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Introduction to Tumor Angiogenesis
Tumor angiogenesis is the formation of blood vessels from preexisting vessels that supplies a
tumor with a rich microenvironment full of oxygen and nutrients to support optimal growth.1
Angiogenesis determines the rate of the tumor growth and metastasis. In a 1950 study conducted
by Algire and his colleagues, it was evident that the transplanted tumor tissue had a vast vascular
network compared to the normal tissue, that was due to rapid tumor growth.3 Tumor growth can
also be affected by pro-angiogenic and anti-angiogenic factors that can either promote or
suppress tumor growth.3
Development of Normal Vasculature to Tumor Vasculature
In the initial steps of vascular formation, the endothelial cells will generate to function as the
basic unit of blood vessels.3 In the stages of vasculogenesis, the endothelial progenitors, or
angioblasts, will differentiate themselves into vascular endothelial cells and ultimately choose to
aggregate de novo on the yolk sac forming an initial vascular network.3 Angiogenesis will then
occur in two distinct mechanisms through sprouting or intussusception.3
The formation of vascular tumor results due a hypoxic state. The hypoxic state leads to
less to no available oxygen accessible within the tissues to a maintain homeostasis, which can
then lead low oxygen and blood supply and promote angiogenic signaling in the tumors to cause
it to grow rapidly and proliferate.2 The microenvironment of a vascular tumor is considered
deprived of oxygen and nutrients in an acidic environment, while normal tissue is rich in its
microenvironment oxygen and nutrient.3
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The Contribution of Signaling Factors
Scientists have been able to do extensive research to determine the signaling molecules and
pathways that drive angiogenesis in cancer and various physiological conditions can be
imperative in normal angiogenesis development.3 The vascular endothelial growth factors
(VEGFs) are an important molecule that regulate endothelial cell proliferation, survival, and
function.3 Angioproteins and their receptors tyrosine kinase also play an important role in this.3
Other molecules are also crucial in vascular development such as fibroblast growth factors,
transforming growth factor beta, Notch and Delta-like ligand, and platelet-derived growth
factor.3 It has also been strongly suggested angiogenesis is due to pro-angiogenic and anti-
angiogenic factors.3 They can serve as potential targets for cancer therapies.
Conclusion
Since the many years of research that have been conducted, it has been determined that
angiogenesis can be a potential cancer therapy treatment. These treatments may be effective as a
potential chemo or radiation drug to inhibit the vascular tumor growth.3 There is some resistance
in tumors with angiogenesis inhibitors due to the alteration in expression of differing pro-
angiogenesis and anti-angiogenesis factors or change within the tumor stroma.3 However, even
with all the information and research that is known about vascular tissue and angiogenesis, there
is still more research that needs to be done to understand how specific signaling factors can
contribute to cancer therapies.
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1References
1. Ellis LM. Tumor angiogenesis. Surgical Research.
https://www.sciencedirect.com/science/article/pii/B9780126553307500368. Published May
9, 2007. Accessed February 12, 2023.
2. Emami Nejad A, Najafgholian S, Rostami A, et al. The role of hypoxia in the tumor
microenvironment and development of Cancer Stem Cell: A novel approach to developing
treatment - cancer cell international. BioMed Central.
https://cancerci.biomedcentral.com/articles/10.1186/s12935-020-01719-5. Published January
20, 2021. Accessed February 12, 2023.
3. Mendelsohn J, Gray JW, Thompson CB, Israel MA. Infectious Agents and Cancer. In: Howley
PM, ed. The Molecular Basis of Cancer. 4th ed. Philadelphia, PA: Elsevier/Saunders; 2015:
257-267.
