7.2　Anti-Angiogenic Drugs

VEGF，also known as vascular permeability factor，specifically acts on vascular endothelial cells through tyrosine kinase receptors（VEGFR-1，2，3），and initiates intracellular signal transduction pathway-mediated angiogenesis.And increase the permeability of blood vessels.Activated endothelial cells express a variety of MMPs.MMPs can degrade extracellular matrix（ECM）and basement membrane.Tumor cells invade ECM，endothelial cell ECM interacts，form vascular lumen，and grow in a budding manner to form blood vessels，loop，net，through a series of complex and orderly processes to form new blood vessels in the tumor.Abnormal vascular microenvironment of tumors leads to insufficient oxygen supply.Hypoxia accelerates the proliferation of tumor cells and abnormalities in vascular structure and function in tumor tissues，and angiogenesis regulators，which are mainly regulated by hypoxia，are VEGF.(https://www.daowen.com)

A series of in vivo and in vitro experiments have shown that increasing vegf expression promotes tumor growth and metastasis，while inhibition of vegf signaling pathways inhibits tumor-induced angiogenesis and inhibits tumor growth.Vegf has been shown to be the most important currently discovered.Growth factors acting directly on the vascular endothelium.Tumor angiogenesis is the basis for the overall development and progression of breast cancer.By blocking or inhibiting any aspect of tumor angiogenesis，including inhibition of angiogenic factors and their receptors，up-regulation of angiogenesis negative regulatory factor activity，inhibition of endothelial cell proliferation and promotion of apoptosis，and blocking of related signal transduction pathways related to tumor angiogenesis to inhibit tumor growth have become an important target for clinical treatment of breast cancer.The therapeutic drug for cancer angiogenesis is directed against the tumor cells themselves.Compared with traditional chemotherapeutic drugs，the normal tissues of the body have less adverse reactions，which makes them a hotspot in basic and clinical research.