Switch to the angiogenic phenotype during tumorigenesis

Area of Science:

• Oncology
• Molecular Biology
• Cancer Research

Background:

• Tumor growth and metastasis are dependent on angiogenesis (new blood vessel formation).
• Solid tumors exhibit a prevascular phase with limited expansion before becoming angiogenic.
• The transition to an angiogenic phenotype is a critical step in tumor progression.

Purpose of the Study:

• To investigate the mechanisms underlying the switch to an angiogenic phenotype in tumors.
• To utilize transgenic mouse models that exhibit predictable prevascular and vascular tumor development stages.
• To identify the molecular events and factors involved in tumor neovascularization.

Main Methods:

• Employing transgenic mice with specific oncogenic transgenes (bovine papilloma virus and SV40 large T antigen).
• Observing tumor development through prevascular (fibromatoses) and vascular (fibrosarcomas) stages.
• Quantifying tumor growth and analyzing the secretion of endothelial cell growth factors.

Main Results:

• Bovine papilloma virus-induced fibrosarcomas secrete endothelial cell growth factors, unlike their non-angiogenic fibromatosis precursors.
• SV40 large T antigen-driven pancreatic tumors show a transition to an angiogenic phenotype, coinciding with acidic fibroblast growth factor (aFGF) secretion.
• Neovascularized hyperplastic islets develop into tumors significantly larger than pre-angiogenic islets.

Conclusions:

• The switch to an angiogenic phenotype is driven by the secretion of specific growth factors by tumor cells.
• Transgenic mouse models effectively recapitulate tumor angiogenesis and provide platforms for anti-angiogenic therapy discovery.
• Targeting the source of angiogenic activity, alongside inhibiting vascular endothelial cells, offers a potential therapeutic strategy.