The tumor microenvironment (TME), as a key and core issue in modern tumor biology, has attracted widespread research interest in recent years. It is not only a key factor in the occurrence, growth, and metastasis of tumors, but also profoundly affects the diagnosis, treatment, and prognosis of tumors. With the advancement of science and technology, especially the development of molecular biology, cell biology, and genomics, people's understanding of the tumor microenvironment has gradually deepened, providing new perspectives and strategies for tumor treatment. This article will explore in detail the definition, characteristics, composition, mechanism of action, and clinical applications of the tumor microenvironment.

1、Definition and characteristics of tumor microenvironment

The tumor microenvironment refers to the local environment composed of tumor cells and their surrounding cells, extracellular matrix, immune cells, and secreted factors. This environment not only includes the structure, function, and metabolism of the tissue where the tumor is located, but is also closely related to the internal environment of the tumor cells themselves. Tumor cells alter and maintain their survival and developmental conditions through autocrine and paracrine pathways, promoting tumor growth and development.

The tumor microenvironment has four main characteristics: interdependence. The growth of tumors relies on the nutrients, oxygen, and growth factors provided by the microenvironment. The microenvironment is also reshaped through the metabolic activity of tumor cells, forming an environment conducive to the survival of tumor cells; Mutual resistance, the metabolism, secretion, and immune function of the body will limit the growth and development of tumors, and tumor cells will also evade or resist these immune attacks through various mechanisms; Confronting each other, tumor cells require nutrients and blood support provided by the body, while immune cells in the microenvironment suppress their growth by engulfing and killing tumor cells. This struggle runs through the entire process of tumor development; Mutual promotion, as the tumor grows, the microenvironment becomes more favorable for the survival and development of tumor cells, forming a positive feedback loop and promoting rapid tumor growth.

2、Composition of tumor microenvironment

The tumor microenvironment is a highly heterogeneous ecosystem that contains multiple cell types and molecular components. The main components include:

1. Tumor cells: As the center of the microenvironment, tumor cells interact with surrounding cells by secreting signaling molecules such as growth factors and chemokines.

2. Immune cells: including T cells, B cells, macrophages, dendritic cells, etc., play a complex role in immune surveillance and regulation in the tumor microenvironment. Some immune cells, such as Treg cells and MDSC cells, may even promote tumor growth and metastasis.

3. Fibroblasts: Tumor associated fibroblasts (CAFs) play an important role in the tumor microenvironment, providing support for the growth and migration of tumor cells by secreting extracellular matrix components such as collagen and fibronectin.

4. Vascular endothelial cells: Tumor blood vessels are crucial for tumor growth and metastasis. Endothelial cells regulate angiogenesis and permeability, affecting the nutrition and oxygen supply of tumor cells.

5. Extracellular matrix: a complex network composed of fibrin, collagen, matrix molecules, etc., providing structural support and microenvironment for the survival of tumor cells.

3、The mechanism of action of tumor microenvironment

1. Promote tumor growth and invasion: Multiple components in the tumor microenvironment work together to provide favorable conditions for the growth and invasion of tumor cells. For example, CAFs promote tumor cell proliferation and migration by secreting growth factors and extracellular matrix components; Tumor blood vessels provide nutrients and oxygen to tumor cells, supporting their rapid growth; Immune suppressive cells such as Tregs and MDSCs help tumor cells evade immune surveillance by suppressing immune responses.

2. Inhibition of tumor growth and immune surveillance: Although the tumor microenvironment mainly promotes tumor growth and invasion, some of its components also have certain anti-tumor effects. For example, M1 macrophages have pro-inflammatory and anti-tumor effects, and can engulf and kill tumor cells; Certain subsets of T cells can also specifically recognize and kill tumor cells. However, in the tumor microenvironment, these anti-tumor components are often inhibited or insufficient in quantity, and cannot effectively exert their effects.

3. Impact on treatment response and prognosis: The state of the tumor microenvironment has a significant impact on the treatment response and prediction of tumors. For example, the presence of immunosuppressive cells can weaken the effectiveness of immunotherapy; Abnormal tumor vascular structure can affect the delivery and distribution of chemotherapy drugs; The density of extracellular matrix increases the tumor's resistance to radiation therapy. Therefore, during the treatment process, it is necessary to fully consider the state of the tumor microenvironment and adopt targeted treatment strategies.

4、Application of tumor microenvironment in clinical practice

1. Diagnosis: Certain components and features in the tumor microenvironment can serve as biomarkers for tumor diagnosis. For example, early diagnosis and recurrence monitoring of tumors can be achieved by detecting circulating tumor cells (CTCs) or circulating tumor DNA (ctDNA) in the tumor microenvironment. In addition, the application of emerging technologies such as spatial transcriptomics provides new ideas and methods for tumor diagnosis.

2. Treatment: Treatment strategies targeting the tumor microenvironment are becoming a new direction in cancer treatment. For example, by inhibiting the activity of CAF or blocking its secretion of growth factors, tumor growth and invasion can be inhibited; By enhancing the anti-tumor effect of immune cells or clearing immunosuppressive cells, the efficacy of immunotherapy can be improved; By altering the generation and distribution of tumor blood vessels, the efficacy of chemotherapy and radiotherapy can be improved. In addition, with the development of high-tech such as gene editing and artificial intelligence, precise treatment targeting the tumor microenvironment will also become possible.

3. Prognostic evaluation: The state of the tumor microenvironment can also serve as an important indicator for prognostic evaluation. For example, by analyzing the types and quantities of immune cells in the tumor microenvironment, the density of extracellular matrix, and the generation of tumor blood vessels, the treatment response and recurrence risk of tumors can be predicted. These pieces of information are of great significance for developing personalized treatment plans and monitoring treatment outcomes.

The complexity and heterogeneity of the tumor microenvironment are key areas in tumor biology, posing significant challenges to tumor research. However, with the launch of the Beacon device by Redbert (Beijing) Biotechnology Co., Ltd., it can save you a lot of screening time and greatly reduce production costs. The Beacon Optofluidic System can directly operate and cultivate individual target cells from the beginning of the experiment, with highly reliable and efficient results. This system combines unique optoelectronic positioning technology with innovative nanofluidic design, enabling fully automated experimental operations such as import, culture, detection, and export of single cells or monoclonal antibodies. It provides an integrated and efficient research platform for all single-cell based development and applications, and is expected to reveal more mysteries of the tumor microenvironment, providing new ideas and methods for tumor diagnosis, treatment, and prognosis evaluation. In the future, research on tumor microenvironment will continue to drive the development of oncology and make greater contributions to human health.

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