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The surprising secret of tumor antigens: Why do some antigens only appear in tumors?
Cancer immunology is a multidisciplinary branch of biology focused on the role of the immune system in the development and progression of cancer. With the rise of cancer immunotherapy, researchers have gradually uncovered the complexity of tumor antigens, the existence of which is crucial to developing more effective treatment plans.
Tumor-specific antigens (TSAs) are antigens that are found only in tumor cells, while tumor-associated antigens (TAAs) are antigens that can also be found in healthy cells but are abnormally expressed in tumor cells.
In this article, we will take a deeper look at the mechanisms of tumor antigens and explain why some antigens are only found in tumors and what this means for cancer treatment.
Types of Tumor Antigens
Tumor antigens are divided into two categories: tumor-specific antigens (TSAs) and tumor-associated antigens (TAAs). TSAs are only found in tumor cells and are usually caused by mutations or viral infections. For example, the E6 and E7 proteins of human papillomavirus can contribute to the development of cervical cancer, while the EBNA-1 protein of Epstein-Barr virus is associated with Burkitt's lymphoma.
TAA is an antigen that also exists in healthy cells, but the expression amount, location or time in tumor cells may be abnormal. Well-known examples include fetal antigens such as alpha-fetoprotein (AFP), which is expressed in hepatocellular carcinoma, or carcinoembryonic antigen (CEA), which is present in ovarian and colon cancers.
Immunoediting: the game between tumors and the immune system
Cancer immunoediting is a process that describes how the immune system interacts with tumor cells. This process can be divided into three stages: elimination, balance and escape. During the elimination phase, the immune system destroys tumor cells, but in some cases, some tumor cells mutate and escape immune detection, entering the equilibrium phase. During this stage, the tumor does not grow but the immune system is unable to fully recognize all tumor cells.
The escape phase is a critical moment during which tumor cells gain dominance over the immune system, begin to grow and establish an immunosuppressive environment.
This process can be seen as an analogy to Darwinian evolution, where tumor cells mutate and evolve clones that are able to resist the immune system.
Tumor escape mechanismsTumor cells have a variety of mechanisms to evade immune responses. Among them, CD8+ cytotoxic T cells are the core of anti-tumor immunity. Tumor cells can reduce the expression of MHC class I molecules on their surface to evade detection by these T cells. Some tumor cells express inhibitory molecules, such as PD-L1, which inhibit the activity of T cells.
Such evasion mechanisms allow tumors to survive and multiply despite the immune system's surveillance.
In addition, suppressive cells in the tumor microenvironment, such as myeloid-derived suppressor cells (MDSCs) and complementary macrophages, also aggravate immune suppression and further promote tumor growth and spread.
Immunomodulatory methods
To boost immune responses, scientists have developed a variety of immunomodulatory methods. Immune checkpoint inhibitors, such as anti-CTLA-4 and anti-PD-1 antibodies, can relieve the inhibition of T cells and promote their attack on tumor cells. In this regard, significant progress has been made in the development of drugs such as ipilimumab and novartis.
In addition, the development of chimeric antigen receptor T cell (CAR-T) therapy and cancer vaccines is also opening up new directions in cancer treatment. These approaches aim to strengthen the immune system to produce a durable anti-tumor response.
ConclusionThe study suggests that how cancer cells die may be crucial in mobilizing an immune response, which in turn affects the success or failure of treatment.
Faced with the challenge of cancer, the research on tumor antigens shows endless potential and hope. Future treatments will increasingly rely on understanding these antigens and regulating how the immune system works together to fight tumors. In this ongoing research, we can't help but wonder: What key role will tumor antigens play in future cancer treatment?
