Tumor angiogenesis is a complex and important biological process, which refers to the development of new capillaries from existing capillary networks or post-capillary veins. This process is crucial for tumor growth, invasion and metastasis. The following is a detailed analysis of tumor angiogenesis:
First, definition and background
Definition: Tumor angiogenesis is the process of microvascular growth induced by tumor tissue and the establishment of blood circulation in tumors, which is a key step in the development of tumors.
Background: As early as the 1970s, Professor Folkman proposed that tumor growth and metastasis depend on angiogenesis, which provides a new idea for subsequent tumor treatment.
Second, biological characteristics
Low reactivity: Tumor blood vessels are less responsive to physiological and pathological stimuli.
High permeability: The structure of tumor blood vessels is not perfect, and the permeability is high, which is not only the need for rapid tumor growth, but also one of the important ways of tumor metastasis.
Low oxygen supply capacity: Due to the abnormal structure and function of blood vessels, tumor tissues are often in a state of hypoxia, which further promotes the formation and remodeling of tumor blood vessels.
Third, the basic process
The basic process of tumor angiogenesis can be summarized in the following steps:
1. Endothelial cell activation: stimulated by growth factors (such as VEGF, bFGF, etc.), endothelial cells are activated and exhibit a angiogenic phenotype.
2. Matrix degradation and cell migration: the extracellular matrix at the site of blood vessels changes, the basement membrane degrades, and endothelial cells form new blood vessel buds through budding, proliferation and migration.
3. Formation and stability of blood vessels: the new endothelial cells gradually form tubular capillary loops and lumen, and then recruit pericytes to stabilize the newly formed capillary network and eventually form mature blood vessels.
Fourth, clinical significance
Tumor growth: Tumor blood vessels provide necessary oxygen and nutrients to tumor cells to support their continuous growth and proliferation.
Tumor metastasis: Due to the high permeability of tumor blood vessels, tumor cells can more easily penetrate the blood vessel wall and enter the blood circulation, resulting in distant metastasis.
Therapeutic targets: Compared with traditional therapies targeting tumor cells (such as chemoradiotherapy), angiogenesis inhibitors target tumor vascular endothelial cells and have the advantages of low toxicity, broad spectrum and resistance resistance. Therefore, inhibition of tumor angiogenesis has become an important strategy of tumor therapy.
Fifth, research progress
In recent years, with the in-depth study of tumor angiogenesis mechanism, it has been found that a variety of cytokines, growth factors and non-coding RNA molecules play an important role in tumor angiogenesis. At the same time, new ways of angiogenesis (such as invasion-type angiogenesis, involvement of endothelial progenitor cells, etc.) have been gradually revealed. These research results provide new ideas and methods for the diagnosis and treatment of tumors.
In summary, tumor angiogenesis is a complex process involving a variety of cells and molecules, which plays an important role in tumor growth, invasion and metastasis. Through in-depth study of the mechanism and characteristics of tumor angiogenesis, people are expected to develop more effective and safe tumor treatment methods.
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