1) compared to normal pituitary tissue.
• VEGF-C and PGF expression strongly correlated with endothelial marker expression in tumors.
• VEGFR inhibitors demonstrated efficacy in inhibiting tumor-induced angiogenesis and prolonging survival in a mouse model.

Conclusions:

• Human pituitary tumors exhibit enhanced sprouting angiogenesis, distinct from normal pituitary tissue.
• Placental growth factor (PGF) and vascular endothelial growth factor C (VEGFC) are key regulators of angiogenesis in pituitary tumors.
• Angiogenesis inhibitors, particularly VEGFR2 inhibitors like cabozantinib, warrant further investigation as potential treatments for aggressive pituitary tumors.