Tumor growth and metastasis are facilitated by the formation of new blood
vessels, a process known as angiogenesis. The blood vessels formed around the tumor
supply it with oxygen and nutrients, which together support its progression. Moreover,
the newly formed blood vessels serve as channels through which tumor cells
metastasize to distant organs. Tumor blood vessels, and especially the endothelial cells
lining tumor blood vessels (tumor endothelial cells, TECs), have therefore gained
interest as targets in cancer therapy. Although newly formed tumor blood vessels
originate from pre-existing, normal vessels, they have a distinctively abnormal
phenotype, including important morphological alterations. The balance between the
angiogenic stimulators and inhibitors regulates angiogenesis in the tumor
microenvironment. Furthermore, TECs constitute a heterogeneous population,
exhibiting characteristics induced largely by tumor microenvironmental factors. In this
chapter we review recent studies on TEC abnormalities regarding to cancer progression
and consider the therapeutic implications thereof.
Keywords: Angiogenesis, Angiogenic factor, Anti-angiogenic therapy, Basement
membrane, Blood vessel, Cancer, Drug resistance, Endothelial cell,
Heterogeneity, Hypoxia, Invasion, Metastasis, Migration, Pericyte, Side effect,
Tumor, Tumor angiogenesis, VEGF.
